Damp advice

[ant87]

Damp issues. 

 

In 2023 I had a lot of damp work done. My house is a solid wall house (mix of solid brick and stone with no cavitys at all) old semi detached 1910 bulit. 

I had the front stone wall repointed, than masonary cream added. Side of house rerendered due to rising and penetrating damp. They said they used a lime render on the front and side.

I also had inside walls in the living room and 2 bed rooms striped back to the original stone and brick, there specialist waterproof system and salt retandant render used to prevent moisture and salt damage ( what they said would fix the damp issues). Damp course injected into the walls and finished with gypsum plaster.

 

After all above, guess what still damp issues. We have damp and 16 to 17% moisture levels of damp in the living room walls which is noticeable.

Upstairs I haven't noticed any damp or mold on the walls yet ( moisture levels same 16 ) but have on the skirting boards but I reglossed them a few weeks back and haven't noticed any mold back on them yet.

 

I have read a few different buliding forums that the problem is that gypsum plaster isn't suited for solid brick/stone houses as it doesn't let them breath, holding in the moisture with no where to go and lime plaster should of been used.

 

Also these injected damp course don't do much and should be a slate damp course ( which all makes sense to me as we had the house done up 15 years ago and a few years after it was done we had damp again as they used injected damp course and gypsum plaster. No lime used) when done 15 years ago and the problems happened than I thought it was cause the buliders were cowboys ( didnt know at the time) but the same has happend when using new buliders with a good representation. 

 

We also have an issue with condensation but same buliders installed a piv unit in the loft. We have trickel vents and I open windows when cooking and have the hobs on etc.

It is as simple as the only way to fix this is to have it all hacked off and lime plaster used? Or any fixes with keeping the gypsum plaster on ( maybe some how lime being added into the walls)? would air vent/brick vents make any difference at all with it still being Gypsum plaster to stop the mold?

 

Also they left big gaps all along the bottom of the walls, which have since had skirting boards added over the top of them. At the time I thought this was weird and questioned it but they said this is where the damp course is and shouldn't be plastered over. 

 

The company I used are damp specialist ( or so they say ) from checkatrade and very good reviews so that's why I used them and fully trusted what they said and did but don't any more. 

 

I had one of there specialist in yesterday to take a look and said about the above and what I researched but all they did was defend there work by saying we used the same materials with every house both new and old and never had an issue with damp coming back and go on to say maybe have vents put in as it's nothing to do with the plaster or a failed damp course but seems poor ventilation. ( none of which makes sense as we have the fan they installed and had an engineer last summer look at it and its working fine ). They go on to say that any moisture levels above 18 is a concern ( as thats what they have been told by there training guidelines) and they levels are below that so must be condensation they say. I have done the research and different damp specialist seem to go by different figure's but the ball park seems to be anything over 15 to 16 needs attention. 

 

It is the winter and I get levels ofc are higher but remember what I remember in the summer the levels of moisture where a bit lower but not by much.

Any advice would be great on how to deal with the company and fixs for the issues.

 

I have add a number of photos to this poster of the current damp and mold. Photos of when the work was being done ( down to the original stone and brick. Plaster work etc)

 

Many Thanks.

[Redbeard]

Sand/cement pointing to front wall in a form ('strap pointing') which was common in the 1980's but is almost certainly not how the original pointing was finished (it was (a) lime and (b) probably 'rubbed' quite flush. The good news is that, as far as I can tell from a picture, your stone does not look soft. If it were, there could be a risk that, years down the line, you could have stone which erodes because the pointing is stronger than the stone. The opposite should be the case; lime is 'sacrificial', and will succumb to frost damage before the stone will.

 

How are you measuring the percentage moisture content? 'Pointy-pokey' damp meters are generally most accurate in wood, and much less so in masonry. 18% in wooden joists is considered healthy, so I am not sure if the reading you are getting (if it is accurate, which it may well not be) is a major issue. (I know a lot less about moisture content in stone than in timber).

 

Most of all I note that, as far as I can see, you have no insulation on the walls. It therefore would not be surprising if you get condensation in cold corners, particularly if there is no airflow the 'chase moisture away'. This is not to say that it could not be penetrating or rising damp, but these issues (while sometimes blindingly obviously the case) are sometimes overstated. The most reliable damp test in masonry is a carbide test (sometimes known as a 'speedy' test). It does not rely on a meter which performs best in wood. Tony on GBF is known for drilling out dust samples and working out % moisture content by weighing them before and after a spell in the oven.

 

There is, I feel,  a big difference between 'specialists in using proprietary damp 'solutions'' and real (old building and) 'damp specialists'

 

I would suggest an accurate test and diagnosis followed ideally by insulation of external walls with a breathable material. My preference is wood-fibre or cork.

 

As far as ventilation goes, while there may be reasons for the 'damp' other than condensation, use this 'opportunity' to review your ventilation provision. Older houses have often had all the original ventilation (which included the leaks round sash windows) 'improved out'.

 

 

 

 

[lookseehear]

Firstly - welcome to the forum and sorry to hear all the issues you've been having. Old houses are a bit of an enigma in terms of damp. Some will be fine when you expect them to be damp and some damp where it doesn't make sense. In general it's probably good to start by making sure you've covered the basics.

• Are all gutters and other RWG in good repair?
• Any high external ground levels?
• Ventilation it sounds like you have covered

It seems like the work you have had done is all to contain water within already wet walls by tanking and re-rendering with highly waterproof products (I'd be highly suspicious of the lime they said was used in the render - throwing in a bag of lime hydrate into a cement render doesn't make it a lime render). The pointing looks like standard cement pointing to me as wel. Wet, uninsulated walls will generally be cold in winter because wet walls require so much more energy to heat than dry walls and are much worse at insulating than dry walls. This means that even if the moisture within the walls is contained via tanking, you're much more likely to get mould and damp spots in corners because you have cold walls in areas that are hard to ventilate.

 

I highly suspect that the walls being wet all the time is bad for their general structure over time, and can lead to joist ends rotting, but that seems to be the direction the damp proofing industry has gone because it's easy to hack off what's there, stick a load of tanking stuff on the walls and charge a lot for sorting it out.

 

The 'heritage' approach would be to repoint all the walls with a lime putty based mortar, remove the tanking products and plaster with a lime putty (non-hydraulic) based plaster. These are time consuming tasks because they can be seasonal (you can't use lime putty mortar in winter) and take a long time to set in the right conditions (days to weeks). It's also hard to find tradespeople who do this and do it well for a reasonable price, so a lot of people learn to DIY it.

 

How attached are you to the house? It looks like quite a lot of disruptive work to make it right in any case.

[ProDave]

Chances are, a lot of the "damp" is condensation due to moisture in the house hitting cold walls and possibly not enough heating in the house or ventilation of the house.   If you dared to ask a "damp specialist" then of course they will say it is damp and give us lots of £££ to fix it.

 

 

[torre]

2 hours ago, ant87 said:

installed a piv unit in the loft

Sorry you're having trouble. I'm very anti PIV in older houses. The idea is you're replacing the moist inside air with drier air from outside, but how is all that moisture supposed to get out? Sure some via trickle vents, but in an older draughty house a lot will be pushed out through the structure via lots of little gaps cracks and holes, so your pushing moisture into the fabric of the home.

 

I much prefer dMEV - continuous extract ventilation. You're still replacing moist air with drier air, but now you are drawing all the moist air out through the extract ventilation, and the drier air in through those little gaps etc in the fabric of the home, so pulling moisture out of the home. These also have humidity sensors so they will automatically boost when you're creating more moisture through cooking, drying washing etc. Cheaper to install than the damp specialist's solutions too.

 

Breathable plaster, paint, insulation, render are all important too and we've done that on a renovation too but it's expensive to take on, so I'd start with reasonably low cost options like dMEV and also turn the heating up a bit and see if things start to improve.

[Mr Punter]

I am a big fan of dehumidifiers.  I would suggest getting a couple of Meaco units, piping them to the outside with a bit of garden hose and leaving them on constant.  They running costs for the pair should be about 6p per hour.  You can dry your washing indoors without any issues.