Looking to do a loft conversion...

[DanGovier]

Hi guys, I'm looking for a bit of advice please.

I've got a 3 bed semi and I'm looking to convert the loft into some usable space. From what I can see the purlins are constructed from two separate pieces with a diagonal join in the middle, which are in turn braced against the chimney breast with diagonal supports. There are also a number of horizontal braces, a couple of which attach to the purlins and the rest attach to the rafters. The apex of the roof is a good 8-9ft high... I'm 6ft and I can't reach it.

My plan was to add new horizontal bracing between each rafter to create what in effect would be a 7ft ceiling, and then add some vertical studwork under/behind the purlins (attached to the joists and rafters) for both additional support and cupboard space.

Would that be enough support to be able to remove the current horizontal bracing? And, at some point I'd like to remove the diagonal supports holding up the purlins. I assume that means I'll have to replace the current purlins with steel beams?

Here's a couple of pics:

Thanks!

 

[Ian H]

I DIY'd a loft conversion.

For ages I tried to avoid paying for a Structural Engineer but in the end I had to and it turned out to be the best money I spent on any part of the house.

The cost to give peace of mind is well worth it so I would recommend you do the same

 

[Doggit]

But you did it properly Ian, and got the builders in as well as the SE. So, first pertinent question, is this a DIY job, done under a building control notice, or just a cheap DIY job to give you a bit of space.

An SE would tell you if the purlins were strong enough to provide support on their own, they would also tell you the size of joists needed to support the new floor, and whether you need steels under the purlins to support them, and whether the bracing for the ceiling would provide the additional support required. Do you have a central wall that the new floor joists can sit upon. You can't take out the struts from the purlin to the chimney, and then take the to the ceiling joists, as they aren't strong enough, so this does need careful consideration; it can be done by yourself, and you could do it without building control, but you need to serious professional advice to make sure the roof doesn't sag,or even worse.

 

[Ian H]

But you did it properly Ian, and got the builders in as well as the SE.

Well, I guess I half DIY'd it

 

[Doggit]

Yes you did, and you should be proud of what you achieved.