Dampness around window

just do it

Folks

Pictures attached of a dampness issue on the inside of the inner leaf around the upper window on the western gable on an exposed site wide open to the Atlantic. The worst spot is below the window. This developed soon enough after the house was built in '04. It's regular build, 100mm cavity with insulation board, celtic tiger build quality:(

So what are the potential causes and how do I fix it?

RKQ

Just do it, Its difficult to say. There are a number of holes in the external render. Has the cavity been pumped with insulation?

I doubt it is condensation as there are no visible signs of black mould. It could be caused by a damaged dpc over the window & a damaged or missing dpc at the window cill level.

Its very difficult to say wheather its wind drive rain crossing the cavity or condensation. Is there an en-suite in this room? If so is the extractor fan working.

Is there any similar damp patches on the ground floor, around the bay windows?
Is that a parapet wall with coping or is it a cement barge to the gable?

Sorry I can't be more help. Maybe if you upload a few more pics I might be able to help.

DOCARCH

Possibly missing a DPC/cavity tray over the ope and/or vertical DPC at cavity closer and/or DPC around cill. One or other or all are possibly the cause? I am always amazed how many builders do not understand the need for DPCs (other than at ground floor level)!

To solve the problem, you really need to open up the structure to see what's happening. You could consider painting on a water repellent externally but this will/may only temporarily solve the issue.

mickdw

I would suggest doing a little opening up works in the top attic, right above the window. If you were to knock a hole out of the inside wall up there you could look down to check if there is a tray over the window or also if there is any evidence of water running on the inner block in the cavity - I feel you may possibly have a fault in the concrete overbarge among other faults.

I would confidently say that you have / will have issues at the head of your ground floor bay windows too.

Edit: It appears you have pumped that gable also at a later date. This will make it more difficult to pinpoint the issues in my opinion.

DOCARCH

mickdw wrote: »

I feel you may possibly have a fault in the concrete overbarge among other faults.

I did think that myself, there could be an issue with water ingress where the roof finish abuts the barge but this could explain the dampness to the head and reveals of the window.

Looking at the pictures, the main area of damp is under the window/window board. The cause of this could be possibly be the absence of a DPC around the cill.

just do it

Thanks for replies folks

The owner wasn't interested in investigating prior to pumping the cavity this January so that option isn't there. The builder did some remedial work on the barges around 2 years ago but it has done nothing to remedy the problem.

I hazard a guess that the lack of a dpc is the main issue given there is dampness above, at one side, and particularly under the window cill. Given the level of short cuts I've already discovered I doubt very much there are cavity trays in situ.

So onto remedies. How about a waterproof render from the barges to below the window cill level?

RKQ

just do it wrote: »

So onto remedies. How about a waterproof render from the barges to below the window cill level?

Waste of time IMO. Find the problem and fix it. End of...

The cost of hacking off existing render, putting on new waterproof render, scaffolding hire etc must be more that retro fit dpc to head & cill of window, investigating barges etc.

There are a number of companies offering easy to install retrofit dpc / trays.

Jonny Harris

Hi
With my self build I installed all relevant dpcs above and below windows projecting about an inch for trays and vertical dpc. Got a local "expert" to plaster outside. Went to shops and on return every DPC was cut back as far as poss.No care or consideration to damp. They just wanted an easy life .Luckily no damp penetration

just do it

mickdw wrote: »

I would confidently say that you have / will have issues at the head of your ground floor bay windows too.

No problem there so far and luckily they are not directly below so hopefully we'll escape issues with them given the house is 8yr old at this stage;).

just do it

RKQ wrote: »

There are a number of companies offering easy to install retrofit dpc / trays.

RKQ
Any chance you could PM me some names, websites?

just do it

Take a look at this http://www.dampbuster.com/wall_video.html

Now I'm not saying my problem is as bad as this:D;)

RKQ

That video just goes to show how important it is to keep the cavity clean & clear of debris.

PM sent

YouWantWhat

Thats penetrating damp, no doubt about it. On exposed sites the wind will drive moisture through even a hairline crack. It could be the concrete barge, looks like its cast in-situ, is there a dpc under it? When the wall was pumped with insulation, you might have made the problem worse, chances are there's mortar on the wall ties and the insulation will aid the transfer of moisture to the inner skin. It also looks like there is moisture getting in around the window, so that also needs to be sorted.

I would try the following initially :
Mastic seal around the window externally and make sure there are no obvious gaps. Water will find its way into the window frame (thats why there are drain holes at the bottom of the frame), but the water may not be fining its way out through the drain holes, and instead leaking into the building. Try opening the window pouring some water along the frame and see where the water ends up. Also put a level on the base of the frame and see if the water runs towards the drain outlet.
Also you could try a water repellant, I know someone previously frowned on this, but I have used it in the past and has worked a treat. I would not use the stuff you buy in the hardware shops, but an industrial grade. You can get 10 litres for under €100 delivered to your door (you'll have to pm me for the details). I would certainly use this on the barges and probably on the whole of the gable wall, its simple to apply and two coats should do.

Other than that you'll have to start opening up works. Is the builder still around - he'd be obliged to put it right.

Good Luck.

YouWantWhat

Hi Again,

another thing you should try : the next time there is rain/damp appearing, go up into the attic and see if the inside of the gable end wall is damp. Could be that rain is getting in between the concrete barge and slates, ie. insufficient flashing or rain being blown up under the flashing. The wall should have stepped cavity trays under the barge, but these might have been omitted.