Tackling damp when we can't find the source

Dinah93

We completed on our first house on Friday, and went and got the keys on Saturday. When we went into the house we were hit by the smell of damp. Going around there is black mould on the walls in the dining room on the 3 corners that meet the exterior walls, and black mould on the underside of the window opening in this room. There is also black mould across the outside wall of the downstairs bedroom (room next to the dining room, also on the north east facing front of the house), but this room also has mould and damp inside the built in wardrobes which are on the wall between our house and the semi next door. There is also mould growing in the corner of the fully tiled bathroom, again at floor height.

We asked a builder friend around yesterday to look at some work we want doing, he said there are 5 airbricks across the front of the house which should be sufficient to keep those rooms free from damp, he had the floor boards up and went on the roof, and can't find where any of it is coming from.

We did pay for a full structural survey before purchase, I'm not best chuffed no damp was picked up when its obviously a pretty major issue.

Is this likely to be as simple as its a 1960s house which has been double glazed without trickle vents and therefore the house can't breathe? If so is it possible to retrospectively install trickle vents without installing all new windows?

The dulux bathroom paint which is guaranteed mould resistant for 5 years - is it worth using this in these rooms, or is this just going to trap moisture in the walls and exacerbate the problems?

Sorry for rambling, I just want to get this fixed properly and any advice would be much appreciated.

Niv

Was the house empty for a time before you moved in? My first impression is that this is maybe due to inactivity in the house. Air bricks should have solved most of these issues in the first place however if internal doors were closed there could still be a lack of air flow. As for built in waldrobes, this is fairly common to get a little damp and this is due to the lack of air flow. I get the same problem as you with that and currently keep the door open when possible, eventually i will install some vents in the doors of the wladrobe.

As for the house generally, I would clean any mould off the walls, and air the house out for a while and see if it returns. I would not repaint any walls etc at this time personally

Dinah93

No, the house was occupied up until Friday.

I've already stripped the paper off the walls in the dining room to try to dry it out a bit, can't really strip the marble tiles off the bathroom though. Although that room needs an extractor. It just seems to be an airtight house!

WestonDave

My instinct from what you have described is that most of the mould is due to poor air circulation - its relatively common in a house that has been allowed to run with higher than average relative humidity (a lot of moisture in the air!) to find that in little pockets tucked away behind furniture or in corners, warm moist air has gone in, cooled, condensed and left moisture on surfaces which has then bred mould.

Even something as simple as a bin in the corner of the bathroom could be enough (if not cleaned regularly) to allow mould to start.

I would get in some of the polycell/cuprinol (whoever makes it now!) mould killer spray and use it to clean off all the mould you can see, then put a preventative spray of it back on the surface.

You then need to start dealing with the ventilation - a bathroom without an extractor is literally asking for mould. There are posters on here who have a lot of experience with damp matters like Dave Aldred and dampdaveski - have a search for their postings and see if anything they say is relevant. They may well come on and help out anyway. I suspect putting trickle vents into the windows is going to be hard work and possibly expensive. It might be worth considering one of the loft based ventilation systems (PIV) that blow fresh air in - this is drier than internal air and helps lower humidity. In any event you certainly need to make sure a window is open when you shower/bath/cook, and try to avoid drying washing in the house on radiators etc. On a day like today I would have every window open getting lots of nice hot dry air in from outside to really dry it through.

Although it probably looks really bad its surprising how much apparent mess something small like static furniture can cause in mould terms and so I wouldn't be overly concerned about it being a big problem. Its very possible that the surveyor didn't pick it up precisely because it was just a localised problem hidden behind furniture etc.

dampdaveski

Hi dinah,
Congrats on your new house ;-)
I don't think you've got a major problem,
as others have described it sounds like a condensation and ventilation related problem.
you've done the right thing as in stripping defective decorations off, you can use a bleach type product to clean off the mould (careful you don't get any on your skin or eyes) and keep an eye on it.
We use a specific product that is far better than bleach, and we also put a paint additive into paint to prevent it coming back.
I would NOT recommend slapping bathroom paint all over the house because it's overpriced slop
The one I use the most of is on www.condensationproducts.co.uk
You can get similar ones elsewhere, but 1. I cant be bothered to find all their links:D and 2. I use gallons of the mould killer and paint additive and have never had any problems with it
So moving on
Immediate questions that spring to mind are
1. Was it an old lady / gent who lived there before?
2. are there extractors to the kitchen & bathroom (you say there isn't one to the bathroom)
3. does it have cavity insulation

Not that I like sticking up for chartered surveyors, he or she could have missed it because when they did the survey it had been cleaned away by the previous owner, or it simply wasnt there, in the same vane it could be because he or she is a complete numpty!
Hope this helps, any more questions just stick 'em on or send me a pm

And if you think i've put in a long winded reply, wait till you see David Aldreds (sorry David, Couldn't resist;))

DD

hethmar

Dont worry, lots of houses of that sort of year have condensation probs. You have had some good advice here. Stop worrying and enjoy. Just also check out that your gutters arent blocked.

ariba10

Have a read of this

http://www.harfordsonline.com/downloads/condensation%20info.pdf

iamcornholio

Dinah93 wrote: »

We did pay for a full structural survey before purchase, I'm not best chuffed no damp was picked up when its obviously a pretty major issue.

You need to confirm what survey you paid for. If you had a structural survey, then this would be done by a Structural Engineer and would be to look for specific structural issues - he would be very unlikely to comment on mould or damp even if it was in front of him as that is not part of his remit.

If you had a full Building Survey (of condition) carried out by a building surveyor, then mould (if present at the time) should have been commented on, and causes explored and solutions offered. If not, you need to refer back tot he surveyor for an explanation. Even a cheaper HomeBuyer Survey should comment on mould

Anyway, the type and location of this mould is typical of condensation dampness and not structural/penetrating dampness. Whether this was due to the previous occupants lifestyle or because it was empty for a while does not matter, as you will most likely live a bit differently - so it may not occur again.

You need to wash the mould off with a proper fungicide (not bleach) - strip any paper back to bare plaster and treat the plaster, and then redecorate. If you have an air brick or window vent to the rooms, then along with heating then you might find that the issues does not re-appear

There could be a possiblity of defective external pointing/render making the areas cooler, but that is furhter down the list of possiblities. Check the condenstion prevention info on here or via google

Dinah93

Sorry, a building survey is what we had. Apparently there are 3 levels, valuation, homebuyers and building, and we had the top one.

Thanks very much for that document, I will go back to the house this weekend and give it a good scrub. I have to say I'd never thought of something so simple as a dehumidifier!