Concrete Garage Roof Fix/Repair Help

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Concrete Garage Roof Fix/Repair Help


Mar 4, 2022
United kingdom
Hi all,

I am trying to figure out the best way to repair/fix up my concrete garage roof. There are 2 issues as far as I can tell, and I have very little experience with concrete (especially outdoors).

1. It has a draining hole towards the back of the roof, but that hole doesnt seem to be the low point anymore. The roof is no holding water in spots, which seems to be making the walls saturated and never dry.

2. There used to be a raised concrete border that was ramped shaped to stop the water draining off the sides of the roof and make sure it went down the draining hole. The concrete has separated from the roof and I was able to lift off the "ramp" and it was wet underneath, so I think it actually helping keep the roof wet!

The concrete is really coarse, probably from age and erosion?

I am not planning on staying in this house for too long, but don't want to leave the buyers with a rotting garage. One idea was to build a timber flat roof on top of the concrete with a decent gradient and felt it. (about £350 for materials).

Do you think this is the best way to go, or is repairing the concrete in some way a cleaner, cost effective solution? (self leveller of some kind, re do the retaining ramp and treat with something? will the old concrete need prep work for a good bond etc??)

Any way, I am a bit stuck on how to proceed without eating in to my profits when I sell!

Any help would be greatly appreciated.


Established member
Oct 11, 2011
Father in law had his ‘concrete’ corrugated roof, not sure if you mean a slab roof…
Either way you can replace with ‘box profile’ roofing replacing the corrugated concrete or, as I did over a friends flat slab roof, overpanel it with box profile…you will need to support it at the recommended distances and go no less than 12 degree slope