Basements

[dog]

I have a Georgian property in Islington. One neighbout had his basement excavated and since then, I have been having damp problems. Ideally, I would not have my basement excavated, but the damp is causing problems. I recently got a quote from the London basement company to (effectvely) excavate the basement and put in a big concrete box. I have many queries about this. This is my first post on Period Property. I put "London basement company" in as a search term, but nothing came up. Has anyone had any experience and can advise?
Dog

 

[Nigel Watts]

Welcome to the site!

How is the damp manifesting itself?

I am not sure why someone would need to excavate a Georgian basement in an Islington townhouse. These were generally lived in (by the servants), and were where the kitchens were located. They should therefore have enough headroom and not need their floors lowered. Lots of basements get excavated in places like Fulham, where the houses are late Victorian and the basements were only ever designed for the storage of coal, without enough headroom to stand, the kitchen being at the back.

The reason for the damp could be that your neighbour's property has been made so watertight that the natural moisture in the ground has has to seek an alternative escape route, or it could be a drain problem. Friends of ours who did a basement excavation in Fulham had a number of nasty floods in their swish new kitchen. These were all drain-related and I believe they have now solved it by installing pumps.

It is close to sacrelige on this site to recommend anything but naturally porous and breathable materials as a solution to damp problems, but if the problem is of the first kind you may have to damproof your basement with a floor membrane and tanked plasterwork. I have to confess that this is what I did.

Nigel (a fellow Islingtonian)

 

[Juju]

My brother has a beautiful property in Islington - he owns 3 floors of the house but there is also a self-contained basement flat. I think as Nigel says there often is good head height in the basements as they were designed to be kitchens, etc but for example, the basement in his property was excavated in the 1970s I assume to improve the head height and they didn't underpin it at the time and it started moving! Anyway, it was all remedied at huge expense by the previous owner but being an end terrace, it has still has a very definite scary lean! I thought he was brave to take it on (a neighbour stopped us in the street just before he bought it and said 'don't buy that house - it has endless problems!) but to be honest, he's lived there 4 years with no problems so far. He also viewed dozens of houses and rejected several because the basement ceilings were too low (he's 6' 4").

Sorry, that's not an answer to the issue about damp - I just love talking about Islington houses!
Juju

 

[Penners]

The reason for the damp could be that your neighbour's property has been made so watertight that the natural moisture in the ground has has to seek an alternative escape route

That sounds a very plausible idea. Unfortunately for you, damp problems can be hugely difficult to pin down to a precise explanation, so it may be that you'll end up on the "suck it and see" trail, as many people do. You just have to make a list of all the possible causes, then start eliminating them, one by one.

After each step you have to wait and see whether it has worked, and then - if not - move on to the next one.

Needless to say, it's best to start with the cheaper possibilities before you move on to the wallet-draining ones.

 

[MattW]

As fellow owner of an islington georgian house I can sympathise! While I doubt they had a full basement excavated, it is quite possible that they dug down a little, say 0.5m to improve ceiling height. Also it is possible the original floor had been replaced with a poured concrete floor in the 50s without insulation & DPM and hence they might have choosen to replace that while doing other works.

In terms of the damp, I would find out from your neighbours how the damproofing was done - cement render to the walls effectively trying to keep the water out, or full height cavity drain membrane (e.g. Delta or Triton) that will channel any interior damp down to drains & a sump. In the property that I bought, both neighbours had had new concrete floors poured and their basement walls waterproofed with cement. I suspect but can't obviously prove that any water under their floors / in the walls can no longer come out on their side, so naturally came out on my side. Either way, my property had a permanent tide mark of damp up to c.4' on both side party walls (the end walls were damp free). Prior owner had attempted to rectify this with a chemical DPM but needless to say this totally failed.

Rather than compound the problem further by putting my own concrete floor and cement render on the walls, I am having a cavity drain membrane fitted to the walls & floor to allow the damp to come out and evapourate / flow to the drain if v.wet, while keeping the interior walls dry. Cost of this for 50 m2 floor area, 2.8m high is c.£10K, excluding any redecoration costs etc.

The other thing that you should consider is whether they signed a party wall agreement with you prior to installing any damproofing on their side - though often overlooked, I understand that your agreement should have been sought prior to the work being undertaken, especially for cement rendering.

 

[MdB]

Rather than compound the problem further by putting my own concrete floor and cement render on the walls, I am having a cavity drain membrane fitted to the walls & floor to allow the damp to come out and evapourate / flow to the drain if v.wet, while keeping the interior walls dry.

Can you take some pics of the installation as it is done and post here so people can see what it is like. The cavity membrane approach appears to be the best way of sorting a damp issue where it is impossible to remove the cause of the damp so it would be useful to point people at someone who has had it done. Cheers, MdB

 

[MattW]

Can you take some pics of the installation as it is done and post here so people can see what it is like.

Yes of course - it is going in as we speak, so will be able to post some pics fairly shortly.

 

[Moo]

Surely it's about time that you Islingtonites arranged a little social get-together?
It's lovely, putting faces to the names and having a good snoop round the houses.

 

[middi]

.........and with a bit of luck you will all be invited to your next door neighbour's heated basement swimming pool :wink:

 

[dog]

This discussion is all very helpful and making me have a serious rethink. The other thing I worry about is quality of workmen. I'm new to this site, but is it possible for Matthew to indicate who he used if he is happy with their work?
Thanks you all and I'm keen to see the pictures when they're available.
Dog

 

[Penners]

It's lovely, putting faces to the names and having a good snoop round the houses.

I second that.

 

[Nigel Watts]

Surely it's about time that you Islingtonites arranged a little social get-together?
It's lovely, putting faces to the names and having a good snoop round the houses.

Count me in. Anyone else interested? My local's the Duchess of Kent in Liverpool Road, but it's best avoided when Arsenal's playing at home.

 

[MattW]

I'm in also.

 

[dog]

I'd be interested in meeting up too

 

[Penners]

Dog, shouldn't you stay at home to guard the house?