Corrugated bitumen garage roof - flashing ?

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Hi,

I'm replacing the asbestos concrete roof this weekend with some corrugated bitumen sheets from Wickes. At one end of the garage there is a wall along which the straight (long) edge of the sheeting will butt up against. What should i do here so that water doesn't leak between the two ? The current roof looks like it's been fixed in with a small amount of now crumbling concrete, i'm guessing this is not the best way to do this. Is there some sort of flashing i can use with corrugated bitumen sheets ? What do you guys recommend ?

Thanks for any help
Alistair
 
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The best way would be to use lead tucked into the mortar joints on the wall. You'd need to remove the mortar though and then fix the lead with special clips then fill the joint with lead sealant.

Tricky job for diy, a lot easier if it's just a straight run though as opposed to stepped flashing.

Or you could use flashband, about a tenner a roll, but you'll need to follow the instructions to the letter.
Won't last as long and is prone to failure under the wrong conditions/ bad job.
 
You need to do a long-serving job, so there is no point in bodging it. Buy (£50 ish) or borrow a 4" diameter angle grinder and fit a diamond edge blade. Buy sufficient lead flashing from the builder's merchants. Using the grinder, cut a 25mm slot in the wall (in the mortar but its not essential). This is best done using a temporary wooden guide fence (screwed in to the wall) for the blade's metal guard to follow, thus ensuring a straight cut. Having made this first cut, remove the fence and, using the existing slot as a guide, cut along the slot again, below it this time until the slot is slightly wider than twice the thickness of the lead. Depending on the thickness of the blade you might only need the first cut anyway.

Now the clever bit (as shown to me by my neighbour).

Cut a 5-10mm wide strip of lead from the flashing and place it to one side. Make a fold along the edge of the flashing, about 30mm from the edge. Turn the flashing over, such that the fold is underneath. Push the folded flashing into the slot as far as you can, but leave some of the fold (underneath) outside the slot. Next, bend the flashing up above the slot to expose the lower edge protruding from the slot and push in the strip between the edge and the lower side of the flashing. You are now trying to push 3 thicknesses of the lead into a slot slightly bigger than 2 thicknesses of lead. Using a thin hardwood drift and soft mallet, bang the strip tight into the slot. It will never fall out. You will note that the join between the flashing and the wall will be tight, waterproof and very presentable. You can fold the lead as required for the roof, but obviously make sure that it terminates on a downward slope of the corrugations.
 
I thought they sold corrugated end/wall pieces @ the stores- that just lay on the sheets/ against the wall..............then do a cover flashing .......google on B+Q needed :?: Maybe I saw them @ Wickes :oops: :idea:
 
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Agree with Nige

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This would be the easiest way(?) then just a straight forward lead flashing into brickwork mortar or if the wall rendered then chop it out with render stop beading and make good
 
Hi guys,

Thanks for the replies. I'm actually needing to do the long (non-corrugated) edge rather than the corrugated edge as shown in the diagram above.

By sounds of things, lead flashing or flashband is the way forward. Since i'm a novice at these things i might try the flashband route though it's perhaps not ideal.

Cheers
Alistair
 
almonkeyfinger said:
Hi guys,

Thanks for the replies. I'm actually needing to do the long (non-corrugated) edge rather than the corrugated edge as shown in the diagram above.

By sounds of things, lead flashing or flashband is the way forward. Since i'm a novice at these things i might try the flashband route though it's perhaps not ideal.

Cheers
Alistair

Clean all surfaces thoroughly.
Use the flashing primer that they sell alongside it instore.
Apply it with your hands, making sure there are no big creases.
Use a hairdryer/ heatgun to warm it up whilst going over with a seam roller. (As used for wallpapering) Not too hot though and don't leave the heat on it for too long.

Also be aware that flashband won't last as long in a sunny spot.
 

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