I wonder if anyone can offer some advice or help, I live in an old property, approx 150 years old.
The problem I have is that moisture is showing up on the wall paper, in the form of little patches all over the wall, not low down though. The property has had replacement double glazed windows fitted and the exterior wall is rendered. The wall has been tested for rising damp but I have been told it is moisture causing the patches to appear on the wall. The property does have a DPC and it also has a cellar, if this makes any difference.
I have been running a de-humidifier and this seems to reduced the problem, so I don't think it is coming from the exterior wall in.
I don't really want to run a de-humidifier for ever and would like to, if possible, reduce the problem or stop it all together. I have found a product called SEMPATAP, which seems to be advertised as reducing or possibly stopping the problem that I am currently having.
Does anyone have experience or knowledge of this product? As it is quite expensive to buy and if it isn't going to work, I would rather invest my money elsewhere.
Or, does anyone have any other tips or known ways of curing this problem?
The most likely cause of your problems is lack of ventilation. If the windows have trickle vents make sure these are open, if not set the windows in their night vent position and see if this helps.
It is likely that your property is of solid wall construction and that the air bricks have long since been plastered over.
The long term solution to condensation is 1. Increased ventilation thereby carrying away the moisure laiden air or 2. Increase the temperature of the surface upon which the air is condensing.
Insulated linings and plasterboards are very effective at doing this. So much so that now the Building Regulations require that where external solid walls are being re-plastered it must be done using insulated plasterboard.
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