Damp , Damp and more damp

[Estrella]

As you may have grasped from the title I have a damp problem, and when I say I , i mean my house.
Its 140 yrs old , but does have a DPC and the damp is upstairs.
Our bedroom in particular is very damp feeling. We filpped the mattress last week and there was mould underneath And when we woke up this morning the outside of the duvet felt damp.

We are a family of six who shower daily with no extractor fan. to counteract this I have a dehumidifier running 10 hrs a day.It is worth noting that the dehumidfier doesnt run in our room but on the hallway and our room is shut so presumably it gets no benefit.

The house is double glazed , but at the rear where our room is its wooden DG and pretty crap.

Any bright ideas as to how I can counteract this ?


Many thanks

 

[NickStone]

If you're running your dehumidifier 10 hours a day, what happens when it's switched off? There will be residual moisture in the air and people are still breathing. With six people in a house with double-glazing, that's a lot of moisture-laden air that cannot escape. You might be better off with a dehumidifier that has a humidistat to sense when it needs to come on. Might be better running 24/7. (Mould starts to form at 68% saturation, which is lower than the saturation needed for condensation.)

One other observation - old houses were never designed for double-glazed windows. Building methods were different, including the type of plaster, and the structure needs to breathe. When people put in dg, condensation is then forced into the structure, which will absorb the excess moisture and the result is mould in the hidden parts of the building. You might want to think about putting in a bathroom extractor, ensuring that the trickle vents on your dg are always open and maybe even putting in some airbricks. Have a look at this, too:
//www.diynot.com/wiki/building:condensation_in_houses

 

[Estrella]

Excellent, thanks Nick.

My wife says its caused by me being to tight to turn the heating on Its just that I dont feel the cold , and she does !

Ventilation is a good idea , but I have massive problems getting a vent through the wall for extractors. 18 unch wide and 2 inch thick pieces of slate are what the outside walls are made of

There is also no gap between the roof and the attic ceiling that I can poke a pipe out of.

i'll revisit it and see if I can do something.


Many thanks again

 

[NickStone]

You're welcome . Your wife's point about turning the heat up is a good one. However, although warm air holds more moisture than cold, it doesn't hold it forever and once that saturation point is reached, it will condense somewhere if it can't get outside. Having said that, I used to have a house built in 1860 with an Aga. The Aga kept the whole place at an even temperature and I've never lived anywhere with so little condensation on the windows in the mornings. The other thing that helped was open fireplaces. Chimneys are great sources of ventilation but people often seal them up to stop draughts. If there's one in your bedroom, you might think about opening it up.

 

[Estrella]

Yeah , good point about the chimneys. I have one downstairs and there is no damp there. The one in our bedroom is blocked off , but I am pretty sure that the boiler vent pipe in the room below us goes up through it, so I dont know how practical that is.

Cheers

 

[r896neo]

box cleva,

Open up the chimney for a nice feature and some much needed fresh air!

I doubt your boiler vents into it as it would not be safe to simply have the flue terminating half way up the chimney. If you think it is lined all the way up there's also the question of how did they get into what is essential a pretty small brick tube!