Leaking Felt Flat Garage Roof

[calgary]

Hello everyone,

I've only just joined after reading through many previous posts for similar issues.

I have a double garage flat roof that is leaking in several areas. The chipboard/plywood underneath is wet in several places and so we need to fix it asap. We had two quotes come in for fixing the roof ranging from £1200 to £4k (contractor that refused to do a makeshift fix and wanted to replace felt and plywood.) We plan to convert half the garage next year where we'll likely replace the whole roof and make it pitched and so want to minimize the expediture right now. However, I don't want to cause structural problems by doing the wrong 'thing'.

From reading through old posts it sounds like painting the whole roof with Acrypol for about £250 will be a good interim measure. It should make it waterproof and as it allows moisture to pass through the wet boards should eventually dry out. Is this correct or are there better solutions?

Thanks!

 

[Burnerman]

Its probably as good as anything - there is another solution by a firm called Aquaseal. Either way, they are just put you off treatments.
Anyway, a double garage flat roof is a considerable area, and one which will have considerable expansion when the sun comes out so roll on the pitched conversion!
If your roof boards are chipboard, it will have swollen to twice its thickness - if its ply then it will rot and delaminate eventually. Keep as much air flow through the garage as you can to help it dry out.
John

 

[SASroofer]

I'd roll and pour a layer of elastomeric felt over it using hot bitumen for £450, will last as long as you need it to.

 

[Ethorathius]

I would tear it down as flat roofs are terrible and do your proposed work now. Why spend a few hundred quid on a temp fix only to alter it all at a later date. throw some plastic sheeting over it as a dirt cheap fix or do a proper job and get a good pitch on it.

 

[fushionjulz]

It's a big roof, alright...but it could be done properly for around £500 as a DIY project...Shame it's so late in the year where good (dry and light) days are not guaranteed...

Personally, I'd strip it back to the beams...then use either sheets of 18mm 13lam ply or planks of 4x1" treated timber to provide a new, solid base...
Then 2 layers of underfelt tacked and stuck and a final top layer stuck down with adhesive bitumen only...
That would last 10yrs+ and be entirely waterproof...

If you do this, don't forget you need a run-off slope (no flat roof is 100% level)