Water ingress under window

[vivienz]

We had a little rain last night and the wind is blowing today. I've noticed some water ingress from under the window units so I assume that they arent as well sealed as they should be. This is a 3 pane non opening window, sitting on sarnafil membrane that continues outside to a gully behind a parapet wall. The membrane was completed and made watertight a couple of days ago.

 

What is the best way to seal this and does it need to be done from inside or outside or both?

 

 

[Mr Punter]

This should be sealed on the outside with Compriband or mastic.

[Pete]

We have a similar setup on our roof terrace. Once window was sealed I used external window tape to seal to the purenit under the window frame and then the external sill was fitted using sealant and screws. (Internorm windows)

[ProDave]

Am I miss understanding something here?

 

You have windows that go down lower than the parapet. So there is a thin gap bwtween the parapet and the window.  Where does the water that goes down that gap drain to?  Inside the house seems the answer at the moment

 

Can't help feeling I would have had the window higher with a window sill lapping onto the parapet avoiding that awkward gap to detail.

[lizzie]

Have you got screws going through the sarnafil? Is that a reflection of inside scewed plate on the outside.

 

Is there any drainage at the bottom of those frames if so you need to be careful not to seal up the drainage holes.

[vivienz]

Thanks for the replies, all.

@ProDave there is a gully behind the parapet and in front of the window, so the water won't be lapping up against the window.  The gully depth is about 100mm. It has a fall on it and drains to a gutter.

 

@lizzie - yes, there is a reflection of the inside screws, none on the outside.

 

The fit of the windows was quite tight on a few of them and the compriband didn't fit into the gap, so they were sealed with foam.  My main worry is that this isn't the first window that has had some water ingress after they should have been sealed but, of course, it only comes to light after it has rained and the wind is in the 'right' direction.  Other than throwing buckets of water at the windows with a wind machine on it, is there any simple way to check that it's all sealed as it should be?

[Barney12]

2 minutes ago, vivienz said:

Other than throwing buckets of water at the windows with a wind machine on it, is there any simple way to check that it's all sealed as it should be? 

 

Pretty much the approach I had to take with my windows. A long hosepipe and blast them to simulate the wind and rain whilst the installers were locked inside the house to prove to them they leaked!

[vivienz]

Just now, Barney12 said:

 

Pretty much the approach I had to take with my windows. A long hosepipe and blast them to simulate the wind and rain whilst the installers were locked inside the house to prove to them they leaked!

 

That's me buggered, then, I can barely get a dribble at ground level.  No chance of a decent blast from a hosepipe up at the first floor!

[lizzie]

I went through more than 6 months of this with my windows we had that many hosepipe/bucket demos I lost count.  We used what felt like the entire stock of local builders merchants silocone, foam etc all to no avail in my case.

 

I spent last Christmas day water testing.......in the end I covered the bottom of the frames in sticky back plastic to keep the water out of the house so we could get on.

 

I hope you get yours sorted quicker.

[Onoff]

Testing is usually carried out with a "spray bar". A horizontal pipe with holes in with water at a certain pressure for a certain duration. 

[Cpd]

Can you hire a water pump or something like a garden hose pump, fill a dustbin with water and then use the pump to spray the windows. would have this as a priority job as winter is on its way...... I have just had to refit some of my timber frames as I got a detail wrong...... and needless to say water was seeping in and this was going to eventually cause much bigger problems if not dealt with ASAP.  

[Mr Punter]

Expanding foam will not work as a seal.  It is good for insulating but you will need mastic if Compriband does not fit.

[vivienz]

Thanks, all.  I've emailed the window company today to raise my concerns about the poor seal around the windows.  I know that it was a tight fit on a number of them and so they didn't use compriband and instead used what looks like expandable foam to me.  I've asked them to return and seal everything from the outside with mastic wherever they were unable to fit the compriband in.  I await their reply but I'm optimistic as their service has been good so far.

[Onoff]

On the 2G windows and sill sections I fitted recently there were "ribs" all round about 6mm high inbthe window and a channel under the sill. I just fitted Compriband inbetween the ribs/channel before it "grew" on one window and slid it into the hole. You have to have the window in to make sure it fits then out again to put the Compriband on. Then need to be pdq getting it back in.

 

Lovely cold bridge where the window meets the sill here as an aside!

 

 

[vivienz]

3 minutes ago, Onoff said:

On the 2G windows and sill sections I fitted recently there were "ribs" all round about 6mm high inbthe window and a channel under the sill. I just fitted Compriband inbetween the ribs/channel before it "grew" on one window and slid it into the hole. You have to have the window in to make sure it fits then out again to put the Compriband on. Then need to be pdq getting it back in.

 

Lovely cold bridge where the window meets the sill here as an aside!

 

 

 

 

Hmm.  I think my chances of their taking all the windows out then putting them back again are somewhere between zero and nil.  I'll see what they come back with re. the mastic request.

 

Cold bridges - brrr.

[Onoff]

22 minutes ago, vivienz said:

Cold bridges - brrr.

 

If it wasn't for this forum I'd have never given them a second thought! Previously I thought 3G was a phone standard! 

[ADLIan]

Does the window sit on the Sarna membrane that continues from the outside flat roof to the inside? Are you then trying to weatherproof this detail using sealant? If this is the case this detail will always be a problem and I doubt complies with Sarna recommended detailing. Would normally expect the window to be sat on an upstand with the Sarna membrane dressed up the outside of this.

[vivienz]

The window does sit on the membrane and this is the detail that the window company asked for.

Should be all sorted now, a guy will be here in a couple of hours to re-do the seals at the bottom. Once this is done, the membrane will be turned up against the frame and made airtight by MBC. I will take plenty of photos once it's underway as it's all a bit of a dark art as far as I'm concerned and details are helpful for the uninitiated like myself.

[PeterW]

3 hours ago, Onoff said:

On the 2G windows and sill sections I fitted recently there were "ribs" all round about 6mm high inbthe window and a channel under the sill. I just fitted Compriband inbetween the ribs/channel before it "grew" on one window and slid it into the hole. You have to have the window in to make sure it fits then out again to put the Compriband on. Then need to be pdq getting it back in.

 

Lovely cold bridge where the window meets the sill here as an aside!

 

 

 

Looks like an older sill profile as they are multi chamber these days - most of the gap between  gets silicone in it (or should) so the bridge should be quite small

[Weebles]

Am re-opening this in the hope of some help / advice.

Got home tonight to find this:

 

 

MBC frame and slab.  All battened out and air tested (when I get time I will update the blog).  Insulation being blown in and some had collected in the corner and under the sliding door (to the right of this photo) and was sodden after the rain today.

 

House still not rendered but don't think it is this as the render board is on in this location and its alot of water.  So looked outside and saw this:

 

 

Apologies for the photo in the dark.  This shows the EPC from the foundation, the DPC over the top of it, and then the sliding door cill sitting on top of that.  We poked a tissue in the gap between the DPC and the cill and it was sodden so I think we have found the issue.

 

Any tips on how to solve it please?  How do we seal this? 

 

 

 

 

[lizzie]

@Weebles that made me shudder.....Looked just like mine.

 

Mine was an install problem, no provision made for level threshold. Hope you can get to the bottom of it.

[jamiehamy]

I'd be tempted to peel the dpm/membrane back and run a decent bead of clear ct1 along the full length where it meets the window (dry it and clear all dust/debris). With your finger, run along it and make sure its pushed right down into the concrete. That should provide some respite, however the main issue appears to be the fact there's a vertical dpc but nothing to stop water travelling horizontally, hence your issue. The above will go someway to help but you need to get the edge of the membrane sealed properly. Possibly then get rubbery mastic and paint it thick over the concrete and embed the rubber down onto it. 

 

On the inside where I could see foam under the window, I'd be tempted to push that in under the window/compress it, and again, a good bead of ct1. I did that there for an almost identical issue. Never leaked again even in driving rain. 

 

(I should add, I had this issue twice both at the level thresholds) 

[Weebles]

Window fitter came out and suggested trimming down EPS so water naturally runs away from the window on top of the DPC rather than in under the window. So will do that. Then clean and dry it and use @jamiehamy sealant tip. And then mastic the hell out of it.

 

The inside has already been latexed in so no access to the underside any more. In a way we are pleased that we have been able to see the effects of heavy rain before doing any internal finishes.  

[Russell griffiths]

1 hour ago, Weebles said:

Window fitter came out and suggested trimming down EPS so water naturally runs away from the window on top of the DPC rather than in under the window. So will do that. Then clean and dry it and use @jamiehamy sealant tip. And then mastic the hell out of it.

 

The inside has already been latexed in so no access to the underside any more. In a way we are pleased that we have been able to see the effects of heavy rain before doing any internal finishes.  

 

Should this not have been done before the doors went in. 

I thought it would be standard practice to have a 5 degree slope on a cill with a cill pan installed

and then seal window onto cill pan. 

[lizzie]

1 hour ago, Russell griffiths said:

 

Should this not have been done before the doors went in. 

I thought it would be standard practice to have a 5 degree slope on a cill with a cill pan installed

and then seal window onto cill pan. 

Good point @Russell griffiths wish you had been supervising not only my window install but also slab pour when no cill pan recess was created.

 

Have no idea on Weebles install but ours had no cill pan and was just stuck straight onto the slab, no provision for drainage at all, ours were level thresholds. 

 

We ended up having to cut out the eps and some of the slab and then get waterproofing membranes under as best we could (as with weebles inside was already stuck down).  Then as stated mastic etc.  The threshold underside drainage holes on ours had to be left exposed so water can drain ....I am left with level thresholds 10mm off the ground, still hoping someone will come and be able to fix this for me.

Edited December 23, 2018 by lizzie