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Mould around windows getting worse

About 10 years ago we had new double glazing on the front of our 1930s semi for vanity reasons, there was no mould on our old windows but the rooms were getting colder so it seemed like a good idea.

A neighbour (a glazier) installed the new windows and I asked him to let me keep the old wood sills as they are nice and wide. As soon as the windows were up I noticed that the room didn't seem as warm...could smell the garden even.

Still, time went on and right from the start the black mould has been around the windows and twice a window has been cracked and we have had to replace them...never had this trouble with the old ones. We never told our glazier because hes a tad uppity!

We get alot of wind and rain bashing the front of the house and I recently noticed mould on the outside upstairs. Our neighbours next door (not attached) have managed to make a claim for storm damage on their front bedroom (find it laughable when we are in the hot south but they claim for anything) but I'm thinking have we got it too?... the room is unlivable and I dont know if its the weather or the windows are rubbish. just some thoughts please, many thanks.

PS I do ventilate this room but doesn't make any difference.

2 Answers from MyBuilder Window & Door Fitters

It sounds like the windows are not pressured meaning ....they are not sealed as the cills should have been fitted as they are a part of the performing system ie modern cills vent from underneath or front vent if none are fitted.When the windows were made this should be of been mentioned.
Sorry for need new cills.


Answered 2nd Mar 2015

If old cills have been kept , the new frames should have drainage holes outside at the bottom normally with caps placed over them. If not then the frame when it was manufactured probably has concealed drainage left in , in this case any water entering the frame will end up soaking the timber cill directly under the frame.
This would explain why you have this problem.
Unfortunately the way to cure this would be to remove the cills (if lucky without taking frames out) and block drainage holes underneath replace cill then drill face drainage to outside bottom of frame.
Alternatively remove cill , leave drainage as it is and replace wood cill with pvc cill
which also can be purchased with wood effect if needed.
If this is not the cause check all sealant round frame and make sure existing drainage holes are clear.
Lastly check outside walls are not porous and soaking up water which can happen if this is the case treat walls with a water repellent such as stormdry which has a 25 year guarantee.
Hope this helps.


Answered 7th Dec 2018

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