Floor and Wall Repairs to Resolve Damp Issues

[Ferdy Feldwit]

My cottage is Victorian. The walls at the side are single-skinned. I have SBR bond, PVA, Tanking Slurry and Liquid Applied DPM available for repair.

The first photo shows the inside of the meter cupboard which is on a side wall. After having smart meters installed I wanted to improve the interior which was bare brick. I used cement on the walls and floor but now understand that cement will stop the bricks from breathing. I believe this could contribute to potential damp issues. Should I chisel out the cement and replace with hydraulic lime mortar, or leave it be and paint over it with a DPM paint, slurry or PVA?

The second photo shows a portion of the lounge wall (single skin of brick) that had some damp issues. I removed the skirting and found the wall to be rather broken up bare brick with some plastic sticking up from the DPM plastic sheet beneath the concrete screed. The edge of the screed is broken where I had to chisel out the wooden grips that were glued in place (for the carpet). My plan is eventually to have an engineered wooden floor. My first instinct was to fill all the gaps and render the wall with cement. I have since learned this is a mistake. So I have chiseled out most of the cement. My dilemma is what to do next. There seem to be two schools of thought. One is that it is an old building and the bricks need to breathe, so I should perhaps only point with hydraulic mortar and try to maintain a gap between the wall and the floor. The other approach is to seal in to prevent damp issues. I have also been advised to use PVA and sharp sand and cement to repair the screed, and then paint with a DPM paint (including the exposed wall). I also cut back the plastic to improve the sealing – but that may have been a mistake too. I would appreciate some clear guidelines as to what to do now to resolve this issue. Let me add one other thing. I also drilled and inserted silicon rods. I now think this also was a mistake. I want to be as thorough as possible and this may mean I have gone too far in the wrong direction!

The third and fourth photos show the floor under an arched area between the lounge and the kitchen. The wall is the original back wall of the cottage. At some point an extension was added to incorporate the kitchen including a raised floor. This area is at the centre/heart of the cottage and there have been some damp issues. My plan is to have an engineered floor in the lounge. To prepare for this, I have started to remove the carpet and pull up the wooden grips that were glued to the concrete screed. This meant that the screed became broken up at the edge. It was also very cracked at this point, so I removed the worst. This has exposed what was under the screed where the two rooms join. The kitchen area has bitumen (like roofing material) projecting out, over the plastic sheet under the screed. I cut back the bitumen with a view to repairing the whole section. I am trying to decide what is best to do. The plastic is not sealed (not my fault for a change!), so there may be the means for damp to enter into the wall. I removed some of the soft wall at this point.

My inclination is to paint PVA or SBR over the area and then use sharp sand and cement (and/or a dryish mix of tanking slurry?), and paint over with the DPM. But will this adequately seal the area or just create a barrier for dampness to find its way around? I Would appreciate any clear guidance to resolve these matters. (Can I add here that at another place I drilled and installed some silicon dry rods – but did them from the outside and too low. These may have pierced the plastic membrane under the screed. I could chisel out that small area to check and follow whatever instructions I am given to deal with the problem above.)

[Mr Punter]

Do you have damp in the floor, the walls or both?

 

Where is the external ground level in relation to the inside floor?

 

Have you checked for any possible leaking drains, gutters and pipes?

 

I have seen the silicone rods and they seem a cleaner way of installing a DPC than the liquid, where it was hard to adjust dosage etc.  Did yours fail?  If so, did you follow the manufacturers instructions?

[Redbeard]

There is no mention of insulation. Is that simply because you have not 'got there yet', or because you do not intend to include any? If you are planning to insulate the walls then your strategy for the 'damp' (have you established that it is definitely rising or penetrating damp, or could it be condensation?) needs to take that into account. If, for example, you used your 'liquid applied dpm' to 'dry' the wall, and then insulated internally, you would effectively have a vapour control layer (VCL) in the wrong place in the 'sandwich'.

 

If you were not planning to insulate the walls please let us persuade you to do so!

[Ferdy Feldwit]

Thanks Mr Punter,

No damp issues at the moment. I had some patches that were making the paint rather papery. Two areas were on the wall shown with the meter. On the other side is a tunnel and the wall has a masonry coating on it. It has been suggested that these issues were condensation rather than rising damp. The interior paint and outer coating may be hindering moisture escaping. The more concerning area is where I have dug out some of the wall - because this is not an exterior wall. It has been suggested that the DPM between the kitchen and lounge area either side of this wall, are letting moisure through. I found the mortar here to be like soft clay - elsewhere it is powdery.

I cannot comment on the success or otherwise of the rods because I only recently put them in. I also used some cream - but the rods are far better to use.

The inside floor is not lower than the outside. I have not seen dampness in the floor - yet! (note my fear I may have punctured the plastic sheeting).

I am hesitant to take action until I am sure because I have found it very easy to think I was doing the right thing (following my instinct) only to discover I was wrong (note my over-application of cement).

Thank you for your interest. This is what I think I could do: paint all exposed areas with PVA or SBR; fill in with sharp sand and cement mixed (not too damp); mix tanking slurry with the cement??; paint over the whole with DPM liquid paint (Drybase). Eventually, if I can get the nerve together, I would hope to use a latex self-leveller for the whole screeded floor in preparation for an engineered wooden finish. My concern is that if the DPM is significantly breached under that wall, that it is only a matter of time until dampness might creep up. Let me add that I used a moisture gauge (just touched the wall - not penetrated) in the relevant places in winter and the score was off the scale - but I am told these can be unreliable.

Any insights you might have on the above, gratefully appreciated.

Thanks again

Ferdy

P.S. I am able to write at length because I have the time - retired and twiddling my thumbs because I want to get on with this but feel I need a lot more knowledge and wisdom before proceeding!

[jayc89]

Applying damp proofing to a single skin construction is asking for trouble. No matter what you do moisture will find its way in eventually and ultimately cause damp. With cement on both sides of the wall you're basically trapping any water vapour that gets in there. 

 

You need to find the source of the damp and fix that, rather than trying to treat the symptoms. It's typically caused by:
- cementitious materials on both sides of the wall

- broken drains

- broken gutters

- high external ground levels

[Ferdy Feldwit]

Thank you Redbeard.

I was not considering insulation. I did think of putting tongue and groove over the area under the stairs - I could make a feature of it - but I couldn't do it by the front door (another problem area) without doing the whole wall. Just to illustrate how my instincts can lead me astray: I thought maybe the answer would be a heavy flock wallpaper. Now I am told that would be a bad idea. Again this all shows a tension for me in that there are those that advocate letting the walls breathe. If I watch them on Youtube, they remove all the modern coatings, point with lime mortar - but don't show what they do next!

Or, I go for something like Zinssor (sic) to thoroughly seal the wall (but i suspect that the moisture stays trapped and slowly causes the bricks to detriorate.

Thank you again for your interest.

I will post another photo of the area near the door. You can see where I peeled off some of the paint (and lining paper?). Also I had some rods left over which I drilled in from the inside - these can be seen at the bottom of the wall. If you look closely you can see an opening in the screed and one of the rods I put in from outside - and I did this too low. It looks as though it might have peirced the sides at least of the plastic DPM under the screed.

Cheers,

Ferdy

[Ferdy Feldwit]

Thanks Jayc89,

I don't know how to respond to individuals without just adding to the thread, but I really appreciate all the input I am receiving - this is a brilliant site!

I explain above that one wall (the one in the photo above) is my side of a tunnel. My cottage has a flying freehold - so I connect with next door upstairs. The tunnel wall has some kind of masonry coating on it - so maybe that inhibits breathing. The inner wall has a very nice painted finish (where I haven't peeled it off) but it is probably some plastic based paint that again stops the wall from breathing. I am told the wall had serious cracks, but before putting it on the market, the seller had it plastered and finished. On the whole they have done a good job I think, but it might not be best for a single skin of bricks. There is no way water is penetrating from outside - nor do I think it is rising damp. There is no mould or dark patches. So I guess it is condensation - not enough ventilation - double glazed windows etc. I had a Damp company review it before I moved in and they said it was rising damp - the review was free but I guess they would want a reason for work. Others told me that as it was an old house, there would always be issues. I may have overreacted with all the dry rods (about 160 punctures now in the mortar of this old cottage!!)

Hope my answer is clear, and thanks again,

Ferdy

[Roger440]

As has been pointed out, covering the wall in tanking, cement, gypsum plaster etc will stop it breathing/drying out. The net result will be the wall is wet.

 

From your description of some of the mortar being like clay, id suggest its very wet already.

 

Without a DPC in the walls, trying to stop moisture getting into the wall is pointless. Never going to work. Those rods? Forget about them, never going to work.

 

If you want a dry wall its needs to dry out. Yes, some of that moisture will be inside the house. With good ventilation and or dehumidifiers it can be. But both sides of the wall need to be able to dry out or "breathe" as the traditionalists would say. Do this and it will likely dry out. I say likely, as this is reliant on the walls being able to disperse the moisture faster than the bottom of the wall is absorbing it. You cant know the answer to that until afterwards. Having done all this, i was astounded at the speed it all dried out.

 

The DPC under your concrete is likely making the walls wetter than they might otherwise be, but short of digging up the floor (i did) theres not much you can do about that.

[Ferdy Feldwit]

Thanks Roger. Very helpful. I regret doing the rods - but I did it in the light of the survey that wanted to strip down the plaster etc, and charge me £4500! I only put the rods in - I did not take off any plaster because I don't think it is rising damp. Having said that, I'm not quite sure what I can do short of stripping the walls back to the brickwork or at least taking the paint and lining paper off. But what happens after that? There needs to be some interior decorating after all. 

Cheers,

Ferdy