damp in placo walls

[Dunkie38]

Have read other info re this problem which has been very helpful but want to know what to do about damp which has appeared on the internal dry liner walls. It first showed itself in the grouting in the floor tiles and thought it may be a leak in the pipes.Have taken readings of the water meter counter & it isn`t that.The builder wants to put in "drainage" on the outside wall as he is convinced that it is a leak from outside which is feasable.However the walls showing the damp(black and brown) are in front of very damp stone walls and I`m concerned about paying out a sum of money for drainage if the original walls should have been treated against the damp before putting up the dry liner walls.This problem has arisen over  2 to 3 years.We have dry liner walls in our house in uk and have never seen this problem before and we live in a very damp area of uk. There are no vents in the dry liner walls but there is insulation.Any ideas please as the quote for the drainage is 2000euros and we`d thought we`d finished paying the builder!

Pat

[Nick Trollope]

1st point - you cannot successfully "damp proof" stone walls. They were built without DPCs and are meant to "breathe".

2nd point - If you put up a sealed dryline wall against a damp stone wall, you will just move the damp out of the wall and into the plasterboard. For this reason, you should not insulate between the 2 walls (it moves the dewpoint closer to the internal wall).

So, I would install the land drain (if the outside ground is higher than the floor level of the house), plus I would ensure that the internal walls are vented to the stone wall (just put a couple of 50mm vents top & bottom of the wall). Thirdly, I would install a VMC.

 

[Dunkie38]

Thanks Nick but what is VMC. The builder used a lot of insulation but not sure if he put it behind this particular wall as even though it`s internal it also forms part of the dependance which we are not renovating.. However the floor level in the dependance is above that of the house. The builder is only talking about putting the drainage on the side wall of the house whereas we think it should be behind rather than on the side. Perhaps we need to have more discussions with him and in more detail.

Pat

[BJSLIV]

VMC?

Its the low speed ventilation system that draw the damp air out of rooms such as  kitchens, bathroom, and WCs.

It runs 24 hours a day, and keeps the air fresh, and minimises condensation.

[Bannon]

I have the same problem (mine is actually damp around the fireplace) and I plan to cure it by digging a 10m trench to the required depth along the outside wall, lay a concrete base along the bottom, line the wall with 'protection soubassment', run a plastic tube with holes in it (I think in the UK we actually call this a 'French Drain' - but what it's called in French I've no idea!).... and then fill the lot back in with gravel.

In my case the trench needs to be dug by hand because of services running under - lots of hard work ahead of course but better that paying out even more dosh.

....now where's that spade.

[Nick Trollope]

Whatever you do, don't lay concrete at the bottom of the trench (unless you need to underpin the building, in which case damp is the least of your worries!). It will trap water that will run into the wall (even if you do tank it).

TBH, every time I've had this problem, I've cured it with a trench, gravel and a drain. Dig below the floor level by about 150mm, add thin layer of gravel, drain - slots up - (don't forget a membrane to stop the stones) then more gravel. Again, IME, tanking can trap water (coming from below eg.) in the wall.

 

[Victor Meldrew]

The dampness on the walls is the symtom, have you worked out the cause?

Is there a gutter and downpipes to take away rain water? if not then this could be part of your problem.  I did a job on a property some while ago and the lack of guttering was the problem as the rain water was passing under the outside walls and being picked up be the central internal wall. 

Hope the advice helps.

Victor

[shimble]

nick ami right in thinking you bury a drain at the base of the wall with a run of f say 5mtrs away and the cover the drain with stones .....dont suppose youve got any pictures ...just want to make sure i undersatnd this correct.....what membrane do you use .....and would you consider this all round a property or just in the affected areas.... i presume you mean the drains that come in metre length sections.... or ami completely getting the wrong end of the stick?

[LEO]

A very good website resource for drainage info is; www.pavingexpert.com

The web's most comprehensive guide to paving, drainage and hard-landscaping techniques.

 

[Bannon]

Ah.

I'd seen builders do this Nick and thought that was the way to do it - that it stopped any water going passed and under but as you say it may get trapped. Thanks