Damp???

[01484]

I have attached an image to this post of what looks like patches of damp? This is appearing in my bedroom window. i initially thought it was the roof first so replaced the whole roof of the house (added roof shield felt made sure there were no holes etc) so i thought the problem should be over. Decorated the room and after a month it comes again.
The room downstairs also had this problem the sides of the windows are turning black (both sides). Im not really sure what it is. Was hoping someone can help.
Thanks

 

[01484]

image:
//www.diynot.com/network/01484/albums/

 

[joe-90]

Looks like condensation to me. You replaced the whole roof just for the heck of it?

 

[01484]

Thanks for your reply well some of the old felt had holes in it etc and was in pretty knackered condition so i thought better to replace it all and i had a feeling that it may be due to the roof leaking, but doesnt seem like it.
Its starting to appear on the roof now aswell.
Is there anything i can do in order to stop it?
i had a look online cant remember where it was but there was someone who said that they used this kind of solvent/paint and then the dampness never came back. I dont know what it is but would buy it if i knew.
Thanks for your reply.

 

[jeds]

There are anti-mould treatments that will prevent mould from forming but they don't last forever. 6-12 months if you are lucky. You'd get something from B&Q or something stronger from an online trade supplier such as www.mgcltd.co.uk

To deal with the route cause reduce moisture sources, increase ventilation (or increase air movement) and increase temperature of the surfaces. Bedrooms are the worst rooms in the house because people give off huge amounts of water vapour overnight and tend to have doors and windows closed - and the wall surface temperature is colder. All that increases vapour pressure difference resulting in condensation, resulting in mould growth.

 

[Blagard]

i had a look online cant remember where it was but there was someone who said that they used this kind of solvent/paint and then the dampness never came back. I dont know what it is but would buy it if i knew.
Thanks for your reply.

There are stains that can bleed through paintwork often odd damp stains (not condensation) Some barrier paints work to stop the bleed through happening again. They will not cure condensation.

I had a quick look at the photo and I agree it looks like condensation. But I do wonder if the window may be fitted too far forward so that the entire frame is in the outer leaf with part of the same outer leaf just inside where plastered. This could cause a cold bridge resulting in condensation just where the outer leaf extends inside. Usually the inner leaf and outer leaf are separated by a DPC that gets hidden behind the window frame.

It is just an idea as the mould band looks so narrow.

Edit: The "leaf" term means the outer brickwork skin or the internal blockwork skin in case you find the term unfamiliar

 

[Blagard]

The junction where the mould is, is frequently a cold spot due to the proximity with the outside. Even when constructed correctly.

One potential solution when you next decorate is to have the old plaster reveal hacked off and insulation backed plasterboard fitted instead. It is not a solution for everyone as the width of the frame does not always allow for the thicker insulated reveal. The insulation comes in varying thicknesses so you use the best one you can fit.

example of insulated plasterboard

 

[AronSearle]

It's also possibly (or likely) that when the new windows were fitted, the cavity around the window was not insulated, and that they just put a few pakcers around the frame to fit the window, leaving gaps that allow cold bridging.

You may find if you hack the plaster around the window, and can see gaps, you can fill these gaps with squirty foam.

That's the easy bit.

Next comes where the window is fitted in line with the cavity insulation (if you have any), it may be if you have no cavity insulation, and the window is set foward into the front of the brickwork, where the mould is appearing is the uninsulated cavity.

If it's happening on the roof, it's the same thing, the wall surfaces are too cold (lack of insulation, or cold briding due to gaps in the insulation).

Lowering the humidity by increasing ventillation or running a dehumidifier is another fix, it depends on how much you want to spend, the latter are quick and cheap (though over time cost you more in heating/leccy).

 

[freddiemercurystwin]

Aye classic condensation where the a cold bridge occurs at the jamb and ventilation is lacking. Thousands of threads on the forum addressing this issue.