TIMBER FRAMING USING AS 1684.2 SPAN TABLES

TIMBER FRAMINGUSING AS 1684.2 SPAN TABLES

AS 1684 Teaching Guide

AS 1684-2010 Residential timber-framed construction

• Go to www.education.WoodSolutions.com.au for up to date teaching resources including an annotated copy of the standard.

• This powerpoint presentation is part of a series that has been revised to reflect the requirements of AS 1684 Parts 2 & 3 – 2010 Edition.

• Some major changes to this edition include amendments to wall nogging requirements, inclusion of ring beam systems and an Appendix of building practices for engineered wood products (EWPs).

• The MGP span tables provided with the Standard have also been amended.

AS 1684-2010 Residential timber-framed construction

http://www.education.woodsolutions.com.au/

the timber framing standardAS 1684RESIDENTIAL TIMBER-FRAMED CONSTRUCTION

Currently you should be using the 2010 Edition.

Provides the building industry with procedures that can be used to determine building practice to design or check Construction details, determine member sizes and bracing and fixing requirements for timber framed construction in Non-Cyclonic areas (N1 – N4).

AS 1684TIMBER-FRAMING STANDARD

AS 1684.2 – CD Span Tables

Contains a CD of Span Tables (45 sets in all) for wind zones N1 - N4 for the following timber stress grades:Unseasoned Softwood:F5, F7Seasoned Softwood:F5, F7, F8MGP10, MGP12, MGP15Unseasoned Hardwood:F8, F11, F14, F17Seasoned Hardwood:F14, F17, F27


Each set of Span Tables contains 53 separate design tables


Using AS 1684 you should be able to design or check virtually every member in a building constructed using timber framing.


BearersStumps or piles

Floor joists

Battens

Roofing

Ridge beam

Ceiling

Flooring

Ceiling battens

Floor joists

Lintel

Wall frame Wall stud

FlooringInternal cladding

External cladding

Ceiling battens

First floor wall frames

Hanging beamsRafters

AS 1684TIMBER-FRAMED CONSTRUCTION

WHERE CAN AS1684 BE USED?

AS 1684Scope and Limitations

Plan: Rectangular, square or “L”-shapedStoreys: Single and two storey constructionPitch: 35o max. roof pitchWidth: 16m max. (between the “pitching points” of the roof, i.e. excluding eaves)

16.0 m max.W

16.0

m m

ax.

W

16.0 m maxW

AS 1684Physical Limitations -

Width

16.0 m max.

Pitching Point of main roof.

P itching Point of garage roof.

P itching Point of verandah orpatio roof.

P itching Point of main roof.

16.0 m max. 16.0 m max.

Main houseGarage Verandahor Patio

AS 1684Physical Limitations - Width

The geometric limits of the span tables often will limit these widths.

Wall Height

The maximum wall height shall be 3000 mm (floor to ceiling) as measured at common external walls (i.e. not gable or skillion ends).

AS 1684Physical Limitations – Wall Height

Design Forces on Buildings

LIVE LOADS (people, furniture etc.)

DEAD LOAD (structure)

Construction loads (people, materials)

DEAD LOAD (structure)

Suction

Internal pressure

Suction (uplift)

Wind

(a) Gravity loads (b) Wind loads

AS1684 can be used to design for Gravity Loads (dead & live) and wind loads.

AS 1684Physical Limitations – Design Forces on Buildings

Wind Classification

Non-Cyclonic Regions A & B only

N1 - W28N 100km/h gust




AS 1684Wind Classification

Wind Classification

Wind Classification is dependent on :

Building height

Geographic (or wind) region (A for Victoria)

Terrain category (roughness of terrain)

Shielding classification (effect of surrounding objects)

Topographic classification (effect of hills, ridges, etc.)

AS 1684Wind Classification

AS 1684Wind Classification – Simple References

Geographic Region A

Site Location Top ⅓ of hill or ridge

Below top ⅓ of hill or ridge

Suburban siteNot within two rows of:•City or Town perimeter (as estimated 5 years hence)•Open areas larger than 250,000 m2

N2 N1

Less than 250m from:•the sea •open water wider than 250m

N3 N2Within two rows of:•City or Town perimeter (as estimated 5 years hence)•Open areas larger than 250,000 m2

Rural areas

Design fundamentals & basic terminology

Roof framing

Wall framing

Floor framing

(Click on arrow to move to section required)

AS 1684Using Span Tables

DESIGN FUNDAMENTALS

&

BASIC TERMINOLOGY

AS 1684Using Span Tables

Design FundamentalsAS 1684 SPAN TABLESDesign Fundamentals – Load Path

You build from the Bottom up.

But you design from the Roof down because loads from above can impact on members below.

So start with the roof and work down to the ground level.

Understanding the concept of a ‘load path’ is critical. Loads need to be supported down the building to the ground.

Indirect Load path due to cantilever

Roof

Load

Ground level

AS 1684 SPAN TABLESDesign Fundamentals – Load Path

Indirect Load path due to cantilever

Roof

Load

Ground level

AS 1684 SPAN TABLESDesign Fundamentals – Load Path

It is possible to decrease timber member size when:Sharing loads across many members.Using members with higher stress grades.

As a general rule it is necessary to increase the timber member size when:Load increases (a function of dead, live, wind loads).Span increases (a function of load paths across openings).Indirect load paths occur (e.g. cantilevers and offsets).

Loads are distributed equally between Points of Support.

Of the total load on Member X one half (2000 mm) will be supported by the beam or wall at “A” and the other half (2000 mm) will be supported by the beam orwall at “B”.

BA

MEMBER X

Loads distributedAS 1684 SPAN TABLESDesign Fundamentals – Load Distribution

Beam A will carry 1000 mm of loadBeam B will carry 3000 mm(1000 mm plus 2000 mm on other side)Beam C will carry 2000 mm

If Member X is supported at three or more points it is assumed that half the load carried by the spans either side of supports will be distributed equally.

A B C

MEMBER X

AS 1684 SPAN TABLESDesign Fundamentals – Load Distribution

A B C

Terminology - Span and SpacingAS 1684 SPAN TABLESTerminology – Span

Span is the “face-to-face” distance between points capable of giving full support to structural members or assemblies.

Joist Span (between internal faces of these support members).

Bearers and Floor Joists

S i n g l e s p a n

S i n g le s p a n S i n g le s p a n

S a w c u t J o in t o r l a p

AS 1684 SPAN TABLESTerminology – Single Span

The span of a member supported at or near both ends with no immediate supports.

This includes the case where members are partially cut through over intermediate supports to remove spring.

The term applied to members supported at or near both ends and at one or more intermediate points such that no span is greater than twice another.

C o n t i n u o u s s p a n

C o n t i n u o u s s p a n

NOTE: The design span is the average span unless one span is more than 10% longer than another in which case the design span is the longest span.

AS 1684 SPAN TABLESTerminology – Continuous Span

Span 2 is not to be greater than twice Span 1.This span is used to determine the size using the Continuous Span tables.

Span 1 (2000 mm) Span 2 (3925 mm)

1/3 (2000 mm)

The center support must be wholly within

the middle third.

6000 mm

1/3 (2000 mm) 1/3 (2000 mm)

75 mm 75 mm 75 mm

Example: Continuous SpanAS 1684 SPAN TABLESContinuous Span Example

Rafter

Terminology – Rafter Span and Overhang

Rafter spans are measured as the distance between points of support along the length of the rafter and NOT as the horizontal projection of this distance.

AS 1684 SPAN TABLESTerminology - Rafter Span and Overhang

Terminology - Span and Spacing

Bearers and Floor joists

AS 1684 SPAN TABLESDesign Fundamentals – Spacing

Spacing is the centre-to-centre distance between structural members unless indicated otherwise.

Joist Spacing(Centreline-to-Centreline)

Bearer Spacing(Centreline-to-Centreline).

Loadbearing wallA wall that supports roof loads, floor loads or both.

Non-Loadbearing internal wallA wall that does not support roof or floor loads but may support ceiling loads and act as a bracing wall.The main consideration for a non-loadbearing internal wall is its stiffness (i.e. resistance to movement from someone leaning on the wall, doors slamming shut etc.).

Terminology – Wall ConstructionAS 1684 SPAN TABLESTerminology – Wall Construction

Ridge board

Rafters & Ceilin g Jo ist m ust befixed to geth er a t the p itch in g po in ts

Ceiling jo is t

Rafte r

o therw ise there is no th in g to stopth e w alls fro m spreading

and th e ro of fro m collapsing

Ceiling jo is t(C olla r Tie )

Rafte r

R idge board

T his m eth o d of roo f co nstru ctio n is n o t covered by A S1684

Terminology – Roof Construction

Coupled Roof - rafters are tied together by ceiling joists so that they cannot spread.

AS 1684 SPAN TABLESTerminology – Roof Construction

Non-coupled roof - a pitched roof that is not a coupled roof. It includes cathedral roofs and roofs constructed using ridge and intermediate beams

R id g e B e a m

R a fte r In te rm e d ia te B e a m

Such roofs rely on ridge and intermediate beams to support the centre of the roof. These ridge and intermediate beams are supported by walls and/or posts at either end.

AS 1684 SPAN TABLESTerminology – Roof Construction

ROOF FRAMING

AS 1684 SPAN TABLESUsing Span Tables

The “footprint” of a building generally consists of a rectangular block or multiple blocks joined together. Roof shapes are made to cover the footprint while also providing sloping planes able to shed water.

HipSkillion

Gable (Cathedral or flat ceiling)

Dutch Hip (or Dutch Gable)

Hip and valley

AS 1684 SPAN TABLESRoof Framing – Typical Basic Roof Shapes

R i d g e b o a rd

C o l la r t ie

U n d e r p u r l in

S t ru tS t ru t t i n g b e a m

C e i l i n g jo i s tS t r u t

R a f te r

To p p l a te To p p l a te

AS 1684 SPAN TABLESRoof Framing – Typical Members

3. Rafters – take batten loads and transfers them to the support structure below e.g. walls.

Support wall

AS 1684 SPAN TABLESRoof Framing - Transferring loads to Pitched Roof

1. Roofing material - takes live/dead/wind loads and transfers them to the Battens.

2. Battens - takes roofing loads and transfers them to the Rafters/Trusses.

Typical ProcessStep 1: Determine the wind classification to factor in wind loads (e.g. assume non-cyclonic winds N1 or N2)Step 2: Determine type of roof (e.g. tiled or sheet.)Step 3: Determine batten spacing – typically 330 mm for tiles, or 450, 600, 900, 1200 mm sheet Step 4: Determine batten span – this will be the supporting rafter spacing. Batten

Span

Batten

Spacing

AS 1684 SPAN TABLESRoof Framing – Batten Design

AS 1684 SPAN TABLESRoof Framing – Batten Design

Step 7: Select column in the table for the previous batten “spacing and span” assumptions.

Step 5: Look up relevant Batten Span Table (i.e. non-cyclonic winds N1 and N2) in AS1684 Vol. 2.Step 6: Choose a table reflecting preferred stress grade.

AS 1684 SPAN TABLESRoof Framing – Batten Size Example

Inputs required Wind Classification = N2 Timber Stress Grade = F8 Roof Type = Steel Sheet (20 kg/m2) Batten Spacing = 900 mm Batten Span = 900 mm

AS 1684 SPAN TABLESRoof Framing – Batten Size Example

Batten Span = 900 mm

Wind Classification N2

Timber Stress Grade F8

Roof Type - Steel Sheet (20 kg/m2)

Batten Spacing = 900 mmA 38 x 75 mm F8 Batten Is adequate

Simplify

table

2006

Step 1: Determine the wind classification to factor in wind loads. For this example assume non-cyclonic winds N1 or N2.

Step 2: Determine dead/live loads on rafters . For this example assume loads are as for a tiled roof with battens (e.g. 60kgs/m2)

Step 3: Determine the rafter span. For the example assume a 2100 mm single rafter span.

Step 4: Determine the rafter overhang which creates a cantilever span adding extra load. For the example assume a 500 mm overhang.

Step 5: Determine the rafter spacing as this determines how much roof loads are shared between rafters. For the example assume a 600 mm spacing .

Ridge beam

Overhang

Rafter span

RafterSpacing

AS 1684 SPAN TABLESRafter Design - Cathedral Roof Scenario

Step 6 Look up AS1684 Vol 2

Step 11 Read off rafter size – 90x45mm

Step 7 Choose table reflecting preferred stress grade

Step 8 Determine which column in table to select using the previous “rafter spacing” and “single span” assumptions.

Step 9 Go down the column until reaching assumed 2100 mm rafter span and 500 mm overhang

Step 10 Check the spans work with assumed roof load of 60kgs/m2



Inputs required Wind Classification = N2 Stress Grade = F8 Rafter Spacing = 900 mm Rafter Span = 2200 mm Single or Continuous Span = Single Roof Mass (Sheet or Tile) = Steel Sheet (20 kg/m2)

Simplify table

Inputs required• Wind Classification = N2• Stress Grade = F8• Single or Continuous Span = Single• Rafter Spacing = 900 mm• Rafter Span = 2200 mm• Roof Mass (Sheet or Tile) = Steel Sheet

(20 kg/m2)

Inputs required• Wind Classification = N2• Stress Grade = F8• Single or Continuous Span = Single• Rafter Spacing = 900 mm• Rafter Span = 2200 mm• Roof Mass (Sheet or Tile) = Steel Sheet

(20 kg/m2)

A 100 x 50mm F8 rafter

is adequate

Maximum Rafter or Purlin Span & Overhang (mm)

At least 2200mm

2006

Determine Rafter Size

Ceiling Joist Design

Design variables• Timber Stress Grade• Ceiling Joist Spacing• Ceiling Joist Span• Single or Continuous Span

Ridge board

Ceiling Joist

Rafter

AS 1684 SPAN TABLESCeiling Joist Design

Ceiling Joist DesignAS 1684 SPAN TABLESCeiling Joist Design Example

Inputs required Wind Classification = N2 Stress Grade = F17 Overbatten = No Single or Continuous Span = Single Joist Spacing = 450 mm Ceiling Joist Span = 3600 mm

Ceiling Joist Size

Inputs required• Wind Classification = N2• Stress Grade = F17• Overbatten = No• Single or Continuous Span = Single• Joist Spacing = 450 mm• Ceiling Joist Span =

3600mm

Inputs required• Wind Classification = N2• Stress Grade = F17• Overbatten = No• Single or Continuous Span = Single• Joist Spacing = 450 mm• Ceiling Joist Span =

3600mm

Simplify table

A 120 x 45mm F17

ceiling joist is adequate

At least 3600mm

2006

Some members do not have to be designed using span tables. They are simply called up or calculated based on members framing into them.

Member Application Minimum size (mm)

Unstrutted ridge in coupled roof Depth not less than length of the rafter

plumb cut 19 thick

Strutted ridge in coupled roof with strut spacing not greater than 1800 mm

Depth not less than length of the rafter plumb cut 19 thick

Ridgeboards

Strutted ridge in coupled roof with strut spacing greater than 1800 to 2300 mm

Depth not less than length of the rafter plumb cut 35 thick

Stress grade F11/MGP15 minimum and no less than rafter stress grade

50 greater in depth than rafters 19 thick (seasoned) or 25 thick

(unseasoned) Hip rafters

Stress grades less than F11/MGP15 50 greater in depth than rafters min. thickness as for rafters

Valley rafters Minimum stress grade, as for rafters 50 greater in depth than rafters

with thickness as for rafter (min. 35)

Valley boards See Note 19 min. thick width to support valley gutter

Struts to 1500 mm long for all stress grades 90 45 or 70 70

Roof struts (sheet roof) Struts 1500 to 2400 mm long for all

stress grades 70 70

Ridge boardAS 1684 Span TablesOther Members And Components - Ridge board

The loads from roof members often impact on the design of members lower down in the structure.This impact can be determined from the following load sharing calculations:Roof Load Width (RLW).Ceiling Load Width (CLW).Roof area supported.

AS 1684 Span TablesRoof Member Load Impacts

AS 1684 Span TablesRoof Member Load Impacts – Roof Load Width

RLW is the width of roof that contributes roof load to a supporting member. It is used as an input to Span Tables for:Floor bearers.Wall studs.Lintels.Ridge or intermediate beams.Verandah beams.Roof Load Widths are measured onthe rake of the roof. A

B

3000

15001500

AS 1684 Span TablesRoof Member Load Impacts – Roof Load Width

ayx

2

RLW wall A = byx

2

RLW wall B =

x ya b

A B

The roof loads on trusses a re d is tr ibu ted equally betw een w a lls 'A ' and 'B '.

AS 1684 Span TablesRoof Member Load Impacts – With Trusses

ax

2RLW wall A = b

y

2RLW wall B =

R LW R LW

R LW

213

x ya b

RLW RLW

A B

**

AS 1684 Span TablesRoof Member Load Impacts – Without Ridge Struts

For a pitched roof without ridge struts it is assumed that some of the load from the un-supported ridge will travel down the rafter to walls 'A' and 'B'. The RLWs for walls A & B are increased accordingly.

Underpurlin 1 =

x yRLW RLW

BCA

ba 1 23

RLW

Underpurlin 2 =3y

Underpurlin 3 =3y

AS 1684 Span TablesRoof Member Load Impacts – With Ridge Struts

2x

Ceiling load width (CLW) is the width of ceiling that contributes ceiling load to a supporting member (usually measured horizontally).

A B

x

CLW

AS 1684 Span TablesRoof Member Load Impacts – Ceiling Load Width

CLW is used as an input to Span Tables for hanging beams and strutting/hanging beams

Hanging beam

Ceiling jo ist

Hanging beam span

'x '

Hanging Beam Strutting/Hanging Beam

Strutting beam span

Ridgeboard

Underpurlin

Strutting beam

Roof strut


CLW Hanging beam D =2

x

A B C

ED

x y

CLW CLW

FIGURE 2.12 CEILING LOAD WIDTH (CLW)


A B C

D E

yx

CLWCLW

CLW Strutting/Hanging beam E = 2

y

Example: The Strutting Beam Span Table requires a ‘Roof Area Supported (m2)’ input. The strutting beam shown supports a single strut that supports an underpurlin. The ‘area required’ is the roof area supported by the strut.

2

B

2

A

This is calculated as follows:-Roof Area Supported =

Sum of half the underpurlin spans either side of the strut (A/2) multiplied by the sum of half the rafter spans either side of the underpurlin (B/2).

AS 1684 Span TablesRoof Member Load Impacts – Roof Area Supported

A

Stru tting Beam Span

Strutting Beam

Underpurlin

S trut

A/2

B/2

B

AS 1684 Span TablesStrutting Beam Design Example

Inputs requiredWind Classification = N2Stress Grade = F8Roof Area Supported = 6m2

Strutting Beam Span = 2900 mmSingle or Continuous Span = SingleRoof Mass (Sheet or Tile) = Steel Sheet (20

kg/m2)

Roof Area Supported = 6m2

2 x 140 x 45 mm F17 members are adequate

Roof = SheetStrutting Beam Span = 2900 mm

AS 1684 Span TablesStrutting Beam Design Example

Return to menuAS 1684 Span TablesWall Framing

WALL FRAMING

Return to menuAS 1684 Span TablesWall Framing

T im b e r o r m e t a l b r a c in gTo p p la t e

B o t t o m p la te

J a c k s tu d

J a m b s t u d

W a l l i n te r s e c t io n

N o g g in g

C o m m o n s t u d

L i n te l

S h e e t b r a c in g

Return to menuAS 1684 Span TablesWall Studs Design Example

Inputs requiredWind Classification = N2Stress Grade = MGP10Notched 20 mm = YesStud Height = 2400 mmRafter/Truss Spacing = 900 mmRoof Load Width (RLW) = 5000 mmStud Spacing = 450 mmRoof Type = Steel Sheet (20 kg/m2)

Wall Framing – Wall Stud Size

Inputs required• Wind Classification = N2• Stress Grade = MGP10• Notched 20 mm = Yes• Stud Spacing = 450 mm• Roof Type = Steel Sheet (20 kg/m2)• Rafter/Truss Spacing = 900 mm• Roof Load Width (RLW) = 5000 mm• Stud Height = 2400 mm

Inputs required• Wind Classification = N2• Stress Grade = MGP10• Notched 20 mm = Yes• Stud Spacing = 450 mm• Roof Type = Steel Sheet (20 kg/m2)• Rafter/Truss Spacing = 900 mm• Roof Load Width (RLW) = 5000 mm• Stud Height = 2400 mm

Simplify tableAt least 5000mm

70 x 35mm

MGP10 wall studs

are adequate

2006

Return to menuAS 1684 Span TablesTop Plate Design Example

Inputs requiredWind Classification = N2Stress Grade = MGP10Rafter/Truss Spacing = 900 mmRoof Load Width (RLW) = 5000 mmStud Spacing = 450 mmRoof Type = Steel Sheet (20 kg/m2)

Wall Framing – Top Plate Size

Simplify table

Inputs required• Wind Classification = N2• Stress Grade = MGP10• Roof Type = Steel Sheet (20 kg/m2)• Rafter/Truss Spacing = 900 mm• Tie-Down Spacing = 900 mm• Roof Load Width (RLW) = 5000 mm• Stud Spacing = 450 mm

At least 5000mm

2 x 35x 70mm

MGP10 top plates are adequate

2006

AS 1684 Span TablesWall Framing – Wall Lintel Design Example

Inputs requiredWind Classification = N2Stress Grade = F17Opening size = 2400 mmRafter/Truss Spacing = 900 mmRoof Load Width (RLW) = 2500 mmRoof Type = Steel Sheet (20 kg/m2)

Wall Framing – Lintel Size

Simplify table

Inputs required• Wind Classification = N2• Stress Grade = F17• Roof Type = Steel Sheet (20 kg/m2)• Roof Load Width (RLW) = 2500 mm• Rafter/Truss Spacing = 900 mm• Opening size = 2400 mm

Inputs required• Wind Classification = N2• Stress Grade = F17• Roof Type = Steel Sheet (20 kg/m2)• Roof Load Width (RLW) = 2500 mm• Rafter/Truss Spacing = 900 mm• Opening size = 2400 mm

Use 3000mmUse 1200mm

A 140 x 35mm

F17 Lintel is

adequate

2006

Return to menuAS 1684 Span TablesFloor Framing

FLOOR FRAMING

Floor bearers

Floor joists

AS 1684 Span TablesFloor Framing – Floor Members

Perimeter Brickwork

Platform Floor Sheets

Bearers are commonly made from hardwood or engineered timber products and are laid over sub-floor supports.Bearers are sized according to span and spacings – typically a 1.8m (up to 3.6m) grid

Bearer spanBearer spacing Bearer SpanBearer Spacing

AS 1684 Span TablesFloor Framing – Floor Bearers

AS 1684 Span TablesFloor Framing – Floor Load Width Example

If a = 900 mm x = 2000 mm y = 4000 mm

FLW A = 1900 mmFLW B = 3000 mmFLW C = 2000 mm

4500

Simple rectangular shaped light-weight home

Gable Roof =25o pitch

Steel Sheet = 20 kg/m2

Wind Speed = N2

Wall Height = 2400 mm

Elevation

3600

Section

Floor joistsBearers

AS 1684 Span TablesFloor Framing – Bearer and Floor Joist Example

Bearer A

And a floor load

Supports both a Roof Load

3600

Section

1800

Floor Load Width (FLW) Bearers at 1800 mm centresFLWA = 1800/2 = 900 mm

Floor Joists at 450 mm crs

AS 1684 Span TablesFloor Framing – Bearer Design Example

x ya b

RLW RLW

A B

ayx

2

Roof Load Width (FLW) for Wall A =


a = 496 mm

x = 1986 mm

Total RLW On Wall A = 1986 mm (say 2000 mm) + 496 mm (say 500 mm) = 2500 mm


Inputs required• Wind Classification = N2• Stress Grade = F17• Floor Load Width (FLW) at A = 900 mm• Roof Load Width (RLW) = 2500 mm• Single or Continuous Span = Continuous• Roof Mass (Sheet or Tile) = Steel Sheet (20 kg/m2)• Bearer Span = 1800 mm

Floor Framing – Bearer Size

2006

Inputs required• Wind Classification = N2• Stress Grade = F17• Floor Load Width (FLW) at A = 900 mm• Roof Mass (Sheet or Tile)= Steel Sheet

(20 kg/m2) Single or Continuous Span = Continuous

• Roof Load Width (RLW) = 2500 mm• Bearer Span = 1800mm

Inputs required• Wind Classification = N2• Stress Grade = F17• Floor Load Width (FLW) at A = 900 mm• Roof Mass (Sheet or Tile)= Steel Sheet

(20 kg/m2) Single or Continuous Span = Continuous

• Roof Load Width (RLW) = 2500 mm• Bearer Span = 1800mm

Simplify table

Use 1200mm table

Use 4500mm

2 x 90 x 35mm F17 members joined

together are adequate

AS 1684 Span TablesFloor Joist Design Example

Inputs requiredWind Classification = N2Stress Grade = F17Roof Load Width (RLW) = 0 mm(just supporting floor loads)Single or Continuous Span = Continuous (max 1800)Roof Type = Steel Sheet (20 kg/m2)Joist Spacing = 450 mm

Floor Framing – Floor Joist Design Example

Simplify table

2006

Inputs required

Wind Classification = N2

Stress Grade = F17

Joist Spacing = 450 mm

Roof Type = Steel Sheet (20 kg/m2)

Single or Continuous Span = Continuous (max 1800)

Roof Load Width (RLW)= 0 mm

Joist span = 1800mm

Inputs required

Wind Classification = N2

Stress Grade = F17

Joist Spacing = 450 mm

Roof Type = Steel Sheet (20 kg/m2)

Single or Continuous Span = Continuous (max 1800)

Roof Load Width (RLW)= 0 mm

Joist span = 1800mm

At least 1800mm

90 x 35mm F17 floor joists at 450mm crs

are adequate

Further Information

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TIMBER FRAMING USING AS 1684.2 SPAN TABLES

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