Damp Issue - London Basement Flat - Help greatly appreciated

[livingonaprayer]

Hi All,

New member here. I am in the process of inheriting a leasehold basement flat from a parent who passed away suddenly. My parent often complained of rising damp when they were living in the flat but due to financial difficulties, was never in a position to deal with renovating the whole flat. I am now in a position where I can look into the issues with the flat. This is all very daunting.

I originally thought I would get the people who gave damp reports now some 5 years ago, back in for an updated quote. When they gave quotes, the flat still had the kitchens, built in wardrobes in etc. - now the flat is a shell, no kitchen or bathroom with plastering stripped back etc. so in theory, one should be able to assess very well the situation vis a vis any damp

On doing more research I have learnt that a lot of damp proofing companies are selling products which supposedly only treat the symptoms rather than the root causes and that many of them are incentivized to sell products, intuitively this makes sense. This is giving me second thought as I need to carefully make sure I do any damp related work at the right time e.g. before/after 1st fix electrics and certainly before any plastering etc.

Whilst I don't doubt that there was damp historically in the property, I am tearing my hair out, unsure what type of damp it was and what the causes really are and what the right solution is. I have been looking at sample damp reports by seemingly independent surveyors which have sometimes recommended works like reducing the ground level but I am not sure this is realistically possible given that it is a basement flat. Not sure if given the time it has been left alone that maybe some of the damp has gone away with the flat being allowed to breathe naturally. I never realised that there even was a fireplace as this was plastered over. Appreciate the forum is not a substitute for a surveyor but any help would be greatly appreciated as the overall costs for the renovation are frightening and the number of supposed scammers out there.

 

[alexander]

all these pictures are from inside rather than outside , most dampness will be coming from external sources, if the walls are below ground level then it will most likely be penetrating dampness while you can cover this the water coming through the walls still has to go somewhere usually via a sump pump, the pictures themselves are confusing as it shows some rooms with wooden flooring which must be above the external ground level with air vents to allow under floor venting, so is the flat below or above ground as there are different ways to solve different issues.

 

[livingonaprayer]

The entire flat is lower ground with steps going down from pavement level. I wouldn’t know anything about wooden flooring needing to be above ground level, news to me. Maybe it is the cause of issues but from I’ve put together, the flooring was never identified as culprit. Flat is part of a Victorian style building, bay windows etc. - hasn’t been done up in very long time so maybe best practices not yet in place. Only pictures I have of the are now attached, appreciate not full pictures but hopefully gives an idea

 

[Cubist]

The only real difference with a basement flat and any other structure regarding damp is that one or more of the walls may be underground at all times and nothing can typically be done to remedy that fact. Come what may the structure will be at risk from penetrating damp from the earth directly below and from around the subterranean sections. Like Cnut we cannot defy the Natural Laws and the best we can ever do is to seek to limit the incursion to protect some of the structures fabric and those of our possessions we lodge within that structure. In other words, we are all largely limited to actions targeted on managing the effects rather than the root causes - certainly of naturally occurring water incursions.

In my personal opinion there is no effective treatment or measure that can prevent damp penetration through the walls of a basement short of excavating all the soils from around the structure. Some might suggest tanking or chemical injection treatments of the internal faces of the below ground level brickwork but this often has the disadvantage of, in effect, encouraging the damp to find an alternative escape route - it will either climb higher into the walls or appear in other unprotected places.

In your shoes my first concerns would be with the wooden floors and the conditions below these. Damp rising from the ground below and the brickwork upon which the joists of those floors are mounted could be in a poor state - particularly if airflow below the floor is blocked or prevented in any way. Investigation of and remedial work for problems here would be at the top of my ToDo list. The floorboards might also be an indicator of damp in the brick walls. If you examine the edge of the boards closest to the walls you may be able to see signs of water staining which in turn may suggest that the walls have been saturated to at least that level.

There are other mitigation actions and I'm sure that others, like Alexander, will be along shortly.

One thought occurs that may put some limits on your concerns - if the neighbouring properties to either side of yours are also basement flats or cellars then your risk of penetrating damp is limited only to the floor and other unnatural causes.

 

[livingonaprayer]

Yes, I have one basement flat behind me from the same building and another basement flat to the left/right of me from another building. Excavating all the soil underneath sounds prohibitively expensive and not something the freeholder would be happy to pay. Thoughts? What is the next best alternative

 

[Cubist]

I am afraid your options are severely limited but your main threat axes, assuming that none of the external walls comprising your flat is in direct contact with soil as you seem to be saying, is limited to damp rising from the earth upon which the foundations of all the walls stand. Setting aside the contractual rights, obligations and duties associated with the Leaseholder v FreeHolder arrangements, there is little that I feel you could practically do to make an appreciable and effective direct improvement to reduce the occurrence of that damp.

Your options are, in my opinion, limited only to how you manage the effects. The wooden floors are potentially the greatest element of the flats physical fabric which is at risk. Before you do anything at all with these you should first determine whether the Freeholder has any responsibility for repair or replacement of the floors. Damp rising through the foundation brickwork can result in rot of the wooden joists, in particular the ends of these where they are usually housed in or upon the brickwork, which in turn carry the floorboards themselves.

I note that much of the old plaster has been removed already. You must ensure that a lime plaster is used to replace this as it will help any damp rising through the brickwork to more rapidly escape to atmosphere. In addition to this you must also ensure that ventilation, meaning effective airflow into and back out of the flat, is as good as you can make. This is particularly important under the wooden floors and is vital to all your property inside the flat. Stale, damp laden air will quickly cause moulds and mildew so you need to be cautious with wardrobes and the like that typically are sited next to walls.

You also need to remember that humans and our activities produce and exude huge amounts of moisture into the atmosphere. Active ventilation fans are essential for bathrooms and kitchens. Passive vents high up in any external walls will also help basement dwellers. Another tip is never to allow none-breathable paints or other wall coverings to be used in the flat.