War against damp, whats next?

[Chaang]

There is a small coalhouse on the back of my house I want to use as a utility room but first I need to prevent it getting so wet inside.

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I have tried adding an airbrick and just done the roof because felt and tiles were damaged.

I still get damp on the walls which I think can only be condensation. It is most obvious at head height. There is no heating in this part of the house so it is always a lot colder. There is no ceiling except some polystyrene tiles. The wall is double brick with a small cavity.

I have bought a dehumidifier because the door was sticking and this seems to help.

What should I try next? I am thinking trying to insulate it better, maybe add a ceiling and some loft insulation?

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[^woody^]

Looks like you've got water running down the wall soaking up the wall too, which is not going to help

 

[Chaang]

I don't think that there is any water running down now, I think the green staining is from before the roof was fixed.

 

[noseall]

That outhouse roof looks like plain tiles on a very shallow pitch.

If they are plains then they are unsuitable and are at risk of admitting water.

 

[noseall]

I reckon the pitch to be about 14 degrees, far to shallow for most tiles let alone plains.

 

[Chaang]

Not sure what you mean by plain tiles? They are the same as the original ones. What should they be?


Cant see any water getting through the roof. Even if the tiles are no good, there is new membrane underneath. Neighbour has same tiles and pitch but says he does not have damp problem. Polystyrene tiles on underside are not damp. Water is on the walls.

 

[mointainwalker]

I still get damp on the walls which I think can only be condensation.

If no heating, very unlikely to be condensation unless you leave the separating door open so that warm air escapes from house into outhouse.

 

[digdilem]

If one room is colder than the others in the house, and the door is open, all the warm, moisture-laden air will condense its water load on any cold surfaces, which'll be your outhouse.

Also damp from the floor is possible, but if it's unheated and un-insulated, condensation would be my first guess. Get it insulated (thermal plasterboard perhaps). Ideally get it heated too, but if not leave it well vented to the inside of the house (door open) for a month or two and see if that helps.

 

[Chaang]

I may go with the plasterboard idea but not sure If my skills are up to it!

 

[anobium]

Just a thought , is the wall single brick, the old outhouses usually were.
Check and let us know

 

[Chaang]

Its double with a 1/2 inch cavity

 

[anobium]

Its double with a 1/2 inch cavity

Thats a small cavity , they are usually 2".
I would check the pointing as with a cavity that small, there is a strong possibility you may have penetrating damp.

PS. Just had another look at your pic of the brickwork and there are some headers which suggests the walls are solid, ie no cavity.
Above still stands but if pointing ok drylining may help.

 

[Chaang]

Its condensation.

Not wet when its raining but gets wet when we are drying clothes or cooking.

The problem is definitely because its too cold in there. I have seen it at 10 degrees C and this pushes the relative humidity up to 80%. Walls are cold to touch and doors are sticking because they are also absorbing the moisture.