A number of years ago the "warm homes scheme" supplied thick silver foil panels to me to put behind the radiators on external walls. I have been having problems with damp walls behind radiators only and suspected a new damp course was needed. Damp behind all the radiators that had been fitted with the foil. Taking the bull by the horns in the worst room I removed the radiator and took all the damp plaster off the wall. Behind it the brickwork is completely dry. No sign of damp anywhere even when I removed the skirting board and can see to the ground. No smell of damp either since the plaster removed. This must have been condensation and I suspect all the other rooms are the same where the foil is fitted. Has anyone experienced a similar problem like this with the foil. Maybe some plumbers can provide the answer.

needawin, October 2011

Condensation occurs,as you know,when moisture laden air reaches a colder surface, such as windows, or any impervious surface, such as foil behind your radiators. Unless the radiators are not turned on, ie cold, it should not present a problem; however, if the radiators are cold, it could be that there is insufficient air circulation between the radiators and the wall. The house may be high in background dampness, which will not show as visible dampness on walls etc. You could try using a de-humidifier if all else fails. Hope this helps.

davidj, October 2011