damp walls

hobo123

Hi I am looking for some advice re damp on internal walls, the damp was caused by slipped tiles on my roof which has been repaired we let the walls dry out (we thought) and papered them but today I have noticed that the damp is coming through onto the paper and it is covered in black and white mould. Should I have done something else before papering? Any help much appreciated as I am stressing out about this thanks.

weekendwarrior

You should of tested the wall with a cheap damp detector to ensure that it was dry before papering, you can get these for a few quid-

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A235331&ts=23632&id=41970



The mould will need treating with a fungicide- Mould

Is it an internal wall? If it is an external wall then it could be penetrating damp that is causing your problem!

[Deleted User]

Hi,

once you've cleaned the walls of mould, before papering again you could give the walls a couple of coats of sealant, or 50/50 pva/water.

ormus

just bought a gallon of pva today from wickes for 7 quid. (own brand).

it was 22 quid at BQ and 32 quid at TP!!!

roswell

When you say damp how high up the walls is it eg a few inches / a few feet / upstairs.

somefriendlyuk

hi, hobo.couple of questions. Is the damp upstairs. if so where on the wall is it and roughly how old is you property-the reason for this is i want to know what type of plaster is on the wall. Please don't seal anything yet.

hobo123

Hi the damp is upstairs and it is on the top half of the wall the property was built in about 1900 approx
Thanks for your help

somefriendlyuk

hi -the damp is penetrating dampness from the leak and the moisture has got into the plaster.Unless the walls have been re-plastered down to the brick at some time you will have a sand/lime plaster. This is very good at withstanding dampness and drying out so it may be you did not give it long enough -at least a month or two in good weather. If this is the case i would cut the paper around the leak area and let it dry back for some time before you do anything else.this said-if the leak has been ongoing for some time the plaster may never dry back properly.
After a decent drying period:-
if all looks well and the plaster is not soft or fluffy and tests ok for dampness you may be now able to re-paper.
If however the plaster has become 'fluffly' and soft it may be that the plaster has dried back but the leak has been to much for it and this area may have to be hacked of and re-plastered. It is very very important that normal plaster such as browning is not used-the way this plaster is made is not conducent to withstanding dampness and any damp left in the brickwork(the bricks can take a lot longer to dry out) will imeadiately be sucked out by this type of plaster making it appear more damp than before.i often describe it a putting a sponge on the wall! You must use a plaster called renovating plaster -its only about a £1.50p more (about a fiver a bag) than browning so this makes sence not chancing it -alternativerly you can use a sand/cement render with a good water proofer.The mould by the way is black spot mould and is partly due to warm moist air in the house causing condensation. If you have had a leak the wall will be colder at this point so the moist air in the house will condense there.It may be a good idea to increase ventilation as well -an easy way to do this is to have any double glazed windows locked in an slighly open position-most do this.
sorry to go on!
hope it helps a bit

hobo123

Hi thank you so much for your help just wanted to run one more thing past you spoke to a guy who does work re this for the local council and he advised that we had to cut out the plaster on the section affected and put some mesh thing on it which stops the damp coming through onto the new plaster you put on. He did say this mesh was expensive but he managed to give us some, is this correct advice? your help is much appreciated thanks

somefriendlyuk

hobo123 wrote: »

Hi thank you so much for your help just wanted to run one more thing past you spoke to a guy who does work re this for the local council and he advised that we had to cut out the plaster on the section affected and put some mesh thing on it which stops the damp coming through onto the new plaster you put on. He did say this mesh was expensive but he managed to give us some, is this correct advice? your help is much appreciated thanks

hello, without seeing this i can only assume its a type of plastic membrane possibly what we use sometimes on basements. You can skim striaght onto it but i have never liked that idea and won't do it that way. I personaly would not use it in this situation-for a start you have to have special sealed fixings for this to work and secondly you have to have the depth of plaster to get anything other that skimming(finish plaster) onto it-by this i mean to get anything other that finish on you have to have a mathing depth of the original plaster or it will be 'prould' .As finish plaster is a patent lightweight plaster (ie sponge) i don't like the idea of it being that close to the brick work without a water resistant base coat- even with the plastic mesh.remember the brick will still be damp for a while so you need this- again this is a faily simple problem-if it doesen't dry out -chip the plaster of around the damp area-it is always good to go a little further -it wont make any difference to the re-plastering price if it half a yard or a full square yard.then leave for a little week if you can bare it (fresh warm air does a power of good but isn't strictly necessary). Re-plaster with a renovating plaster and skim finish. We would charge about £160-00-£200 for this. By the way you can cliam on the insurance for this work. Remember do not let the plasterer use browning.Renovating or sand/cement render with a good waterproofer in and skimmed finish.