Dampness on walls

Rockapotomus

Hi all,
In the last few weeks I have serious dampness on a couple of walls in the house. These are external walls, I am getting mildew as well, I have scrubbed it all off but in a few hours the moisture is coming back again. I have put heaters in the affected rooms now to attempt to dry out the walls, has anyone any long term solutions? It is a very old house, former tiny farmhouse with rooms built on over the years. 2 years ago the whole thing was replastered as you could see the plaster cracking up along the gable ends. It was stripped down to the stonework and the lads that did it told me they were adding stuff to help stop the moisture going through. I will have to sort something though, can anyone give me any tips?

agfasfos

Could well be a ventilation problem, do you have air vents installed ?.

Rockapotomus

No vents, it's an very old house, prob about 100 years but renovated in the 70's, i don't know if there was dpc installed or what. the external walls of the house are old stone walls. the dampness is only on these walls. We had a stove installed a while back and the house is a lot warmer now I'm wondering if this is causing extra condensation on the walls?

dpofloinn

Hi Have you checked what condition is the external plaster in?Are the gutters clear? How is the drainage around the property? Does the building have damp proof coursing?You may have leaking pipework anyone of these could be contributing to the dampness

Rockapotomus

the house was replastered a couple of years ago so is in good nick. there is a bank at the side of the house alright, there have been a few small instances of dampness down through the years but nothing excessive. I haven't checked the gutter but haven't noticed anything spilling out or anything. I'm not sure if there is a dpc, my parents did up the house which was previously an old farm cottage when they bought it in the 70's but the auld fella has passed away since so don't know what was done! the damp is maybe 3 feet high up from the bottom of the floor with some spots higher up too. would a dehumidifier be worth a crack?

dpofloinn

You could use a dehumidifier but that will will only serve to hide the issue .I came upon a similar situation a few years ago where 2 rooms in an extension to an older house similar to your case,had damp issues the first idea was to use a dehumidifier because they believed it was a condensation issue. It turned out in the end to be a burst pipe under the floor so it might be worth checking your plumbing and heating pipes.The easiest way to do this is turn off all taps,washing machine,dishwasher etc then check your storage thanks aren't filling.I would also check that all the drains and shores around your house are clear and free of debris this could cause water to log around the base of your house.Also you mention a bank at the side of the property,can you tell if this drains onto to your property?

Rockapotomus

There are no water pipes in the vicinity of the damp so I wouldn't say that's it,in any case the heating was only put in after the house was built so the are all visible along the wall. I will check the gutters and the drains but I don't see much evidence of water gathering outside. I'm just surprised it came on out of nowhere when there was never much of a problem at all, the only thing that has changed recently is the addition of the stove so that's what makes me think it may be condensation due to the increased heat in the house but I'm only guessing!!

agfasfos

Did the problem only arise after the installation of the stove & did you carry out other work, ie, extra insulation etc. I have seen quite a few cases like this & inadequate ventilation has been the culprit but in an older house you can't be sure, some of the other responses are well worth checking.

dpofloinn

With all those other variables ruled out it comes down to inadequate ventilation simple things like opening a window or leaving the room doors open for periods at a time will let air circulate and may reduce the dampness

2 stroke

In the past moisture laden air probably made its way to the chimney. Fitting a stove reduces the draught on the chimney, reducing the ventilation in your house, and alowing moisture laden air to circulate. Basicaly it sounds like you need more ventilation.
Are you drying clothes indoors? somebody hogging the shower?
Also you mention a bank against the house, it was often done in the past that a house was set into a hill, and the people of the time had a way of working that limited moisture ingress, but is was necessary to clear debris regularly, to ensure surface water drained away.

sbsquarepants

Could be worth checking if the ground has risen (or the house has sunk!) so that the ground level is now above the dpc. I'm not a builder or anything, but i seen it on a diy tv show before. Some scheister was charging thousands to retro fit a dpc by injecting the walls with something or other, but the solution turned out to be as simple as digging down 7 or 8 inches outside the house (was an old georgian house if i recall correctly)and the original slate dpc could do it's job again.

Rockapotomus

Thanks for all the responses lads. It seems to have come about since the stove was put in it yeah but maybe that's a coincidence. the windows are open on a regular basis alright. I got a dehumidifier to help for now at least. A few people have recommended dry lining the walls, but won't this just mean the stone walls will be wet behingd the plaster? amd I only masking the problem? Can't afford to spend thousands on a big job like installing a DPC or whatever. Liek I say the house is newly plastered so it must either be coming up from the ground or else it's a ventilation/condensation issue. Does anyone know how much drylining costs?

MicktheMan

Rockapotomus wrote: »

Thanks for all the responses lads. It seems to have come about since the stove was put in it yeah but maybe that's a coincidence. the windows are open on a regular basis alright. I got a dehumidifier to help for now at least. A few people have recommended dry lining the walls, but won't this just mean the stone walls will be wet behingd the plaster? amd I only masking the problem? Can't afford to spend thousands on a big job like installing a DPC or whatever. Liek I say the house is newly plastered so it must either be coming up from the ground or else it's a ventilation/condensation issue. Does anyone know how much drylining costs?

From what you describe, there are a number of things going on which are resulting in the damp walls:
1. If no dpc in walls then moisture will rise from the ground up through the wall. This moisture then drys to the internal and external depending on the conditions. The external walls were replastered externally with a sand/cement/something else to make them moisture tight. (Were the original walls plastered with lime plaster by any chance?) This may have had the effect of restricting the rising moisture from drying to the external and therefore your walls are wetter and can only dry now to the internal. This in turn is adding to the moisture load of the internal air in the house resulting in increased condensation etc.
2. You dont have a ventilation system in the house. You recently replaced an open fire with a stove which has significantly reduced the ventilation. Remember that a household of 2 adults & 3 kids generate somewhere between 12 and 18 liters of water per day which needs to be exhausted from the house.
3. The stove heats the house (and internal air) to a higher temperature allowing the air to support more moisture, so more moisture is available for condensation on the cooler wallls and windows.

So, if this is what is happening, don't dryline the external walls (drylining external walls is rarely a good idea!). You need to think about a proper ventilation system or strategy to remove the internal moisture (where ever it is coming from). Opening the windows for an hour or two is not a proper strategy. Ventilation generally needs to be happening 24/7.
On top of this, is it possible to install a french drain around the house to remove moisture from the external walls?

Finally, this observation and advice is soley based on my experience and what has been posted here and getting a proper survey done will yield the best longterm solution.

Rockapotomus

Thanks Mick, very detailed and you summed up the situation! It was the inside I was going to dry line though, my concern is that the dryline will just hide the damp, i.e the moisture will still be on the wall behind the plasterboard. Others have told me if I dryline inside that it will stop the moisture from being drawn up from the ground....Humidifier to start anyway and dry the place hopefully! I know its not a long term solution but it's a start!

3ndahalfof6

Sounds like it is from the ground up, PVA would stop the visual problem, but the building would be getting weaker as time goes by, an injection of damp proof at foundation level could fix it, it looks like it is an outside problem, so no fix on the inside will get rid of the problem,(but it might make it look better),

foundations seem to be the problem on this occasion, or water running to the house via a spring, is your house built on a lower level than the land around you.

MicktheMan

Rockapotomus wrote: »

It was the inside I was going to dry line

That's what I meant.

paddylonglegs

Folks. Will be installing a stove soon in a room that depends on the chimney as a ventilation source (I discovered this when I closed the draft excluder and resulted in wet walls after a few days). The house is 1850s with no dpc. Is there a way that. I can continue to have a vent in the chimney flue even though I will be putting in a new flue for the stove? The outside of the house has a cement render applied in the 50s which is stopping the walls breathing properly.

limeg

Was it plastered with lime render?

starlit

I've ventilation/insulation installed in the attic but the walls I have in a room are beside the garage making them cold but do have bad ventilation. Try getting a humidifier to balance out the moisture and a de-humidifier to absorb the moisture. Steam and hot water with a mop will do just the job.

Fister

Hi guys, as you all seem very knowledgeable could i butt in for some help. There are some external/internal cracks in our home along with some damp issues. We have had an architect look at the issues & he has made some recommendations which we are considering. He has suggested removal of old external paint as the one in situ may not be breathable & replastering (as we also want to get rid of old pebbledash (1960's build) or external insulation which he feels could resolve our two issues i.e external appearance/cracking & internal damp. We are moving towards the replastering option but as it is a 2500 square foot house we obviously want to get a very reputable & good plasterer...does anyone know how to go about getting the best. I am about 30 mins from cork city.....thanks so much ....