2013 straube rain vermont bbbd - building science corporation
TRANSCRIPT
Rain Control for Walls: Venting, Ventilation and Drainage
Dr John Straube, P.Eng.
www.BuildingScience.com
Overview&
• Rain&Control&basics&review&• Role&of&ven8la8on&and&drainage&• What&makes&them&work?&• When&do&we&need&them?&
Controlling&Rain&Penetra8on&• Deflec%on(
– reduce&water&on&building&– redirect&water&away&&– slope&surfaces,&use&flashing&
• Drainage(/(Exclusion(/(Storage(– enclosure&design&choice&– provide&drainage,&barrier&or&storage&
• Drying(– allow&any&remaining&water&to&dry&
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 1 of 14
Deflec8on&Overhang
Drips at OpeningHeads & Sills
200minSplash Height
! Surface(&(site(features(are(also(important(
7&
Deflec8on&
8&
Durable(Wooden(Buildings(
Lake&Baikal&
Forbidden&City&
Southern&Germany&
New&Zealand&
Rain&penetra8on&test&
Building&Science&2008&
&&Joseph&Ls8burek&–&Rain&Control&9&
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 2 of 14
Building&Science&
&Rain&Control&10&
Many&claddings&leak&
• Brick&• Wood,&vinyl,&fiber%cement&siding&• Stucco&• Metal&panels&
• Joints&leak:&window,&precast,&curtainwall&
Drained&Walls&
Building&Science&&
&&Rain&Control&12&
Requirements(for(a(Drained(Enclosure(
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 3 of 14
DRAINAGE(PLANE(
Drainage&Plane&
Building&Science&
&&Rain&Control&15&
Lapped(Housewrap,(paper,(membrane(
Building&Science&&
&&Rain&Control&16&
17&
Laps(are(the(most(reliable(
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 4 of 14
HighEperformance:(thick,(selfEsealing(adhered(
Building&Science&&
&&Rain&Control&19&
Laps&
• &&
DRAINAGE(GAP(
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 5 of 14
2013%02%11& John&Straube& 22&
Drainage&Gaps &&
• We&have&long&built&gaps&in&walls/roofs&• Why?&Both&drainage&and&ven8la8on&use&gaps&
• What&is&the&proper&gap&size&for:&– Drainage?&– Ven8la8on?&
• When&do&I&need&drainage?&Ven8la8on?&
23&
Drainage&Gaps&&• Gap&avoids&hydrosta8c&pressure&
– drains&away&water&
• Reduces&8me&of&wetness&on&housewrap,&membrane,&cladding&
• Requires&only&small&gap,&e.g.&<1/16”&
2013%02%11& John&Straube& 24&
Leaks&&• If&obstruc8on,&head&builds&up&and&small&nail/staple&holes&leak&
• Some&housewraps&come&with&pre%manufactured&holes&
Drained&gap&&behind&brick&
Building&Science&
&Rain&Control&25&
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 6 of 14
26&
• Vinyl&drains&well&with&no&strapping&
2013%02%11& John&Straube&27&
Lap&Siding&• Water&ran&out&the&front&of&wall&– Good&design&for&drainage&
1&2&3&4&5&6&7&8&9&10&11&12&13&14&15&16&17&18&
“Adhered&Veneer”&
www.BuildingScience.com& 29&
JJAC(Test(house(2001(
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 7 of 14
30&
Stucco&s8cks&to&paper/housewraps&
• leaks&
31&
Water(drained(astonishingly(well(between(sheets(of(building(paper(
32&
FLASHING(+(WEEPHOLES(
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 8 of 14
J.&Straube&2002& 34&
Water(can(build(up(here(EE(we(need(a(waterproof(barrier(
Note(standing(water((
Building&Science&&
&&Rain&Control&35&
Flashing&
• Need&to&direct&water&outward&
Building&Science&&
&&Rain&Control&36&
Leaky&windows&
• Leaks&around&windows&occur&• Collect&and&dump&onto&drainage&plane&w/&flashing&
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 9 of 14
Building&Science.com& 38& Building&Science&2008&&
&&Joseph&Ls8burek&–&Rain&Control&39&
Building&Science&2008&&
&&Joseph&Ls8burek&–&Rain&Control&40&
Building&Science&&
&&–&Rain&Control&41&
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 10 of 14
VENTILATION(
www.BuildingScience.com&
Requirements(for(a(VenSlated(Enclosure(
2013%02%11& John&Straube& 44&
Ven8la8on&Drying&
Clear Air Spaces
Vent Holes Above& Below Window
Vent Holes at Top& Bottom of Wall
• VenSlaSon:(design(to(allow(some(exterior(air(to(flow(between(cladding(and(sheathing(in(an(air(gap(• Usually(driven(by(solar(heaSng,(someSmes(by(wind(&
How&much&Ven8la8on&do&you&need&
• Are&materials&adjoining&the&gap&moisture&sensi8ve,&e.g.?&– Are&you&drying&the&cladding&back?&
• Wood&siding,&fiber%cement&
– Are&you&drying&the&wall&sheathing?&• OSB&exposed&to&wet&cladding&like&stucco,&brick,&etc&
• Are&you&controlling&inward&vapor&drives?&– Moisture&storing&claddings,&with&vapor&permeable&sheathing&
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 11 of 14
Building&Science&
&&–&Rain&Control&46&
VenSlaSon(helps(drying.((But(not(always(needed.(
47&
Previous&Ven8la8on&Research&• Fraunhofer&Ins8tut&
– Cladding&on&wet&AAC&– Test&hut&– Ven8la8on&allowed&
faster&drying&
• Hansen&(2002)&– Ini8ally&dry&test&hut&– No&effect&of&
ven8la8on&found&– No&weker/drier&
48&
Lab&test:&Drying&vs&flow&
-200
0
200
400
600
800
1000
1200
1400
1600
0 24 48 72 96 120 144 168 192 216 240 264 288 312 336
Time (h)
Wei
ght C
hang
e fr
om S
tart
(g)
No Flow
0.2 L/s
0.4 L/s0.8 L/s1.6 L/s
ASHRAE&RP%1091&PSU& 2013%02%11& John&Straube&49&
Ven8la8on&Research:&ASHRAE&1091&
Ven8la8on&drying&study&Wood&frame&walls&
! Brick,(boYom(vents(only(w/(Tyvek(! Brick,(venSlated(w/(Tyvek(! Brick,(venSlated(w/(#15(Felt(paper(! Vinyl(w/(Tyvek(! Vinyl(w/(#15(Felt(
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 12 of 14
2013%02%11& John&Straube& 50&
Example&Field&Results:&ASHRAE&RP1091&
Induced(we]ng(event(
Brick(w/Tyvek(venSlated(Brick(w/#15(felt(venSlated(
Brick(w/Tyvek(nonEvenSlated(
Building&Science&&
&&Rain&Control&51&
Specified(1”(gap(Actual(….(
Drained(gap(behind(wood(
• Taped&Foam&
Building&Science&&
&&Rain&Control&53&
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 13 of 14
www.BuildingScience.com& 2013%02%11& John&Straube& 55&
Summary(
• We&need&gaps&to&provide&drainage&– flashing,&esp&at&penetra8ons,&cri8cal&
• The&required&size&of&the&drainage&gap&is&very&small&(in&the&1/16�+)&
• Larger&gaps&can&be&useful&for&ven8la8on&drying&(1/4”-&¾��clear)&– We&don�t&always&need&ven8la8on&drying&
Better Buildings by Design Rain Control for Walls: Venting, Ventilation and Drainage February 6-7, 2013
Straube © buildingscience.com 14 of 14