damp and mould on windows

[paulandclaire]

We have recently (December 2013) had our windows replaced as our old windows were showing signs of condensation and also looking pretty tired. We went for quite a high quality window frame and glazing as we wanted to ensure the temperature within the house was at a decent level all year round. Unfortunately we seem to have unvovered a big problem. On all the reveals and ceiling there has been a steady increase in damp patches and build up of mould. The damp and mould start at the bottom of the window and work up steadily. We never had this problem with the old windows so we started to investigate. In 2009 we had our cavity filled with a breathable fibre. The company who did the job came out to look at the problem today as I thought we may have a 'cold bridge' problem, I didn't mention this as I wanted to see what they thought. The drilled several holes externally and sent in a camera. They said that the problem was that the window fitters had either removed some of the fibre or pushed it back and this was creating a cold bridge and subsequently the problems in the house. It does make sense and I have to say I tend to agree but im still not totally convinced and wonder if there are specialists out there who would be able to come in and give an impartial verdict and hopefully a solution?
Cheers
Paul

 

[skenk]

What's the ventilation like? the more you insulate and make airtight a building, the more mechanical ventilation you need (typically extract fans, trickle vents etc) to prevent the buildup of condensation. Drying clothes indoors, cooking and breathing(!) are some of the things which contribute to high levels of humidity which can cause damp problems if there is not enough suitable ventilation.

 

[AronSearle]

Sigh, another response obsessed with ventilation.

Sounds like the typical shoddy installation leading to cold bridging. If the cold bridging is bad enough, you will get condensation even with reasonably low levels of humidity, yes ventilation and managing humidity will improve the issue of condensation, but it is not fixing the defect (poor fitting/cold bridging).

It does make sense and I have to say I tend to agree but I’m still not totally convinced and wonder if there are specialists out there who would be able to come in and give an impartial verdict and hopefully a solution?

You want to get some surface temperature readings of the affected areas on a cold night, you already know that insulation is missing, so you do have cold bridging, now you need to establish if it is leading to excessively cold surface temperatures (likely if this is the only area you have condensation). You can hire a fancy thermal imaging camera, or get a basic cheap surface temperature reader of ebay, you don't need to hire a specialist unless you intend to use his statement against the window fitters.

If you are getting internal surface temperatures of around 6c or less (unlikely but not unheard of), you will find it very hard to avoid condensation short of leaving windows permanently open, or maintaining uncomfortably low levels of humidity with a dehumidifier.

With temperatures of around 6C-12C it becomes a little more manageable, but you still need to be provide enough ventilation for lower than average humidity, condensation occurring on surface temperatures higher than 12c and you do likely have too high a humidity level that needs to be rectified.

***********************

I would have to say at this point you have already identified that it is a shoddy fit, they should have installed some cavity closers or bunged in a load of expanding foam, why not just knock them on the head with the information you already have?

**********************

 

[paulandclaire]

Thanks for the information. I was wondering if it might be best to actually remove the windows and put some expanding foam in?

 

[JohnD]

if you want to DIY with expanding foam, no need to remove the windows. You can inject foam through holes drilled in the wall, or the frame, or a gap (if there is one).

The cans come with a plastic tube for the nozzle, drill holes that it will fit snugly.

Excess foam is very sticky, I found that to prevent it sticking to the frame or wall, you can put sticky tape tightly on the surface, and punch a hole that the nozzle fits. This gives a fair chance that any bulge will stick to the tape, not the wall.

Drill plenty of holes, in a vertical column, and start filling from the bottom. When it starts to show in the next hole up, you know you have a good fill. If you start at the top, it will drip down and probably have big air gaps in the fill.

If the window company comes back, look to see that the gap is well packed with insulation.

Ventilation is the best cure for condensation.

 

[paulandclaire]

Again great advice and much appreciated. In regards to the holes, can I assume that id be drilling in the centre of the reveal and working upwards?

 

[JohnD]

there may also be a gap underneath.

 

[AronSearle]

Probably a hiding to nothing, but I would be shouting at the installers, at the very least they can cover the cost of materials.

http://www.windows-are-us.co.uk/wp-content/uploads/2014/01/CE-GGF-Installation-Guide.pdf

Page 27

Open cavities discovered between inner and outer skins of brick or blockwork should be closed with an insulating material

Page 30

Wherever practicable, an insulating fill should be
inserted or injected around the full perimeter
of the frame

 

[paulandclaire]

Its a bit of a tricky one asking the installers to come back as they are friends of the family. Not very good friends I hear you shout. Never the less it seems from the advice given that its a fairly straight forward task and if im honest id rather shell out a few quid and it hopefully rectify it than go down the route of asking the installers back,.less hassle all round. Thanks all once again for the quick and fantastic responses

 

[gregers]

AND?
if they have caused you problems then get them to sort them out,simples.

 

[AronSearle]

If you don't tell them they have done it wrong, then they will just carry on doing it wrong, think about how many windows such people install and how many people they will be screwing over with crap installs. Why do you think UK tradesmen have such a poor repuation, they repeatly get away with shoddy work and when challenged say "But I have been doing it this way for X years".

Alternativly, post dog poo through their letterbox.

 

[nebjamin]

Alternativly, post dog poo through their letterbox.

LOL!

If I did that for every shoddy workman I've had there would be no need for dog waste bins in public spaces