BCGCA3004BConstruct Wall Framing

Wall Framing

• Building Code of Australia states that

• All timber framing is to be done in accordance with AS 1682

• This is an all encompassing standard which details the allowable construction methods

Wall Frame Members

• Parts of a frame perform specific functions- supporting live & dead loads- resist Racking Forces- resist Overturning Forces- resist Sliding Forces- resist Uplift Forces -Most members provide a face to accept linings (this means that member sizes may be limited)

• Timbers Generally Used- Radiata Pine- Oregon (Douglas Fir)- Various Hardwood Species

• Various combinations of -timbers, -engineered wood products-materials such as steel

may be used WHY?

Structural Steel

Radiata Pine Studs

Engineered Timber (LVL) Lintels

Galvanized Steel Strap Bracing

Engineered Timber (I Beams) Deep Joists

• Other more exotic Timbers such as Cypress Pine may be used.

-Why?

Wall Frames• Frames are classified into 2 categories1. Load Bearing – They are structural frames, they

transfer loads from roof or upper floor to the supporting floor frame. They can be either external or internal walls.

2. Non Load Bearing –- do not support any structural loads.- They support their own weight- Non structural loads doors and frame, kitchen cupboards, driers etc. - support some live loads eg Doors closing.

Therefore there are some minimum requirements for theses AS 1684.2 cl 6.3.5

AS 1684.2 cl 6.3.5

Basic Frame Components

Refer page 187 TAFE Guide

Refer AS1684.2 cl 6.1.2

Frame Member Functions

Plates

•Horizontal members that form the top & bottom of the frame.•Bottom plate is usually 50mm for unseasoned timber 45mm for seasoned.•Top plate is usually the same section size as bottom plate.•For trussed roof top plates will be 75mm for unseasoned and 70mm for seasoned•Top plate may be made up by 2 x 38 (35)•Thicker top plates means that trusses or upper floor joists do not need to be placed direct over a stud

Plates AS 1684.2 cl 6.2.2

Studs• Vertical members placed between the plates• The set the wall height• Studs in external frames resist Wind Loads• Generally Stud sizes are 75mm or 100mm wide by

50mm or 38mm in unseasoned timbers and70mm or 90mm wide by 35mm or 45mm in seasoned timbers.

• Required Stud sizes can be found in AS 1684.2 Supplements

Studs Continued• Several Different types of Studs

- Common- Door & Window- Secondary Jamb Studs- Jack & Short

Trimmers

• Horizontal members fixed between window studs and door studs.

• Referred to as Sill or Head trimmers• Usually of the same section size bottom plates• Openings wider than 1800mm require

trimmers as specified in AS 1684.2 cl6.3.6.6 & table 6.3

Trimming Studs•Run from Trimmers to Plates•Used to block out Narrow Lintel•Where use in conjunction with Lintel they may take structural loads •Must be same depth as wall frame to accept finishes•May also be referred to as “Jack”, “Soldier”, or “Short” studs

Noggins

•Horizontal Member cut between studs to keep them - straight- evenly spaced- prevent twisting- allows studs to carry higher load- Maximum spacing 1350mm, there walls upto 2700mm require only 1 row of noggins

Noggins AS 1684.2 cl 6.2.1.5

Blocking

• Placed at intersections of wall frames• Normally 3 Blocks per intersection

Blocking AS1684.2

Lintels

• Also referred to as a Head• Horizontal Load Bearing Member between Studs• Purpose is to transfer loads to side of openings• May be made of many materials

- Timber- Engineered Timbers- Structural Steel or Cold Rolled Steel Sections

Bracing

• Provide lateral stability of Walls• Provide resistance against racking forces

induced direct wind loads• Provide resistance to Roof loads induced onto

top plates.

Bracing Methods

Timber Bracing – 50 to 75 mm x 19 to 25mm checked into and nailed flush into face of studs.

Braces must be installed in opposing pairs in external bracing walls.

This method is virtually never used today.

Rated 0.8 kN/m

Types of Bracing

Perforated Metal Bracing- Installed in similar method as timber brace with a saw cut into the plates and studs.

The brace is then nailed flush onto the studs and plates.Braces must be installed in opposing pairs in external walls.

Rated 0.8 kN/m

Types of Bracing

Types of Bracing

Flat Metal or Hoop Iron Bracing• 19mm Wide x 0.8mm• Zincalume• Two braces are fixed in

opposite directions• Fitted with Compression

Clamps

• Rated 1.5kN/m

Types of BracingSheet Bracing• Structural Plywood (Must be Stamped)• Hardboard (Masonite)• Fibre Cement• Resists Strong Wind Loads• Can be used on Narrow Panels – Why?• Usually on external walls in cavity – Why? • Minimum 7mm (Not Necessarily Correct)• Must be nailed off as per AS 1684.2 • Plate Steel can be used in High Wind Load Areas

Bracing AS 1684.2

Location of Bracing• AS 1684 cl 8.3.6.6 states

– Bracing should be evenly distributed and be provided in both directions

– Should be placed initially at corners

Spacing of Bracing Walls

• AS 1684.2 Cl 8.3.6.7 states– For Single Storey Building or Upper Storey of

Double Storey Buildings– Maximum distance between bracing wall shall be

9000mm for Wind Classifications up to N2

Plan & Prepare For Wall Framing

• Stress Grading of Individual Wall Frame Members

• Seasoned Or Unseasoned

Stress Grading

• Refers to the Timbers Strength• Timber must be able to withstand stress loads

placed on them.• Overloading may cause straining or failure• 3 types of stress

CompressiveTensileShear

Note Torsional Stress is not discussed

Stress Grading• Members Sizes will be determined for span

tables• Generally for Residential Construction sizes will

not be specified by designers

• Why?• Architect will not want to take responsibility• Engineer will want to charge extra to do this and • Why would a client want to pay for something

that he can get done for nothing

Stress Grading

• Why are members generally specified on Commercial projects

• AS 1684.2 Residential Timber Framed Construction Guide

AS 1684.2 Limitations1.4.4 The Maximum number of storey's of timber shall not exceed 2

1.4.5 The maximum width of a building shall 16 000mm, Note, if you use AS1684.2 simplified max width = 12 000mm

1.4.6 The maximum wall height shall be 3000mm excluding gable ends

1.4.7 The maximum roof pitch shall be 35 degrees

Structural pine grading A3P has announced that it will not proceed with the introduction of Structural Pine (SP) grading as previously planned.

Continuing contact with A3P members, timber merchants, truss and frame fabricators, designers and specifiers has indicated the introduction cannot be achieved without major disruption and unacceptable burden to industry.

Ordering Timber

• Timber is ordered in lineal metersmay be priced in cubic meters

• Increments of 300mm• Lengths over 3600mm are charged at higher rate• Timber should be ordered as required

- avoid unnecessary exposure to weather- affecting cash flows- theft- storage

Material Storage

• Timber should be stored on gluts

• This allows for airflow• Care should be taken

in stack sizes • Stacks can be

strapped for safety

Storage of Materials

• Timber should be stored as close as possible to work area

What is a Concentrated Load ?

Frame Construction

• Plates• The size of plates will depend on

1. Floor Joist Spacing2. Rafter / Truss Spacing3. Stud Spacing4. Single or Double Storey5. Stress Grade of Timber6. Roof Load Width ?

Roof Load Width (RLW)

Plates• Seasoned timbers are dressed therefore

trenching not required• Rough Sawn Timbers such as Oregon,

Hardwood require trenching.• Housing of plates for studs provides a

constant thickness• Trenching keeps Top & Bottom plates parallel• Restrains Unseasoned Studs from twisting

• Trenching usually appox 10 mm

• Trenching depth is not critical but what is left on is.

• Top Plates fully supported on masonary walls will be sized based on a 300mm spacing

Top Plates AS 1684.2

• cl 6.3.4. states that may be a minimum of 35 mm if1. not required to resist uplift forces (i.e trusses are nominally fixed and

2. Trusses or Rafters are located directly above studs or within 1.5 times the depth of the plate from the stud.

Joining of Plates

• Where plates are butt jointed they may be joined using a connector plate.

Joining of Plates

• Plates may be Scarfed or Lapped jointed.• Theses are time consuming and rarely used

Calculate Plate Lengths

• During Fabrication Top & Bottom Plates are the same length

• Plates should be as long as possible• Consider manpower available to stand frames• Remember Top Plate must be continuous

StudsStud Sizes are determined by1.Stress Grade2.Stud Spacing3.Rafter/ Truss spacing4.Wall Height5.Roof Load Width6.AS 1684.2 tables only specify 450mm or

600mm spacing. These are the most common spacing's

Stud SpacingStud Spacing Determined by1.Stress Grade2.Stud Spacing3.Rafter/ Truss spacing4.Wall Height5.Roof Load Width and6.If applicable External Sheeting Joints (ie Blue

Board etc)

Studs

• Not all external sheeting require critical stud placement

• Check with manufactures manual as to requirements

• Generally studs should be aligned with the internal face.

Harditek (Blue Board)

Studs• Stud sizes are determined from tables in AS

1684.2

Calculating Stud Length

• Finished Floor to Ceiling govern stud length• Minimum Habitable Room is 2400mm Clear• Floor Finishes

1. Carpet 20mm2. Timber Flooring 40mm (Depending on Batten)

• Ceilings1. 10mm Plasterboard2. 13mm Plasterboard

Calculating Stud Length

• Double Storey building may have FFL (Finished Floor Level).

• Allowance must be made for structural members

• Most Importantly Determine if there are any height restrictions

• Type of Roof Will affect Stud Heights

Top & Bottom Plates = 90 x 45 F5

Step 1 – Determine Floor & CeilingFloor Carpet = 20mmCeiling Gyprock = 13mm

Step 2 – Calculate Stud Length

Minimum Clearance = 2400mm Plus Flooring = 20mmPlus Ceiling = 20mm

Wall Height = 2440mmless Wall Plates = 90mm

Stud Length = 2350mm

Ground Floor

First Floor

Ground Fl Finish = Timber (40mm)First Floor = Carpet (20mm)Upper Level Joists = 200 x 50 F5Top & Bottom Plates = 90 x 45

Step 1- Determine SFL (Structural Floor Level)SFL First Floor = 28.950 (FFL First Fl)

-20 (Carpet) SFL= 28.930

SFL Ground Fl = 26.200 (FFL Gnd) - 40 (Timber)

SFL = 26.160Step 2 – Calculate Height Difference

SFL First Floor = 28.930 –SFL Ground Fl = 26.180Height Difference = 2.750

Step 3 – Structural Elements

Height Diff = 2.750Less Flooring = 0.017Less Floor Joist = 0.200Less T & B Plate = 0.090

Stud Length = 2.443Ground Floor

First Floor

Carpet Both Floors (20mm) Ceilings 10mm Plasterboard (Allow 20mm)Dimensions are clear measurementsLower level plates Upper Level PlatesBottom Plate = 90 x 35 F5 Bottom Plate = 90 x 45 F5Top Plate = 90 x 45 F5 Top Plate = 90 x 70 F5

Straightening of Studs

Calculating Door Heights

• On Concrete Slab• Using a standard 2040mm x 820mm • Allow 22mm for Carpet (17mm + 5mm)• 2040 mm Door Height• 2mm Clearance between Door & Jamb• 20mm for Jamb• 10mm Clearance between Jamb & Head• 15mm Clearance between Jamb & Lintel• Total = 2094mm Say 2100mm

Calculation of Door Width

Calculation of Window

•Check with manufacturer if windows are not on site•Generally at same height of doors•Check on elevations for window heights•15mm Clearance between Jamb & Lintel•Allow 10mm under sill

Window Width

•Care should be taken when setting out to brick bond!•Client may want window to line up with internal fitting •Client may want window dead center of room

Lintels

Construct Wall Frames

• Number Wall Frames• Clock Wise Direction• Internal Walls Left to Right• Top To Bottom

Setting Out Plates

• Confirm Dimensions of Slab/ SubfloorSelect Suitable Timber & Cut to LengthTack TogetherMark Appropriate ID Number on Plate

• Mark Required Studs – In Following OrderEnd StudsWall Intersections

Setting Out Plates

• If required prepare a storey rod with the appropriate markings (ie Horizontal & Vertical Bond)

• Set out position of window and doors studs remembering to allow for required jamb studs

• If required adjust position to match brickbond• Set out Common Studs, Jack Studs at required

spacing

Preparing Studs

• Use Storey Rod (Pattern Stud) to cut required studs

• Mark and check out window and door studs

Wall Frame Assembly

What are Advantages & Disadvantages of Prefabricated Wall Frames?

Assembling Wall Frames

Frame Erection

Nominal Fixings For Bottom Plates AS 1684.2

Bracing