roof replacement of out house

[skye16]

I have an old brick built out house with a leaking corrugated (asbestos?) roof. It's about 12 feet square and the roof has a slight slope. The walls are sound.

I would like to convert it into a DIY workshop. What is the best way for me to put a new roof on? Can I put glass in the roof to give more light? Also, there is a worm eaten support post in the middle of the out house, propping up the timber roof framework. When I put a new roof on, will I need to suport it with internal posts?

Thanks very much for any suggestions.

skye16

 

[Shytalkz]

Asbestos: these days, pain the arse to get rid of, licensed contractor, tip etc. Or take it off yourself, bury in the garden in the dead of night and say nothing. To anyone. Ever.

Timbers are most probably inadequately sized to take tiles or glass; post in the middle suggests that it might have sagged already? Size of rafters and need for propping or other intermediate support depends on span. Oh you said 12 foot, d'oh! To span from top to bottom, with tiles, needs 50x175C16 at 400 centres. Bet they're something like 50x75 at the moment, though!

 

[Deluks]

Quite a few asbestos roof related questions in the roofing section, have a browse. Easiest option would be to use corrugated metal or bitumen sheeting, with a clear sheet of the same profile to match.

 

[skye16]

Thanks for your quick responses. I'm not sure if it is asbestos - it could just be very old fibre material.

What I was wondering was if I could cover the area with say 4 x 2 rafters and noggins ? and whether they would be strong enough to support some areas of safety glass. I'm keen on DIY, but don't have much experience.

Thanks once again for your help.

 

[Deluks]

What size and condition are the current roof timbers? You say safety glass but what are you actually going to use as the main roof covering?

Sort the basics first and ask about natural light options afterwards.

 

[skye16]

Thanks for your reply.
All the roof timbers are rotten and have woodworm. As you can see, I'm not sure how to build a framework to support the new roof, or what materials it should be covered with. I would like it to be really weatherproof, if I'm hoping to fit it out as a workshop.
Thanks once again for your help.

 

[noseall]

shytalks has already suggested the structural sized rafters needed in his first reply.

if you use the size suggested then there will be no need for propping and you can fit heavy tiles if you wish.

is it a lean-to roof?

 

[Shytalkz]

Nose, I think it is a lean-to. In which case, I forgot to add that needs a timber plate (50x150) bolted (M12s at 600 say) to the wall at top, with the rafters birdsmouthed over, to stop eaves spread. Size given will deal with tiles of any type, or glazing.

Alternatively, FNT might advise you that I'm talking out of my arse and that you don't need bolts or a plate, just a steel lintel, whatever size they've got in stock at Jewsons, with 150 bearing each end...

 

[noseall]

i have concerns over what the roof will be leaning onto at the high end.

if it is a single, weak 4" wall then there may be issues regards push.

this could warrant a mid-span, purlin?

 

[Shytalkz]

No spread if rafters are adequately sized and rafter is birdsmouthed top and bottom. However if top end is a half brick thick, freestanding wall with no piers, then it's all a bit rickety.

Midspan purlin needs to span the same distance as full span rafters, so will be a sizeable chunk of timber, especially if inclined to the roof slope.

 

[skye16]

I've just got in. Thanks for the helpful posts.
The present roof is sloping (pent) and has two rafters and one cross beam, propped up. It's 4 x 2 timber. Am I right in thinking that I need 50 x 175, which is about 2"x6" for the rafters.
The walls are very sound. One last thing - it's a stand alone building, not leaning against anything.
Thanks once again.