ceilings & basic roofing revision created by michael martin march 2004 / revised april 2007
TRANSCRIPT
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.