Condensation

[DaveBlair855]

All,

Have had a quick blast through the search engine for a solution to this but got a staggering number of hits, so forgive me if I'm covering old ground here.

We have a 16c thatched cottage which has been subject to some "renovation" (read "negative interference") by the previous owners, part of which includes the replacement of a number of the panels between the beams on the first floor with some form of cement render. The result- very cold walls on the North face of the house, which in turn is causing real issues re condensation and the dreaded black mould. This problem is presenting on the first floor landing and to a lesser extent in both first floor bedrooms- the ground floor seems untouched.

I have had the place assessed to ensure that there are no other underlying damp problems and am assured that this is purely a condensation issue caused by inadequate ventilation. We have had the heating in the house re-vamped, although not excessively so, and have also replaced the bathrooom since we moved in.

So the question is this, how best do I improve the ventilation on the first floor to keep the air on the move? I would prefer passive systems as don't really fancy a dehumidifier running all the time with the accompanying expense, but am not sure how this stands with regards to the listing in effect on the building- presumably it will require a degree of hole knocking in walls? I imagine even an extractor fan would assist, but don't know how a CO would react to such a proposal.

Any advice or experiences gratefully received.

 

[MdB]

I would speak to your CO.

Do nothing and your house will suffer problems from the damp. Do something and you will be altering the structure of the building. Neither solution is ideal so there will have to be compromises. Your CO will be able to view your property and go through the different options available and work with you on finding the best result for your building.

(I take it you can't just open a window more?)

 

[Tom]

So the question is this, how best do I improve the ventilation on the first floor to keep the air on the move?

At the risk of sounding flippant....open a window? In fact, if you open a couple of windows, just a little, it should give a reasonable amount of air movement. I'm not suggesting you live in a hurricane or in sub-zero temperatures by having windows wide open :shock:

You could use a dehumidifier that has a collection unit (we used one of these in our caravan). That way you don't need any holes in the wall. However, you're only getting rid of the symptoms....you really need to effect a cure for the problem ie remove the cement-based panels and replace with lime-based panels. The result will be warmer, breathable walls leading to negligible condensation.

 

[JoceAndChris]

Hi Dave

I also live in a damp house but find the more rigorously I control the condensation we produce the better the situation is.

The first thing we did was to pull up horrible old plasticy floor coverings and get a nice breeze going from the cracks between the floorboards. That helped, especially in the bathroom.

After a shower, the bathroom window must be opened for 30 minutes. No laundry is dried in rooms prone to damp - and preferably it's all line dried outside. Bedroom windows are opened for 10 minutes in the morning, and excessive condensation on panes is removed with an old towel.

We keep a dehumifier running 24/7 in the kitchen. Prior to that, I found that food just went mouldy, so I cut holes in all the cupboard doors for ventilation and put anything that would go into an airtight jar into one. Those measures, as well as keeping lids on pans whilst cooking, makes my cellar kitchen a workable space. All summer long, the doors were wide open - so I felt winter began with a good, dry house .

Fires are also excellent as apparently they shift water vapour up the chimney. We'd planned just to close off some rooms this winter to save on fuel, but it hasn't worked out. The wallpaper we put up last year was peeling a bit in the room at the end, so I'm making sure each room gets a twice daily gentle heat and we're rotating where we have our evening fire so all the fireplaces get used.

Rotate your clothes and shoes too or you might get a nasty surprise when you go to your summer shoes next april and find they're blue with mould. Don't leave anything to rest undisturbed, and keep a watchful eye on any woodworm holes.

If none of those measures work, you'll just have to stop breathing!

 

[Flyfisher]

I wouldn't totally dismiss a dehumidifier; it would be a good way of verifying the problem and a self-contained one would also give you an idea of how much moisture you have to deal with. Then you could try a number of different things and monitor their effectiveness by the (hopefully) reduced volume of water collected each day by the dehumidifier.

Joce's list looks like a good set of things to try, although I would also suggest leaving a bedroom window open overnight. We've always done this and on the rare occasions I forget, the windows are full of condensation on cold mornings. As Joce says, the only alternative is to stop breathing. :wink:

 

[Penners]

Prevention always being better than cure, probably the most effective action you could take would be to add some insulation to the cold walls. From your description I infer a timber-frame structure. Could you remove the interior infill between the beams and pack the cavity with insulation (plus the requisite dpm and air-gap)? That would prevent the interior wall surface from getting so cold, thereby reducing - perhaps even eliminating - the condensation.

Failing that, then - as others have suggested - warmth and ventilation will be your best friends. You need warm air to hold as much water vapour as possible, plus ventilation to carry that saturated air out of the house.

 

[middi]

The first thing that springs to everybody's mind ( including mine) is, as pointed out, better air circulation/exchange.
This is all well and good, unfortunately this will only solve the immediate (and partly aesthetical) problem(s) which condensation creates , when condensation is apparent in such a building as yours ( thatched, beamed and cement render infills) there could be a more serious underlaying problem which you cannot see, this is the slow decay of the trapped moisture on the hidden part of the studs/beams.
Cement render being one of it's worst enemy especially if this kind of render also extens to the external facade. Even modern plasterbord and breatheable paints is a better option than internal cement render.

It may pay in the long run if you have the situation propely investigated.