Signs of damp in newly bought house

[somuchcoffeeneeded]

I bought a house and moved in last month. There are signs of black mould showing up on and under the paint around some of the windows. The main bits are in the conservatory (part-windows and part-walls) but I’ve spotted some in the main bedroom this morning. I’m worried it’s just been painted over by the previous owner. The house is less than 20 years old. We have moved from a new build and lived there for ten years without any mould at all so I’m feeling really sad about this new house now. What can I do to tackle the mould apart from using a mould spray? I’ve used the spray in the conservatory and it has got rid of the black dots but I’m thinking they’ll be back unless we tackle what’s causing it!

Dehumidifier

It could be condensation- make sure you open widows to keep the air circulating

Could just be the previous occupants never opened windows and dried a lot of washing inside.
Assuming at 20 years old there's no obvious issues - guttering etc, live in it & ventilate well & you might find it naturally disappears.

I read an interesting blog yesterday about damp in old buildings;

www.heritage-house.org/damp-and-condensation/managing-damp-in-old-buildings.html#:~:text=It's%20inevitable%20that%20you%20will,better%20than%20any%20modern%20house.&text=Almost%20100%25%20of%20damp%20issues,and%20lack%20of%20adequate%20ventilation.

I know yours isn't old but apparently there's no such thing as rising damp, and nearly all damp is caused by condensation due to the walls not being ventilated. There's some interesting points in it maybe worth a read.

Yep, ventilation is the key. We rented a flat out once and the tenants never opened a window and the place was full of mould when we moved back it. It had never been a problem before. They actually said they never opened the windows. Dickheads.

I actually think it can be worse in new builds, you rarely see it in houses with high ceilings. And old houses can have more natural ventilation, gappy doors and windows etc!

You could also try a dehumidifier. And we use one of those window vacuum things to get rid of condensation in the conservatory.

Both rooms it has shown up in are well ventilated. The conservatory is definitely a well ventilated space (breezy!) and the bedroom has a window that needs looking at because it doesn’t quite fit tightly to the frame (but this is the one at the other end of the long window - not the one next to where I can see some hints of black spots). I have little dehumidifiers dotted around both of these rooms and elsewhere. Washing is dried either in the tumble dryer or hung in the utility room with extractor fan and window and no mould showing up in there so far. Trickle vents on all windows apart from the conservatory.

I’m very interested in this window vacuum thing that a PP mentioned. Off to Google!

Any signs of problems such as moss/cracks on the walls outside where the damp is on the inside?

Yes - check your brickwork (or equivalent outside), plus around windows and drains etc.

We have had three different problems (older house). Two linked to the drains and one linked to a small crack in the mortar, letting in water.

I have a more serious damp problem.

Tips:

Other than black mould spray the most effective destroyer of mould is tissue soaked in bleach. Wear gloves. Apply bleach papier-mâché. Open windows. Leave for 24 hours. mould dead forever.

Airing out the house will be a big help - heating on windows open.

I’m getting lots of advice re: removing gas hobs... not following through myself but had does make water when you burn it so I get the point.

Make sure your bathroom door is closed and that you close your doors for kitchen. Confirm That your extractor fan is extracting to the outside (our flaps keep shutting). Make sure doors are sealed enough too.

Dehumidifier for laundry but have been informed by a humidifier seller that whacking in the heat and opening windows will dry faster.

Lastly and perhaps most importantly get the guttering cleaned. Who is to say that has been done in 20 years.