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What flashing is required for joining these two Colorbond roofs?

Hi guys,

Just wanting some advice around a poorly done patio extension prior to us buying. I'm wanting to repair, and it seems like whoever did this hasn't installed flashing between the original roof and extension causing some water to seep back in. I'm wondering what flashing would suit best. (The second roof has a very low pitch, which im also investigating).

Thanks.

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Comments

Jason

Welcome to the Bunnings Workshop community @Andythommo97. We're pleased to have you join us.

Apologies for the slow reply. Let me tag one of our resident Bunnings D.I.Y. experts in @EricL to assist you, as well as some other helpful members such as @JacobZ95, @tom_builds and @TedBear.

Thanks,

Jason

EricL

Hello @Andythommo97

My apologies for the late reply. Can you please tell us how far apart the corrugated roofing is? Can you also please post a photo of the gap from up top if possible. It might be possible to use a product such as Consolidated Alloys 100mm x 10m Weatherproof Byute Flash Flashing Tape.

This will allow you to cover the gap of the roofing on the condition that they are not too far apart. It is possible to get a wider flashing tape, but it becomes untenable if the gap is too large. The tape will begin to sag under its own weight so it's best to have the gap very small.

Inserting galvanized angled flashing is also an option, but you'll need to know the angle of the slanted roof. It becomes an issue if the flashing is at the wrong angle as it will begin to gather water instead of letting it flow away.

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

Eric

JacobZ95

Hey @Andythommo97,

Unfortunately, I don't think there is an easy fix to this one. I've had a look through Lysaght's flashing guide (Flashing Guide) and the best example I can find is the below image.

This style of flashing is called an "apron flashing". They are produced by Lysaght and can be ordered through the special orders desk at your local Bunnings.

This would likely require you to remove a row of screws from the upper pitch of the roof in order to slip the flashing underneath before fixing into place. You will note that the bottom edge of the flashing has been trimmed to sit flush with the profile of the lower roof pitch. This can be achieved by using a combination of Left, Right and Straight tin snips. You would then need to silicone the bottom edge using something like Selleys 300g Cottage Green Roof and Gutter Silicone Waterproof Sealant to prevent water flowing back underneath the lower edge of the flashing.

Hope this helps,

Jacob

KJP

https://www.workshop.bunnings.com.au/discussion/comment/36070#Comment_36070

Noted on all answers to date, regarding getting an apron flashing made up - the idea of scribing and cutting out the shape for my colourbond custom orb profile on three low pitched roofs, each 5 meters long sounds tedious and old fashioned. Does the apron flashing come with a lead skirt attached on one side so can be easily molded to the existing roof profile? Is that a thing here or not? If its not a thing and I am not a fan of the flashing tape previously mentioned can lead flashing be used instead?

EricL

https://www.workshop.bunnings.com.au/discussion/comment/86231#Comment_86231

Hello @KJP

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

The apron flashing does not come with a lead skirt. In regards to the lead flashing there are a few alternatives.

Here are some lead-free flashing products:

All these flashing products can be moulded and shaped to your roofing profile. It can also be painted except for the Weatherflash as it is uncoated aluminium. I suggest visiting your local store and having a look at the lead-free flashing to see if it will suit your needs.

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

Eric

KJP

https://www.workshop.bunnings.com.au/discussion/comment/108455#Comment_108455

Hello Eric, the Wakaflex looks like an option. Is it installed the same way as a metal apron flashing i.e. half goes underneath top roof iron and half on top of lower roof?

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/121513#Comment_121513

Hi @KJP,

The edge can be installed under the top sheet. However, this product is typically designed to be adhered to two surfaces. Alternatively, you could use just a standard lead flashing.

Mitchell

richp

https://www.workshop.bunnings.com.au/discussion/comment/36071#Comment_36071

Hi @Andythommo97

@JacobZ95 + Can also be advised to add return fold on top edge, commonly also called a transition flashing. This would be custom folded. Ideally, scribed to corrugated profile on lower edge, but could also so foam infill to assist with waterproofing between flashing and bottom roof.

https://www.bunnings.com.au/suntuf-black-corrugated-foam-infill-4-pack_p1010499

Good luck1

EricL

https://www.workshop.bunnings.com.au/discussion/comment/86254#Comment_86254

Hello @richp

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

Thank you for sharing knowledge and experience in regards to the flashing.

Were keen to hear more about all your projects and plans around the house and garden. Please feel free to reach out whenever you need assistance or would like to share a project with the community.

Eric

Stuckster

Before you do anything, you mentioned the lower roof had a very flat pitch. If it's less than 5 degrees then a corrogated profile should not have been installed. If you want the roof to pass code then you may need to replace it with a trapezoidal profile such as Trimdek.

Once this is established, transition flashing should ideally be installed which would require pulling up the top section of roof.

Foam infills (designed for the specific sheet profile) stuck down with double sided butyl tape would be the easiest way to protect the bottom end of the flashing from any blow back. Otherwise the bottom edge of the flashing will need to be custom cut to fit the sheet profile which can be tedious over longer lengths.

If you want to do a cheap and nasty and you're not concerned with bringing the roof up to code, I'd just pull up the top sheets, stick down some foam infill to close the gap, check that all the valleys along the top edge of the bottom roof sheets are turned up and screw the top sheets back down again.

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