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

[MitchellMc]

Welcome to the Bunnings Workshop community Daniel @dyfuse. It's wonderful to have you join us, and many thanks for your question about sealing a pergola.

Typically that gap would be sealed with flashing. I'd suggest either a polycarbonate barge capping adhered to the wall with Sikaflex 11FC, or you could potentially could fix a steel barge capping. I think the clear barge capping would be relatively unintrusive.

What alternatives had you envisaged?

Please let me know if you have any questions.

Mitchell

[dyfuse]

Thanks for the quick reply @MitchellMc!

It is difficult for me to safely access the top side of the polycarbonate roof in order to place flashing and apply adhesive, so I was curious to alternatives that I would be able to install/implement with access via the underside of the roof.

Do you have any suggestions as to how to either install the barge capping solution you mention above or an alternative solution if I primarily have underside access only?

[Jewelleryrescue]

Hi @MitchellMc  and @dyfuse 

I found this purpose built  Roof sheeting solution for myself and  @dyfuse  completly by accident  instore and it fits the bill perfectly as it was designed to do and it can be done  completely from under roof.   @MitchellMc  would know I recently extended polycarbonate roofing the house facia so no rain in outdoor room.

Oh  more colours avaliable this is an example.

Suntuf 300 x 45 x 20mm Classic Cream Back Channel FrameI/N: 1010805 $24

https://www.bunnings.com.au/suntuf-300-x-45-x-20mm-classic-cream-back-channel-frame_p1010805

Suntuf 20 x 20mm x 3m Back Channel Foam I/N: 1010487 $25.60

https://www.bunnings.com.au/suntuf-20-x-20mm-x-3m-back-channel-foam_p1010487

Suntuf 300 x 45 x 20mm Windspray Back Channel Frame I/N: 1010803 $24
Predrill  channel  use sandwich foam (i like the concrete expansion foam to 10mm thick some time is  has pull away  strips or  cut it to size)  and pre silicone it on and let it set  over night Easier to juggle up  high when set. Then  when you screw channel to wall  the foam will seal it and allow movment OR optional silicone bead to timber  and channel  join  all from underneath access for wall seal.

When installing  channel roll it up and over  roof edge  Long side on top of sheeting there is a 20 mm gap in channel to put screw though your predrilled channel into the wood at nice even hight with the roof resting natuerally against top channel longer lip.  

Now its a simple process from underneath to neatly push in  custom sealing foam along bottom lip try to keep foam square shape if possible.

No roof access required  .

[MitchellMc]

You could install the flashing from underneath, but it will be quite fiddly to install it correctly, @dyfuse. Flashing needs to go above the roof and not under it. The idea is that water hits it and runs off, inhibiting it from accessing the joint between the sheet and the wall. If you install the flashing under the sheet, the water can make it to the joint between the sheet and the wall, and your flashing might fail. 

We certainly wouldn't want you to get injured, so it might be best to consider employing the services of a professional to complete the flashing installation for you. If you did decide to complete the project, please read through this helpful guide: How to use ladders safely.

Mitchell

[Jewelleryrescue]

Hi @MitchellMc  @dyfuse 

Those two  suntuf items are commercially  designed and made you might need to address this issue  with them and or advise Bunning not to sell them . They are dead easy to install . 

[MitchellMc]

Hi @Jewelleryrescue,

To clarify my above comment, the product you've suggested has a portion above the roof's surface and is suitable. I was simply stating that it wouldn't be advisable to, say, glue a right-angle length of flashing under the roof. 

Mitchell

[Jewelleryrescue]

So  your saying  via  your drawing which mirrors  my original diagram100%  and  description and Suntuf products x2  and Bunning product description are  right all along because  it is a  legitimate,  underroof  installation  plan as  per suntuf product designs. Well thanks for that at least.

[MitchellMc]

My apologies for the confusion, @Jewelleryrescue. My reply was to @dyfuse about being able to install flashing on the underside of the roof, not to you about your suggestion of using a back channel. Back channel is perfectly fine to use, and I agree with your recommendation.

Mitchell

[Jewelleryrescue]

All good

@MitchellMc  

I am a tiny bit sorry for wanting to be right this  time as that is absolutly not why I post.  Your  idea works too so we both have solutions

I try to only to add  share solid ideas  brain storm if you will then we can pick best  combination of  ideas. 

I never see this  back channel  before at Bunnings as it not in the metal area so I was pleased to share especially as I just installed it too and  had first hand knowlegde.

I was just using the back channel a super simple solution purpose  made. 

I flipped the back channel as water was not an issue here but if it was  we could just add pre cut foam siloette lengths to seal back channel to roofing from underneath.

No wind rattle either.  

There is a  tip for colour bond wind noisy fence owner s use clear silicon  with a fine nozzle and  put a dab of silicon between  rail and  fence peaks touch point every 4th touch point and same at top .  Use  plastic nozzle to force small gap between rail and  peak and insert nozzle 10mm so silicone dosnt show. No more noisy fence. I should do  a post on that.

simple egde fixing for polycarbonate sheeting