How to seal gap between polycarbonate roof sheets and adjacent brick wall?

[dyfuse]

Hi workshop community,

I have a decked pergola area with polycarbonate roofing adjacent to a brick wall. There is a gap of approx 1 cm between the edge of the polycarbonate and the wall and during heavier rain, the deck ends up getting wet! The previous owner who had the pergola installed did not have any flashing or similar put in to prevent water leaking onto the deck.

As a temporary measure, I've inserted a 10 mm polyethylene foam in the gap which understandably fails to improve the situation - the water just ends up running behind the foam and down the wall. 

Can anyone suggest a solution to seal the gap? I would be interested if anyone had a solution other than flashing that might be just as effective.

Cheers,

Daniel

[dyfuse]

Thanks for your replies @Jewelleryrescue and @MitchellMc! These are very helpful and also gives me an idea of some of the different solutions available.

@MitchellMc, if I choose the clear barge capping solution you first suggested, once I place the barge cap so it sits against the wall in the orientation as per your diagram, how would you suggest I best glue it to the brick wall? And how to do so without rain water getting in and running down behind the barge cap (in the gap indicated by the orange arrow in the diagram below)?

Also should I be concerned with any water dripping down the wall via the mortar 'channels'?

[Jewelleryrescue]

Oh   @dyfuse @MitchellMc 

I  See that brown strip on the wall is foam running along the polycarbonate edge, I hoped was timber but you  where already thinking on the right track as to a seal.

Well @dyfuse try use that as your wall to angle  seal or what ever you choose against as the foam looks like cement expansion foam  at 10mm thick that should depress into most mortar joints by screwing it flat and tight enough to form a seal but to do this you  will will need to screw angle  in multiple short gaps every 30mm or every 50mm or a  vertical mortar joints   if you use thicker wall 3mm 5mm aluminum it wont counter flex away from foam  compression.

Well @MitchellMc  has that solution for that design so  follow his  suggestion s it will work too,  Both our ideas will work 

[MitchellMc]

You'd glue the flashing to the wall with Sikaflex 11FC, @dyfuse. The bead of Sikaflex will fill the mortar lines and prevent water from travelling down the rear side of the flashing. 

Looking at your image again, that polycarbonate flashing will touch the roof timbers when you place it into position. So, you'll need to cut it to fit around them or go with the other option of back-channel flashing or steel barge capping.

Mitchell

[dyfuse]

Thanks for clarifying @MitchellMc. I agree the polycarbonate flashing will be issue to fit in the gap between the roof timbers and the brick wall, and I'd prefer not to cut it.

I'll try the back-channel flashing option with the Sikaflex 11FC and see how I go.

Thanks for all your help @MitchellMc and @Jewelleryrescue!

[umarali1990]

Hi Mitchell 

I am having same issue as water run from back of sheet, where it is touching fascia under the gutter.. May I drill back channel flashing with fascia under the gutter?

and also some water leakage from screws. is there any option to seal it without changing roof screws? as it is very hard to go on polycarbonate sheets. it can break?

[MitchellMc]

Welcome to the Bunnings Workshop community @umarali1990. It's splendid to have you join us, and many thanks for your question about roofing.

To create a seal between the polycarbonate sheets and your gutter so water doesn’t blow back toward the fascia and drip underneath, you would typically install a foam infill strip. These strips are shaped to match the corrugations of your roofing and are sandwiched between the roof sheet and the gutter edge. This prevents water from flowing back up under the sheet and keeps the fascia dry.

Regarding the screws, could you confirm whether they’ve been installed on the peaks or in the valleys of the corrugations? In Australia, they’re generally fixed through the peaks, which helps keep water from sitting around them. Each roofing screw should also have a rubber washer that seals the hole. If these washers have perished or cracked over time, that’s likely the cause of your leaks. In that case, replacing the screws with new roofing screws and washers is the most reliable solution.

While you could try applying a bitumen or silicone sealant around the screw heads, it’s really only a short-term fix. Since the sealing has to be done from the top side, and accessing the roof can risk cracking the polycarbonate (especially if it’s older and more brittle), it’s best to tread carefully. If you need to get up there, spread your weight using a wide board across multiple corrugations. If you’re not comfortable doing that, it would be worth engaging a roofing specialist or handyman to handle the repair safely.

Please let me know if you have any questions.

Mitchell