Advice with Georgian basement kitchen

[Drrjparkes]

I am hoping someone can help me. We own a Georgian terrace house in London that we have done extensive renovations on. The one remaining aspect is our basement kitchen which we now plan to have replaced along with the current basement flooring. The kitchen suffers from the usual damp of these houses. It's liveable but we would like to be able to improve it as much as possible and have already made much progress without having to resort to retrospective installation of a damp course. My question is regarding our plans to replace the floor. This is current porcelain tiles which I believe are laid on concrete. Obviously this is not sufficiently porous to allow evaporation. I am wondering if it is worth/possible removing the concrete subfloor and replacing with limecrete? I don't want to risk causing any structural damage or have to do any underpinning. Is this feasible and will I need advice from a structural engineer? We would plan to top this with some breathable tiles (maybe reclaimed terrocotta).

Any advice on this and general use of limecrete in basements would be greatly appreciated

Richard

 

[Zebra]

When you say basement, is it entirely underground? How far underground is it? How old is it? Was it originally a habitable room? When was the concrete laid? Is it possible there is already a damp proof course, or damp proof membrane installed? How damp is it? What do you think is the cause - condensation onto cold walls from damp activities like cooking and washing, or penetration from outside? Sorry for the barrage, I think we need more information.

 

[bobby spray]

I don't know your house or about limecrete but I suspect that if it's a decent sized property that the basement might have been originally used for servicing the main house. My own basement originally had a mix of suspended and soil floors. soil in the laundry and kitchen, suspended in the living quarters. The soil floors have been replaced with concrete- and like yours suffer from damp. It's probably best to identify the source of the damp and (if you can) deal with it. that way you can put down whatever flooring you please.

 

[Flyfisher]

My only experience of a cellar is our smallish one under one room. It has been largely untouched (it would seem) since it was built, the walls are soft brick with lime mortar and it has been limewashed over the years, though probably not in the last 50 or so, and it has good ventilation in one west-facing wall. And it is very damp - for which I use a dehumidifier during the summer months to, hopefully, keep the timber so the floor above reasonably dry.

The cellar is completely empty and unused so condensation from daily activity is unlikely. It seems obvious to me that the damp is simply penetrating through the breathable walls from the surrounding ground. We often discuss damp walls here and a standard recommendation is to ensure that external ground levels are at least six inches lower than the inside floor level, which allows moisture in the wall to evaporate to the outside. But of course this cannot happen with a cellar and so damp walls are only to be expected and the more breathable the walls the worse the damp must surely be, because the wall is hardly going to lose moisture INTO the surrounding ground.

From the little I've read, modern cellar damproofing relies on some form of impermeable tanking or an impermeable 'room within a room' with a water collection sump and pump arrangement, though I have no experience of such things.

All of which is a roundabout way of questioning whether the replacement of a cement floor and porcelain tiles with some form of breathable limecrete is actually worthwhile. To my inexperienced mind it would seem to be a recipe for increasing any damp problems, not reducing them. But I'm just thinking out loud really and am very open to being corrected (oo-er missus).

 

[Drrjparkes]

It is a typical London Georgian terrace basement kitchen with an open stairwell to the front that goes down to the same level as the basement floor. To the rear we have excavated the garden and there are doors that open outto steps that go up into the yard. As such the front and rear are essentially at ground level (sort of!) thus reducing moisture pressure. There is blocked up chimney breast (no longer useable) in one corner of the kitchen which was seriously damp before we excavated the yard. However, we opened this up and removed debris which has reduced moisture pressure and the damp problem significantly. Two one side there is another Georgian terrace with a similar basement. To the other is a Victorian block of flats which was built closely adjacent. One of the walls on this side has damp and I believe this is due to debris in the gap between the houses trapping moisture. We hope to try and improve this by clearing out an existing a ventilation brick between the houses but this is going to be very difficult. Beyond this there is some moderate rising damp at several places in the walls characterised by salt bubbling on the paintwork.

I really don't know what the original purpose of the basement was. It is a small narrow Georgian terrace so not one of the really large grand ones. Basement plus three stories.

I don't believe the damp is caused by condensation as the activity is limited to daily cooking. However, until I rip out the kitchen I can't be sure there isn't some leakage from plumbing as the previous owner was a bodge job merchant.

My understanding is that a concrete floor will cause any moisture to be force up the walls and exacerbate the problems. The basement is liveable and we know that to an extent it's just the way it is but we will be doing this once and want to do everything we can to improve things as much as possible. The reading I have done on the subject seemed to suggest limecrete would be a best option but I am not an expert or builder so really don't know how big a job removing the concrete would be. I don't know if a damp course was installed but I really doubt it.

 

[Drrjparkes]

Can no-one help me with this? I have pretty much given up on limecrete as it has a minnum depth of 25cm which would involve excavation that I don't think we want to go through. However, I am wondering if it's worth digging up and replacing the existing concrete floor to modern standards and the whether this would require having a structural engineer and listed buildings consent etc. our alternative is just to lay new floor on the existing concrete replacing the current tiles but I don't want to waste this one opportunity we have to improve things as much as possible.

Any advice is appreciated

 

[88v8]

What RH do you have?
In the house?
In the basement?

Our cellar, which leads down from the kitchen and is open to half depth at the front/north, has breathable membrane on the walls and a concrete floor (both bequeathed by PO) and a sump pump installed by us to deal with the inflow from a spring. The RH is typically ten points higher than the house. We have a dehumidifier which runs all year, otherwise it would be twenty points. Currently, because of the dehumidifier, there is an RH inversion, with the house at Peak Seasonal Damp, c 75%, and the cellar at around 70%.

Limecrete, as you say, will help with some problems, as it allow moisture to disperse rather than being forced up the walls, but the moisture is still coming into the house and has then to be dispersed by what used to be known as ventilation but is now called 'draughts'. A 10" depth (5" limecrete 5" LECA) is about the minimum, depending on the span.

Oddly enough, your blocked up chimney might have been helpful as it would create a strong ventilation pull, assuming there are sufficient external vents to allow air into the room, of course.

Daily cooking and washing up can generate a lot of airborne moisture, unless you have a good extractor and actually use it! Again, an extractor can only work effectively if there is air coming into the room. The airflow in->>-fan needs to pass across the source(s) of steam.
In our kitchen I installed one of those big olde Expelair fans one sometimes sees in pubs. It moves a lot of air, but does not actually capture the steam from the hob unless the adjacent window is opened a little to allow air to flow over the hob.

Other enemies are clothes drying, and unvented tumble driers. I expect you know all this.

Cold surfaces such as tiles are another problem as they are a focus for condensation.

How does the damp manifest? Is there mould? Generally or at certain points?
One of these could help identify cold spots, despite the price they are surprisingly discriminating.
https://www.amazon.co.uk/dp/B01BWLWNSM?psc=1

On the whole I tend to agree with Flyfisher. Without substantial and expensive interventions it is likely that a certain degree of damp must be expected.
And even with intervention, it may reappear, after the cheque has cleared of course.
If you visit any stately home, the dampness of the cellar is usually apparent. It's just the way they were.
Perhaps rather than siting one of the most damp-generative household activities in the cellar, it could be repurposed, but I guess with the house nearly completed the thought of moving the kitchen does not appeal.

Sorry not to have any immediate bright ideas.

Ivor

 

[Greg.Hobson]

Can no-one help me with this?

Your plea struck me, thinking as I do that I am really no-one!

My experience of Damp issues is limited but nonetheless does exist. You state that your cellar is open to the front and rear (in the sense that the outside levels are approximatley the same as the inside levels) and that one of the side walls is similar in that there is an equivalent room next door. To the other side your description is a little ambiguous, but I will assume it is the only wall completely underground.

Like 88v8 I agree that the chimney no longer being able to be used is a shame, but that, and yours and others mentions of a dehumidifier, set me thinking that a single-room MHVR setup may be an option, and my apologies up front if you have already looked at these. This ( http://andyduffell.com/techblog/?p=1270) item was the first reasonably independent real-life analysis I stumbled blindly across. You mentioned clearing out a ventilation brick which, if open it opens to the outside, mirrors exactly the example used on the site, but your plan is for a kitchen whereas the site installed theirs in a bathroom.

Whilst I have no experience of this type of kit, I could easily be convinced that this would emulate the conditions of old inasmuchas it provides both the outward pull that is expected of an open chimney in addition to the internal ventilation provided by the coarse breathability (is that a valid construct?) supplied by ill-fitting windows and doors. It also adds the benefit of warming the incoming air. On this last point, some loss of heat is to be expected as nothing is ever 100% efficient (and that comment is probably open to some debate with those more knowledgeable than I).

Whilst I don't think this could be promoted as a total fix, I reckon it has the advantage of being able to be installed prior to any planned renovation and its efficacy in the proposed location being able to be assessed.

 

[Tony.]

http://www.dampbuster.com/publication.html

I would recommend Mike's book. It's a good read.

I have attended one of his lectures and the advise is very good.

No connection to the above

Look at all the rainwater goods
Check for damaged drains
Check for leaks
Check ground levels
Under floor Ventillation
No cement
No damp 'experts' recomending 1 metre of wall hacked off and repaired with a special waterproof render
Look at heating
Look at not drying clothes inside

Get a couple of temp/RH meters from flea at, I got one for under £7

Have patience as repairs will take time to show up on damp walls etc

 

[MatthewC]

Two one side there is another Georgian terrace with a similar basement. To the other is a Victorian block of flats which was built closely adjacent. One of the walls on this side has damp and I believe this is due to debris in the gap between the houses trapping moisture. We hope to try and improve this by clearing out an existing a ventilation brick between the houses but this is going to be very difficult.

You state that your cellar is open to the front and rear (in the sense that the outside levels are approximatley the same as the inside levels) and that one of the side walls is similar in that there is an equivalent room next door. To the other side your description is a little ambiguous, but I will assume it is the only wall completely underground.

If that's a correct interpretation then the issue is largely with that gap to the adjacent block of flats. Apart from debris trapped there, is there a source of water into the gap, e.g. neighbour's downpipe or ground water etc?

Look for the obvious as well as the difficult. On the church near here, there is a subterranean boiler room with a sump pump. Two years ago we found that the sump pump sent the water back to ground level but the drain it went into did not actually go anywhere, so the same water was then re-circulated back to the boiler room! Sigh. It's now a lot drier.

 

[Tony.]

A dehumidifier wet to the appropriate RH would be a good purchase- one with the ability to connect to a drain is best.

Add a condensate pump next to it the dehumidifier can empty into the condensate promo, this in turn can pump up to Adrian if necessary through a small note flexible pipe/ the condensate pump contains a float switch and brings itself on and off as required.

 

[88v8]

:shock:

 

[88v8]

A dehumidifier wet to the appropriate RH would be a good purchase- one with the ability to connect to a drain is best.
Add a condensate pump next to it the dehumidifier can empty into the condensate promo, this in turn can pump up to Adrian if necessary through a small note flexible pipe/ the condensate pump contains a float switch and brings itself on and off as required.

What a superb example of the autosabotage feature in action.
Isn't modern technology wonderful.

Ivor

 

[Tony.]

Apologies for predictive text spelling errors

 

[a twig]

Poor Adrian, constantly having condensate pumped into him

 

[DavidB]

Richard,

I remember reading another post on here previously about someone who was thinking about digging up their concrete floor and was worried about the structural damage that might be caused.
If you do a search for 'breathable kitchen floor' or 'digging up kitchen floor' you will hopefully find the post. Several replies reassured the OP that this can be done without causing the house to fall down. One suggestion (as I recall - apologies if this is not 100%) was to leave the floor immediately adjacent to the wall alone and remove the bulk of the central part of the floor.

I had a much smaller problem in my house where I had a very clear damp spot in the floor. The wooden sole plate (half buried in cement and layers of screed) was very damp. The patch was so precise I was convinced I had a burst water pipe. I took an angle grinder and started to excavate the small patch. I only had to dig down a short way (couple of inches) and it seemed to dry out in front of me. At that stage I managed to get hold of the previous owner and he confirmed that there were no pipes in that area of the floor. So I stopped digging and monitored it. The sole plate dried out! The little trench/hole I made adjacent to the previously damp sole plate was literally a couple of feet long and only an inch or two deep.

Similarly, I recently renovated a downstairs shower room. The brick plinth wall was soaking wet under the paint. I scraped this off and the cement render over the bricks. In doing this I created a small trench between the cement floor and the plinth wall (i.e. where previous layers of flooring had been applied and butted up to the cement render on the wall - when I removed the cement on the wall the bit between the floor covering came away quite easily and left a neat trench). The effect of this was again quite visible - the wall and floor dried out. When making good the floor I filled the small trench with lime render rather than cement. I am still monitoring this as the work was only completed this July. But so far it looks promising...

If I was you I would experiment before committing to a large outlay such as limecrete. I would make an exploratory hole in the floor and see what I found - I would be really careful about how I did that in case there was a dpc and I would avoid cutting through it!

I would be tempted to try and break the seal between the cement floor and the walls and see if that reduces the damp. This is based on my experience and my house is older than yours and doesn't have a basement. So I'm not suggesting it is fool proof - but a few test holes will not cost you anything and you will find out more.

The other suggestion you have planned about clearing out the debris in the gap between your house and the neighbouring one seems to be a very good idea and I would make that a priority as it could have an immediate impact. I appreciate it would be difficult getting in and removing the rubble in such a tight space, but I think that would be a case of every little helps...

 

[Drrjparkes]

Great stuff. Thanks for all the advice. Have decided to continue to attempt to sort out the issues with the adjacent property and invest in a new dehumidifier. The idea of digging up the basement floor fills me with dread and probably wouldnt help.

 

[Drrjparkes]

When i say wouldnt help i mean wouldnt help unless we were willing to dig down and probably underpin the house which i am not keen on we will test some areas of the existing concrete but my guess is it is pretty shallow and the house likely has minimal foundations.

 

[a twig]

The wonderful old soul of a previous owner here decided to replace a beautiful original traditional stone floor in two of the rooms with 2" of concrete.

I too had damp problems, so I did some test drillings down into the concrete (was only 2" thick) with a coating of blackjack and 80s newspapers on top. It turned out in two of the rooms that the soil underneath was completely dry, so I was content to patch the small hole and leave it be. Third room on the other hand is a different matter, but it has definitely saved me forking out on limecrete in two rooms to no avail.

Maybe a similar course of action might help you?

 

[Pennyviz]

I was looking at a limecrete floor, but have decided against it. Not least because it meant being without a kitchen for 6 weeks and mess/costs involved (let alone someone to do it). CO was not keen and wanted to try minimum intervention first. I am heartened to hear of other earth floors that have worked as that is my current plan - to remove porcelain/lino surface. If your building is listed then you can forgo building regs I think and have a bit more flexibility in terms of depth etc of limecrete if you want to go down that route.