help! cavity wall insulation done and now mould grows!

[steveo777]

Hi all,

Sorry for this newbie question but I've been searching for help on this for a quite a while and just thought it would be easier to join and post a question.

I moved into a end of terrace house 2 years ago and the 1st winter here was absolutley freezing. The following spring I had cavity wall insulation and loft insulation done which made it a lot warmer the following winter. However I now get mould growth in most rooms. What can I do about this?

Some advice I've received is to put air bricks into most of the rooms but only go from the inner wall into the cavity and not all the way through the outer wall as it'll make the house cold. Does this sound right? Will this help?

I've also been advised to leave a small window open all the time but obviously this isn't ideal security wise and don't want to lose heat from the house in winter.

I'm trying to be proactive and get ready for this winter as the mould has ruined some of the wallpaper and plaster that I had decorated when I first moved in. I've tried treating it last winter but it just seems to keep on coming back!

Any help/advice would be most appreciated.

Thanks

Steve

 

[freddiemercurystwin]

You either need to retrofit trickle vents into the heads of the window frames or fit air bricks that go from the inside to the outside (not into the cavity). The choice is yours. There are other alternatives but they're £££s and loads of work.

 

[flameport]

Ventilation is the solution, however:

Do you dry wet clothing on the radiators?
Does your bathroom have an extractor?
Does you kitchen have an extractor which vents to the outside (not one of those recirculating efforts)
Do you cook food in pans with no lids?

 

[steveo777]

Hi,

Thanks for replies.

Would I not be making the house colder if I fitted air bricks making the cavity and loft insulation pointless? How many air bricks would people suggest? There are two outside on the kitchen wall allready and all they seem to do is make the kitchen tiles, floor and cupboards really cold in the winter.

To answer the other questions. I don't put wet clothes on the radiators but do air them in the spare room which was one of the worse rooms. I had moisture all over the ceiling and windows. I had brought a new shelving unit and moved the old one out of the way to find that the wall was covered in mould behind the old unit. It also turned the ceiling pink as I had used the white paint that goes on pink so you know where you've been.

I don't have a extractor in the bathroom but always have the window open during and after a shower. I do have a kitchen extractor which is always on when cooking. I try and do my best to get most of the moisture out of the house but have found mould growing in quite a few places.

I can't believe that this has happened since the cavity insulation as I thought this would be a benefit especially with the rising cost of gas and electric but I think I've probably spent more on mould treatment and redecorating than it has probably saved me!

Any other suggestions?

Thanks

Steve

 

[freddiemercurystwin]

Unfortunately houses require ventilation otherwise they suffer from damp. end of storey. There is no other solution.

You have moist air inside generated by people, the heating system, boiling the kettle, taking a shower etc. The moisture in that air has to go somewhere. If you do not provide a path to the outside it will try and get through the structure. Its not very good at getting through solid masonry so whilst some of the air can get through it leaves the water contained within it behind as condensation which over time turns into mould. You have to provide a path to the outside.

Even brand new houses have ventilation.

//www.diynot.com/wiki/building:condensation_in_houses

 

[flameport]

I can't believe that this has happened since the cavity insulation

The insulation has made the problem worse, because the air in your house is now warmer than is was before. Warmer air will hold more moisture - until it finds a cold surface to condense on, which is usually the bottom of walls behind furniture.

You need to get an extractor fitted in the bathroom - open windows are generally useless, since they rely on air entering through one window and exiting through another.
Unless the wind happens to be blowing in just the right direction, either nothing will happen, or the damp air in the bathroom will be forced into the rest of your house.

 

[Stoday]

Your problem is lack of ventilation.

To avoid the damp problems you now have, you'll have to exchange some of the damp warm room air with the cold air from outside. The cold outside air, even if it's damp, will become very dry when it warms up inside.

Yes, you'll lose heat warming up the air, but that is a price you have to pay.

You can get a heat recovery ventilation unit that recovers over 75% of the heat in the air leaving the house using it to heat the incoming air. Google "heat recovery ventilation".

 

[merlin50]

http://www.askjeff.co.uk/cavity.html

 

[steveo777]

Hi,

Thanks everybody for the responses with help and advice. I've installed a air brick into the spare room today so fingers crossed it'll help. I'll see if the mould problem continues and install more air bricks if necessary.
Thanks

Steve

 

[diydone]

Don't forget to consider getting a dehumidifier.

I have a similiar potential problem.., living in a rented terraced house with an airflow problem. I was told by the landlord to leave windows open.., but as u say.., not nice proposition when there are icicles around outside.., but I also don't want mould.

So I spent £80 getting a secondhand Ebac 2850e dehumidifier which is big enough for a four bedroom house. It has picked up an effective amount of water (even helped when my OH kept spilling water everywhere when changing some taps). It won't help with airflow too much but will definitely deal with the excess water that helps mould grow. Either the 2650 or the 2850 has a saver switch that switches the dehumidifier off when the moisture content of the air goes low so it doesn't stay on all the time.

 

[peterperfection]

Ventilation ventilation ventilation.
We cant have it all .
We want to trap the heat inside our houses- --ok- but we also trap everything else . Water vapour, bugs and all the other eeby jeebies that frequent our little palaces.

Cast your minds back (those who are old enough--to the pre-war/ post war days when there were no washing machines and tumble driers and lots of houses had a 'maiden' hanging from the ceiling with wet clothes on (now now- guys- dont get excited).
No complaints at that time about damp patches, mould on the walls or ceilings etc .
Thats because most houses had 'natural' ventilation --ie: draughts in doors and windows- and best of all- a OPEN fire ..

No double glazing when I was a kid- and I cant say I ever noticed our windows getting wet on the inside .

Ventilation is the answer--it's a bit of give and take.
We give a bit of heat back to nature and nature takes a bit of condensation and eeby jeebies back in return.
We CANT have it all.


So- NEVER vent a inside air vent into the cavity. ALWAYS vent it to outside and make sure you fit a sleeve through the cavity 9if the house has a cavity).
Hees another piece of info that seems to have passed people by.
How many people have noticed a 'plastered over, wallpapered over ' 'air vent' in the top corner of a room ????.
There lies your answer.
Any queries- just ask- I will be happy to explain.

 

[Nige F]

So cut a 9x9 hole in a bedroom wall so you can hang damp washing there . Let`s all go back to the old days where the inside temp. was 2 degrees F. higher than outside

 

[peterperfection]

So cut a 9x9 hole in a bedroom wall so you can hang damp washing there . Let`s all go back to the old days where the inside temp. was 2 degrees F. higher than outside

Now Now Nige,
You ever noticed how many houses these days get mould on inside walls ?
Dunno about your drying habits- but most houses have a tumble dryer nowdays for drying clothes.
Ever noticed how modern built house seem to harbour smells ? Compared to older houses ?.
Ever wondered just why building regs insist on ventilation to all rooms- especially bathrooms ?.
I could talk about it till the cows come home- but- no point - everyone has their own opinion.
Thank you for commenting though

 

[peterperfection]

Try www.admsystems.co.uk they were great when they fitted our heat recovery ventilation system

c'mon Dave - cant knock you for promoting the company- but- just how much does a system cost from yourselves ?.

 

[peekay53]

use black hole vents and they will solve your prblem and no howling gales blowing through