Splurge of water ingression during heavy rain.

[MoonMan2]

I have an issue on the single floor room extension of my house. It's a streak of water penetration that usually appears after very heavy rain, which we've had a bout of, over the past couple of days.

Around 6 or 7 years back, I got a roofer out. The two gentlemen said it was to do with the grey parts (he had a technical name for them) not being siliconed enough and that water ingression was occurring at the gaps. So I paid him to silicone the gaps (black stuff):

Now this appeared to fix the problem, though on checking I'm sure I've always saw a tiny bit of a shadow of water appearing on the ceiling on that same area over the years.

But certainly in past couple of days it's been obvious.

I got my ladder out and had look:

This is the side of the ceiling where the ingression occurs. On following the slate 'dips' from left to right, it's the line of the fourth dip (parallel to all other lines of dip). Obviously I didn't lift these 'fourth dip' slates as I'm no roofer but I lifted the first couple and saw no issues of concern.

Here are some more photos, the nail has been placed on the 'fourth dip' to indicate the line (in parallel, see window for orientation assistance) where the ingression into the ceiling occurs.

Any suggestions?

I can't see anywhere on the roof where this water could be coming in?

I takes around 12 hours AFTER the rain has occurred for the splurge of water stain to appear at its worst on my ceiling (then it begins to dry out over the next few days).

 

[foxhole]

Looks like the shallow channel at verge against the wall simply can’t cope with heavy rain .

 

[Mr Chibs]

Perhaps, would be better if the flashing (dark grey bit) would be over the tiles as they abut the wall.

maybe the water pools at the bottom of the channel, in heavy rain, then runs into the roof the felt (black stuff under battens, in roof) should take this away into gutter.

 

[MoonMan2]

I have a theory too.

Take a look at this:

You can see that the two adjacent tiles don't 'flush' overlap like the rest. The set of tiles above is the same, though the gap isn't so big.

In lifting the bottom left tile, you see this:

The circled area (where the nail is cosily still) is a small tench that runs the entire width.

Now let's imagine the tile put back and it raining.

Under 'normal' rain conditions, the rain falls down the tiles (as expected) but doesn't overflow at these bottom tiles, where the gap is. Even with persistent rain, as long as it's not too heavy, there is no problem: the curved indent of the tile copes with rate of water passing over it, channelling it towards the gutter as intended.

However, with very heavy rain, much more water flows down the tiles. Remember that the bottom tiles will need to 'accommodate' more water as it is ALL the rain that has collected from the apex all the way down that needs to be dealt with. (Tiles at the top only need to accommodate rain that falls on them so are unlikely to overflow their curved indent).

You can see the gaps along the edge of the tiles better in this photo (in earlier, original post).

What I believe could be happening is; due to these these gaps in the bottom roof tiles, their curved indents can't cope with the flow rate. Their curved indents simply overflow in heavy rain with the increased rate of water flow. This rain water then readily flows over and underneath the adjacent tile, collecting in the small trench. This trench water slowly makes it way through the felt, the wood and trusses to finally splurge the ceiling half-a-day later.

Does this sound feasible?

I have tried everything I can to try and make these tiles flush but it seems impossible due to physicality of everything beneath them.

 

[Alastairreid]

Check the window above the roof is sealed.
Doesn't look like you have cavity trays either.

 

[MoonMan2]

To test my theory, I've filled in the gaps where I believe the water could be overflowing into the felt/wood.

 

[foxhole]

To test my theory, I've filled in the gaps where I believe the water could be overflowing into the felt/wood.


View attachment 241318

View attachment 241319

That’s not filled ? Sticking a j cloth in just opens the gap to allow more rain in.

 

[MoonMan2]

That’s not filled ? Sticking a j cloth in just opens the gap to allow more rain in.

It's pretty jam-packed the cloth. I had to cut it into strips in order to get the tight fit needed, so overflowing rain will have some difficulty penetrating through that.

Yes, the gap(s) are perhaps a millimetre or two bigger but hopefully the gain from the rain water not being able to overflow, through the gaps in these slates will nullify these few mm.

 

[foxhole]

It's pretty jam-packed the cloth. I had to cut it into strips in order to get the tight fit needed, so overflowing rain will have some difficulty penetrating through that.

Yes, the gap(s) are perhaps a millimetre or two bigger but hopefully the gain from the rain water not being able to overflow, through the gaps in these slates will nullify these few mm.

No , the tiles are not the problem.

 

[MoonMan2]

No , the tiles are not the problem.

I see you don't think there is any credence in my theory (overflowing of water through gaps in tiles during heavy rain).

I'll leave this 'experiment' running for a while until my theory is either proved or disproved.

 

[Mr Chibs]

A lot of roofs have a tile or two that don’t connect very well, you see this a lot around velux windows.. and yet they don’t all leak.

Don’t blame you trying something, but not the cloths, that’s not where the issues are, flashing and channel are where I would start.

Let us all know how you get on, looks dry for a few days, so guess we’ll all have to wait.

 

[MoonMan2]

There was some heavy rain a few days back and a splurge did form in that same area on my ceiling , albeit not as large, perhaps less than half the size.

I called out a roofer. He got on the roof to examine it. He lifted a few tiles, looking underneath. He also examined the flashes at the side and the 'lip', as he called it, where the water runs down between the different heights of roof.

He saw nothing untoward. The only thing he could recommend was to use a wire brush to clean off all the moss, as it can have a sponge effect and possible water ingression that way. He said he would text a quote fir him to clean the roof of moss and then left. He made it clear his work wouldn't guarantee to stop the splurging.

Two days passed and no word from him so I decided to brave it myself. I bought a wire brush from B&Q and went up the ladders, onto the roof and started scraping off the moss at the apex.

A few minutes later I noticed this;

Closer look:

For spacial comparison, the yellow arrow points to the line of water splurge on my ceiling:

I set off to B&Q again and bought this:

Silicone applied, gap filled.

 

[Alastairreid]

Did you check the gable window and pointing?, the chipped ridge wouldn't cause the ingress..

 

[MoonMan2]

Did you check the gable window and pointing?

The bottom ledge of windows (two of them) need re-siliconed. I'll do that in due course. I never cast an eye over the bricks; once again, all in due course.

I wasn't comfortable being up there and just wanted it overwith.

the chipped ridge wouldn't cause the ingress..

Oh dear, I so wanted to believe I'd sorted the problem.

For now I'll see what happens with the two 'fixes' I've done.

 

[Mr Chibs]

If there is water getting in the ridge, it wants sorting, and it looks like you’ve done something about it.

As Alistair Has said, don’t think that is your cause. My money is on the flashing needing some reworking. Wait for the next batch of rain and report back your results.

Good luck.