Leak Coming In Behind Concrete Cill

[MrMiller]

Hi Folks

I'm redoing our bathroom and having knocked away the old plasterboard around the window noticed a couple of wet spots on the interior brick work below the cill. I've highlighted them here:-

Under normal circumstances, I'd never have seen them as our sink / cabinet where based there.

Anyway, I'd looked outside I thought I'd found the issue with a massive gap below the actual pvc window frame on the outside:-

I filled that with sealant and had fingers crossed that would solve the issue. However, I dried the area off but after some heavy rain again last night there are signs of a small amount of water coming in again.

I'm a bit at a loss now as to where it could be coming from but just wondered if it was possible it was working it's way in through the lintel itself? If you look at the picture above you can see the paintwork was pretty badly flaked off. I'm not sure re what these old lintels were made of but is it possible it's porous and with the paint gone in places there's no protection?

I've gone over it with some masonry paint just now, so it will have a couple of coats by the end of the day and this is what it looks like from the outside:-

I can't see any other possible places for ingress, so is that poor paint work really a possible cause?

 

[23vc]

That stone/conc cill needs a drip groove under it, may not have one, or the dashing has covered it. I’d seal the underside of it, as well as the whole perimeter of it against the dashing, and see if that resolves it

 

[MrMiller]

That stone/conc cill needs a drip groove under it, may not have one, or the dashing has covered it. I’d seal the underside of it, as well as the whole perimeter of it against the dashing, and see if that resolves it

Thanks - Will try getting that done as well if we get a couple of warmer days again!

It's impossible to see from that first picture but there is some kind of old flashing running along the layer of bricks below the lintel on the inside:-

So it may be be that's running right across the two layers between the cavity - with the lintel on top - and channeling water inward.

 

[Koolpc]

Its a cill not a lintel...

 

[Koolpc]

Water could be coming from above the window too. Working its way down inside the stonework until it finds a way out.

Check area around the guttering and the edge of the roof there...

 

[MrMiller]

Its a cill not a lintel...

Excellent point! Corrected

 

[catlad]

Well, looking how the original fitters have left the window, you have to wonder if they bothered sealing both ends when attaching the stub cill to the frame.

 

[MrMiller]

Well, looking how the original fitters have left the window, you have to wonder if they bothered sealing both ends when attaching the stub cill to the frame.

Sorry, I'm not particularly au fait with the terminology here (as I've already proven!) but when you say stub cill, do you mean the lower pvc protrusion on that second photo?

 

[catlad]

Yes, were you showed the gap that hadn't been sealed, that cill is called a face drain style, and there are different sizes

 

[MrMiller]

Yes, were you showed the gap that hadn't been sealed, that cill is called a face drain style, and there are different sizes

Thanks - I'm contemplating removing that 4x2 beam underneath on the inside (I probably should) and building up additional brick & mortar there, so I would see if it was lacking further sealant around that from the inside. If not though, I'll run some extra on the outside between the base of the window frame and that stub cill...

 

[ToolboxTalks]

Old lintels can be porous, especially if the paint has flaked off, so rain could soak through and work its way down inside the wall. Masonry paint will help, but it might not fully stop it if the brick or lintel itself is very porous. You could consider adding a small flashing or drip edge above the cill to redirect water away from the wall.

 

[MrMiller]

Old lintels can be porous, especially if the paint has flaked off, so rain could soak through and work its way down inside the wall. Masonry paint will help, but it might not fully stop it if the brick or lintel itself is very porous. You could consider adding a small flashing or drip edge above the cill to redirect water away from the wall.

When you say above the cill, do you mean essentially cover the now repainted section with something coming down from the stub cill?

Someone above mentioned a potential lack of drip groove at the bottom as well - which does seem to be the case, so it may be that...

 

[MrMiller]

That stone/conc cill needs a drip groove under it, may not have one, or the dashing has covered it. I’d seal the underside of it, as well as the whole perimeter of it against the dashing, and see if that resolves it

Thanks - Went back out and had a look:-

You can see that some of the dashing has even worn away there on the top right hand side especially.

And there's no dip grooves either.

So I'll run some more sealant right along the top of that underside there and that will hopefully do the job. I'm hopeful that is the cause of the issue as that lines up exactly with where it's coming through on the other side and it's only a very small amount anyway, so that would seem to fit...

 

[MrMiller]

So I've run sealant along that underside of the cill, which hopefully will stop the problem for now.

However, I'm not sure I can call that a permanent solution and basically all our cills are like this - with the pebbledash leaving a pretty minimal extrusion. So I don't think I can realistically use an angle ginder or something to put a drip groove in under there.

Therefore what are my options - Some sort of plate that I would attach into the edge of the concrete?

Problem is, once I've done the bathroom walls and I have backerboards / tiles on the inside, it's going to be watertight and therefore I'll never see if water does coming in again.