Rising Damp

ballamory

Hello StocktonFlyer

There is a very large radiator in the living room, on the long part of the T shaped wall that was described above, that shows the damp.   It's possible that the pipes connecting to this radiator run through the end wall shown in the picture, and these could be leaking.   Would getting a plumber out to inspect the central heating help determine this?

StocktonFlyer

I'm not a plumber but I've had the exact same problem in my house (1910 build purchased 3 years ago) and got an independent damp survey done to find out the cause. Leaking pipes were a possible cause, but as the boiler maintained pressure it was ruled out. The likeliest cause in my case was that the concrete floor (installed by the developer that I purchased the house from) did not have the membrane fitted properly (we are assuming it does have one) as it didn't overlap the edge of the floor and correctly tuck into the wall (I'm not a builder either). The assumption is that it was cut to the edge of the concrete (assuming it actually exists). The meant that the natural moisture under the floor evaporated and emerged at the edges of the room leading to damp internal walls.
The remedy for this was too expensive and so we decided to manage the issue instead. We purchased a decent dehumidifier and it has worked well in that regard and the problem isn't a major issue anymore. However recent energy price increases may mean it is cheaper to dig up and relay the floor

jonnydeppiwish!

Giving that it’s only appear in the last few months, and the weather hasn’t been particularly wet, it’s another one for a leaking pipe of some sorts

ballamory

StocktonFlyer

I've already supplied the tenants with a dehumidifier, but it doesn't seem to have been as effective at managing the problem as in your case. I'm not aware of a drop in boiler pressure - a new boiler was fitted a couple of years ago, and to the best of my knowledge it is working fine. 

The cause could be something similar - incorrectly laid membrane.  The patches of wall affected are located in both the kitchen and the hallway, so for it to be leaky pipework, it is either a long pipe running through the house, which it could be, or several pipes which have corroded simultaneously.   I'm open to either suggestion.     I'm guessing if the membrane is the problem, that's a very expensive problem to fix, on all internal walls?  Hence the fact you've chosen to manage, rather than fix the problem?

StocktonFlyer

I purchased this - Ebac 3850E 21 Litre Dehumidifier with Air Purification and Laundry Mode | Appliances Direct which is a bit heavy duty and is on 24/7 but the Smart control turns it on and off as required. I reckon it's added about £20 per month to my electric bill which at less than a pound a day seemed reasonable given the issues we were facing (mould and damp cold) and definitely cheaper than the alternative which I didn't have the money to do. I've had a corresponding drop in gas usage which I'm putting down to heating savings as the damp cold has gone which offsets the cost (if I'm right).
It is worth investigating the cause though as it may be something cheaper to fix.

stuart45

If the property was built in 1962 if might not have a membrane, as they were not a reg until 1965. It was common practice until more recent times to cut off the DPM at the joint of the slab and brickwork to make life easier to start the blockwork. 
BRE used to recommend 3 coats of synthaprufe over the join because of this. Nowadays it's tucked into the joint with the DPC.

StocktonFlyer

stuart45 said:

Nowadays it's tucked into the joint with the DPC.

That explains it. My concrete floor would have been installed in 2018 as the house was purchased by a developer who "did it up" before selling onto me. My damp survey suggested it was cut at the slab when it should have been tucked in which was causing most of my issues. Sorry for hijacking your thread ballamory.

ballamory

That's fine, Stockton flyer. It's all very educational! 

So, if I understand correctly, Stuart45,  there may be no membrane over the concrete in my floors at all, because of the build date (1962).  This makes it more likely that moisture from the ground might seep into the walls, is that right?  But presumably lifting the floor and installing a membrane is likely to be a very expensive fix, I guess?

If there's no membrane installed, and it's not a leak that's causing the problem, what are the options to deal with the problem?

stuart45

As the problem has only just started, it's probably unlikely the floor is the problem as the moisture would be coming through the floor in other places. People sometimes say when they install a new floor with a DPM in an older property it then sends the moisture up the wall a bit. 
The problem with discounting rising damp completely is that what if there is no other explanation. I have known people put a physical DPC in the wall by cutting out and installing and they say it cured the problem. Even with a leaking pipe it is still rising up the wall.

ballamory

Hi again Stuart45

I'm not discounting any explanation, because I know very little about the issue.  I'm just sceptical about spending £1,100 on a solution that might not be a proper solution, and end up having to spend more later down the line. 

If the problem was indeed caused by this  (supposedly mythical) 'rising damp', I would be hopeful that there would be some sort of diagnostic indicators, like wet brickwork beneath the plaster?  That gets wetter the closer you are toward the ground?

I've also read statements online that say only load bearing walls could ever suffer from rising damp, because only they reach down to the ground.  Partition walls do not.   How do I easily tell whether a wall is load bearing, or a partition?  If some of these walls are partition walls, then following this logic, they cannot be suffering from rising damp, surely?