Flashing a polycarbonate roof against a brick wall

[Russ42]

I have just completed roofing the pergola with polycarbonate and now need to flash the high side against a brick wall. Do I need to cut a channel into a mortar line and sit the polycarbonate flashing into this channel and water proof with silicon?

1. is there an alternative to channeling the wall

2. is silicon the best sealant for this job? Which silicon/product for this external application?

3. what should I do if the poly flashing doesn't line up with a mortar line?

[MitchellMc]

As aluminium doesn't rust, it would be a good choice to use in close proximity to the beach @Russ42. For instance, you'll often find it used to build boats. You need to be careful with stainless steel as there are many grades, and the readily available lower grades rust easily. Aluminium tarnishes and corrodes in very salty environments, but this can be almost completely negated by coating it with an etch primer and epoxy-enamel paint. I'd take bare aluminium over a lower grade stainless steel any day in a salty environment.

Mitchell

[Russ42]

I was thinking of the fixings. Gal screws are no good, aluminium is not strong enough to make screws, same with plastics, leaves SS.....unless you have an alternative.

[MitchellMc]

I apologise @Russ42, I presumed you were talking about the flashing.

Why did you not want to use galvanised screws?

Climacoat screws are both suitable for treated pine and have a protective coating on them which will prevent corrosion. If these screws are to hold down the polycarbonate, you'll need Buildex 26mm Dome Sealing Washers on them to prevent leakage. You'll also need to fix into the peak of the ridges, often people make the mistake of fixing in the troughs. If you fix in the trough's water pools and drips through the holes. Another tip is to oversize your pilot holes otherwise when the sheeting expands and contracts it'll rub against the screw, making a squeaking noise.

Mitchell

[Russ42]

Elsewhere, Gal fittings, even the RSJ's that are not completely covered, rust. The gutter fittings are rusty, for example. I will need to replace these fittings one day up 2 stories (I put plastic gutters and fittings on the new verandah roof). SS rust, sure, but rusty SS screws I think last longer than rusty gal screws....? I used Gal screws on the Suntuf as I couldn't find an alternative. These will be relatively easy to replace down the line. My partner used to make repurposed jewellery and so she has a box full of the rubber and aluminium washers for the roofing screws... Thanks for your help, Guys. I have a bag full of questions I have no answer for. I will post a few more over the next few weeks

BTW, I used the Climacoat screws, I think, elsewhere into treated pine. I found the square hole very inferior to the Philips head of regular screws. The tool rounded quite readily, even though I tried to use it carefully.

[MitchellMc]

Generally, unless it is hot dipped Gal with a sufficient coating, you can still have rust issues @Russ42. As you've mentioned, it sounds like stainless might be your best option.

It's interesting to hear about your experience with square drive screws. It took me a long time to convert from Phillips, and I was very dubious of how effective square drive would be. To date, I have now put in well over a couple of thousand and can't say I've ever had a rounded bit. Perhaps you might have had a bad bit supplied with the screws? I wouldn't write them off completely and encourage you to give them another go at some stage. If you experience the same issue, I'd be happy to troubleshoot it with you or organise a refund on the screws and bit. 

I look forward to seeing some images of your finished project. Please keep us updated.

Mitchell

[Russ42]

Thanks Mitchell, i am going to give just SSing (short for Silicon/Sikaflex....) the wall ends and see if that seals it up. Is not a critical spot (open verandah beneath). I screwed that end down in the valleys as I wanted the flashing to sit down on the ridges of the Suntuf and not sit proud on the screw heads (I do get "you are overthinking it" a lot...). I will coat these screw heads with SS anyway to try to stop them rusting.

I have not given up on the square drive screws, largely because there is no alternative for treated timber. I haven't tried the driver bit in the packet. I didn't know there was one. I bought one from the tool section.

[Russ42]

Well, I have "finished". I hope to attach a photo. The flashing on the edges are Gal and I will have to replace them from time-to-time because of the proximity to the ocean. I just siliconed the Gal to the tiles and it leaks there. Not surprised. Will add a silicon bead along the top when it has all dried out. Perhaps the bead I put in behind the Gal was not continuous. Not ideal, but I didn't want to put holes in the tiles as the substrate behind is Hebel and I have just "finished" cutting out the rusted rio in the planks and re-rendering overhead (never want to do that again!). Also I screwed the Suntuf down on the wall end in the valleys. I know this is wrong but I figures

1.the high side of the sheets would be fairly safe,

2. I siliconed the screws to put off their rusting

3. the verandah below is just that and not a sealed up room

4. the heads of the roofing screws would prevent the aluminium angle from sitting neatly on the top of the Suntuf.

Also, I omitted to predrill the Suntuf. I screwed it down before I got the word to do so. I did know this was recommended but when I researched it I read that since the roofing screws are self drilling now, it wouldn't be necessary.....wrong, I think. Perhaps this is why the edges of the sheets are curling up a little?

I learned quite a lot and will be putting the same sort of roof over the verandah's above this one. Thanks for your advice, will see how it goes and make the necessary adjustments for the next ones.

[redracer01]

Hello @Russ42 

Very nicely done! It's always a win when in the middle of a Reno you get new knowledge from first hand experience. From the pictures you posted it looks expertly done. I reckon your next roofing project should be perfect as you've picked up more information about the process. As to adding an extra bead at the top of the galv flashing may I suggest Selleys Storm silicone seal. It is an all weather sealer that should provide you with a superior seal against harsh weather. Looking forward to your next project! 

Cheers, 

Red

[MitchellMc]

Wonderful work, @Russ42! It's great to see that this project has been successful, and many thanks for updating us.

As @redracer01 has mentioned, we look forward to your next project, and as always, we'll be here to help.

Well done.

Mitchell

[hk_Engineer]

Do you need council permission for this type of job and if so, then how a DIY gets approved from Council