roof framing & roofing army fm5-426

7/24/2019 Roof Framing & Roofing Army FM5-426

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The r oof's mai n pu r pose i s to keep out th e r ai n, col d, or heat. I t m ust be strong enough to w i th stan d

hi gh w ind s; sl oped t o shed water ; and , in ar eas of heavy snow, i t m ust be constr ucted m ore r i gid l y

to bear th e extr a wei ght. Th i s chap ter w i l l fam i l i ar i ze car pent er s w i th t he most common types of

r oof constr ucti on and m ater i al s. Th i s chapter al so cover s r er oofin g.

ROOF FRAMING

Roofs for TOs a re chosen to suit t he building; the clima te; the estim a ted length of time thebuilding will be used; a nd th e ma teria l, t ime, and skill required for const ruction. TO constra ints

dicta te simple design a s show n in F igure 7-1.


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ROOFING TERMS

When fra ming a roof (Figur e 7-

2), ca rpenters must be familia r

w ith commonly u sed roofing

terms (Figures 7-3 and 7-4).

RAFTERS

Raft ers make up the main

fra mew ork of a ll roofs. They a re

inclined members spaced from

16 to 48 inches apart. They vary

in size, depending on lengt h a nd

spa cing. The t ops of in clined

ra fters are fast ened to the ridge

or another ra fter, depending on

the t ype of roof. Raft ers rest on the t op w a ll plat e.

Ra fters are na iled to the plate, not fra med into it . Some are cut to f it t he plat e, while in ha sty

constr uction th ey a re merely laid on top of the plat e and n a iled in place. They ma y extend a short

dista nce beyond th e wa ll to form the ea ves and protect the sides of the building.

Types of Rafters

Exa mples of most t ypes of ra fters a re shown in Figur e 7-3. The four t ypes are

Common Rafters. These are fram ing members tha t extend a t r ight a ngles from the plate line tothe r oof ridge. They a re called common ra fters because t hey a re common t o all ty pes of roofs a nd

ar e used a s the ba sis for lay ing out other types of ra fters.

Hip Rafters. These ar e roof members th a t extend dia gonally from t he corner of the plat e to theridge.


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Valley Rafters. These raft ers extend from the plat e to th e ridge along the lines wheretw o roofs int ersect.

J ack Rafters. These ar e a common ra fter. The th ree kinds of ja ck ra fters a re the

Hip jack, which extends from th e plat e to the hip raft er.

Va lley ja ck, wh ich extends from th e ridge of the va lley raft er.

Cr ipple ja ck, wh ich is placed betw een a h ip raft er a nd a va lley raft er. The cripple jack ra fter is

a lso par t of a common ra fter, but it t ouches neither th e ridge of the roof nor the ra fter plat e.


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Collar Tie and Beam

A collar tie or b eam (Fig ure 7-7) is a piece of stock (usua lly 1 x 4, 1 x 6, l x 8, or 2 x 4) fa st ened in a

horizont a l position to a pa ir of raft ers betw een the plat e an d th e ridge of the roof. This ty pe of

beam keeps the building from sprea ding. Most codes a nd specifica tions require t hem t o be 5 feet

a par t or every t hird ra fter, wh ichever is less. Collar t ies are na iled to common raft ers wit h four 8d

na ils to each end of a 1-inch tie. If 2-inch mat erial is used for the t ie, they a re na iled w ith t hree

16d na ils at each end. This t ype of bra cing is us ed on sma ll roofs w here no ceiling joists ar e used

a nd th e building is not w ide enough to require a trus s.

In sm a ll roofs tha t cover only na rrow buildings in w hich the raft ers ar e short, t here is no need forinterior support or bra cing. In long spa ns, the roof w ould sa g in th e middle if it were not

str engthened in some w a y. To support long ra fters, bra ces or other ty pes of support s must be

installed.

Rafter Layout

Ra fters must be laid out a nd

cut wit h slope, length, a nd

overhang exactly right so

tha t th ey will fi t wh en pla ced

in the roof.

Scale or Measurement

Method. The ca rpent ershould first det ermine the

length of the rafter and t he

length of the lumber from

wh ich the ra fter ma y be cut .

If he is w orking from a roof

pla n, he lea rns t he rafter lengths a nd the w idth of the building from the pla n. If no plans a re

ava ilable, the w idth of the building must be measured.


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Step 1. To determine t he ra fter

length, first find one-ha lf of th e

horizontal distance (total run)

of the ra fter. The am ount of

rise per foot will not be

considered yet. (For example, if

the building is 20 feet w ide,

ha lf of the spa n w ill be 10 feet.

See th e example below .)

Step 2. After th e length ha s

been determined, lay the

timber on saw horses (saw

benches), w ith the crown or

bow (if it ha s a ny) a s the top

side of the ra fter. If possible, select a st ra ight piece for t he patt ern ra fter. If a str a ight piece is not

ava ilable, have the crown a wa y from the person laying out the ra fter.

Step 3. Hold the squa re w ith th e tongue in your left ha nd, the blade in your right , a nd the heel

tow ar d your body. P lace the squa re as nea r the upper end of the ra fter a s possible. (For example,

in Figure 7-8, page 7-6 (step 1) the figures 8 on the tongue and 12 on the blade are placed along the

timber edge tha t is t o be the top edge of the raft er.)

Step 4. Ma rk a long th e outside tongue edge of the squ ar e, which will be the plumb cut a t t he ridge.

Step 5. Since the length of th e ra fter is know n t o be 12 feet a nd 1/6 inch, mea sure t he dista nce

from th e top of the plumb cut a nd ma rk it on the t imber. Hold the squa re in the same ma nner w ith

th e 8 ma rk on t he tong ue directly over t he 12-foot 1/6-inch ma rk. Ma rk a long th e tongue of th e

sq ua re to give the plumb cut for t he sea t (Figur e 7-8, step 2).

Step 6. Measure off,

perpendicular to this mark, the

length of overhang along the

timber. Make a plumb-cut ma rk

in the same w a y, keeping the

squa re on the sa me edge of th e

timber (Figure 7-8, step 3). This

will be the ta il cut of the ra fter.

Often, the ta il cut is ma de square

across the timber.

Step 7. The level cut or w idth of

the seat is t he width of the plat e

measured perpendicular to the

plumb cut, a s shown in Figure 7-

8, step 4. Using a try squar e,

squa re the lines down on the

sides from a ll level and plumb-

cut lines. Now the rafter is ready

to be cut (Figure 7-8, step 5).


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Step-Off Method. The ra fter length of an y building ma y be determined by "st epping it off bysuccessive steps w ith t he squa re, as follow s:

Step 1. St ep off the sa me number of steps a s there a re feet in t he run. For exam ple, if a building is20 feet 8 inches wide, the run of the rafter would be 4 inches over 10 feet.

Step 2. This 4 inches is ta ken ca re of in the sa me ma nner a s the full-foot ru n; tha t is, w ith t he

square a t the last s tep

posit ion, ma ke a ma rk on the

ra fters at the 4-inch ma rk

(Figur e 7-9, st ep 1).

Step 3. With t he squa re held

for the sam e cut a s before,

make a ma rk a long the

tongue. This is the line lengthof the raft er. The seat cut a nd

ha ngover are made as

described above and s hown in

Figu re 7-9, steps 2, 3, an d 4.

NOTE : When laying off

rafters by any method, be

sure to recheck the work

careful1y. When two

rafters have been cut, it is best to put them in place to see if they fit. Minor adjustments

may be made at this time without serious damage or waste of material.

Table Method. The fram ing squa re ma y ha ve one or tw o types of ra fter ta bles on the blade. Onetype gives both the line length of an y pitch of ra fter per foot of run a nd t he line lengt h of any hip or

va lley ra fter per foot of run . The difference in lengt h of th e jack ra fter, s paced 16 or 24 inches (on

center), is also shown in th e ta ble. Where th e ja ck, hip, or va lley ra fter n eeds side cuts, t he cut is

given in the ta ble. The other t ype of ta ble gives the actua l length of a ra fter for a given pitch and

span.

Raft er Tabl e, Type 1. Type 1 (Figu re 7-10) a ppears on th e face of the bla de. This t ype is used t o

determine the length of the common, valley, hip, and jack rafters and the angles at which they


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must be cut to f it a t t he ridge and pla te.

To use the ta ble, th e ca rpenter must first know w ha t ea ch figure represents.

The row of figures in t he first line represents t he length of common ra fters per foot of run , a s

th e title at t he left-ha nd end of the blade indica tes.

Ea ch set of figures under ea ch inch division ma rk represents th e lengt h of raft er per foot of

run, w ith a rise corresponding to the n umber of inches over the n umber. (For exam ple, under

the 16-inch ma rk a ppea rs t he number 20.00 inches. This num ber equa ls the lengt h of a ra fter

w ith a run of 12 inches a nd a rise of 16 inches. Un der th e 13-inch ma rk a ppea rs t he number

17.69 inches, w hich is th e ra fter lengt h for a 12-inch run a nd a 13-inch rise.) See t he Type 1

lay out example below.

NOTE: The other five lines of figures in the table will not be discussed, as they are

seldom used in the TO.

The rema ining procedure for la ying out the ra fters a fter th e length h a s been determined is as

described previously.

Ra f ter Ta b le , Type 2. Type 2 (Figure 7-11, page 7-8) a ppears on t he ba ck of the bla de of some

squa res. This shows the ru n, rise, an d pitch of rafters of the seven most common pitches of roof.


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The figures are ba sed on th e horizonta l measur ement of the building from th e center to th e

outside.

The ra fter t a ble a nd t he outside edge of the back of the sq ua re, both t he body a nd tongue, ar e in

tw elfths. (The inch ma rks ma y represent tw elfths of an inch or tw elfths of a foot.) This ta ble is

used in connection wit h th e marks a nd figures on the outside edge of th e squa re. At t he left end ofthe t a ble ar e figures representing t he run, the rise, and t he pitch:

In th e first column, th e figures a re a ll 12 (12 inches or 12 feet). They r epresent th e run

of 12.

The second column of figures represents various rises.

The t hird column of figures (in fra ctions) represents th e va rious pitches.

These three columns of figures show t ha t a ra fter w ith a run of 12 a nd a rise of 4 has a 1/6 pitch,

12 and 6 ha s a 1/4 pitch, an d 12 an d 12 ha s a 1/2 pitch. For exa mple, use t his sca le for

A roof w it h a 1/6 pitch (or t he ri se of 1/6 th e w idt h of th e buildin g) an d a ru n of 12 feet . Fin d 1/6

in th e ta ble, then follow t he sam e line of figures to the right un til directly benea th t he figure

12. Here a ppear t he numbers 12, 7, 1O, w hich is the ra fter length r equired an d w hich

represent s 12 feet 7 in ches, a nd 10/12 of a n inch. They a re w rit ten a s follows: 12 feet 7 10/12

inches.

A roof wit h a 1/2 pitch (or a rise of 1/2 the w idt h of th e building) a nd a run of 12 feet. The r a fter

lengt h is 16, 11, 6, or 16 feet 11 6/12 inches .

A roof w ith a run of more tha n 23 feet. F or exa mple, if the run is 27 feet, find t helength for 23 feet, th en find t he length for 4 feet a nd a dd t he tw o. The run for 23 feet

w it h a pit ch of 1/4 is 25 feet 8 5/12 inches. For 4 feet , t he r un is 4 feet 5 8/12 inches.

The t ota l ru n for 27 feet is 30 feet 2 1/12 inches.

NOTE : When the run is in inches, the rafter table reads inches and twelfths instead of

feet and inches.

See the Type 2 ra fter ta ble la yout exam ple at the top of the next pag e.

After t he length of the ra fter ha s been found, the raft er is laid out a s explained previously.


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TRUSSES

A tr uss is a fra med or jointed structur e composed of str aigh t m embers connected only a t t heir

intersections in such a w a y tha t if loads a re applied at t hese intersections, the str ess in each

member is in t he direction of its lengt h. St ra ight, sound t imber should be used in t russes. The

types of tr usses used in building construction a re show n in Figure 7-12. (The How e a nd F ink

trusses are most commonly used.) Truss terms are listed in Figure 7-13, page 7-10.

Trusses a re used for la rge spa ns to give wide, unobstructed floor space for such la rge buildings a s

shops a nd ha ngar s. Sometimes sma ll buildings a re trussed to save ma terial . These small trussesact a s ra fters and give the roof rigidity.

The w eb members of a t russ d ivide it into tria ngles. The members indicat ed by hea vy lines

norma lly carr y tensile str esses for vert ical loads. S ometimes the top chords of th ese trussesslope slightly in one or t w o directions for roof dra ina ge, but this d oes not cha nge the t ype of trus s.

The necessa ry n umber of subdivisions, or pa nels, depends upon the length of the spa n a nd t he type

of construction.

Truss Supports

Trusses a re supported by bea ring w a lls, posts, or other t russes. To bra ce a tr uss to a w a ll or post,knee braces ar e used as sh own in F igure 7-14. These braces tend t o make a tr uss of the entire

building by tying t he wa ll to the roof.

Purlins

P urlins a re used in roof const ruction to support corru ga ted sheet met a l if it is used, or t o support

the sheat hing of roofs fram ed with trusses.

In sm all roofs, purlins are inserted betw een th e rafters a nd na iled through the ra fters.

In large buildings w here heavy trusses a re used, the purlins are continuous members tha t r est


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on the trusses and support the sheat hing.

In sm a ll buildings, such a s bar ra cks, mess halls, a nd sma ll wa rehouses, 2 x 4s are used for

purling, with the na rrow side up.

Truss Layout

To lay out a tr uss, use Figur e 7-15 a nd t he follow ing st eps:

Step 1. G et th e ma teria l to a level spot of ground wh ere work benches will be almost level.

Step 2. Obta in from the blueprints the mea surement of all pieces to be used in the tr uss.

Step 3. La y out the length on the different sizes of timber a nd cut them a ccurat ely.

Step 4. After a ll lengt hs a re cut, lay t hem in th eir correct position to form a t russ.

Step 5. Nail them together temporarily.

Step 6. La y out t he location of all holes to be bored. Recheck th e measu rements for a ccura cy.

Step 7. B ore holes to the size ca lled for on the print. U se a bra ce a nd bit or the w oodborer tha t

a ccompanies th e a ir compressor. Bore holes perpendicular to the fa ce of the timber.


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Step 8. After the holes ha ve been bored, disma ntle the truss and withdr aw the na ils.

Truss Assembly

Assembling a tr uss a fter it ha s been cut a nd bored is simple (Figure 7-16). In most cases, t imber

connectors ar e used where different m embers of the tr uss join. Str a ight, sound timber should be

used in trusses.

Assemble the truss with

th e timber connectors in

place.

P lace the bolts in the holes

and t ighten them.

P lace wa shers a t the head

a nd nut ends of each bolt.

Ra fters are usually made into

trusses, as shown in F igure 7-

17. Two rafters are connected

at the top, using a collar t ie

well nailed into both rafters.

B efore an y ties or chords ar e

nailed, the rafters should be

spread at the lower end to

equal the width of the


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building . This is done by

using a t emplate or by

measuring the dista nce

between the seat cuts w ith a

tape.

A 1 x 6 or 2 x 4 chord is nailed

across the rafters a t the seat

cut to t ie them together. This

chord forms a truss w ith the

tw o rafters. A ha nger or

vert ical mem ber of 1 x 6 is

na iled to the ra fter joint a nd

extends to the chord a t

midpoint , tying t he rafter t o

the chord.

In w ide buildings where the

joists or chords must bespliced an d th ere is no

support underneat h, the

ra fter a nd joists support one

an other a s shown in F igure 7-

18.

If no additiona l bracing is

needed, th e truss is set in

place on th e pla tes. If

a dditional bra cing is needed,

a kn ee bra ce is nailed to the

chord. The kn ee bra ce form s

a 45 angle with the wal l

stud. F or easier erection, the

knee brace may be omitted

until the raft er truss is set in

place.

Raf ter f raming w ithout the

use of ridgeboar ds ma y be

done rapidly by using a t russ

a ssembly jig or templat e. The

templa te is laid out to form apattern conforming to the

exact exterior dimensions of the tr uss.

Layout. La y out a t emplate a s shown in F igure 7-19 a nd a s follow s:

Step 1. Measure and ma rk a stra ight line on a ny selected surface. Mark t he exact length of the

joists t ha t w ill form th e truss chord. This is ba seline A.

Step 2. Fr om the center of the baseline a nd a t righ t a ngles to it , la y out a centerline (C) to form t he

leg of a right tr ian gle, th e base of which is ha lf the length of the baseline (A), a nd t he hypotenuse


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of w hich (B ) is the length of th e raft er measur ed as indicat ed.

Step 3. Na il 2 x 4 x 8 blocks flush w ith t he ends of ba seline A a nd centerline C a s shown in Figur e

7-19. Mark th e cent erline on t he center jig blocks.

Assembly. Assemble with a templat e as sh own in F igure 7-19 a nd a s follow s:

Step 1. St ar t t he assembly by set t ing a ra fter in the jig with t he plat e cut f i t ted over t he jig block

a t one end of th e baseline. The peak is flush w ith t he centerline on th e peak jig block. Na il a

holding block outside the ra fter a t point D.

Step 2. La y one 2 x 4 joist or chord in pla ce a cross th e bas e blocks.

Step 3. Lay tw o 2 x 4 raft ers in place over the joist.

Step 4. Center one end of a 1 x 6 ha nger under the rafter peak. Center the ra fters aga inst the peak

block.

Step 5. Nail through the ra fters into the hanger using six 8d na ils.

Step 6. Line up one end of the chord.

Step 7. Nail through t he rafter w ith 16d na ils.

Step 8. Line up th e other end of the chord.

Step 9. Nail as a bove.

Step 10. Cent er the bott om of the ha ngers on top of the chord a nd na il with 8d na ils.

Installation of Trusses

After the ra fters are

assembled into trusses, they

must be placed on th e

building (Figu re 7-20, page 7-

14). Assemb le th e first set of

ra fters either in the end

section of the building or a t

the center. Ra ise rafter

trusses into position (by

ha nd) and na il them intoplace w ith 16d na ils.

(Tempora ry w orkbenches

ma y be built for the workers

to sta nd on while erecting

tr usses.) These tr usses mu st

be tempora rily braced a t t he

end section of the building

until the sheathing is applied.

Knee bra ces a re not used on

every r after t russ unless


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needed. Install trusses as follows:

Step 1. Mar k the proper positions of all tr uss a ssemblies on t he top pla te. The ma rks must show

the exa ct position on th e face of all ra fters (such a s south or north ).

Step 2. Rest one end of a t russ a ssembly, peak down , on a n a ppropriate ma rk on the top plat e on

one side of th e stru ctur e.

Step 3. Rest the other end of the t russ on t he corresponding ma rk of the top plat e on the other side

of the str ucture.

Step 4. Rota te t he a ssembly int o position using a pole or r ope.

Step 5. Line up and secure the raft er faces flush aga inst the ma rks.

Step 6. Ra ise, align, an d na il the thr ee a ssemblies into position. Nail tempora ry 1 x 6 bra ces a cross

these thr ee assemblies. Repea t w ith t he oth er assemblies as t hey ar e brought into position. Check

the ra fter spacing at the peaks as t he braces a re nailed on.

Step 7. B ra ces ma y be used as a platform w hen ra ising those trusses for w hich th ere is not enough

room for rota tion (Figu re 7-21).

ROOF OPENINGS

Ma jor roof openings are th ose tha t int errupt th e norma l run of ra fters or oth er roof fram ing. Such

openings ma y be for ventila tors, chimneys, tra p-door pa ssa ges, or skylight or dormer w indows.

Figu re 7-22 shows roof-opening const ruct ion.


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Roof openings are framed by headers and trimmers.

Double headers are used at right a ngles to the ra fters,

wh ich a re set into the headers in the same w ay as joists in

floor-opening construction. Trimmers are actually double

ra fter const ruction in roof openings. Na iling strips ma y be

a dded if needed.

ROOF DECKING

Procedures for installing plywood sheathing is similar to

installing wall sheathing except it is laid perpendicular to

the rafters a nd trusses.

ROOF COVERINGS

Aspha lt a nd a sbestos-cement roof coverings a re most

frequently used on pitched-roof st ructures. B uilt-up

roofing is used mainly on fla t or near ly flat roofs.

ASPHALT AND ASBESTOS-CEMENT ROOFING

Asphalt roofing comes in rolls (usually 3 feet wide) called

r oll ed r oofi ng, in rolled strips (usua lly 15 inches wide a nd

3 feet long), and as individual shingles. The type most

commonly used is the flat str ip, often called a st rip

shingle.

A 1 x 3 squa re-but t s hing le is show n in Figu re 7-23. This

shingle should be laid 5 inches to th e weather , meaning

tha t 7 inches of ea ch course should be overlapped by th e

next higher course. The lower, exposed end of a shingle is called the butt. The shingle shown in

Figure 7-23 ha s a sq ua re butt divided into thr ee ta bs. Va rious other but t sha pes are

ma nufa ctur ed. Asbestos-cement roofing usua lly consists of individual s hingles.

Laying Asphalt Roofing

The firs t st ep in covering a

roof is to erect a scaffold to

a height w hich w ill bring

the eaves a bout w aist-high

to a ma n standing on thescaffold.

Before any roof covering is

a pplied, the roof sheat hing

must be swept clean an d

carefully inspected for

irregula rities, cracks, holes,

or other d efects. N o roofing

should be applied unless

the sheathing boar ds are


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absolutely dry.

An un derla y of roofing felt is first a pplied to

the shea th ing. Roofing felt usua lly comes in

3-foot-wide rolls and should be laid with a 2-

inch top lap a nd a 4-inch side la p.

B undles of shingles should be distribut ed

along the scaffold before work begins. There

a re 27 str ips in a bund le of 1 x 3 as phalt

st rip shin gles. Three bun dles w ill cover 100

squa re feet .

After t he first course a t t he eaves (th e

star ter cour se) is laid by inverting the first

course of shingles or t he sta rter s trip of

mineral-surfaced roll roofing, each course

tha t follows is begun by stretching a

guideline or by s na pping a chalk line fromedge t o edge. This positions t he course.

Figure 7-24 shows t he meth od of la ying a 1 x 3 aspha lt st rip-shingle roof. St rip shingles should be

na iled with 1-inch copper or hot-dipped, ga lvan ized roofing na ils, tw o to each ta b; this m ean s six

na ils to each full str ip. Nails should be placed a bout 6 1/2 inches from th e butt edges to ensure th at

each na il will be covered by t he next course (bl ind-nai l ing) a nd driven through tw o courses.

An a sbestos-cement roof is laid in about th e same w a y as t he aspha lt str ip shingles.

Applying Shingles at Hips and Valleys

One side of a hip or va lley shingle must be cut a t a n a ngle to obta in a n edge line tha t w ill

ma tch the line of th e hip or va lley r a fter. One w ay to cut th ese shingles is to use a pat ternmade as follows:

Select a piece of 1 x 6 ma teria l about 3 feet long. Det ermine the unit length of a common ra fter in

the roof. Set t he fram ing squa re back up on the piece to the unit run of a common ra fter on the

tongue an d the unit lengt h of a common ra fter on the blade, as sh own in Figur e 7-25, A. Dra w a

line along the tongue. Saw the piece along this line and use it a s a pat t ern to cut t he shingles as


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shown in Figure 7-25, B.

Installing Flashing

Places especially susceptible to leakage in roofs and outside walls are made watertight by the

insta llat ion of f lashing. Flashing is sheets or strips of a w at ert ight , rustproof ma terial (such a s

ga lvan ized sheet or sheet copper a lloy for valleys a nd felt for hips). Fla shing deflects w a ter from

places tha t a re susceptible to lea kag e. The places in a roof most subject to leaka ge a re the lines

a long wh ich a djoining r oof surfa ces int ersect (such a s t he lines follow ed by ridges, hips, a nd

va lleys) a nd t he lines of intersection betw een roof surfa ces an d th e wa lls of dormers, chimneys,

skylights, and the like.

Ridge lines an d hip lines na tura lly tend to shed w a ter; therefore, they a re only modera tely

subject to lea kage. A strip of felt pa per usua lly ma kes a sa tisfa ctory ridge or hip fla shing.

The ridge or hip is then finished a s shown in Figure 7-26. Sq ua res a re ma de by cut ting

shingles into thir ds. The squa res a re then blind-na iled to th e ridge or hip as s hown in

Figure 7-26.


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Since wa ter ga th ers in the roof valleys, they a re more subject

to leaka ge. Va lley flashing va ries w ith the ma nner in w hich

the va lley is to be finished. There a re t w o common types of

va lley finish: the open val l ey and t he closed val l ey.

Figure 7-27 shows part of an open valley. The roof

covering does not extend a cross t he va lley. The fla shing

consist s of a prefa bricat ed piece of galva nized iron,

copper, zinc, or similar m eta l, wit h a splash rib or ridge

dow n t he center an d a sma ll crimp at the edges. The

flashing is na iled down t o the valley, wit h na ils driven in

th e edges (outside t he crimps), a s sh own in F igure 7-27.

Ca re must be ta ken not to drive na ils through the

fla shing in side th e crimps, t o avoid leaka ge. Figure 7-28, pag e 7-18, shows a n open va lley

using rolled roofing.

In the closed va lley, th e roof covering extends a cross th e valley. Sheet m eta l flashing is cut int osmall sheets measuring

about 18 x 10 inches,called shi ngl e ti ns. This

flashing is laid under each

course of shingles, a long the

va lley, as th e course is laid.

After t he first course of the

double course a t t he eaves

is laid, th e first s heet of

flash ing is pla ced on t op of

it. The second cours e is la id

over this one so that themeta l is pa rt ly covered by

th e next cours e. This

procedure is continued all

the wa y up the valley.

Shingle tins mea suring a bout 5 x 7

inches ma y a lso be used to lay flashing

up the side wa lls of dormers, chimneys,

skylights, and similar openings. Ea ch tin

is bent a t a r ight angle so tha t part of the

tin extends up the side wa ll and t he restlies flat on the roof covering. This is

called si de fl ashi ng. In a ddit ion t o the

side flash ing, a d ormer, chimney, or

skylight ha s a strip of fla shing ca lled a n

apron a long th e bott om of the outer wa ll

or face. A chimney or skylight ha s a

similar st rip, ca lled t he saddl e 1?ashi ng,

a long t he bott om of the inner w all or fa ce.

Figur e 7-29 shows vert ica l w a ll flashin g.


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BUILT-UP ROOFING MATERIAL

The following building papers are used on a built-up roof. Their purpose is to prevent the seepage

of bitum en th rough roof sheath ing on w hich a built-up roof ha s been applied.

Rosi n paper i s a felt pa per, usually pa le red, filled with r osin compound.

Kr aft paper is a light brown paper tha t is usually glazed.

Sisal kr aft consists of tw o lay ers of gla zed kraft paper wit h a center section of sisa l embedded in

a bla ck bituminous compound and la mina ted by heat a nd pressure.

Roofi ng fel t i s a felt paper tha t h as been sa tura ted w ith a bituminous compound (heavy pitch or

asphalt oils). The basic

ingredients are usually either

a sbestos or ra g felts. The roll

ma y va ry fr om 32 to 36 inches

w ide. Weight s for built -up

roofing vary from 15 to 65

pounds per sq ua re. The 15-

pound felt is most commonlyused beca use of its light

weight .

A binder is us ed to bond t he

roofing felt together a nd form a

wa tert ight seal . Asphalt and

coal t a r a re the two main types

of bitum inous binders used.

Drying out of the binder causes

deterioration of built-up roofs.

If th is did not ha ppen, a built-up roof w ould last indefinitely. Aspha lt is th e preferredbinder. It is used on roofs sloping u p to 6 inches per foot (1/4 pitch). Aspha lt h a s a melt ing

point of 350' to 41 0 F. A roof covered w ith a spha lt s hould be protected w ith a covering of

sla g, gra vel, or oth er protective ma teria l. Ta r ha s a low er melting point (300 to 350 F)

than asphal t , soit w ill move more easily; th erefore, it is n ot recommended for roofs ha ving aslope of more t ha n 3 in ches per foot (1/8 pitch).

Aggr ega te, crus hed st one, or gr a vel from 1/4 to 5/8 inch in dia met er is em bedded in a coa t of

a spha lt or tar to hold the roof covering down. I t a lso prevents the binding from disintegra ting

because of the weather.

G ra vel stops on slag or gra vel-surfa ced roofs, a nd met a l-edge strips on smooth -surfa cedbuilt-up roofs a re used to finish a ll exposed edges an d ea ves to prevent w ind from gett ing

under t he edges and causin g blow offs. The gra vel stop a lso prevents t he loss of gra vel or

sla g off th e edge of the roof. The f lashing flan ge of the gra vel stop or edge st rip is placed

over th e last ply of felt. It should be na iled securely t o the roof decka nd double felt st ripped.Then the finished coat of bitumen and surfacing or cap sheet should be applied. The lip of the

gra vel st op should extend a minim um of 3/4 inch above t he roof deck. The lip of the edge st rip

should be a ma ximum of 1/2 inch a bove the deck. B oth sh ould be securely fa st ened t o th e fas cia

board.


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RE ROOFING

This section provides information on reroofing for the following types of roofs: asphalt-shingle

roofs, asphalt-prepared roll roofings, built-up roofs, slate roofs, tile roofs, asbestos-cement roofs,

metal roofs, and wood-shingle roofs.

ASPHALT-SHINGLE ROOFS

The following t ypes of a sphalt str ip shingles ar e used for r eroofing hospitals a nd mobilization-type

buildings w ith pitched r oofs. These shingles a re a pplied directly over t he existing roll roofings.

Standar d-wei ght shin gles should be four-tab, 10 x 36 inches, and intended for a 4-inch maximum

exposur e. Weight per s qua re (100 squa re feet) a pplied should be a pproximat ely 210 pounds.

Sh ingles a re fa st ened w ith 1 1/4- or 1 1/2-inch na ils w ith hea ds h a ving a minim um d iam eter of 3/8

inch. Zinc-coated nails are best.

Th ick-butt shi ngles should be thr ee-ta b, 1 x 3 feet, a nd int ended for a 5-inch ma ximum exposure.

The entire sur face of th e shingles should be covered w ith m inera l gra nules. The bottom part of

each shingle, including the par t int ended to be exposed a nd a section a t least 1 inch a bove thecutout sections, should be th icker tha n th e remain der of the shingle. Weight per squa re a pplied

should be a pproxima tely 210 pounds. S hing les a re fa st ened w ith 1 1/2- or 1 3/4-inch na ils w ith

head s ha ving a minimum diam eter of 3/8 inch. Zinc-coat ed na ils a re best.

Preparation of Roof Decks

The follow ing st eps assu me th a t t he roof decks a re covered wit h smooth or minera l-

surfaced, aspha lt-prepared roofing an d t ha t t he shingles w ill be applied directly over t heexisting roofing.

Step 1. Dr ive in a ll loose a nd protruding n a ils flush with the existing roll roofing.

Step 2. Cut out all vertical a nd horizonta l buckles a nd w rinkles in the existing roofing. Nail down

th e edges of the cuts w ith 3/4-inch or 1-inch roofing na ils so tha t t he ent ire roof deck is smooth.

Step 3. If shingles a re a pplied over s mooth-surfa ced r oofing or over m ineral-surfa ced r oofing w hich

does not ma tch th e shingles, apply an 18-inch sta rting str ip of minera l-surfa ced roll roofing a t t he

eaves. Use roofing surfa ced with g ra nules of the sam e type a nd color a s the shingles.

Step 4. Before the strips are applied, unroll them carefully and lay them on a smooth, flat surface

unt il they lie perfectly fla t .

Step 5. Na il sta rter st rips at t he top a t a bout 18-inch interva ls. The low er edge, bent dow n a ndna iled to the edge of the s heat hing board, should extend a bout 3/4 inch beyond t he edge of the

board t o form a dr ip edge. Space the na ils in the edge of the sheat hing board 6 inches apar t.

A sta rt er strip need not be used if the shingles are th e same color a s th e existing roofing a nd th e

existin g roofing is not bu ckled. Fig ure 7-30, pa ge 7-20, show s a n exa mple of roof replacement.

Application of Shingles

Shingles are a t t ached in different w ay s, depending on the ty pe.


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Standard-Weight, Four-Tab, 10- x 36-Inch Shingles.Sta rt t he first course with a full shingleplaced so tha t one edge, cut off flush w ith t he ta b, is also flush wit h t he side of th e roof. The

bott oms of th e ta bs a re placed flush w ith t he eaves. P lace na ils about 3/4 inch a bove each cutout

section and in t he sam e relative position at ea ch end of the shingle. Use tw o nails at every cutout.

Nail at the center first, then above the cutout sections nearest the center, and finally at the ends.Na iling ma y sta rt a t one end a nd proceed regula rly to the other. Complete the first course wit h

full-w idth shin gles applied so tha t t he ends bar ely touch each other.

Sta rt t he second course with a shingle from w hich ha lf a t ab h as been cut . P lace it so tha t t he

bottoms of the ta bs a re flush w ith t he tops of the cutout sections of the shingle in t he first course.

Complete this course w ith full-w idth sh ingles.

St a rt t he third course with a shingle from w hich one ta b ha s been cut; the fourth w ith one

from wh ich one a nd one-ha lf ta bs ha ve been cut; a nd so on, unt il eventua lly a full shingle

is used aga in.

Thick-Butt, Three-Tab Shingles. Follow t he sam e method described for sta nda rd shingles.Alwa ys na il these shingles t hrough t he th ick par t, a bout 3/4 inch a bove the cutout sections. The

importa nce of na iling through th e thick part of a spha lt shingles ca nnot be empha sized too

str ongly. Pra ctica lly all difficulties experienced with as pha lt shingles on Army buildings ha ve

resulted from nailing t he shingles too high.

Hips and Ridges.Finish hips a nd ridges wit h individual shingles furnished especially by th ema nufacturer or with shingles cut from str ip shingles. Hips a nd ridges may also be finished w ith a

str ip of minera l-surfa ced roofing 9 inches w ide, bent equa lly on each side a nd n a iled on 2-inch

cent ers 3/4 inch fr om th e edges.


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Open Valleys. Open valleys may be flashed with 90-pound, 18-inch-wide mineral-surfaceda spha lt roll roofing (Figu re 7-31) pla ced over

the va lley underlayment. I t is centered in the

valley with t he surfaced side dow n a nd the

low er edge cut flush with t he eaves flashing.

When it is n ecessa ry t o splice the ma teria l,

the ends of th e upper segments a re laid to

overla p the low er segments 12 inches a nd a re

secured w ith a spha lt plast ic cement. A 36-

inch-w ide str ip is placed over th e first s trip,

centered in th e valley with t he surfaced side

up and secured w ith na ils.

B efore shingles a re a pplied, a chalk line is

sna pped on each side of the va lley for its full

length. The lines should sta rt 3 inches from

the valley on both sides. The chalk lines

serve as a guide in trimming t he shingleunits to fit the valley. The upper corner of

each end sh ingle is clipped to direct w a ter

into the va lley (Figur e 7-31). Ea ch shingle is cemented to th e valley lining w ith a spha lt cement t o

ensure a t ight sea l. No exposed na ils should appear a long the valley fla shing.

Closed Valleys.Closed valleys can be used only with strip shingles (Figure 7-32). This methodha s the a dva nt a ge of doubling the covera ge of the shingles throughout the length of the valley. A

va lley linin g ma de from a 36-inch-w ide str ip of 55-pound (or hea vier) roll roofing is pla ced over t he

va lley underla yment a nd centered in th e valley (Figure 7-32).

Va lley shingles are laid over the lining by either of two methods:

Applying both r oof surfa ces a t t he sa me time, wit h each course in tur n w oven over th e valley.

Covering each surfa ce to the point approximat ely 36 inches from the center of the valley a nd

the va lley shingles woven in place la ter.

Either w ay , the first course at the valley is

laid a long the eaves of one surfa ce over t he

valley lining and extended along the

a djoining roof surface for a t least 12 inches.

The first course of the adjoining roof surface

is then ca rried over t he va lley on top of the

previously a pplied shingle. E a ch coursethereafter is la id a lternately, weaving the

va lley shingles over each other.

The shingles a re pressed tightly into the

valley and na iled in the usual ma nner

except th a t no na il should be located closer

tha n 6 inches to the va lley centerline and

tw o nails are used at the end of each

ter mina l st rip (Figu re 7-32).


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ASPHALT-PREPARED ROLL ROOFINGS

There a re tw o types of aspha lt-prepa red roll roofing: minera l-surfa ced a nd sm ooth-surfa ced.

Mineral-Surfaced Roll Roofing

Minera l-surfa ced, a sphalt -prepared, t w o-ply roofing should consist of a lay er of 15-pound a spha lt-

sa tur a ted felt a nd tw o plies of roll roofing, cemented t ogether w ith hot a spha lt. Cut roll-roofing

ma teria l into lengths of 18 or 20 feet, sta cked free from w rinkles a nd buckles in protected piles.

Mainta in the roofing mat erial at a tempera ture of at least 50 F for 24 hours before laying.

First , cover th e roof a reas w ith a lay er of 15-pound a spha lt-sa tur a ted felt , with a ll joints la pped 2

inches. Nail as required t o prevent blowing off during the a pplica tion of roofing. Next, la y either

plain, dry uns urfa ced roofing or dry m ineral-surfa ced roofing as a sta rter sheet. La y this upside

down pa ra llel to an d flush w ith t he eaves. Nail th rough tin or fiber disks on 12-inch sta ggered

cent ers; tha t is, wit h one row of na ils on 12-inch centers placed not more tha n 2 inches from t he

low er edge, an d w ith a second row on 12-inch cent ers sta ggered wit h respect t o the first a nd a bout

8 inches a bove the first .

Over the low er ha lf of this sheet, a pply a uniform coat ing of hot a spha lt a t t he ra te of 30 pounds

per 100 squa re feet. P lace the first sh eet of roll roofing in t he as phalt . Cover the entire roof a rea,

lapping each successive sheet, t o obta in a tw o-ply roofing w ith a 2-inch head la p. Cement t he low er

or minera l-surfa ced portion of each sheet w ith hot a spha lt to the preceding sheet. Nail th e edge

thr ough tin or fiber disks on 12-inch sta ggered centers. U se tw o row s of nails. P lace the first r ow

on 12-inch centers not m ore tha n 2 inches a bove th e minera l surfa cing a nd t he second row on 12-

inch centers sta ggered wit h respect to the first a nd a bout 8 inches a bove the first.

P erform th e work in such a w a y tha t no fastenings or aspha lt will show on the finished

surfa ce. Apply the a spha lt imm edia tely before unrolling the sheet of roofing. D o not a pply

the a sphalt more tha n 3 feet a head of the roll. St ep the edge of each sheet int o the aspha ltso tha t a ll la ps are securely sea led. P lace the end la ps 6 inches in widt h w ith t he

underlyin g edges na iled on 6-inch cent ers, a spha lt-cement th e overlying edges, and st epdown firmly. P lace one ply of roofing at eaves a nd edges, tur n down nea tly, a nd secure it w ith a

wood member nailed on 8-inch centers.

Smooth-Surfaced Roll Roofing

B efore la ying th e roll-roofing ma teria l, cut it into 18-or 20-foot lengths. S ta ck th em free of wr inkles

and buckles in protected piles, and maintain them at a temperature of at least 50F for 24 hours.

For TO constr uction, a pply sing le-ply roll roofing horizonta lly w ith a t least 4-inch side laps a nd 6-

inch end la ps. Nail t he underlying edges of laps t hrough t in or fiber disks on 6-inch centers.

Cement overlying la ps wit h hot a sphalt or an a pproved cold-a pplied sealing compound. Step down

firmly on th e edges to provide proper a dhesion. Double the roofing over t he ridge w ith a t lea st 4-

inch laps. Turn r oofing down nea tly a t ea ves a nd edges. Na il the roofing in pla ce on 6-inch centers.

Figure 7-33 shows a n exa mple.

BUILT-UP ROOFS

B uildings w ith r oofs of relatively low pitch (less tha n 2 inches per foot), origina lly roofed wit h

a spha lt-prepared r oll roofings, s hould be reroofed w ith smooth-surfaced as phalt built-up roof1ng or


24/30

w ith coa l-ta r-pitch built -up roofing.

U se smooth-surfa ced a sphalt built-up roofing on buildings w ith original sm ooth-surfaced roll

roofing.

Use asphalt built-up roofing or coal-tar-pitch built-up roofing on mobilization-type buildings with

roofs of rela tively low pitch (usua lly 1/2 inch per foot), origina lly roofed wit h w ide-selva ge, miner a l-

surfa ced roll roofing. If th e roof is nearly fla t so wa ter collects a nd sta nds, th e lat ter ty pe of roofing

is best. Aspha lt r oofs ma y be sm ooth- or m inera l-surfa ced. Coa l-ta r-pitch roofs mus t be minera l-

surfaced.


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Asphalt Built-Up Roofs

P repa re the roof deck by driving in a ll loose and protruding n a ils and cutt ing out a ll


26/30

buckles a nd w rinkles. Then a pply a th ree-ply, smooth -surfa ced a spha lt built -up roof a s

follows:

Step 1. La y one la yer of 15-pound a spha lt-sa tur a ted felt over th e entire surface. Lap each sheet 3

inches horizonta lly a nd vertically a nd na il the laps on 12-inch centers. Also nail th rough th e center

of ea ch sheet on 12-inch centers st a ggered wit h respect t o the nails a t t he horizont a l laps. Us e

na ils long enough t o penetra te int o the shea thin g a t lea st 3/4 inch. They should be driven th rough

tin or ha rd fiber disks.

Step 2. Mop the entir e surface wit h a uniform coat ing of hot a spha lt, using 25 pounds per 100

squa re feet .

Step 3. Over t his coat ing of aspha lt, la y t w o addit iona l lay ers of 15-pound, 36-inch, aspha lt-

sa tur at ed felt . La p ea ch sheet 19 inches, an d lap the sheet ends not less tha n 6 inches. Na il these

felts th rough tin or ha rd fiber disks 1 inch from t he ba ck edge on 12-inch centers. U se na ils long

enough to penetr a te int o the w ood shea th ing a t least 3/4 inch.

Step 4. Mop each of these sheets t he full widt h of the lap w ith h ot a spha lt, using 25 pounds per 100

squa re feet .

Step 5. Apply a uniform mopping of hot a sphalt over t he entire s urfa ce, using 30 pounds per 100

squa re feet of roof surface.

NOTE: Do not heat asphalt above 400F. Lay the felt while the asphalt is hot, taking careto keep the surface free from wrinkles or buckles.

The materials needed per 100 square feet of roof surface for the three-ply, smooth-surfaced asphalt

built-up roof are

Asphalt: 80 pounds. Aspha lt-sat ura ted felt : 45 pounds.

If t he existing roofing is so rough t ha t it is impossible to obta in a smooth surfa ce by t he

method described a bove, remove the origina l roofing a nd apply a thr ee-ply, smooth-surfa ced,a spha lt built-up roof. Su bstitut e 30-pound a spha lt-sa tura ted felt for t he 15-pound felt originally

specified.

If a sla g or gr a vel-surfa ced roof is desired for mobilization-type buildings, a t s tep 5 a bove, apply 45

pounds of hot a spha lt inst ead of 30 pounds per 100 squa re feet. Int o this hot coating, pla ce 300

pounds of roofing sla g or 400 pounds of roofing gra vel per 100 squa re feet of roof sur fa ce.

Coal-Tar-Pitch Built-Up Roofs

Prepare the roof surface as previously described, then apply a three-ply, coal-tar-pitch built-up roof

a s follow s:

Step 1. Apply one layer of 15-pound coal-tar-saturated felt over the entire roof surface. Prepare it

a s described in st ep 1 of " Aspha lt B uilt-U p Roofs."

Step 2. Mop the ent ire surfa ce w ith a uniform coa ting of hot coal-ta r pitch, using 30 pounds per

100 squa re feet.


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Step 3. Over this coat ing of coal-ta r pitch, lay tw o additiona l lay ers of 15-pound coa l-ta r-sa tur a ted

felt 36 inches wide. Lap each sheet 19 inches over the preceding sheet. If 32-inch felt is used, lap

each sheet 17 inches. Na il the felt 1 inch from the ba ck edge on 12-inch centers t hrough t in or ha rd

fiber disks. Use na ils long enough t o penetra te int o the wood sheat hing a t lea st 3/4 inch. La p the

ends of the sheets a t lea st 6 inches.

Step 4. Mop each sheet t he full widt h of the la p wit h hot coal-ta r pitch, using 25 pounds per 100

squa re feet .

Step 5. Apply a uniform pouring of hot coal-tar pitch over the entire surface. Use 55 pounds per

100 squ a re feet. While th e pitch is hot, place over it 300 pounds of roofing sla g or 400 pounds of

roofing gra vel per 100 squa re feet.

The ma teria ls required per 100 squa re feet of roof surfa ce are

Coa l-ta r pitch: 110 pounds.

Coal-ta r-sa tur a ted felt : 45 pounds.

Roofing sla g: 300 pounds.

or

Roofing gra vel: 400 pounds .

NOTE: Do not heat the coal-tar pitch above 375F. Lay the felt while the coal-tar pitch is

still hot, taking care to keep the surface free from wrinkles or buckles.

SLATE ROOFS

Very old slat e roofs sometimes suffer failure beca use of the n a ils used to fast en the sla tes. In suchcases, remove a nd replace the entire roof, including t he felt un derlay ma teria ls. Remove or dr ive in

a ny protrud ing na ils. Ma ke every effort t o obta in a sm ooth, even deck similar t o th e origina l one.

Apply 30-pound as pha lt-sa tur a ted felt h orizonta lly over t he entire roof deck. La p the sh eets not

less tha n 3 inches. Turn t hem up 6 inches or more on vertical surfa ces a nd over 12 inches or m oreon ridges an d hips. Secure the sheets along la ps an d exposed edges with lar ge-hea d roofing na ils

spaced about 6 inches apar t.

Re-lay a ll origina l slat es tha t a re in good condition. Repla ce defective slat es wit h new slat es of the

sa me size, ma tching the original color a nd textur e as nea rly a s possible.

Recommended sla te sizes for lar ge new buildings a re 20 or 22 inches long; for sm a ll new buildings,

16 or 18 inches long. Use sla tes of uniform lengt h, in ra ndom w idths, a nd punched for a head lap ofnot less tha n 3 inches.

La y roof slates w ith a 3-inch head la p. Fasten each slate w ith tw o lar ge-head slat ing na ils a nd

drive them so tha t t heir heads just touch th e slat e. Do not dr ive the nails " home." The opposite is

tr ue of wood shingles; th erefore, workmen a ccustomed to laying w ood shingles must na il slate

carefully.

B ed all sla tes in a n a pproved ela stic cement on each side of hips and r idges with in 1 foot of the top

a nd a long gable ra kes wit hin 1 foot of th e edge. Mat ch slate courses on dormer roofs wit h th ose on

the ma in roof. Lay sla te w ith open valleys.


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TILE ROOFS

B efore reroofing w ith t iles, restore th e roof deck a s nea rly a s possible to its origina l condition.

Replace defective boards a nd a pply a spha lt-sa tur a ted felt (30-pound t ype) or prepared roofing. La p

the sheets n ot less tha n 3 inches. Turn t hem up on vertica l surfa ces for at least 6 inches a nd over

ridges a nd hips for at lea st 12 inches. Secure th e sheets a long la ps and exposed edges with la rge-

head r oofing na ils spaced about 6 inches apa rt.

Tiles must be free from fire cracks or other defects t ha t w ill impa ir th e dura bility, a ppea ra nce, or

w eat her tight ness of th e finished roof. Special sha pes are provided for eaves st a rters, hips, ridges,

top fixtures, ga ble ra kes, a nd finia ls. Specia l shapes for field tile at h ips a nd va lleys may be

factory-molded or ma y be job cut from w hole tile a nd ru bbed dow n t o clean, s ha rp lines. Roof tiles

for use on Army buildings a re genera lly furnished in one or more of th e follow ing t ypes:

M i ssi on t i les ar e stra ight-bar rel-type, molded to a tru e ar c and m a chine-punched for one na il

a nd a 3-inch head la p. Use regular cover tile for ridges a nd hips. Finish w ith plain m ission

finials. E a ves closures a nd hip sta rters a re ava ilable. Approved sizes are genera lly 8 inches

w ide by 14 to 18 inches long. Spani sh t il es a re S-sha ped a nd ma chine-punched for tw o nails a nd a 3-inch head lap. Ea ves

closures and h ip sta rt ers a re ava ilable. Use mission-type cover tiles for hips a nd ridges.

Approved sizes a re gen era lly 9 1/2 to 12 inches w ide by 12 t o 18 inches long.

Sl ab-shi ngl e ti l es a re the fla t, nonint erlocking ty pe, punched for tw o na ils an d a 2-inch

hea d la p. Approved sizes a re 6 to 10 inches w ide, 15 inches long, a nd 1/2 inch th ick.

Mission and Spanish Tiles

B efore sta rt ing to lay t iles, mop the w ood na iling strips wit h hot as pha lt. Fill the spaces in back of

the cant str ips w ith a spha lt cement. La y tiles wit h open valleys. Set ea ves closures back 3 inches

from the low er edge of eaves tiles. Lay pan t iles w ith un iform exposure to the w eat her. La y covertiles in a un iform pa tt ern, except wh ere oth erw ise necessar y to ma tch existing r oofs. Give a ll tiles

a minimum la p of 3 inches a nd extend pan t iles 1 inch over the rea r edge of the gutt er.

Cut th e tiles so th a t t hey meet projections wit h finished joints a nd point t hem up w ith roofer's

cement. Wa terproof the spaces between field tiles a nd w ood na iling strips a t ridges a nd hips wit h a

fill of roofer's cement. Fit a ll tiles properly a nd t hen secure them w ith n a ils long enough t o

penetra te a t least 1 inch int o the w ood base.

Fill spaces betw een pan a nd cover t i les in t he first row a t t he eaves with solid cement morta r ma de

of one part P ort land cement, three part s f ine sand, a nd enough clean w a ter to form a plast ic mix.

Wet a ll tiles before a pplying morta r, then press th em firmly into the morta r bed. Mat ch the tile

courses on dormer roofs with t hose on th e main r oof. Cut sur plus morta r off nea tly. P oint up all

open joints. Remove loose mortar from exposed surfaces.

Where hur ricane w inds can be expected, consider reinforcing t ile roofs by la ying a ll field t iles in

P ortla nd cement m orta r. To do this, fill the ends of tiles a t ea ves, hips, ridges, rakes, a nd spa ces

beneat h ridges solid wit h cement morta r. Fill the full w idth of laps between the tiles, both pa ra llel

and perpendicular to the eaves, with cement mortar.

Slab-Shingle Tiles


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La y sla b-shingle tiles wit h a 2-inch head la p. Secure each tile wit h tw o la rge-hea d roofing

nails. Double the tiles at eaves and project them 1 inch over the rea r edge of gutt ers. La y a lltiles w ithin 1 foot of hips, ridges, and a butt ing vertical su rfa ces in r oofer's cement. La y 10- or 12-

inch tiles wit h 1-inch head lap on t he sides of dormers. Ma tch t he tile courses on dormer roofs with

those on th e main r oof. La y tile roofs wit h open va lleys.

ASBESTOS-CEMENT ROOFS

B efore reroofing w ith a sbestos-cement s hingles, restore th e roof deck a s nea rly a s possible to its

original condition. Replace defective boards, a nd a pply new 30-pound a spha lt-sa tura ted felt or

prepared roofing in horizontal courses. Lap th e sheets not less tha n 3 inches. Turn t hem up a t

least 6 inches on vert ica l surfa ces a nd over a t lea st 12 inches on ridges a nd hips. Secure th esheets a long la ps and exposed edges w ith la rge-head r oofing na ils spaced a bout 6 inches a part .

Re la y a ll as bestos-cement shingles th a t a re in good condition. Replace defective shingles w ith n ew

shingles of the sa me size, ma tching the origina ls as near ly a s possible in color a nd t exture.

La y each shingle with a 2-inch head lap a nd secure it with tw o lar ge-head slat ing nails. Drive the

na ils so tha t t heir hea ds just touch t he shingles. Do not drive the nails " home" a s in la ying w oodshingles. B ed all shingles on each side of hips an d ridges w ithin 1 foot of the edge in a n a pproved

elast ic slat er's cement. P roject t he shingles 1 inch over the rea r edges of gutt ers. La y shingles w ith

a 1-inch head lap on sides of dormers. Ma tch th e shingle courses on dormer roofs w ith t hose on t he

ma in roof. Lay s hingles wit h open valleys.

METAL ROOFS

To conserve critical ma teria ls, repla ce meta l roofs w ith n onmetallic roofing ma teria ls.

WOOD-SHINGLE ROOFS

When old roofing is r emoved

Restore th e roof deck as n ear ly a s possible to its origina l condit ion. Replace rott ed

boa rds a nd pull out or drive dow n a ll protruding na ils.

Insta ll flashings an d apply new shingles.

If t he existing s hingle roofs ca n be ma de smooth a nd can be na iled properly, apply new w ood

shingles directly over w eat hered w ood-shingle roofs. Reroof over existing w ood sh ingles a s follow s:

Step 1. Na il dow n or cut off curled a nd w a rped shingles. Nail loose shingles securely, a nd remove

or drive down protruding n a ils.

Step 2. Cut off th e old first-course shingles at the ea ves just below th e butts of the second course.

Replace them w ith a 1 x 3 or 1 x 4 str ip nailed flush with th e ea ves line.

Step 3. Cut ba ck the shingles at the ga ble ends a bout 3 inches. Replace them w ith a 1 x 2, 1 x 3, or

1 x 4 str ip nailed flush with the ga ble end.

Step 4. Remove w eat hered shingles at the ridge. Replace them w ith a str ip of beveled siding, th in

edge dow n, to provide a solid bas e for na iling the ridge shingles. Trea t t he hip the sam e as t he

ridges.


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Step 5. Fill open valleys w ith w ooden strips level w ith t he old shingle surfa ce or with a n a rrow

str ip placed across the 'V" of the va lley to act as a su pport for new flash ings.

Step 6. Inspect fla shings carefully. Repla ce terne a nd ga lvanized flas hings. Reuse old flashings if

they a re in good condition.

Step 7. Use the follow ing na ils in applying shingles over a n existing roof:

5d box or special overroofing na ils, 14-ga uge, a nd 1 3/4 inches long for 16- a nd 18-inch sh ingles.

6d na ils, 13-ga uge, a nd 2 inches long for 24-inch sh ingles.

One sq ua re of roofing w ill need a bout 3 1/2 pounds of na ils.

Step 8. Apply new shingles as recommended by their ma nufa cturer.

roof framing & roofing army fm5-426

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