insulated backing paper for a condensation problem ??

[luke100]

Hi All,

new to the forum, seems like some excellent advice on here.

I am doing up my ex-council house in Tooting, London. The house has a real problem with the external bay window walls (up stairs bedroom and downstairs living room). If the outside temp drops below 6 degrees condensation drips down the walls and damp areas to touch. The house is very dry else where and we have really minimised the moisture inside the house.

The walls are unusual. The house was built in 1905 using black clinker/fly ash (railway spoil) block work. The external walls suffering are clinker and brick (external wall is 24cm thick). The front of the house is pebble dashed and south facing. In the day time the walls are dry.

I am a chertered engineer and been through all the usual suspects. The ventialtion is good (trickle vents fitted),not rising damp, not coming from outside etc.. dehumidifier not an option I want to use.

was going to try 3.5mm lining paper by "wall rock". claims to really improve the thermal bridging. Do not want to do the thermal plasterboard as there are lots of round curves in the window bays which would be lost and a messy/big job.

Any one have much success with this lining paper ?
thanks
Luke

p.s photos are uploaded to my album for all to see.Can'tseem to post them in this bit.

 

[AronSearle]

The paper "may" just rise the surface temperature in places to avoid condensation, but it must be vapour resistant, or use a vapour resistant paint, or it will just happen immediately behind the paper backing.

I think it is dubious however, the temperature difference it will make to surface temperatures will be small, I cant see that such products will help unless the building is already somewhat modern and has a light thermal bridge fault (like lightweight blocks, and cold bridging is occurring through mortar joints).

You are best biting the bullet and just doing thermal backed plasterboard, make sure it has (or you use) a vapour control layer, that is properly taped/joined at panel junctions, or you may still get damp issues building up within the fabric.