damp on interior wall.

[madsey]

I've just started to renovate a 100yr old brick terreced house that only has a 1 brick (4'') dividing wall from next door,i've noticed some damp (not alot) on this wall.
Could i knock of the plaster to a hight of 1mt and cement render back up with a waterproof additive mixed in or knock off all the plaster and completely drywall the complete wall,which would be my best option???
My neighbour says he's not got any damp.
All replys most welcome and appreceated. Thanks madsey.

 

[masterbuilder]

u need to check the damp with a damp meter, they don't cost much.
if there is damp hack off all the plaster at laest 500mm past the damp and replaster the wall with the vandex system.
they will explain what this is when you buy the products at your local merchant.
it should consist of
a scratch coat of render with chemical additive
2 coats of vandex slurry or similar there are different makes
a coat of cement based plaster
skim with multi finish
you might find it easier to get a proper firm in to do the job properly with minimal mess

 

[masona]

You got to find out what causing the damp in the first place, these chemical stuff are completely waste of time and money. One of the biggest problem is lack of ventilation.

 

[masterbuilder]

I surmised his problem was rising damp from the info he gave.
i've treated damp such as this in exactly the way i've described with minimal comeback, to numerous victorian properties with no dpc in them.
how you can say they are a waste of time and money is somewhat remiss.
what's your solution then?
i always assume a wall this old, if it is damp, has started to effloresce
these chemical layers eradicate this very well.
even if the damp is caused by condensation, over time the wall will start to effloresce(salts within the wall crystallise on the surface and continue to do so whether the cause of the damp is removed or not)

 

[Tony6]

I have to agree with masterbuilder on this one .

To say chemicals are a waste of money is somewhat ignorant.

I think masterbuilder has discribe what should be done and how to do spot on!

My only point would be ,do not muiltifinish the wall after it has been rendered but leave it and black jack it and build another wall with a cavity between .This then treats the old wall as best as can be and creates a new dry wall to work on ,plus it will give you better fire protection and sound insulation.

 

[masona]

Yes sorry, I didn't mean to sound rude, I didn't write that much about it as I didn't have time !

The way I see it if you're putting a chemical barrier on the walls, am'I right saying the damp is trapped in the wall and cause damp to go somewhere else ?

It has been mention before, see this.

I'll be interested in your opinion as well.

 

[Tony6]

Yes you are right there should be a barrier in the wall if it is rising damp

But this will be hard to achieve without expense as the party wall is only 4 inch brick and without removing the bricks and replacing them with engineering bricks and dpc which will cost lots of money and possiblly p**s off the neighbours

The advice given from masterbuilder is possibly the next best thing?

Allthough the damp problem will possibly move next door as there is only a 4inch brick wall?

 

[shaggy]

There's been no mention of the type of floor. Masona has mentioned ventilation, and if it is a ventilated suspended floor then the problem may simply be caused by the vents being blocked.
I share the opinion of deciding what is causing the damp before covering it up. That may be the only option in the end but it shouldn't be the first choice. It's a bit odd that the neighbour doesn't have any damp and the fact that it's an internal wall.

 

[masona]

The advice given from masterbuilder is possibly the next best thing?

Maybe but I'm not sure because I think the damp will still be there, so maybe only a short term solution.

Allthough the damp problem will possibly move next door as there is only a 4inch brick wall?

Quite possible depending what the damp is or where the damp is coming from.

 

[masterbuilder]

finding and eradicating the source of damp is complicated.
walls can take months to dry out.
once walls start to effloresce, this will continue to come through any decorated finish. if the source of damp is removed the wall will draw moisture from the air and continue to effloresce indefinitely.
the only way to deal with it is as i've described earlier.
if the wall is subject to water pressure from outside it will need to have a silicon dpc injected as well as a possible dpm and floor screed.
if the wall is well below ground level it will need a special insulated membrane to counter the effects of condensation, and then dry lined. we have carried out this type of work on the seafront where some businesses are situated under the road, fronting onto the beach, formerly used by fishermen for storage
it is of little value waiting months or years for a wall to dry out, when u want to decorate and live in it.
getting back to madsey, who posted for a bit of practical advice which i gave him and in a cost effective way.
i am not looking to score points here over people, just offer a bit of advice which i hope is helpful.
how much practical advice to madsey has actually been offered to give a solution to madsey's problem with his damp wall?
masona, u haven't said what you would do to sort it, and how will you deal with the efflorescence.
also, the wall is probably 225mm thick, i would be surprised if it were only 100mm.
have you ever done work to rooms supposedly damp- proofed 6 months ago and then the efflorescence starts coming back through and the 'builder' does a vanishing act leaving the client needin it all totally re-done properly with a vandex type membrane put in?
yes.
have u ever had comeback from the said client?
no.

 

[tim00]

My two cents worth:

As was mentioned, dont attempt to disturb the party wall brickwork. Wether it's "rising damp" or more likely condensation(given the scattered pattern) hacking off the plaster to 1m ht. and rendering up in a lime and sand mix, or even a lime -sand- cement mix and skimming with a remedial finish such as "Limelite" is the way to go.Also, consider the internal ventilation.
Is this a suspended or solid floor? Solid floors are always suspect.
Problems of ventilation below the floor will cause timber decay but dont affect the brickwork. Worth crawling under to check, esp. the vents.
Dont use any kind of damp proofing chemical on the walls int. or ext. it will only cause further problems.
Ref. the dpc "surveyor": if the original owner requested a variation ie. no plastering, then it will have been noted on the "Guarantee".

 

[tim00]

Further after noticing Masterbuilders latest post. Like him i'm not here to "score points" but i do have a bee in my bonnet about this subject.
Whatever "Vandex" is ,a chemical barrier is not necessary and will cause chemical/mechanical future problems not to mention the environmental/health effects.
Efflorescence is common in new and remedial plaster work, it's of no consequence and soon goes, or a mild wash will remove it. It is not the same beast as the chemical blooming commonly seen in damp degraded plaster where salts have been brought from the earth.
How can injecting"a silicon dpc" prevent lateral water pressure? Surely, if that were the case then why not inject all walls of a damp basement?
Capillary action is a different kind of pressure to the gravitational pressure of the water table.
Perhaps this will clear up a few points or perhaps i'm wrong.

 

[masona]

i am not looking to score points here over people, just offer a bit of advice which i hope is helpful.

100% agreed and no way I'm trying to score points here and this is what the forum is all about (can get heated sometime ) if I'm wrong then I hope someone would correct me because I'm still learning

how much practical advice to madsey has actually been offered to give a solution to madsey's problem with his damp wall?

Like you say very difficult without seeing the problem.

masona, u haven't said what you would do to sort it, and how will you deal with the efflorescence.

From what I understand you can only get efflorescence from rising damp if the dpc failed (?)

Sadly we did have a good surveror on this forum, Gwailo who knew all about damp problem. Copy & paste from one of his link.

The internal faces of walls can get damp from condensation: the relatively high U-value of solid brickwork, coupled with poor ventilation of rooms, will often lead in winter to damp patches, especially in pockets of still air behind furniture.

"Finally water can get into a wall from the ground: rising damp will bring with it dissolved salts which when they dry out leave efflorescence on the wall. Attempts to seal a wall with waterproof coatings outside or modern waterproof plasters inside inevitably fail as the wall acts like a wick and will continue to draw water up to a level at which it can evaporate: the efflorescence simply migrates higher up the wall. In extreme cases the damp can rot out a timber first floor construction if this is the only place it can escape. The only effective treatment for rising damp is a horizontal damp proof course at low level, and this can be difficult to insert retrospectively in a traditional manner, e.g. using a lead or a course of slates. An injected chemical d.p.c is often the only solution for a damp brick wall, but need not entail the often recommended and expensive unnecessary removal of internal plaster to a height of 1 metre. This extreme action should only be considered if a year after installing the damp proof course there is still a problem with efflorescent salts erupting from the wall."

Should the crystals appear on the surface of the wall, simply brush them away gently with a soft brush, and allow further time for the wall to continue drying out before decorating the wall.

Like you say it's difficult when you live there and want it decorated & your solution maybe the correct way to go but not sure about long term problem though.

 

[masterbuilder]

i would say tim00 u have absolutely no experience of carrying out remedial damp work, and if you have' what's going to stop the damp then ?
you have just told madsey to do work which is a complete waste of time.
Do you think i have spent what must amount to thousands of pounds on chemical products that prevent damp instead of 'rendering the wall with a sand and lime mix' as you suggest.
i don't think you've got a clue about the problems that come up with renovating old places.
i've used horsehair, lime and dung in some plaster mixes and i think the latter component compares to the advice you've just given in this thread

 

[masona]

Like I say I'm listening & still learning because damp problems is still a grey area as I have been to many property with re-occuring damp problem done by the professional company.

If you're saying you have no come back on damp problem doing your method then that's great as you have been doing it for 30 years then I will look into it.

What I can't get round my head is, if you put a barrier of any chemical on the wall, am'I right saying the damp will goes somewhere else ? or do you wait for the wall to dried out then treat it ?