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Rafter birdsmouth

i am matching the existing roof but the problem is we dont need a birdsmouth cut as the timber is inline with the roof without cuting it,so what can i put under the timber now to fill the gap

3 Answers from MyBuilder Roofers

Best Answer

The Idea of the birdsmouth is so the rafter has a sound base for fixing also stops the roof spreading. should have used wider timber rafters however if its to late for that then cut small wooden chocks to fit under neath the rafter and fix through the ceiling joist with a good fixing. Bit of a cowboy way to do it but if the roofs on now not a lot you can do.


Answered 18th Aug 2011


Surely you're using a smaller sized rafter then? Can't you use same section rafters? so you can have a birdsmouth... and then under side of the rafter would line up?

You need a birdsmouth to stop the rafter sliding out at the bottom. Otherwise the roof could collapse. You could cut one in the timber you have... then make up the difference with batten or a timber ripped down to suit. Then fix it on top of the rafter. It's not an ideal job though... a bit Clint Eastwood


Answered 18th Aug 2011

building control wont have it done that way , you will have to change the timber to the right size


Answered 18th Aug 2011

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