Condensation in One Downstairs Room

[seethrubabyblue]

Hello everyone,

I have a condensation problem (not severe) in one large downstairs room (4.85x3.65m) which is unheated and unused (no central heating). The problem is on a south-west wall which has a working fireplace for burning coal or logs etc.(does not draw very well). There is an unheated single storey garage on the other side of the wall. The house itself is two storey and the wall in question is cavity with foam (house built 1968). The other outer wall faces north-west and has a double-glazed window with a veranda on the other side which blocks quite a lot of sun.

What would be the most economic long term solution, given that the room is unlikely to be used? Many thanks in advance.

 

[Nige F]

Is the chimney partly blocked by nests/debris ? . A flue should be adequate in ventilating the room - also is there warm damp air getting into the room from other parts of the house . P.S Do you have , on the wall a tall mirror

 

[dann09]

1. are you referring to one room or two rooms?

2. as Nige says, check the flue, or flues, and c/stack terminals. perhaps sweep all your flues?

3. your cav. insulation will be a retro effort, and well suspect for creating more difficulties than it claims to solve, esp. in the vicinity of an outrigger - a garage or conservatory.

4. in essence, again as nige said, deny warm, humid air, and supply heat and ventilation.

 

[seethrubabyblue]

Dan, I'm referring to one room and the cav. insulation was a retro effort - please explain the difficulties this can cause.

Nige, the chimney is clear and has a bird guard fitted (chimney has hardly ever been used). The door is kept closed and the vent in the window kept open.
Would a chimney fan, or a small fan to force air into the room from outside to have an effect like a lofty be worth trying?
Yes it does have a mirror, but the condensation gives a distorted view...

 

[dann09]

1. the cav. insulation installers often skip difficult to access areas - whole brick panels or patches.

2. research here and the web - there's a rake of con's against retro cav insulation, and some are against any cav insulation that "fills" the cavity. It can leave cold spots that create interior condensation. Sodden insulation can assist cav ties in swelling and sometimes causing swollen/damaged brick patterns.

3. I'd recommend staying away from "chimney fans", others with more knowledge might disagree. Attempt to logically, and perhaps expensively, find the root cause(s) of your difficulties.

4. Heat, and more heat, money going up the chimney might be the least expensive option.

 

[Nige F]

You could try insulating the garage side of the wall with slabs of Kingspan (maybe insulate the rest of the garage later to make a hobby room ) The 60`s foam could have large cracks/voids in it , it never was the best way to do cav. fill . Like a lot of strange practices in the 60`s

 

[seethrubabyblue]

Thanks both - takes two to know.

I will insulate the garage side of the wall with Kingspan. Can anything be done with the cavity now?

 

[dann09]

Well you've heard opinions of cavity fill, and in fact, there's no solid evidence that it is the cavity fill being the culprit. The above are merely possibilities based on experience.

Removing a few strategically placed bricks might reveal more to you about conditions in the cavity at the suspect areas.