Ceilings & Basic Roofing

Revision

Created by Michael Martin March 2004 / revised April 2007

General Revision

Textbook questions & answers Review A4 sheets Components sketches All calculation exercises ceilings and roofs

Ceiling Frames Basic set-out of ceiling frame Members & their function

Ceilings continued

What is the function of a hanging beam ?

To support the ceiling joists mid-span, must be blocked at ends and a counter beam?

What is the function of the ceiling joists themselves ?

To support the lining material and also act as a tie between opposing rafters

Ceilings continued

Also support to members

Review your worksheets from this section

Flat roofs

Generally less than 10º pitch

More often ceiling joists and rafters all in one

Skillion roofs

Walls at either end at different heights

Two ceiling types, raked and level

Lean to roofs

Constructed against an other wall or roof

Extensions Carports Verandas awnings

Simplest method of marking skillion roofs

Scribe the birdsmouth

Gable roofs

Members and their function

Finish’s Calculations Revise your

worksheets for this section

Quick Questions

What is the function of a purlin? To give support to the rafters mid span Where can a strut gain support from? It either has to transfer it’s load to a load bearing

wall or a strutting beam What is the function of collar ties? To stop rafters from sagging acting as a tie

between opposing rafters above the purlin

Set out of common rafters

Can be done with steel square or

By calculation

Plumb & level bevel

Remember where they are in relation to the roof

P28 of text handout

Transfer onto steel square

Gable definitions – Review handout Span – horizontal distance overall the wall plates Rise – vertical height from the x-y line to where

the upper edge of rafters would intersect ½ span or run – plan length of rafter Centre line length or set out length – the

hypotenuse in the triangle, formed by the ½ span and the rise

Roof pitch – expressed in different ways, degrees, pitch ratio etc. see P56 of your handout notes

Other roof members – left to right

purlin

strut

Wind bracingridge

Collar tie

Other struts (this one is a half scissor)

Scissor struts

Gable end finishes

Flush gable

Verge overhang ?

Boxed gable ?

Extra members for boxed gables ? With boxed gable ends you have A bottom chord or tie piece Also gable studs for fixing of linings

Or for ties to veneer skin

Calculations

Review you worksheets

Review calculation sheets recently done in class

Now you can build this

Test next week 5:30 to 7:00

Then class continues after dinner break.