Flat roof help

[Kayos]

Evening all, I need to replace the shonky,leaking, failed roof on my garage. It's currently corrugated iron badly fitted in about a million pieces. I'm thinking of a flat roof as i think it will be cheaper, easier and I only need it to last 12 months anyway.

The help I need is what to buy, I'm after a simple system that doesn't need heat, and I don't want to spend more than £250 including the ply

Any brands to buy or avoid? And other than the ply what is actually needed? The beams are good, I've a facia for the sides, the back goes to a gutter and the front is going to be a raised lip, as it's now a brick wall that's getting demolished. It's about 17 square metres

 

[Bobtail4x4]

new wriggly tin would be easier and probably as cheap.

 

[Shedendman]

Exterior grade ply for a start 18mm,where you get it the cheapest is down to you shop around,try a reclaim yard etc screw it down.
Cheap top felt that will last 12mths from B&Q how much you will need depends on the roof itself,15mm clouts and a pot of black sticky stuff (bitumen paint) for your nails and joints

 

[DanielW]

Look on toolstation or screwfix for the corrugated perspex roofing sheets,tis the way to go.

Probably run to about £80 or less as you have to buy a certain amount of pieces?

 

[Rig Pig]

new wriggly tin would be easier and probably as cheap.

+1 for tin as the cheapest option but you will have condensation issues. If you use tec screws the tin will be reusable / re sellable once you have finished with it.

 

[bigegg]

Auction at murton almost always has roofing sheets at silly cheap - I bought 18 sheets of translucent fibreglass(?) box profile - enough to do two 20ftx10ft garages for 84 quid in october.

Could have bought about 10 or 12 24ft sheets of 6inch thick kingspan for 240 quid - IF I could have got them home in my swb transit!

 

[Kayos]

Some great ideas, thanks.

The condensation is a reason I want to move away from tin, clear is no good either as its 18 foot long, so needs 10 foot sheets for an overlap, plus I'm not happy about a clear roof with all the gear in there!

Can get 18mm exterior ply delivered for a good price so just looking into flat roof coverings really, in 12 months ish it's getting demolished and made bigger so cheap but waterproof is the key

 

[DanielW]

http://www.screwfix.com/c/building-joinery/sheet-roofing/cat3830024

 

[bigegg]

know any printers? litho blankets put on rubber side down and painted with bitumen paint will last years.

 

[bigegg]

A thought occurs, based upon my recent experience with the two garages I've just done...
How steep is the slope on the roof? and are the rafters bowed at all?
If they are bowed, and the roof isn't sloped enough (mine dropped 1 inch every 24" panel, so not very), water will pool and force itself through a felt roof..
Corrugated iron doesn't have that problem.

 

[Kayos]

The rafters are good, best bit of it tbh.......

It's a sectional garage so I'm guessing the slope is similar, although it looks more, will get the tape out tomorrow

 

[bigegg]

it might have been 2" per panel, but still not enough, compared to the 45deg slope that felt really needs...

 

[DAPPH]

Wickes sell a fibre & pitch corrugated sheet,they last 30 yrs or so I think the trade name is Oiline or similar, They are not too expensive and don't condense moisture as much as thin wriggly tin sheets do.
You can bitumen seal the over laps , you must always fit them so as to have the side overlaps away from the prevailing harsh weather
( There are plenty of Youtube clips about fitting them )


Alternatively you can do what I'm having done this week & into next week .

I'm having the garage's leaky ( Second hand 30 years ago ) condensing corrugated Plastisol sheets removed & am having it re-roofed in full length flat , rain resisting ,interlocking panels that are Plastisol covered galv sheet sandwiches that have a 3" thick density foam infill. Even though these are seconds with scrapes on the underside they should last 20 years or more .

You might also benefit from clear sealing the garage floor to stop moisture coming in through the floor slab & also to seal the walls with a spray on concrete seal as it's amazing just how much moisture the walls & floors let pass.

I'm also having two small hit & miss 4 " vents put in with a face plate inside &7outside on each ..one in each back corner at just over 2 mtrs up from the floor . This is allow a gentle air flow to stop things sweating should it become really damp & cold for a long time.
.

As these flat sheets are fixed with extra long Tex screws it's so easy to take them off . plug the small holes with plug bolts and sealing washers , then use them elsewhere .
Even as part of a apex'd roof , for there are options to have centre nosed flashing strips
over the top of the apex .

If you have an up & over door it may also be useful to put a well treated with anti rot liquid rain lip deflecting baton down with stainless steel screws on a thick silicone bead. My rain deflecting baton is going to have champhered edges & an aluminum covering over it so I can roll hard nylon castor'd trollies over it with ease.

 

[SmartWerks]

+1 for the wickes felt. Although it is best to fit it in hot weather as it's much easier to work with and get a good neat job. I also silicone the battens, but that's not best done on a hot day which reminds me I need to redo it

SmartWerks

 

[Shedendman]

You dont say how big an area this roof is,for a budget of £250,i'd stick with ply and felt

 

[roofman]

Iff you just want to get 12 months out of it then the most cost effective way would be
6 sheets of 18mm plywood £96
3 rolls of 4mm torch-on sand finnish £117.00
1 19kg bottle of propane £29.00
All plus VAT and should take you a day...iff you was nearer ide do it for you in 3 hours start to finnish. The prices are worked out using my trade discount code which is more or less what you wopuld expect to pay anywhere in the country. hope this helps.

 

[Wendelspanswick]

Wickes sell a fibre & pitch corrugated sheet,they last 30 yrs or so I think the trade name is Oiline or similar, They are not too expensive and don't condense moisture as much as thin wriggly tin sheets do.
You can bitumen seal the over laps , you must always fit them so as to have the side overlaps away from the prevailing harsh weather
( There are plenty of Youtube clips about fitting them )


Alternatively you can do what I'm having done this week & into next week .

I'm having the garage's leaky ( Second hand 30 years ago ) condensing corrugated Plastisol sheets removed & am having it re-roofed in full length flat , rain resisting ,interlocking panels that are Plastisol covered galv sheet sandwiches that have a 3" thick density foam infill. Even though these are seconds with scrapes on the underside they should last 20 years or more .

You might also benefit from clear sealing the garage floor to stop moisture coming in through the floor slab & also to seal the walls with a spray on concrete seal as it's amazing just how much moisture the walls & floors let pass.

I'm also having two small hit & miss 4 " vents put in with a face plate inside &7outside on each ..one in each back corner at just over 2 mtrs up from the floor . This is allow a gentle air flow to stop things sweating should it become really damp & cold for a long time.
.

As these flat sheets are fixed with extra long Tex screws it's so easy to take them off . plug the small holes with plug bolts and sealing washers , then use them elsewhere .
Even as part of a apex'd roof , for there are options to have centre nosed flashing strips
over the top of the apex .

If you have an up & over door it may also be useful to put a well treated with anti rot liquid rain lip deflecting baton down with stainless steel screws on a thick silicone bead. My rain deflecting baton is going to have champhered edges & an aluminum covering over it so I can roll hard nylon castor'd trollies over it with ease.

Onduline is the name you are looking for, I roofed a portable horse shelter with it about 20 years ago and it is still leak proof.

 

[Kayos]

Got this done yesterday, Used 18mm ply, sealed the top of the concrete sections with flexible waterproof adhesive and loads of screws. Ended up repairing the shockingly bad lintel over the door and putting an upstand all the way around it, as well as making a new facia board for the front.
Didn't use torch on felt as I don't have a torch or gas, I used plenty of nails and sealant.

It absolutely lashed it down as I was tidying up and the inside was bone dry, the water from the old roof has even dried out now