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How to close the gap between pergola and roof?

Hi,

We have recently had someone build us a pergola, which is amazing. However, when it rains, the water flows back towards the house and spashes on the iron roof which then splashes over the gutter which wets under the pergola area a lot. Just looking for an idea to block off the gap in the photo so the water won't splash and should just flow into the gutter leaving it dryer for the dogs.

Thank you in advance for reading and for any suggestions you may have 🙂

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Comments

TerryN

Hello brydee,Just looking at your pergola and can see how heavy rain would be a problem if the fall on the pergola roof is towards the house as you mentioned,and both roofs are sharing the gutter on the main roof.I can't see but I don't think the new pergola roof has it's own gutter,so the rainwater would just drop over onto the house roof. Maybe if it had a gutter with a couple of "spreader" downpipes feeding onto the main roof it would slow the flow down and stop the initial splashing, but it looks like the downpipe on the house gutter also has another downpipe feeding into it as well,so it probably has trouble coping with really heavy downpours.As for the gap,maybe the fellow who built it might be able to rig up a bit of purpose cut zincalume sheeting fixed to a few droppers to cover it.Probably haven't been much of a help brydee,but maybe a couple of things to thing about at least.Regards Terry.

EricL

Hello @brydee

Welcome to the Bunnings Workshop community. It's splendid to have you join us, and thank you for sharing your question about closing the gap on your roof.

One way to stop the rain from going on to the steel roof is to attach another gutter onto the falling side of the pergola. However, I strongly recommend that the outlet for that gutter be attached independently so that it does not overwhelm the one currently attached to the lower roof.

Another approach would be to attach Suntuf 3.6m Clear Greca Polycarbonate Sheet onto the falling side of the pergola. The sheet will need to be cut into sections and placed as close as possible to the roof. This will serve as a barrier to the water hitting the iron roof. I've placed a sample sketch below to give you an idea of how to cover the gap.

Let me call on our experienced members @TedBear and @diy_hausdesigns for their recommendations.

If you have any other questions we can help with, please let us know.

Eric

TedBear

Hi @brydee , in addition to suggestions already proposed, I'd suggest considering using some zinc flashing, painted a dark colour to blend in with the timber, attached to the back of the timber backing of the pergola. It would fill the gap (or most of it) and direct any drips from the pergola roof onto the house roof, well back from the gutters.

(Attach it to the back board of pergola only, to sit just above the house roof metal.)

https://www.bunnings.com.au/fielders-1-8m-150mm-zinc-angle_p4790170

jonced3

https://www.workshop.bunnings.com.au/discussion/comment/26546#Comment_26546

Hi, I'm also having to do this. Whilst installing to the back of the pergola roof should be simple, how would you attach the twin wall sheet to the house roof considering it is sloping down?

TIA

WhatsApp Image 2025-10-27 at 3.59.58 PM.jpeg

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/91686#Comment_91686

Good Evening @jonced3

I am not sure if I have it right in my mind what you are describing.

You want to install some twin wall sheets to stop rain/wind splashing through?

Fixing the sheet to the rear outside of the timber should be easy as its flat surface (I would install an aluminium cover over the top to stopr water entering tho) You would only have the sheet come down to around 50mm above the sloped roof, it wouldnt join as then the water could back up in the corrorgations if leaf matter ect builds up.

Dave

EricL

https://www.workshop.bunnings.com.au/discussion/comment/111846#Comment_111846

Hello @jonced3

Welcome to the Bunnings Workshop community. It's wonderful to have you join us.

It's great that you've received excellent advice from @Dave-1. I totally agree with his recommendations in regards to installation. I also suggest using Zenith 12G x 30mm Galvanised Type 17 Hex Head Timber Screws - 50 Pack to hold the twin wall sheet in place.

If you have any other questions we can help with, please let us know.

Eric

TedBear

https://www.workshop.bunnings.com.au/discussion/comment/91686#Comment_91686

Hi @jonced3 , I agree with the advice of @Dave-1 and @EricL . Don't attach the back water deflectors to the roof. The reason there should be an air gap is that these roofs get a build up of very hot air in summer which flows into your house without an escape route. (I have a friend who discovered this the hard way.) Air flow also helps to avoid condensation underneath in winter, which is a bigger problem with metal roofing.

jonced3

https://www.workshop.bunnings.com.au/discussion/comment/111846#Comment_111846

Thank you @Dave-1 @EricL @TedBear for the advice. I assume it will be sufficient/strong enough to only fix the sheet to the rear of the timber pergola at the top?

Illustration below. If so that would be a relatively easy fix!

Screenshot 2025-10-28 101320.png

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/123416#Comment_123416

Yes, you could fix it directly to the back of the beam @jonced3.

Mitchell

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/130997#Comment_130997

Good morning @jonced3

Yeah, thats what I was thinking of as well.

Dave

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