Is this rising damp?

28 Jan 2011
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United Kingdom
House is an end terraced stone built victorian era house. The picture shows the outer wall (along the back) and an inner wall. I have read lots about rising damp and if it exists or not.

The picture shows the problem I have. The outside ground level is lower, so its not penetrating above a bridged dpc. I have had to take the wall back to the stone to let it dry our. Before I did it appears that the previous owner has rendered the inside walls and then plastered over that with normal gypsum multi. Dont know how long its been like that, but the plaster work was like a damp sponge.

I have compared the mortar above the damp with that from the damp area, and the two are clearly different. The mortar from above contains hair, the one from the damp is crumbly and does not contain these fibres.

I dont know if its rising damp or not - but I do know that in the area showing the damp it is not the original render/plaster.

What do you guys think? Whats the best solution? I was gonna use dry zone and re-render it all, but i'm not 100% this is rising damp, although you'd have to agree it does look like it.

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It may be rising damp, I have had RD and treated it with gravity 'injection' into the lime morta over a 2 week period. The area affected did dry out on the inside and outside BEFORE I rendered inside with 3:1 + waterproofer.

But it is rather cold at the moment and you must first elimitate the possibitly that the damp part of the wall is so cold it is below the dew point of the mosture in the air of that room.

Measure the temp of the wall at the damp area and use this

to find if it is below the dew point. You will also need to know the humidity and room air temperature to complete the calcualtion
What do you guys think? Whats the best solution?

Leave it as it is for a couple of weeks. Hire a dehumidifier and leave it running 24/7 in the area affected. I bet by mid feb it's virtually dry.

Then you can look at re-rendering with a waterproofer. The hair's probably horse hair. Doubt you'll need a new DPC - but rising damp does exist :LOL:
these walls where designed to breathe, so it was most likey rendered with lime motar/render.

the repair was done with sand and cement render, plaster etc, which doesnt breathe.

most likey the cause of your damp.

why the repair needed doing in the first place would be my concern.
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You have a solid stone wall of random stone and a probable rubble infill, when it was built it's doubtful that a DPC was used - look for horizontal slate.

Is the outside of the wall/property rendered?

You possibly have a combination of rising and penetrating damp ( and inevitably, some condensation) given the pattern displayed. As suggested, rendering with a lime mix will do the trick for some years but it will probably return. Tanking might work but you would have trouble tieing into that flap of membrane, and limited tanking can drive the moisture somewhere else.

Stay away from all the nonsense injections and creams ,and that Enron magnitude rip-off, Electro-osmosis.
You could always go down the Jeff Howel route:

Jeff believes RD is a myth as has written a book about it. He also writes for the Telegrapth. I find some of his advise to be spot on, some advise lacking, and some to be poor. I have not read his book but if RD is a myth as he claims, why then were DPCs introduced?
The outside of the property is not rendered - its is exposed stone. I believe sometime in about 1984 some sort of damp proofing was carried out. In the lounge, which can be seen through the doorway on the right, there is a line of newew plaster running around the room at about 1 metre from the floor level. Behind this new plaster is a scrathced coat of hard grey cement type materiial. There are no signs of damp in the lounge, i.e. the other side of the wall in the right of the picture is dry.

I wonder if the same stuff has been applied in the kithcen area but has failed. When I took it off it lookes like hardwall plaster over some sort of render.

The wall has been exposed like this for several weeks now and it has not gone any lighter. To the touch it is not too bad, but i'm pretty sure that it is damp. I also think that the render that has been used (on the low part of the wall) is darker than the old lime mortar above and thus making the problem seem worse.

Here's my plan -

The long wall along the back, and hence half the small wall coming out of the photo will have built in units running along it (low level). I plan to re-plaster the walls using hydraulic lime plaster just below the height of the worktops and leave the wall exposed behind them. I will then have vents in the kickboards to allow ventilation behind the units.

What do you guys think?

A builder has come to look at it, he has reccomended installiing Triton Injection mortar into the apparent damp walls and then have them all re-rendered with fresh cement and plastered. Which solution do you think would be the best? I cant afford to pay him to do the work, but i'm more than capable of rendering and plastering - just cant get hold of triton injection mortar.

Another idea was to use Dryzone Chemical DPC and re-plaster with render and skim.

To many options - not sure which route is best/most suitable.

Thanks for any replies.
You've heard my views on DPC products. As a matter of interest: why have people continued to use the above DPC solutions? Same reason as to why very smart people continued to put their money into Bernie Madoff's hands for 30 years - because he's a con man.

Render up with the remedial lime plaster, but dub out first, then two coats if it's possible to match up with the plaster above the 1M level, skim with board or remedial finish. Perhaps do the whole wall to ceiling ht. then you control the thickness of the finish - anyway the window reveal beads are looking rusty?

Note that your return wall is not properly tied into the main wall.

Dont ,whatever you do, fix built-ins against the walls in question - leave clear to breathe. Vents wont be enough.

Where in Glossop are you - in Old Glossop?
Dub out is to fill in all cracks, pockets and unevenness and bring to a roughly even surface, allow to dry and then float a coat over the dubbing out.

That plaster will do fine, but sand lime and cement will do just as good. If you use an additive, mix it with the water before adding to the mix.

Tintwhistle, just down the road from L.S. Lowry's old house. I helped a mate to do up an old cottage in Dinting Vale, met a girl friend and ended up doing up her old cottage in Old Glossop.She gave me advice and instructions, unfortunately the advice and instructions didn't end with the building work.
I would take the opportunity to insulate the wall. This will solve your condensation problems, give you a good dry internal surface and the added benefit of reducing heat loss. (i.e. reducing money loss)

Make good the stone with a renovation plaster to a reasonably flat surface and then fix 40mm or 50mm thermal laminate board with a skim finish. Go for PIR foam rather than cheaper polystyrene.

I've used that spec hundreds of times in this situation. It is reasonably quick and cheap to do and should last many years.
thats an interesting idea jeds, but wouldn't the moisture get trapped behind the plaster board and evenually ruin the decorative finish?
It's not critical which plaster you use in this situation. I have known people use sand:cement succesfully but personally I would prefer a renovating type because it is more flexible.

The wall behind will have some degree of moisture content just because it is an external wall but the majority of your original problem was condensation. The thermal layer will certainly reduce that condensation and most likely eliminate it all together. Providing the external surface is freely breathable (i.e. no cement render/pointing or waterproofers etc.) then the moisture will absorb and evaporate to the external depending on conditions. That's what it is supposed to do and will not cause a problem.

This system is not perfect. Lime plaster and old fashoned ventilation would actually be best. But it is the best you will get in modern living conditions and will last a good time.

Of course make sure the external is well ventilated. Thick planting around the base of the external should be thinned out or removed and particularly make sure external ground levels are well below internal. Make sure downpipes and drains are in good nick. Any pointing to the outside should be gritty lime mortar.

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