Leak Help! Cavity tray? Roof? Help!

[Luke1988]

I’ve had a leak from my flat roof in the kitchen for over 5 years now.

Roofs been replaced, leadwork done, trays inspected etc and still leaking

In the image below I’ve water tested the window area, and the yellow area and it leaks from when testing the yellow area.

Any sort of ideas? It’s a new build and I’ve had another builder come out and do some work and it’s still leaking

Just looking for direction on possible causes. Only tends to leak with driving rain / volume

Similar issues with garage as well! New builds……

 

[Ollyfp]

You're not alone! I've experienced similar issues. Soft reds absorb water like a MF. When the bricks reach saturation point, water can then run down the inside of the outer wall (inside the cavity). If there's no cavity tray fitted, you'll have issues.
One work-around is to use a high-quality masonry waterproofing cream (Bostik, Stormguard, etc). These products are similar to Thompson's Water Seal BUT they are also gap-bridging and effectively fill tiny cracks that might allow water to penetrate.

 

[Luke1988]

Yeah part of me thinks it’s just sheet volume coming in tbh

Everything that can be looked at has been tried.

They’ve both definitely got trays.

I’ve got some water seal in the garage will give that a go.

 

[Ollyfp]

They’ve both definitely got trays.

Weep vents?

 

[Ollyfp]

Obviously, cavity trays are useless without weep vents. You can keep these clear with a vacuum cleaner. Really.

 

[^woody^]

A properly installed cavity tray works. Despite a builder looking at it, how confident are you that it has been looked at be someone who knows what they are looking at? Going by the state of those replaced bricks, implies that they may be a bit crap at their job

Any photos of the tray showing it built in to the inner leaf and extended past the opening, and with no joints?

Where is the tray relative to the roof flashing upstand?

What cavity insulation is in there?

 

[Luke1988]

Yeah there’s weep vents but whether they function or not who knows.

Yeah the brickworks been out twice. 2 different companies. I’ve got no photos of what’s behind sadly.

We had someone put a camera in and take a look and they couldn’t spot anything obvious.

Attached a photo of the leak.

 

[noseall]

Yeah there’s weep vents but whether they function or not who knows.

Yeah the brickworks been out twice. 2 different companies. I’ve got no photos of what’s behind sadly.

We had someone put a camera in and take a look and they couldn’t spot anything obvious.

Attached a photo of the leak.

Are the vertical jamb silicone seals on the upstairs window intact?

 

[Ollyfp]

Noseall might be onto something. Your first floor window has been fitted without sill horns, which isn't an issue in itself, but you might find that the water that is supposed to escape from the drain holes at the base of the window is finding its way into the cavity somehow. It might be worth replacing the old silicone with an appropriate frame sealant.

 

[Luke1988]

Are the vertical jamb silicone seals on the upstairs window intact?

Yes as far as I can see

When I did the last water test it was that area highlighted in yellow which was tested. No water was tested on the windows this side.

 

[Ollyfp]

Thompson's Water Seal didn't solve my problem, but the £90 masonry cream did. As I said, it's gap-bridging. I applied it with a fairly stiff brush and really worked it into the bricks and joints. You'll see that there is no colour change to the treated bricks during wet weather because they no longer absorb water.

 

[^woody^]

For water repellant coatings, Thompsons and any other clear silicone liquid are temporary, as they get degraded by UV.

Look for a silane/siloxane cream as these are very long lasting and perform well. They tend to cost 4-4x as much as the silicones.

In situations like this, ensure that the whole area of wall above which is at risk of letting in water is treated right up to the eaves - not just local patches. The good thing is that these creams are white so you can see where you have applied it - they dry clear though.

 

[wessex101]

Does the cavity tray have stopends? It is surprisingly common to be missed so water runs off the ends of the tray in to the wall cavity rather than out the weep holes.

 

[Luke1988]

Does the cavity tray have stopends? It is surprisingly common to be missed so water runs off the ends of the tray in to the wall cavity rather than out the weep holes.

How can I check that?

 

[Ollyfp]

If you force compressed air in through a weep vent, you should be able to hear it emerging from the other weep vents... if they exist.