How to stop rainwater leaking under metal roof sheets?

[jjk]

G’day everyone,

Just wondering if anyone’s got any advice or has dealt with something similar.

We’ve got metal sheets roof on the front part of our house, and when it rains, some of the water runs underneath and back toward the house, dripping onto our deck. When the rain’s heavy, it pretty much pours down like a tap left on!

Any tips on how to stop the water from getting in underneath?

I’ve attached a few photos to show what’s going on:

• Photo A shows the area near the tiled roof end

• Photo B is the other end of the roof

• The red highlighted section is where the water tends to drip through

   

Thanks heaps in advance — really appreciate any help or ideas!

[JacobZ]

Hi @jjk,

There is an issue that I can see where the flashing runs from the tiled roof to the corrugated iron roof. 

When a roofer installs a flashing like this, the bottom edge is cut to follow the contours of the corrugated sheet. This is called scribing, and if you have a look on YouTube for "scribing metal roof flashings", you will be able to see some examples of what is done.

You can also check out @JacobZ95's comment on What flashing is required for joining these two Colourbond roofs? for an explanation and example.

Once the edge has been scribed to meet the contours of the corrugated sheet, it will be secured in place with roofing screws and these scribed edges will be sealed with roof and gutter silicone.

For the location you've shown on the gutter side of the roof, can we get a photo showing the top edge at the back of the gutter?

How deep are the gutters? Are they installed with an adequate slope to carry the water away?

It seems like the water could be overloading the gutters. This could be because the gutters aren't deep enough or that there is not enough slope for the water to flow to the downpipe.

It's hard to say for sure, but the solution could be installing a larger capacity gutter or adjusting the slope of the gutter so that the water flows away faster. 

Giving the gutters a clean to remove leaf matter will also help.

Allow me to tag @Nailbag, @Noyade and @Dave-1 for their thoughts.

Let me know what you think, and if you have further questions, please don't hesitate to ask.

Jacob

[Dave-1]

Good Evening @jjk

Ive gone straight for an overfull gutter thought as well, possibly clogged with leaves and silt. That section of the gutter is undercover and you would think there is no chance of leaves building up, My roof is a little similar tho open and I still have to keep an eye on that joint as water has come back in during downpours.

Id get up and have a look, maybe even push a long piece of timber or a piece of conduit through the gutter to see if it feels clear. One way to test that theory is to block the down pipes at the gutter top and fill the gutter with water and see what happens. 

Last question, how many downpipes take the water from that side of the house away? As @JacobZ has mentioned the gutters could be at capacity as well, if so Id be tempted to add a downpipe before replacing with a larger gutter.

Dave

[jjk]

Thanks heaps @everyone for the detailed replies – really appreciate you taking the time!

I had a closer look at the flashing where the tiled roof meets the corrugated sheet, and you're right — it doesn’t look like it’s been properly scribed at all. Just seems to be sitting over the corrugations, with no silicone sealing underneath. I’ll check out a few of those YouTube vids you mentioned on scribing flashings to get a better idea of what’s involved, but sounds like I may need to get a roofer in to redo that properly with sealing.

Re: the gutter side, I’ll get a photo of the top edge where it meets the back of the gutter and post it here. Good point about the gutter depth and slope — they look a bit shallow to me, and maybe not quite level.

[jjk]

Thanks heaps @everyone for the detailed replies – really appreciate you taking the time!

I hadn’t thought about blockages because it’s undercover, but now that you mention it, I wouldn't be surprised if there’s some fine debris or buildup over time. I’ll definitely run a stick or conduit through to check for blockages, and try the hose test to see how it drains. As for downpipes, I think there’s only one servicing that whole section — so yeah, possibly overwhelmed in heavy rain. I’ll look into adding another one or upsizing the existing gutter if needed.

Thanks again for all the tips — super helpful!