Garage roof is leaking badly

radioactiveman

Hi
Will keep this short - my garage roof is leaking fairly badly in about 4 places.
3 of the places are along the wall.

The roof itself is done using very simple corrugated iron roofing. The sheets of iron kind of "fit in" to the concrete at the top of the highest wall (the roof is slanted at about 15 degrees), and apart from that they are just nailed into the joists underneath.
It's almost like they nailed on the sheets of iron when they were building it (previous owners of the house), then put concrete over the sheets along the highest wall to keep everything in place :rolleyes: :mad:

There is some black roofing felt over the joists as well but that is pretty much all there is.

Because the leaks are all along the wall I suspect the water is getting in between the corrugated iron and the concrete and just seeping down. In another place it looks like the water is either being blown in between the sheets of iron or just coming in through the hole where the sheet is nailed to the joist.
You can also see the joists all soaked with water (all of them actually) and patches of moisture on the wall.

What is the best way to fix this? There is no lead flashing between the corrugated iron sheet and the concrete. Would adding flashing solve this or would you also need to redo the whole roof and make sure it's properly sealed?

The wall in one spot is constantly damp and you can see the concrete beginning to crumble.

items

Sounds like an awful mess, unless your absolutely certain where water is getting in then a few patch ups with torch on felt could do. Most cases you cant find exactly where water is getting in, you end up chasing your tail, forever patching up areas.

Might sound more the obvious but replacing entire roof may be the only option, many different types of corrugated king span sheets avail all within a good price, they are very self supportive, very little structure required underneath to support sheets. Measure up square foot of roof and make a few phone calls for prices, if its too much then spend some time pin pointing exact leak areas.

If it was me, I'd re sheet roof over the old stuff with a marine grade ply and include tilting fillets (search tilting fillet on net) then paint over the lot with water proof / torch on felt type sealer. Then felt over roof with torch on or just normal felt, flashing for all roof / wall meets.

Got a bit mixed up, you wont be able to fix leaks with torch on, entire roof seems to be corrugated now that I've read over a second time. Enough info there either way, quick con saw to cut a groove in wall for flashing may solve 3 leaks.

radioactiveman

Hi this is a picture of the roof to make it a bit clearer



I wonder would adding flashing on the concrete at the top be enough?

items

Not as bad as I thought. If corrugated sheets go into parapet wall enough then roof should be water tight. What is fixed to ridge, proper ridge tiles / sheets or just poured concrete? If its concrete maybe its deteriorated, break it all off if you can then fix proper ridge tiles / sheets so water can run off / cant travel back with wind etc.