How to build flashing for pergola against two walls of the house?

We are building a polycarbonate roofed pergola over a deck, see model below.

We will run spouting on the lower side and tie into the house spouting.

We live in a windy area. The pergola is engineered for the wind, has 200x200 house posts (8 of them) with 2/190x45 beams and 190x45 rafters on 600 centers and will have purlins or noggins. It's also tied into the deck. The problem is that it's quite a long length of almost 6m and by the time you get to the far end if you have a 5 degree pitch you loose 50cm in height. If you have a 3 degree pitch you only loose 30cm in height. So we are thinking of using a 3 degree pitch roof using 5 rib polycarbonate which is rated for 3 degree slope.

I thought I would run the top part of the roof over the top of the existing spouting or even could potentially run it a little over the roof as well. Something like this maybe? We do realise that it wont be completely water tight and it is an outdoor area. But we want to minimse water coming in through the gaps.

Here are some actual photos of the deck / house. I am not sure about the interaction between the side of the pergola roof and the side of the house (spouting/fascia/eaves). The problem is the side of the pergola roof will go from above spouting height, to alongside spouting height, to below the spouting height. ie. there is a 30cm drop in height (3 degree pitch). The spouting height is probably about 10cm and then there is about 7cm of fascia below the spouting.

Can I please get suggestion on the top flashing and the side (barge) flashing.

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Comments

kiwijunglist

If I have both the upper end of the pergola roof and the lower end of the pergola roof above the spouting it ends up quite a high roof.

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/37973#Comment_37973

Good Evening @kiwijunglist

Thats a nice pergolla/deck! With some solid looking posts 🙂

I actually like either option you have drawn tho if I had to choose between them I would choose the higher roof (second option) with the flashing piece down towards the tiles. Main reason is for cleaning the gutters out. The first option works but lessons the overall width inside the gutter to get your hand in, with the second option the roof may be higher but maintenance wise it will be a lot easier.

I have a gap between my roof decking and the house. I was going to use some lead flashing when I originally designed it but $$$ and time it never got done. Truthe be told not a lot of water comes through there and something like a right angle flashing edge might do the job, pretty much as you have drawn.

The only thing I can suggest to help you decide on the pitch and the height above the roof is maybe put up a fake piece of timber and screw it to the outer posts at either angle, then step back and have a look at how it will impact, also from inside the house as you wouldnt want to loose those views 🙂

Dave

EricL

https://www.workshop.bunnings.com.au/discussion/comment/37973#Comment_37973

Hello @kiwijunglist

Welcome to the Bunnings Workshop community. It's marvellous to have you join us, and thanks for sharing your question about flashing for your pergola.

I would probably go with your first configuration with the roof of the pergola in line with the gutter of your roof. I've seen the configuration of the pergola roof over the house roof and has caused the rain to bounce off the roof and into the pergola itself.

Your proposed idea of having flashing over the gap and into the gutter is best. It provides adequate coverage and prevents bounce back of any rain that should land in the area. I suggest visiting your local store and speaking to the team at the special orders desk regarding ordering a custom galvanized flashing for your pergola.

Let me call on our experienced members @Dave-1 and @Noyade for their recommendations.

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

Eric

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/37973#Comment_37973

Evening @kiwijunglist

Just had another thought. If you wanted the low roof more so then you could potentially install a wider gutter and still do the flashing into the edge of the gutter and be able to clean the gutter as needed.

Dave

kiwijunglist

https://www.workshop.bunnings.com.au/discussion/comment/81211#Comment_81211

The problem with the first option is the side of the pergola roof goes like this:

Although, maybe it's ok to just have a 1cm gap between the side of the roof and the gutters and except 1cm strip of rain?

kiwijunglist

https://www.workshop.bunnings.com.au/discussion/comment/81210#Comment_81210

I cleaned the gutters for the first time this weekend in 7 years, and they were pretty much empty. So I'm not too worried about accessing the gutters.

kiwijunglist

https://www.workshop.bunnings.com.au/discussion/comment/81210#Comment_81210

for higher roof could do a flashing like this?

Here is 3d model of higher roof - https://www.tinkercad.com/things/5eHbYUxwf1u-pergola-high-roof-option

kiwijunglist

https://www.workshop.bunnings.com.au/discussion/comment/81212#Comment_81212

I don't see how a wider gutter would help the low roof design, because the lower pergola roof starts above the house spouting and ends below the house spouting. See diagram above with the red roof line.

I've done a 3d model for both high and low roof.

High roof - https://www.tinkercad.com/things/5eHbYUxwf1u-pergola-high-roof-option?sharecode=ypFYbuRpr2VhYIIBOBYYZ3DrX_zcsCX-G3MkfIiVCx8

Low roof - https://www.tinkercad.com/things/4yUjvuS2y3S-pergola-low-roof?sharecode=ktMG3_sg20nEmZM3gcSvkXyla6D_tL8AFKrkYIOWFcs

EricL

https://www.workshop.bunnings.com.au/discussion/comment/105298#Comment_105298

Hello @kiwijunglist

That is encouraging news when the gutters don't have a lot of debris in them. I take it that there are no tress around your roof top. One of the major causes of gutter debris are dead leaves and branches. You won't believe how quickly they pile up and cause trouble.

The decision is up to you on how you want your pergola built. Just keep in mind that having your pergola roof over your existing roof will make it much taller.

Please keep us updated with your progress, we look forward to seeing your pergola built.

Eric

kiwijunglist

https://www.workshop.bunnings.com.au/discussion/comment/119782#Comment_119782

I guess my main question is what sort of flashing could I use for the side of the roof, if I use the lower roof option?

Do I just use a barge flashing and have a gap? or is there some other option?

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/128581#Comment_128581

Afternoon @kiwijunglist

The barge flashing is what Id be going with, It just needs to stop that spray of rain mist as it hits the roof. (Im not a roofer lol and I am presuming that "barge flashing" is the right angle piece of tin) I dont know if I would worry about the timber facing you have on your drawing. Unless you are going to screw through the barge flashing into it tro secure it?

Dave

kiwijunglist

https://www.workshop.bunnings.com.au/discussion/comment/134223#Comment_134223

I think the side flashing is called barge flashing and it's a right angle.

I think the top flashing is called monoslope ridge flashing (based on my googling)

https://www.google.com/search?q=monoslope+ridge+flashing

I feel that the flashing would need support of a board behind it as if you are running it down into the spout i would be a large flashing

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/137793#Comment_137793

Hi @kiwijunglist,

There are only a few styles of barge flashings designed for basic uses. In your case, due to the design, there's not really a flashing that would provide a better weather seal along the slope. Some lead flashings might be used after installation to try to cover the gaps.

Mitchell

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