condensation problem

Tim Robo · Post by **Tim Robo** » Mon Sep 01, 2008 5:20 pm

Hi all,
This is my first post hope someone can help have read several topics and the advice is excellent.
Have just purchased a terraced property and have been advised that the damp patches on several walls are down to condensation.
The house has had a DPC done it would appear twice previously, the surveyor explained about salt in the re plaster attracting moisture he advised knocking off the plaster and replastering using washed sand and cement with a water proof additive.
Do I need to knock off all the plaster including the dry, I intend installing a positive pressure vent system in the loft and also venting the bathroom.
can the walls be Dot and dabbed using foam to adhere to the brick ?
cheers in advance.
Tim

leebwk · Post by **leebwk** » Tue Sep 02, 2008 6:52 am

Hi Tim robo,

I would be inclined to use a dehumidifer for a few months ie 6 and also keep the house well ventilated ie leave windows open when able this will dry the house out and help the situation also it will keep the damp air to a minimum

Tim Robo · Post by **Tim Robo** » Tue Sep 02, 2008 8:06 am

Thanks leebwk,
Will that dry out the damp bits, will it be quicker to knock the damp bits off and replaster, also plan to skim all the walls eventually.
will keeping ventilated prevent recurrence of the problem ? Finally can I leave the "dry" plaster alone.

cheers Tim

leebwk · Post by **leebwk** » Tue Sep 02, 2008 9:02 am

Hi Tim robo,

Firstly do you have any guarantee's from the damp injection work ?, if so then maybe a call to the company and explain the situation as the DPC could be failing but if this has been done twice, i think there maybe an underlying problem causing this.
Knocking off the damp patches and replastering will only cause the plaster to become wet/damp again, you really need to knock off about 1200mm up from the floor and render using sulphate resisting cement with also a waterproofing additive then skim over the top.

Tim Robo · Post by **Tim Robo** » Tue Sep 02, 2008 9:28 am

Hi leebwk,
No guarantees unfortunately, Am happy the problem is condensation as damp is too high for rising damp (surveyor) will knock off plaster to height recommended on walls affected by moisture - not just patch damp bits - using washed sand with additive and sulphate resistent cement and skim other walls. how does that sound ?

regards Tim

Tim Robo · Post by **Tim Robo** » Tue Sep 02, 2008 9:30 am

Further to tha last post the house was a rental prior to my purchase and shows several classic signs of condensation. rusty radiators, angle bead, mold etc.

cheers

leebwk · Post by **leebwk** » Tue Sep 02, 2008 12:06 pm

yes definitely needs drying out

work sounds fine just keep the building ventilated and aired

hotnuts21 · Post by **hotnuts21** » Tue Oct 28, 2008 9:52 pm

I have a similar, problem I have been in my house about 15 months now and we noticed a serious amount of black mould had began growing behind a wardrobe and the bed (which was away from the wall). Also lots of mould in shoe cupboard etc, ie the winter stuff we havent looked at since last winter :(

The main problem is all on the first floor though, its a small house but we do dry the clothes indoors (we live in wet wales). There is lots of condensation almost permanantly in the upstairs windows.

I have just ordered a dehumidifier, and some mini rechargeable ones which I will put in the shoe cupboard etc. Im also painting the worst wall with an anti mould paint to try and hold that off from coming back

Do you think I should do anything else or look into anything else which maybe causing the problems?

the house was DPC and tanked a while ago before we bought it (still in guarantee)

leebwk · Post by **leebwk** » Wed Oct 29, 2008 8:35 am

Hi Hotnuts,

Your situtation is classic of poor air flow and a build up of condensation.
Clean off with a watered down bleach solution and try to create more of an air flow by leaving the windows open or on vent

hotnuts21 · Post by **hotnuts21** » Wed Oct 29, 2008 9:56 am

Cool, Yes we are trying to increase the air flow, the humidifier is going to be placed in the hallway which gets to each room, so hopefully it will also help a little with air circulation!

Weirdly we have old sash windows at the back and I always thought they were poor for insulation, but must be doing a good job.

I had a look behind the wallpaper last night and noticed its got a polystyrene backing paper, I presume some way to insulate against the cold!! Bit worried about whats behind that though!!