Damp patches on chimney Breast

RelievedSheff

easty said:

neilmcl said:

easty said:

I’m having very similar problems at mines. 

Flashing replaced. Chimney breast painted with some waterproofing stuff. Not getting any better.

Its incredibly frustrating. If this was going to be my long term home, I’d bite the bullet and get the chimney rebuilt, but I only plan to be here another 18-24 months and it’s not worth the outlay.

That sounds like condensation to me.

I have a wood burner and flue liner. Would that cause condensation?

How do you deal with the problem??

Lack of ventilation and a colder surface are usually the main causes of condensation along with the source of the moisture in the air of course.

murphy_joe

What would your suggestions be?

murphy_joe

We’ve put a vent in the hallway. Windows are open and the humidity still won’t go down!

FreeBear

On a day like today (humidity is down to 30% at the moment), some fans to get the air circulating will help. Later in the year, a dehumidifier will do wonders.

RelievedSheff

murphy_joe said:

We’ve put a vent in the hallway. Windows are open and the humidity still won’t go down!

If the house is damp it won't go down magically as soon as the windows are opened. It takes time for the fabric of the building to dry out. You need to fix the source of the damp and then over time the humidity will start to drop with adequate ventilation. A dehumidifier will speed up the process once the source of the dampness is fixed.

We moved into a new build last year and as with all new builds they take a long while to dry out from the construction phase. Last year the humidity in the house in April when we moved in was between 70-80%. It has gradually dried out since and today the humidity in the house is around the 50% mark. To allow it to dry out naturally though it has needed to be well ventilated. 

Slinky

We have similar going on in our bedroom. Got a builder booked to come and cap the chimney and sort flashings as there's some cracking up there. We're bricking up the fireplace in the lounge and having a vent knocked through the back to under the stairs. Builder thinks salts from coal soot have caused the bubbling of the paintwork - brest was only replastered last year when we moved in as a patch fell off, it looked like a historic problem but evidently isn't. We've had the chimney swept and only a minimal amount of soot came down. Hoping that painting with a treatment on the wall before replastering will sort it next time.

OP looks like your house has been newly renovated, have you had it replastered? May be the cause of your humidity.

murphy_joe

We bought the house in October and the plastering was already done. Nobody had lived in the house for a year before.

I’ve had the windows wide open for the past hour and humidity has dropped from 75% to 55%.

With us removing the chimney liner and replacing the cowel (hopefully that was the problem) the house will dry out.

FreeBear

murphy_joe said: We bought the house in October and the plastering was already done. Nobody had lived in the house for a year before.

Not surprising that the house has some damp issues if it hasn't been lived in for a year. Give it another six months of ventilating and heating (when it is cold enough outside), and you'll probably find most of the damp disappears.

You might regret ripping out the liner (and stove ?) - They make for a nice focal point and the chimney breast is a real good thermal store for both the ground floor room and the one above.

Got a stove here, and the chimney breast in the bedroom above is a cosy 25°C after the fire has been burning in the evening. Most welcome on a cold winter night.

murphy_joe

We would have opened it up but it was already bricked over when we bought it.

JohnB47

murphy_joe said:

Sorry we have put a vent on the other side of the chimney breast. We have just removed the old liner from the chimney and replaced the cowl.

What does 'on the other side of the chimney breast mean'? To be clear, do you have vents that allow air to flow through all unused voids within the chimney breast? If the breast is on a first floor, there will be two voids in there - one for the floor you're on and one for the fireplace on the floor below. Curiously, your photos seem to show a single chimney stack but quite a wide chimney breast.