uPVC windows fitted too far away from DPC?

[piper64]

Where should windows be in relation to brickwork and DPC? Should they be as close as possible to the DPC or away from it?

The windows in our ex council house were replaced by the original owners maybe 20 years ago. I have always thought that they were placed too far out as they are only 1cm from the outside line of rendering. Our neighbours either side are the same.

We continually get a cold area all around the inside reveal adajcent to the frame, which then turns to dampness and mould. The frame isn't cold or wet, so I have wondered where the dampness comes from. Recently in this bad weather we have a physically wet patch as big as your hand about 6 inches from the top on one side of a window. There is no break in the silicon on the outside.

As I'm in the middle of doing our kitchen, I had the opportunity to chop the plaster back from one of the windows. The cavity is clsed with a house brick on edge and slate to act as a DPC. The window is 2 1/2 inches away from the slate.

This 2 1/2 inches is the sort of area that we experience damp and mould around reveals.

I'm planning on replacing the windows as I go along and moving them back towards or straddling the DPC slightly. Is this correct?

 

[stuart45]

Frames in the past were often, but not always put in with the back of the frame flush with the back of the external skin. This made the external reveal over an inch.The DPC was tacked to a groove in the frame, or on the back of the frame. The brickwork or blockwork was returned from the inside, so damp didn't penetrate the inside.
If slates were used, 2 courses were built with 3/1 against the external skin.
Nowadays it's preferred to set the frames back into an insulated cavity to prevent any cold bridging.

 

[piper64]

Hi stuart, if you look at my other thread, which I posted after realising this was the wrong section, I have a pic and diagram of how my windows are placed.

Your explanation is how I would imagine they should be fitted, which is different to how they are fitted.

When you say to set the frame into an insulated cavity, do you mean straddling the slate/ DPC? If I do this, won't the fixing bolts for the new window hit the area between the outer block and the slate?[/u]

 

[stuart45]

If you set the back of the frame to just past the DPC it should be fine. Cold doesn't penetrate walls, as heat is the energy force. The loss of heat from the wall can cause a cold spot and condensation.

 

[piper64]

Thanks stuart, I'll do that.