What kind of damp is this??

sudzs

I live in a small house built around the early 80s. It has concrete floors. When it rains consistently for a couple of days the internal relative humidity can, for example, go up to 80% with temperature around 18 °C. If the weather dries up and I open windows the RH will come down but then after closing the windows it will go back up indicating that the moisture is coming from the building rather than from the weather conditions. Had trouble painting the walls last year during a wet period. The paint cracked like a dry river bed in some areas which I believe indicates that the walls are damp and the paint dried from the outside in rather than from the wall out. Also RH differs from room to room suggesting some rooms are damper than others.

This is an ongoing problem but yet there is no sign of mold on the walls and the skirting boards seem ok, none are showing any signs of rotting and because of this I've been told it's not rising damp. However I do ventilate well and have vents open on the windows. There are tide marks on the external concrete wall and after rain you can see several inches of wet concrete while the adjacent path will be dry.

The whole area is generally a bit soggy after rain and there is a park 500m away where springs have popped up after severe rain. Everyone complains of moss in the gardens! Very poor drainage in this garden with 2 extremely wet patches of soil close to the house, front left and back left when looking out so at alternate corners of the building. I wonder if the house could be sitting over some sort of basin in the ground rock that fills up with water. I think the geology is granite.

Any opinions welcome.

10-10-20

Hi, do you know what wall type it is? Are the floors damp at all? Also is there a DPC fitted in the walls? Those are the first things that I'd check as the damp should not be appearing in the lower walls. The other thing that comes to mind if there is a DPC fitted is that the DPC should be around 100 to 150mm higher than the surrounding soil - check that too. Also check for splash-back off leaking gutters of an insufficient overhang at the affected walls.

But the other factor could be that the RH is actually so high in the house that that dew-point (DP) is also very high, and that could trigger the buildup of condensation at the coldest point - which in many cases can be the lower wall junction. That might then create those rivulets in the paint as it fails to dry before the condensation hits it. It might be another good case to install a dehumidifier in a central point of the house.

sudzs

They're cavity walls and were pumped with insulation beads about a year ago. One of the dampest parts of the house is the wall between us and next door which isn't a cavity wall as far as I know. And the gutters are ok.

How would I know if there's a DPC? Would there be something visible on the wall itself? There isn't anything to see so maybe no DPC ??? Is that something that can be pumped in if necessary? Or what options are there?

The problems with the paint occurred near the skirting boards and at the top of the walls. Before we had it painted there were small paint bubbles on the ceilings in the rooms on 1 side of the bungalow. The painter removed them and painted again and more bubbles appeared before his eyes. He said there could be moisture present causing the bubbling.

The problems with the paint were on all walls, even internal ones. I had to repaint the kitchen as the cracked paint was terrible. In order to stop it happening again I actually used pots of steaming water to create a moist atmosphere to allow the paint to dry out from the relatively less damp wall and so avoid that cracking. Also had to do 3 very very thin coats rather than putting on the normal amount of paint. Took me ages but it worked!

Anyway, the fact that the skirting boards aren't crumbling and rotting is a bit of a mystery.

Gutters are ok btw.

listermint

https://www.boards.ie/discussion/comment/122761986#Comment_122761986

The cavity walls were pumped which means that has all but removed any air circulation in the cavity, which probably was the escape for alot of the internal moisture that gathers.

Your issue primarly i think at this point is the 'lack' of adequate ventilation. When cavity walls are pumped the SEAI require ventilation to be permanently available. e.g old fashioned through and through wall vents. In your case it seems to be windows ventilation which tbh i have never seen be adequate at least to moisture levels in this country.

The dehumidifier is the obvious first glance easy choice and is accessible to you. Long term a proper ventilation strategy is required to make the solution permanent and easy to live with. I would advocate for MHRV or MV systems , centralised or per room basis.

Its simply poor transfer of warm moist air that is developed in the house by daily life and dryer cooler air into the house from outside.

Mr321

Are the rooms that are affected colder then the rest of the house and are they facing north also?

Could be a case that there're water getting into the walls somewhere. Is it plaster/render finish and painted. Stone or brick faced?

That SEAI pumping is a complete waste of time also. Anyone I've spoken to that had it rarely seen an improvement.

The Continental Op

Check for damp with this simple method https://www.thespruce.com/test-concrete-floor-for-moisture-1821688 works as well on walls.

listermint

https://www.boards.ie/discussion/comment/122762558#Comment_122762558

its a holistic part of an entire energy management plan, not a panacea on its own.and it shouldnt be seen or sold as such.

sudzs

There was no difference whatsoever to the RH in the house after the walls were pumped.

There's a PIV unit in the attic but it made no real difference other than pushing in musty attic air. Last winter, before the PIV was installed, we didn't have too much of a problem with condensation, it was slight and only on the coldest nights which followed wet weather which had made the house damp. When I moved in 18 months ago there was a patch of black mould in the bathroom which I got rid of. There's no mould problem now, not yet anyway and I put that down to the window vents being open and my ventilating the place. Unless it's very cold, wet and windy I sleep with the bedroom window open year round and in winter I do the German thing of opening the windows at least once a day for around 15 minutes.

The systems you mention sound interesting, I will check them out, thanks.

listermint

https://www.boards.ie/discussion/comment/122762802#Comment_122762802

If there is PIV installed, and this is your experience it's installed wrong, or your attic has ventilation issues also which is a bigger concern. You may have blocked all your attic ventilation with insulation right out to the soffits or your soffits are blanked off and capped with timber/pvc .

You must get this checked ASAP.

sudzs

https://www.boards.ie/discussion/comment/122762558#Comment_122762558

One is north facing the other 2 problem rooms are south facing.

Can't say I felt a huge difference in the place after the insulation, wasn't SEAI btw, I'm in Northern Ireland.

And it's render finish. I think it's a problem with ground water seeping up tbh. But I don't understand why the skirting boards are ok, it seems they have to be rotting to be the proof for a landlord that the place is damp.

josip

Are the window vents the only ventilation in the house? Are there wall vents?

Is there a chimney? Are you drying clothes on a dryer inside?

Has it been like this as long as you've been in the house or did it only start happening after something changed?

sudzs

https://www.boards.ie/discussion/comment/122762873#Comment_122762873

No wall vents,

Yes a chimney but it's not in use, there's an electric fire there.

I don't dry clothes indoors and if they do need to go on an airer when half dried I'll open the window next to them. I even dry the shower tray after a shower!

Yes, been like this all along.

If the weather suddenly changes from very wet to a nice dry air then I open everything, windows and doors to try and dry out the place. The RH will come down but then when I close the doors and windows it goes right back up which says to me the building is emitting moisture. But after a day or 2 of dry weather it's as if the water drains out of hte house

pjdarcy

I'd be inclined to get some wall vents drilled. Those little trickle vents at the top of the windows don't provide anywhere near enough ventilation.

Mr321

https://www.boards.ie/discussion/comment/122762841#Comment_122762841

Yea it's still the same way it's done with the beads pumped. Is the problem rooms colder then the rest of the house? Even though you've vents on the windows is there condensation on the inside of the glass at any time? Detached bungalow house I'm guessing .? No big cracks in the render that you can see.

Carpet on the floor/laminate/wooden? No mildew or mould on or under the carpet or in the joins of laminate/wood?

sudzs

https://www.boards.ie/discussion/comment/122762940#Comment_122762940

They're all problem rooms really it's just 3 are worse! Of which only 1 would be a bit cooler.

There will be a little condensation when cold weather follows a few days of constant rain. Although after a few days of wet weather the other day the back door had condensation on the glass but that was because I was cooking and the RH went up from 82 to 87%. But it was 14 degrees outside so I was surprised to see the glass fogged up a little. And yes I use a kitchen extractor.

Just very thin vinyl on the concrete kitchen floor but I'll be getting waterproof LVT in the new year. Wool carpet in the rest of the house, I though it might help with heating in the winter. And the bathroom has that non slip vinyl that goes up the walls around 12 cm. Horrible stuff! The bathroom is the worst room even accounting for the shower.

I don't know if any mould or mildew under the carpet, it's only down about a year. I must check.

josip

I don't think the problem is with the materials used in constructing/furnishing the house. It sounds like there's not enough ventilation in the house to remove the moisture that is naturally generated by humans living, cooking, washing etc. Not having wall vents without MHRV raises big questions for me. When you say the chimney is not in use, is it blocked off? Without wall vents, the chimney is the main way for moist air to escape.

Mr321

https://www.boards.ie/discussion/comment/122763017#Comment_122763017

When your checking the carpet of you can fold it back just look along the exterior floor and see is there any darker coloured parts of concrete. Could be a case of rising damp is your having problems with paint on walls