# Waterproofing Garage Roof



## Paulg (9 Oct 2012)

I have recently moved house and the garage roof is not in the best of condition. The garage itself is a concrete pre-fab and the roof is concrete panel type. There are numerous leaks in the roof around the joints and possibly from cracks in the panel.

Does anyone know the best way to waterproof (as best as possible) the roof from the inside ? I can't get safe access to the whole top of the roof, and re-roofing is not currently an option due to cost. Ideally, I would like to replace it with a proper brick / block built garage in a few years, so I don't need anything too clever.

Thanks


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## marcros (9 Oct 2012)

Paul,

I am in a similar situation, albeit I can get to the roof. but my need was rather more urgent as there was water pouring through a hole and wrecking stuff inside by the time that I realised.

I bunged a large tarpaulin over the whole roof. Double thickness. I fixed it to the soffits using some battens and nails and trimmed off the excess. It isnt the most elegant of coverings (at least it is green rather than blue) but has bought me enough tome to work out what to do longer term. Like you, I want to rebuiold it in time, but the roof was the most immediate requirement. I think that come spring I will do something more permanent, but like I said, it does for now. A decent covering to replace the stuff you have will cost a reasonable amount money, and then you have a good roof sat on a crappy prefab garage (at least I would have), so I would rather plan what I am going to do and do it once.

HTH
Mark


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## beech1948 (9 Oct 2012)

1) a possible solution for a few years would be to leave your roof in place and cover it with corrugated bitumen panels such as Onduline. Can be had from Wickes and others I think.

2) second idea would be to apply glassfibre either on top or on the bottom of the roof panel and over the joints. Glass fibre is cheap resin is a bit pricey...maybe someone here might let you have some...I don'y know.

Al


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## Racers (9 Oct 2012)

Hi,

I would use black bitumen paint the stuff for repairing flat roofs, its cheap and seems to last well, it's will probbaly last untill you can do a proper job.

Pete


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## No skills (9 Oct 2012)

I would imagine if you try to stop the leaks from the inside you will end up trapping water in the gaps/cracks of the roof panels, couple of possible side effects would be water traveling and making a leak in another place in the roof, the water might freeze in the winter weather and cause more damage to the concrete. Not to mention possible mould problems..

Could you reach all areas of the roof (on the top) with a long handled roller? if so then a large amount of bitumen paint poured and rolled on the roof might give a temperary repair.

HTH


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## Paulg (10 Oct 2012)

Thanks for all the suggestions. The garage is 5m x 3.3m and I only have access to one side and one end. Currently the roof is covered in moss, so I would need to clean that first before putting anything on top. 

I think I will get some bitumen paint and have a go at one end to see how big a job its going to be to clean & paint on top.

Thanks

PG


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## mbartlett99 (10 Oct 2012)

Pressure wash for the moss and bitumen paint would be the easiest and still probably last a few years.


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## Eric The Viking (10 Oct 2012)

Do the bitumen EARLY ON A DRY DAY, pref with sunshine after you've done it. It's water soluble until it's dried (DAMHIK!). :-(

When dry it does work really well.

If you find an obviously damaged area, use Flashbband to patch it. Straight onto concrete, dry and warm it first with a hot air paint stripper, and warm the patch once you've applied it. 

Flashband can be cut with a sharp knife or tin snips and comes in various widths, and places like Wickes and Toolstation do "own brand" versions that are probably cheaper than the brand. There is a 'primer' for awkward surfaces, but although I've got some it's hardly necessary, especially if you heat the stuff. It's also really good for patching roofing felt, and with care you can do it from inside the loft.

E.


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