Do my double glazed windows need to be sealed with mastic

phughes1979 · Post by **phughes1979** » Tue Mar 17, 2009 7:23 pm

My house had 10 windows and a door fitted back in 2005. We bought the house in 2007 and noticed damp in the upstairs bedrooms. We've only got around to tackling it and upon further inspection it looks like the damp is coming in near the sides of each window.

We've inspected the windows outside by chipping off a bit of the render. It appears that the windows have been put in place and no mastic used to seal them in place, the company has just rendered up to them. They are under guarentee but the company that fitted them hs come round to inspect them. They say that although there's no mastic there (and the gap between the window and wall in places is almost 10mm) the damp inside the house is no way connected to the fact there's no mastic. They claim the fact the render is there will have water proofed the windows - but wouldn't the render be porous and let water in. They claim the damp inside is nothing to do with no mastic being used and the fitting is perfectly good and water proof.

I'm not a expert on this at all but it seems to me if there's huge gaps under the render around all the windows then thats going to let water in. This is what our builder told us, he said they should definately be some sealent in there, but they say he's talking rubbish.

thescruff · Post by **thescruff** » Tue Mar 17, 2009 8:02 pm

A couple of pics will help.

leebwk · Post by **leebwk** » Wed Mar 18, 2009 7:50 am

Hi,

Is it damp you are experiencing or black mould?

martyn1967 · Post by **martyn1967** » Wed Mar 18, 2009 1:40 pm

hi my theory on window fitting is any gaps around the frame should always be sealed fully with mastic & then rendered up to, however nearly all encounters ive ad with pvc window companys fitting windows on sites ive been on they have always fitted them and then gone round the frame with expanding foam which forms a similar seal as exp foam is waterproof so not letting water through sides/top or bottom of frame.
sand & cement render with or without waterproofer in it is still porous so if you have non of the above sealants around your frames other than render you will usually end up with damp/water ingress on your reveals. hope this helps

phughes1979 · Post by **phughes1979** » Wed Mar 18, 2009 10:05 pm

Experiencing black mould on some of the internal sealant around some of the windows but the worst is actual damp patches. We've knocked the plaster off one wall and the brickwork is very damp with salts coming out of the bricks. Again, this originates from next to the window.

The windows have no sealant or expanding foam around them, just big gaps I can get my fingers into!

Post by **ultimatehandyman** » Wed Mar 18, 2009 10:14 pm

It's highly unusual not to seal around the frame with either frame sealant or silicone

I know a guy and all he does for a living is seal windows, doors etc.

If they build a new housing estate the builders fit the windows and then he goes and seals them later.

I wonder if this double glazing firm were doing this, but somehow the sealing did not get done

It sounds like the missing sealant is definately causing these problems.

donken87 · Post by **donken87** » Thu Apr 02, 2009 8:31 am

get a quote from your builder to seal the windows and make good the surounding render ect
make shure he puts on the quote the reason why the work is being done

send a copy of the quote to the window company with a covering letter explaining that when the damp their representative witnessed is cured by this work being done you will be seeking to recover your monies which may include extra costs for making good decor the rooms effected.Include photographs of the gaps where sealer should be and the damp areas
then give them the option of contacting you within 14 days with regards to making good their faulty installation themselves.

above the dear sir ect part of the letter write LETTER BEFORE ACTION