1850s House + Damp + Reverting past mistakes!

[adamr]

Hi All,

About a year ago we moved into a blue lias & timber 19th Century house. I've been slowly investigating some of the issues with the house and would appreciate some advice on the damp we have. First a few observations:

* Almost all the internal walls (not the inside of the external walls) are damp (blown plaster, falling-off tiles, 100% disintegrated metal switch boxes)
* The previous owners have had chemical DPCs (which are under guarantee) inserted all over the place on at least 2 different occasions
* The whole ground floor has new stone tiled floor
* There are no obvious sources of external damp
* The walls have lines around them at about 1.5m up which I assume are where new waterproof plasterboard's been installed
* The worst wall (piccies below) is against the staircase and the under-stairs cupboard is pretty damp smelling with some signs of active woodworm in the stairs
* The DPC company have said they'll re-inject the DPC for free (and charge me for the pleasure of replacing the plaster)

From browsing round this forum & website it seems to me this isn't condensation damp (not on cold walls, no mould) which only leaves rising damp. My question (of course!) is how to deal with it? Is the right course of action to rip off the existing plaster and replace with lime-based plaster? Will I need to leave the wall to dry before replastering? Has the new floor meant the walls are going to be damp whatever I do (in which case should I give up and go with the "modern" solution)?

Grateful for any advice!
Thanks a lot,
AdamView attachment 2View attachment 1

 

[Gareth Hughes]

Adam, Welcome

Blue lias rubble, or blue lias ashlar?

The previous owners have had chemical DPCs (which are under guarantee) inserted all over the place on at least 2 different occasions

Which shows that it didn't work twice, and almost certainly won't work again. It would be interesting to know how the guarantee is worded...

It does look like a combination of new floor (presumably on a DPM, to "solve" the damp "problem"), plus injected DPC in a wall construction that an injected DPC will not work in, producing concentrated damp problems.

I could suggest the "perfect" course of action, which would be to dig the floor up, install a DPM-free limecrete one with appropriate final finishes, remove the plaster, improve ventilation, allow to dry, replaster in lime, etc etc. But it's all so much work, and so much expense. The one thing I am pretty certain about is that you've inherited a nasty situation and a warning to others, and I'm really sorry I can't be much more comforting than that.

 

[MdB]

In addition, what is the outside ground level relative to the floor level inside of the house? I realise these are internal walls but you need a high water table to make the bottom of the walls damp. Ideally the outside ground level should be 150mm or so below the inside floor level. I would guess that this isn't the case, I would also guess that this isn't easy to alter either....

 

[Matt Green]

Hi Adam,

Gareth has set out the long and short of it. You've inherited an expensive problem should you wish to fix it for the good of the building. thsi advise from way back still stands and might be useful:

The internal walls are a problem. The concrete floors are pushing ground water up them. Remove the skirtings and check the plaster doesn't run into contact with the floor. Hacking off as big a channel of plaster as can be hidden being the skirting might also limit the damage by maximising the amount of water capable of evaporating through the wall/floor junction.

In this case hack off the existing plaster, re plaster and decorate with something breathable once the wall has dried down then find the tallest pre-treated skirtings you can stand and attach them to the wall with as big a channel behind them as possible and, hopefully, any water moving through the wall/floor junction will evaporate behind the skirtings.


Matt

 

[Lime]

in which case should I give up and go with the "modern" solution?

Using a modern "solution" on older property IS giving up.
The quick fix is only good if it fixes what is wrong...see for yourself.
It does not work.
Modern solutions on older housing create more problems than they solve as your pictures sadly witness.
Often they solve nothing and damage everything.

You are not the only one in this situation.
Most older houses have been damaged by damp "solutions".
Since they became common in the 60s they have evolved into more expensive, but still totally useless remedies for those (usually desperate) wishing to obtain money via a mortgage.
They are lucrative however.

Go with the "modern" solution?
I think it is the modern solution that should be sent packing.

Old houses are fine if they have been cared for and looked after properly with the understanding that they are constructed differently to modern insulated waterproofed "boxes".

 

[Flyfisher]

Just to inject a note of optimism, I don't believe anyone is saying that the problems in those photos are insoluble. As for 'expensive', I would imagine that a lot of money has already been spent on 'repairs' that have clearly not worked and have probably just made the problems worse. THAT is the expensive thing here, both in terms of the damage done and the devaluation of the property.

So, while some remedial work is clearly necessary, the right sort of work as outlined by Matt and Gareth (both professionals in their field Adam) is not really going to be any more expensive than repeating the inappropriate works already carried out - which have demonstrably failed.

As we've so often discussed here, ventilation and breathability is the key, i.e let any dampness gently escape instead of bottling it all up until it causes the sort of problems shown in those photos.

 

[JoceAndChris]

I can't add much to the posts above, which are spot on.

Except to say that if you can't afford to remove all the modern unbreathing materials, and replace with breathable ones, don't lose heart. We bought an old, damp house slathered in unsympathetic cement and paint, with incorrect tanking in the basement. We removed some of the most offending material, increased heating and most importantly, as FF says, ventilation. Two years on, the house isn't damp. You must be ultra fussy with showers and drying laundry indoors as they are the worst offenders. Washing less is extremely effective in remedying damp, and windows or doors should always be opened to allow the saturated air to escape.

 

[adamr]

Thanks for all the really helpful replies

In answer to some of the questions:
Ashlar or rubble: hmm, not 100% sure. Ashlar I guess (picture below).

Guarantee: doesn't seem to be anything particularly unusual in the guarantee. The main bit says "Any recurrence of Rising Damp from the ground to all areas chemically treated for the control of Rising Damp [is covered]".

Ground level outside: about the same height as the floor inside. On one side it's a patio made out of (presumably) the original internal flagstone so a big job to change. The front of the house has flowerbeds along the wall though. Would it help to dig some kind of channel around the bottom of the wall?

Leaving a gap at the floor/wall junction: on looking through the paperwork again I notice the junction has been "sealed"

So I guess my plan will be to hack off the existing plaster, leave the wall to dry for a while, re-plaster with something breathable (+ leave a gap at wall/floor junction) and be careful about the level of humidity in the house. We are considering some internal re-organising of the ground floor so in the longer term replacing the floor in at least one area might be practical as part of that work, though I've no idea how hard that will be to do!

Thanks again,
Adam

P.S. I am quite surprised the damp treatment companies stay afloat. If I agree to their proposal of re-injection and tanking/plastering it'll come with a 20-year guarantee and presumably in that time they'll be back every few years to re-do their work for free. Sounds expensive for them!

Exterior stonework:

 

[Gareth Hughes]

Adam - I do hope you won't mind me pointing out that, apart from the damp, that photo suggests you have bought one or two other, minor problems? :wink:
Best of luck with them

 

[adamr]

Heh heh. It's OK, the ladder's holding it up!

(Thankfully that crack, at least, is long gone . As for other things, no doubt I'll be back here in due course asking for advice!)

 

[Schoolmarm]

Don't forget, you can lower the ground levels on the patio side quite easily by just lowering the row of flags next to the house.

 

[chuckey]

Lift the flagstones next to the house dig down to 6" lower then the floor level, about 12" wide fill with gravel. Replace flags. Then any water will drop down to below floor level. Would be nice to have a slope on the trench so you know where the water is going and some form of exit into the garden.
Frank

 

[Penners]

Adam - I do hope you won't mind me pointing out that, apart from the damp, that photo suggests you have bought one or two other, minor problems? :wink:
Best of luck with them

On the plus side, if the house gets excessively damp at least the water has an escape route.

 

[PC]

Hi Adam,

Let’s start with the basics…………..chemical injection damp proof courses don’t work in random rubble stone walls like Blue Lias and if it’s been injected its almost certainly then been re-plastered with a dense-cement render / gypsum plaster, therefore trapping moisture, preventing moisture / vapour from evaporating i.e. the walls from breathing.

Slightly confused however why only the ‘freestanding’ internal walls are damp and not the internal face’s of the external walls. Is it possible they’ve been dry lined in some manner? Also from the photos the stone floors I’m assuming are laid on a concrete slab?

Putting the “does rising damp exist” to one side for the moment, as Matt and others have stated, modern solid floors with a membrane can encourage damp to move to the wall and increase the risk of dampness at the base of the wall and moisture to rise - via the render/plaster (bridging).

Looking at the extent of damp on the photos I would suggest that the first thing you need to consider is removing the plaster completely on the affected walls and then let the walls dry down. With good ventilation a good deal of the dampness should dry down quickly, although the walls could take many months to dry down completely (if at all).

Assuming that there are no obvious sources of moisture or defects affecting the property or beneath the floor, like a plumbing leak (you will be surprised how many damp investigations I undertake and find are due to leaking pipes) then replastering with lime or a permeable plaster should overcome the problem. Whilst not eradicating the damp it will allow the walls to breathe, unlike the cement render which traps it!

Again as Matt has stated, the plaster (depending on what you use) should be cut short of the floor and any joinery (skirting's) fitted properly treated / isolated otherwise they could eventually rot.

Replacing the floor with Limecrete (as others has suggested) could be considered, although will proof to be expensive and I’m certain something you didn’t anticipate when buying the house.

Over the past 50 years or so many old buildings have had their original fabric (lime plaster etc) ripped out in the name of RENOVATION and replaced with cement renders and pointing etc and people wonder why there walls are wet!

PC

 

[MatthewC]

Hi Adam,

Slightly confused however why only the ‘freestanding’ internal walls are damp and not the internal faces of the external walls.

My brother had this issue in his Victorian house, possibly because the external walls had some foundations (the house was on a hill) but the non-loadbearing internal walls were laid directly on earth at floor level.

 

[adamr]

Thanks all for the further helpful replies.

Lift the flagstones next to the house dig down to 6" lower then the floor level, about 12" wide fill with gravel. Replace flags.

I like the sound of this plan. The whole lot need re-pointing anyway. Can anyone tell me what the purpose of this "foot" arrangement at the base of the wall is? (I hope you can see from the picture. There's the vertical wall, then a 45 degree slope, then the flagstones.)View attachment 1

Slightly confused however why only the ‘freestanding’ internal walls are damp and not the internal face’s of the external walls.

You and me both - I figured maybe the damp is there too, but is evaporating to the outside?

Is it possible they’ve been dry lined in some manner?

No. See piccy of what we found behind one of the radiator cabinets:

Also from the photos the stone floors I’m assuming are laid on a concrete slab?

I've no idea. I'm going to do some digging around (metaphorically and literally) in the understairs cupboard to see if that sheds any light on anything.


Regarding the floor, surprisingly my wife quite likes the idea of replacing the whole thing, which gets me into a whole new ball game of cost/hard work/complication! Does anyone know how much limecrete costs? limecrete.org doesn't seem to mention prices at all (I'm reminded of the saying "if you have to ask the price, you can't afford it"!). Also, are the only suitable coverings bricks or limestone flagstones?

Adam