Major condensation problem

[linconhawk]

Hi all,

Major condensation problem I think....

Ok, here goes, Ill try and get all my facts across...

1940's bungalow, put large extension on back a few years ago.

In the existing bungalow, all internal 3" walls were replaced with 4" walls, new insulation in cavitys where needed.. New UPVC windows throughout bungalow.

Getting massive amounts on condensation on front bedroom windows (North facing), window reveals are now black with mould and usually get puddles on window sills... This problem has been there since we moved in, about 2 years ago...

Always have good ventilation within the house, window trickle vents open, etc.

External masonry good, rendered a few months ago.

Its heart bracking, because we renovated the complete property, spent a fortune, took weeks and weeks to paint and now the reveals are black and ruined !

The only thing I remember not doing on these windows in question is putting in the cavity closers... and I don't think there is any vertical damp course in these two rooms...

We tried a dehumidifier, had it switched on for 5 days solid and it didn't really help... bought various other cheap moisture control gadgets and nothing has helped....

Please, there must be someone that can help or advise...

Feel free to ask any questions or if you need any photos...

Thank you

 

[JohnD]

I wonder where the water is coming from.

Do you drape wet washing inside the house?

Have you verified that the bathroom extractor fan is working effectively?

Have you got a water meter?

Are the gutters or downpipes spilling?

Have you looked under the floor?

 

[linconhawk]

Hi JohnD,
Thanks for the reply.

No, no washing is dried in the house...
Bathroom extractor is working spot on.
Water meter ? Not sure what you mean... If you mean something to measure the amount of water / moisture in the air... No we haven't...
Gutters / downpipes all brand new and are nor spilling....

Under the floor is dry...

Ive been reading on the net regarding cavity closers and the more I read the more it points to this... the fact that non were installed, so the gap is just open.... any thoughts ?

Thanks

 

[JohnD]

water meter, I mean a meter, usually under the pavement, where the water company measures how much water you use, and charges you per cubic metre, instead of by water rates.

If not, look at the stop-cock in the garden or pavement, and consider if the route from here to where the kitchen sink used to be, when the house was built, passes under the damp room.

Does your boiler have a pressure gauge on the front? Are there water tanks in the loft?

Is there a bay window with a little roof that might leak?

Look at the DPC in the walls. How far above ground level is it?

I can't see that lack of a cavity closer would cause excess water vapour to appear inside the room, though there might be rainwater leaks round the window.

 

[linconhawk]

Yes, we are on a meter, its in the pavement in front of our drive, it doesn't pass anywhere near the 2 rooms...

Combi boiler, no tanks

The DPC is about 10" above ground level near the 2 rooms...

 

[JohnD]

OK. Have a look at the water meter. In the middle of the window is an air bubble that spins when water is used. Does yours stop, when all the taps are off? Would indicate a leak, though if your boiler is not losing pressure and the bathroom and kitchen are not nearby, seems unlikely.

Have a look in the loft in case it is the roof.

You said you have good ventilation so I am thinking of a source of damp.

Is yours a detached building, or could next door be damp?

 

[linconhawk]

Its all spot on John, no leaks (all brand new), all new central heating, boiler doesn't loose pressure etc.

Nothing in roof, all brand new...

Do you think there is water coming in then ?

I presumed it was condensation, as the windows are always misted with water, the water on the sill would be from the dripping from the glass and the reveals damp and mouldy due to this water.. ?

Do you think it could be because of the lack of cavity closers ?

 

[JohnD]

I'm stumped

If water is forming on the glass, yes, it is condensation, from water vapour, but if you ventilate well, I can't see where the excess water vapour is coming from. The usual sources seem to be ruled out.

If you see any damp patches on the walls, tape clear plastic tightly over the patch, observe if water droplets form on the room side (condensation) or the wall side (wet wall).

 

[theprinceofdarkness]

Window reveals, starting from the outside, it sounds as though you only have 3" of brick between this and the open air. This means that the reveals are cold. I had this problem on a stone building with 24" thick wall. The condensation induced mould extended for about 8" from the back of the window. I stripped the plaster cut away some of the stonework and installed Aqua thermal pane. This is a cementatious board with 1/2" of insulating foam on the inside of if. To save money I cut a board in half so I did only half the depth of the reveal. The reveal was replastered. Now I have a thin line of mould starting 12" in from the window.
It is not unusual to have condensation on a bedroom window as it is difficult to maintain an adequate air temperature, air flow and noise levels.
Frank

 

[linconhawk]

Hi Frank..
Thanks for your reply...

My external wall is made from huge solid concrete blocks, probably about 6" deep, which have now been covered with render...
However, what you are saying makes sense...

I think my option at the moment is to smash up and take off the reveals to expose the block work and cavity, then perhaps fit some kind of cavity closer if I can fit one in, without messing with the actual window, or maybe use expanding foam to "block" the cavity, then re-apply plasterboard with dot and dab, then re-decorate....

Or, if there is something on the market (bit like what you used...) some kind of special plasterboard with something fixed to the back of it for insulation purposes and then somehow fix to the blockwork, ready to be re-plastered...

The only thing is, is its taken us over 3 years to complete this renovation, sucked all our savings... and now I have to go and smash out the plasterboard reveals..... Something I really don't want to do.....

 

[Nige F]

Hi all,

Major condensation problem I think....



1940's bungalow, put large extension on back a few years ago.


T

Thank you

Is there a chimney?

 

[^woody^]

If you moved in two years ago, and the windows were always getting condensation, then why do you think that your lack of cavity closers is the cause?

I can't see how this can be a cause.

Your north facing elevation is cold and the property is warm and under-ventilated. Have to considered your heating regime and exactly how you are ventilating the property?

 

[linconhawk]

Hi people... Update for you all....

Nige F - No Chimneys....

Woody - Thanks for the reply.... Im not 100% sure it is due to the lack of cavity closers, but the more and more I read on the internet regarding cavity closers, it sounds like my problem... Keep reading that they stop cold / thermal bridging which they say can cause mould on the reveals etc....

Like I have said, the rest of the house is all good, its just these 2 front rooms, which I can remember no cavity closers were put in these 2 rooms, everywhere else cavity closers were fitted...

I also started to read up on windows, where they should be positioned... I read that the actual window should go where the cavity is... I cant get my head around this, because where do you fix to if the cavity is open ? Surely you cant screw into the cavity closer because its just a thin piece of plastic....

All my windows have been screwed through the plastic frame into the external block.... Is this maybe my problem with the 2 front rooms....

I have added a few pics, showing the mould, you will notice how far forward the windows are, being screwed into the external blocks, rather than where the actual cavity is.....

Also, you will notice the mould patch is only about 1" deep...

Any more help would be much appreciated....

 

[JohnD]

looks to me like rain penetration

 

[linconhawk]

Hi John D,

I must admit the photos are not that good.... The photos look like water marks...
That's from when I have rubbed / cleaned the mould it left "marks"... before it was just black mould....

I don't think it can be water penetration... The outside is completely sealed with new render and prior to the render, the windows had been sealed with silicon...