Garage roof options?

sickparrot

Howdy there,

My garage roof is once again giving me loads of grief, in the freezing weather it got loads of frozen condensation on the underside of it which then proceeded to 'rain' on everything inside when it thawed out. It's made of corrugated bitumen sheeting, sloping gently towards the rear. I've had problems with sagging in the past and subsequent leaks because the battens aren't close enough together, so now I'm thinking about replacing the whole thing.

Does anyone have any opinions about these options? (ability to withstand sun, cold, etc)

1. Replace the sagged sheets, put the extra battens in, glue some bits of polystyrene insulation in the gaps to reduce the condensation.

2. replace the whole lot with cheaper corrugated transparent PVC lying on top of a continuous sheet of insulation on top of the existing battens. This would have the benefit of being translucent and let light in.

3. try and source some tin sheeting but this will probably be expensive and still have the condensation problem.

would a bed of plywood eliminate condensation?

cheers for any advice.

ormus

plywood is expensive, use OSB instead. thats fairly cheap. a layer of insulation, and then your chosen roofing material.
8x4 sheet, OSB, is about 12 quid.

you can paint OSB too. with any old paint to help it last longer.

savemoney

EPDM is good roofing material it goes on with glue. I have a garage flat roof, rear extension, front porch and bay window with it, although you can get different get a good thickness as you can tell the difference

I got another garage which has felt on and that constantly fills with water creating ponds but doesn't leak

27col

My garage sized garden shed is close boarded and covered with roofing felt. There is no condensation or sagging. If you board out your shed with OSB or whatever you can get. You can then cover it with whatever takes your fancy, Felt, corrugated bitumen,galvanised tin or anything else. Any of these methods are easy to do yourself. The first thing to do will be to install more roof beams of course. I have never had any condensation in my shed. The boards on my shed roof are about 1" thick. They came from an old bus depot that was being demolished.
As a general rule I think that you will find that cheap corrugated plastic is absolute rubbish. You have only to look at various porches around the neighbourhood to realise this.

sickparrot

Looks like OSB is the way to go then, will 11mm be thick enough?

leveller2911

If its a garage then 18mm thick OSB ......Most garage joists will be either 16" or 400 mm centres or even 600 mm centres between joists..