Birdmouth in middle of rafter

david2012 · Saturday at 9:10 PM

Hello folks.

I’m having a lift conversion done. On one side the carpenter has cut birdsmouth notches into the middle of the rafters to fit a stud wall. Does this look ok, to me it seems a bit pointless putting up a huge piece of wood to suspend the roof and then cutting a notch into it.

robinbanks · Saturday at 9:52 PM

Most be some whopping span on those rafters

noseall · Sunday at 5:54 AM

david2012 said:
Hello folks.

I’m having a lift conversion done. On one side the carpenter has cut birdsmouth notches into the middle of the rafters to fit a stud wall. Does this look ok, to me it seems a bit pointless putting up a huge piece of wood to suspend the roof and then cutting a notch into it.

View attachment 411435

It might be a structural requirement (restraint?) as the floor joists go in the opposite direction to the rafters?

stevie888 · Sunday at 9:16 AM

Is there a load bearing wall under the studs? The base plate seems to be set way down so there may be support provided by the studwork but those are huge rafters so not obvious quite what's going on.

For peace of mind, I would get confirmation from your designer before you go any further

^woody^ · Monday at 4:31 PM

That studwork, if not designed to be load bearing, certainly is now and should be in turn supported by a suitable beam.

tony1851 · 2026-04-02T08:30:23+0100

For the rafters themselves, structurally it isn't a problem. Assuming its a loft conversion, its probably easier to use deeper rafters to accommodate the ridiculous thicknesses of PIR now required for insulation, without having to put too much more under the rafter.
As above, the stud wall will be supporting some weight - assume there is an adequate beam underneath it?

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Birdmouth in middle of rafter

david2012

robinbanks

noseall

stevie888

^woody^

tony1851

DIYnot Local

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