Pitched roof on top of old flat roof

18 Jan 2023
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United Kingdom
Had a leak from upstairs downpipe so fitted a new rubber boss. First time popping my head into garage roof hatch since moving in.

See photos

I’m thinking of tearing the remains of the garage flat roof out and insulating and boarding for storage. Will I be ok removing the short vertical pieces of wood while I do this and once finished put new ones in. Or are they integral to support the roof?

Would it be safe to knock one of them out then insulate/board that area and put new one in before removing another?



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Why would they have put those in if they do not serve a purpose? What is the size and span of the rafters?
Not sure, probably cowboys judging by the other work previously done on the house before we bought it

I’ve no knowledge of roofing so can you describe to a novice how to work out rafter span/size and I’ll pop my head up with a tape measure.

The span you want to measure is from the wall at the top to the bottom bit of timber it's siting on at the eaves, ignore the purin whch is what you want to get rid of. So on this diagram measure the 'calculated rafter span'.


Then measure the depth and width of the rafters. Then measure the distance between each rafter.
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Rafter span roughly ten foot.
Roughly 370mm between each rafter
Rafters are 140mm x 40mm

That sound right?
So you should be OK in theory to remove them, the size of your rafters and spacing's is just about OK for the span, this is an extract from the Building Regulations when they used to list the standard rafter spans:

Proceed with caution and at your own risk though as it is a bit odd they've done it.

Caution noted. I’ll do a section at a time so there’s only one out at any given moment. Then replace it after I finish each section.

Many thanks for your expertise, much appreciated

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