I have gone and purchased a damp house, help!

danhandy

Hello

Let me just start by saying I’m a complete novice to DIY!

I recently purchased a 1900’s mid-terraced, two storey house. The Buildings Survey identified symptoms of rising damp; I borrowed a damp meter to confirm this. All internal walls are damp approx 1m up and the floor (cement) feels damp to the touch (the walls on the upper floor are not damp, nether is the ground floor over 1m). Therefore I have identified the problem to be rising damp.

Here is my plan:
1. Remove tiles which are sitting on the cement floor (is this required?)
2. Remove skirting board and hack the damp plaster off the wall (and .5m above)
3. Leave the heating on for a week to try and dry the brick and floor out
4. Inject a chemical/cream based DPC into the brick (not sure if I should use chemical DPC and hire a pump or use the new cream stuff?)
5. Leave the heating on for an additional week to try and dry the brick and floor
6. Paint on a layer of Liquid based DPM on the brick wall and cement floor
7. Lay down a layer of Insulation foam board
8. Cover the floor and brick with a layer of Polythene DPM (visqueen)
9. Lay foam underlay over the visqueen
10. Cut down the door frames to allow for a wood floor to sit on top of the underlay
11. Put down a solid real wood oak floor.
12. Plaster the walls with special damp proof plaster
13. Fit new skirting boards
14. Wait a month and then decorate

Would anyone change anything about this plan?


Thanks,
Daniel.

Leif

Be careful using a damp meter, they do not give accurate readings on plaster and concrete. A floor/wall can become damp if it is cold, and humid air passing over it releases water vapour i.e. condensation.

Regarding the floor, mine also felt very damp after I removed vinyl floor tiles. It was condensation caused by the floor tiles. It is easy to find out the source of the damp. It is best to try and dry out the surface first, e.g. turn on heating, or open windows etc. Get a piece of foil, 30 cm by 30 cm is okay, and tape is to the 'damp' surface e.g. floor. Get a similarly sized carpet tile, and tape that to the floor, near the foil. Leave overnight or longer. Remove foil and carpet and examine the surface. If the surface beneath the carpet is damp, then there is a source of damp, either condensation, or penetrating damp. If the surface beneath the foil is not damp, then any damp beneath the carpet must be condensation. If it is damp, then it must be penetrating damp i.e. from the material behind the foil, as the foil is impermeable.

Also be careful about companies offering 'free' damp proofing 'surveys'. These companies have a vested interest in diagnosing damp. If you are still concerned, then hire an independent damp specialist.

danhandy

Leif wrote: »

Be careful using a damp meter, they do not give accurate readings on plaster and concrete. A floor/wall can become damp if it is cold, and humid air passing over it releases water vapour i.e. condensation.

Regarding the floor, mine also felt very damp after I removed vinyl floor tiles. It was condensation caused by the floor tiles. It is easy to find out the source of the damp. It is best to try and dry out the surface first, e.g. turn on heating, or open windows etc. Get a piece of foil, 30 cm by 30 cm is okay, and tape is to the 'damp' surface e.g. floor. Get a similarly sized carpet tile, and tape that to the floor, near the foil. Leave overnight or longer. Remove foil and carpet and examine the surface. If the surface beneath the carpet is damp, then there is a source of damp, either condensation, or penetrating damp. If the surface beneath the foil is not damp, then any damp beneath the carpet must be condensation. If it is damp, then it must be penetrating damp i.e. from the material behind the foil, as the foil is impermeable.

Also be careful about companies offering 'free' damp proofing 'surveys'. These companies have a vested interest in diagnosing damp. If you are still concerned, then hire an independent damp specialist.

Thanks for the reply, brilliant information.
If the damp was due to condensation why would the bottom of the walls give very high readings and then a bit further up ( > 1m) give no reading at all?

Mr_Reeman

The bottom of the walls will be colder than the top and so condensation will collect on the colder parts more readily. I am in a similar situation where I have bought a house built in 1911 which has no damp proof course. The previous owners had damp problems and had a damp course injected into the external walls and re-plastered. When we moved in after about a week we noticed water literally pouring off the bottom six inches of the walls and it scared us to death. I couldn't believe rising damp would do that, so realised the problem had to be condensation. My solution has been to open just one window just a crack, less than an inch. Within less that 8 hours the walls were dry and house felt warmer. With the windows open a touch and with the natural air flow we haven't had any damp problems and all walls are perfectly dry to touch now.

I would also look at a few websites about building conservation and how you can use lime plasters instead of getting a dpc installed which will allow the walls to breathe rather than just suffocate them and keep the moisture in. Use lime paints as well rather than wall papers or thick waterproof paints too. Old houses never had dpc and they didn't suffer damp problems. They just had natural ventilation and old natural wall coverings which allows the house to naturally dry out. Trying to restore that solution can be the best thing to do.

ariba10

Have a read of this.

http://www.harfordsonline.com/downloads/condensation%20info.pdf

spannerzone

Some people don't believe rising damp actually exists so some research is well worthwhile! link

In my last 1907 house with solid walls I had some damp and got a company in to inject walls and fit more airbricks (suspended wood floor) - seemed to solve the problem. Looking back I suspect the airbricks solved the problem.

On my current house, 1900 end of terrace with concrete floors, cavity walls with slate damp proof course - I have what you might call rising damp (dampness up to 2feet from floor, now as an experiment I added several external air bricks and it appears to have made a fairly decent improvement in the last 6 months, walls seem a lot drier than before. I believe I have 2 issues, insufficient ventilation in cavity and water ingress via the concrete floor meeting the internal walls and not having a good damp proof membrane on the concrete floor.

To make matters worse, the previous owner has clearly tried to block the damp by plastering with non breathable materials and lining some areas with a self adhesive foil (to keep water from coming through to the wallpaper surface) and papering over all of this meaning the walls can't breath.

I'm still not convinced I've cured it all but the airbrick additions have appeared to made an improvement...I think the concrete floor might be the next issue to tackle and find out if it needs relaying with a modern decent damp proof course.

However if my airbricks continue to make things better than I would agree with Mr Reeman's comments about considering using lime based plaster and breathable paints.