DIY Doctor

Condensation appearing on interior wall

Postby click38 » Sun Nov 21, 2010 11:23 am


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?

Thanks in advance for any help.

Rank: Labourer
Progress to next rank:
Posts: 2
Joined: Sun Nov 21, 2010 11:02 am


Simply Build It

Postby stoneyboy » Sun Nov 21, 2010 9:45 pm

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.
Rank: Project Manager
Posts: 4032
Joined: Wed Dec 10, 2008 6:44 pm

Postby click38 » Thu Nov 25, 2010 10:04 pm

Hello Stoneyboy,

I have also tried to open the windows on vent but unfortunately it doesn't really seem to cure the problem.

I was wondering if the SEMPATAP would be worth a try, in the hope it might insulate the wall a little better and help prevent the moisture from forming in the first place.

Apart from the company advertising its properties, I have had little luck in finding out its true performance potential and was hoping that someone might be able to offer some advice on the product.

Thanks again for your tip.

Rank: Labourer
Progress to next rank:
Posts: 2
Joined: Sun Nov 21, 2010 11:02 am

Postby ICL » Sun Dec 05, 2010 1:11 pm

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.
Rank: Labourer
Progress to next rank:
Posts: 2
Joined: Sun Dec 05, 2010 12:19 pm

Display posts from previous
Sort by
Order by

  • DIY How to Project Guides
  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!

  • Related Topics