1860s stone house Reno

[Herefordhouse]

Evening all,

Newbie to the forum, stumbled across it looking for solutions to the upcoming project I have. So I thought I’d ask some questions specific to my project! Thank you in advance for taking the time to read through it.

My property is in serious need of some TLC. The previous owner did nothing to the property in the 60 years she lived in it, and unfortunately it’s showing.

Its an 1860s stone house and It will effectively need an upgrade of everything.. a full replumb and rewire, along with new windows etc. I’m also doing a two story extension on the property so would be open to opinions on the best render/cladding etc to suite the current property.

It’s got some damp issues, but I haven’t yet consulted a damp specialist. Although have seen that injecting damp proof coursing can be a reasonable fix. I know this approach can lack efficiencies.

I was thinking of stripping back the internal plaster situation (I believe a mix of horse hair and lath and plaster) to the stone and then rebuilding back to put some electrics and plumbing in around mineral wool insulation, followed by lime plaster on top. Although im not sure whether insulating the property is even worth it. I’ve heard it can cause more harm than good (damp) and typically the stone acts as a large thermal mass.

Would I be able to use standard plasterboard on the ceilings (some of the ioriginal plaster has come away from the ceiling)

Would an air source heat pump be viable with no wall insulation but new windows and improved insulation in the attic. There would probably be a mix of underfloor heating where possible with solid floors and in the extension, and large radiators or ceiling heating where there are suspended timber floors.


I’ll be back with many more questions in the future. But thank you for your time and I appreciate any hints tips or advice. I’m a relative newbie so will seeking the trades at most avenues. But any DIY jobs let me know!

Thanks

 

[aockenden]

Just a quick comment to start you on some deeper thinking / understanding: thermal mass is not equal to insulation. Those are two different concepts entirely. A large thermal mass that breaches your thermal envelope is definitely a problem in this UK climate.

Uninsulated thermal mass can work ok in places with violent swings in temps intraday (namely deserts). But in cool, sun-deprived countries like the UK, you’ve got a problem.

 

[Toby Newell]

Injecting a dpc should be the very last port of call. 95% of the time it's other issues and rarely only one. Replace windows and repair roof / gutters and heat and ventilate property before worrying about dpc injections. Condensation in a stone dwelling is also an issue.

No idea what thermal mass has to do with the price of eggs, it simply means you have a slight hysteresis with temperature changes. Nothing to do with insulation whatsoever. A big slab of cold stuff is going to be a condensation magnet. Sandstone is a reasonably good conductor and a very good emitter, so quite a poor insulator.

 

[Herefordhouse]

Thank you for these fantastic replies. Clearly I’ve taken on some crap from what I’ve been reading. The house will get a full refit of gutters/ flashing. The roof seems in good nick but will be looked at also.

The property has been dormant for over 6months so that will have contributed. What’s an efficient ventilation solution

 

[Herefordhouse]

Forgot to say. I spoke to our surveyor who stated a lot of the time insulation causes issues in properties like mine because it’s often done wrong and causes damp. He said he wouldn’t bother.

 

[Toby Newell]

I would do the gutters, pointing, check ground levels / shrubbery, open the windows, put the heating on, run a dehumidifier and go about your business. If it's still damp next winter and you have heating you can start looking at damp issues. Opening windows is the best ventiallation solution. If you seal everything with DG units then a PIV system in the roof space can be a good idea. But if the property was vacant for 6m will take a few months for things to improve.

 

[Toby Newell]

The aok chap might be your best bet to talk about insulative lime plaster he has tried a few novel approaches. He might sell you some bio char.

Insulated lime makes sense as it's very breathable, in general if you have cavity walls pumping shiz in the middle is generally a poor to incredibly bad idea. Technically, the most efficient solution is to insulate the outside, but impractical in most cases. You really want a breathable insulation in a sandstone house (presuming its sandstone)

 

[stuart45]

Injecting the walls is more complex with ones like yours, as the modern methods go into the bed joint. This is easier with a brick wall that's got a continuous horizontal bed joint.
They also put an impervious render on the wall, although some people are using dry rods to DIY nowadays, and not doing the render.

 

[Herefordhouse]

Ok all things to think about. I know I’ll have to comply with building regs if I take down the current plaster.

I’ll have a look at the different methods, I’m not sure what is most cost efficient. / practical. Anything would be better than the current situation.

Are you limited with other finishes, eg paint types, on the walls. In view of maintaining breath ability. I’ll make sure to ventilate and dehumidify the place this summer whilst we get back to the stone.

I’ve heard injecting is only really possible with a pre gel or cement. Again i understand it’s probably best as the last port of call. But we’d prefer to get everything done in one sitting. The windows drainage etc will be fixed and replaced. I perhaps think rising damp may be an issue due to the cellar, hence why I thought the injecting DPC may also help.

 

[Herefordhouse]

Cba I ask whether lime insulation is expensive and difficult to use

 

[Toby Newell]

Injecting the walls is more complex with ones like yours, as the modern methods go into the bed joint. This is easier with a brick wall that's got a continuous horizontal bed joint.
They also put an impervious render on the wall, although some people are using dry rods to DIY nowadays, and not doing the render.

Silane dpc treatments only really work in the mortar course. Rising damp is a common issue that has been dismissed by some zealots but the remedy is often to reduce ground levels, ensure adequate run off, counter splashback and remove foilage. Injections are often a simplistic and uneeded treatment. The waterproof render is often an over proscribed upsell and rarely needed even if the dpc treatment may be effective. If the dpc treatment is effective, for rising damp, then why do you need a waterproof render? You would only need that if you had penetrating damp as well, and now you are making the wall less breathable, so increasing internal condensation. Do these guys look at the pointing? They often say it's because the previously damp wall contains salts, well, ok, so remove the contaminated plaster, but replace it with lime, more breathable, less condensation issues. And they often advise hacking off entire rooms up to 1200mm when usually there are only salts in one corner or along one elevation and maybe only up to 500mm. Like most things the answer lies in the middle. DPC dryrod type treatments should only be considered when all other options have been explored.

 

[Toby Newell]

Ok all things to think about. I know I’ll have to comply with building regs if I take down the current plaster.

I’ll have a look at the different methods, I’m not sure what is most cost efficient. / practical. Anything would be better than the current situation.

Are you limited with other finishes, eg paint types, on the walls. In view of maintaining breath ability. I’ll make sure to ventilate and dehumidify the place this summer whilst we get back to the stone.

I’ve heard injecting is only really possible with a pre gel or cement. Again i understand it’s probably best as the last port of call. But we’d prefer to get everything done in one sitting. The windows drainage etc will be fixed and replaced. I perhaps think rising damp may be an issue due to the cellar, hence why I thought the injecting DPC may also help.

Yes. Applying a non breathable paint to a breathable wall is like putting a bin bag over a Goretex jacket.

No. Injecting is an old technology. Today most companies use siloxane or more often silane compounds applied by sealant guns or drysticks that dissolve over months and react with a mortar course to seal off the pores.

The cellar, aha! More info. Cellars are ALWAYS damp, to some extent, because, physics (even if externally tanked) Cellar walls cannot expire to the air and have constant contact with water laden soil, at the bottom of cellar walls you have added hydrostatic pressure from the weight of the water above. If you have visible damp you may want to consider a perimeter drain and lift pump system. They dig a 600mm internal perimeter trench and fit it with a pre drilled (with holes in the top) sewage pipe running at a fall angle down to an automatic lift pump that lifts and discharges when full, the accumulated water to a nearby soakaway on the surface. The trench is backfilled with aggregate and can be encapsulated. There are cheaper shallow drain designs but these can be very low performing. The best have a large pipe running in a deep trench with a considerable fall.

I am not sure getting everything done in one sitting is economical or practical. Damp issues are often a combination of multiple factors, if you try one solution it may take a month or two to show any great benefit, often many small improvements can add up. If you go for doing everything at once you will spend more money when maybe you don't need it.

See my other replies above. Injecting a dpc 150mm above mean ground level with a damp cellar will improve damp issues above ground but make your cellar worse as now vertical capilliary transmission is cut off and so the walls will expire more into the cellar room.

 

[Toby Newell]

Cba I ask whether lime insulation is expensive and difficult to use

The more expensive system is to fit a breathable insulation like woodfibre board or cork (not really sure how super breathable cork is myself, but ho hum) between the wall and lime plaster and plaster over that. There are more elaborate versions involving several layers of insulation finishing with wood wool cement board, these are often used in new builds as they inrease the wall thickness a lot.

The much cheaper system is to bung some insulative medium into your lime plaster, much cheaper and easier, there are many different materials used to provide this insulative effect, from aerated aggregate to dried hemp stems.

There are many people on here who have used both systems who I am sure can help.

 

[Herefordhouse]

Sorry for my delayed response Toby, a long day at work yesterday!

There’s a lot to digest, but I already know so much more. So thank you so much for sharing your knowledge.

Apologies. Yes there is a cellar! The hope would be to expand into the cellar in future years, but that’ll have to wait until we have more savings ! I’ve heard tanking a cellar is an option, but an expensive one.

Everything makes sense and I get the reasoning behind why to take certain approaches. I’ll work on aforementioned obvious fixes whilst ventilating and heating the property to the removing current damp. Then wait a few months before applying the new insulation to measure the results. A DPC above mean ground level would be a last resort, due to the efficacy on stone and the negative effect on the cellar. But the ground floor up is the priority.

The cost vs efficiency of the insulation plays a large role, one of which I’ll have to get quotes to compare. I’ve already read about many products, some of what you’ve listed above and other solutions (such as Diathonite). Although I worry if I take back the current insulation to the stone, then I have to comply with current U values on building regs. Of which I doubt I’ll be able to achieve unless I take the expensive approaches!

I haven't costed things up yet, but currently I’m thinking of an insulated lime solution. Modernising the internal situation (reducing drafts and improving insulation) will hopefully get to the point where an air source heat pump becomes viable. Then theoretically, the house is back to how it was designed to be, maintaining a constant temperature. I’m not sure how practical an MVHR system is in the Hereford climate or my property, but that could be another avenue.

We still have time before the project will begin, so the research continues! Thank you again, this has been very insightful.

 

[Toby Newell]

Yes. Insulated lime seems like a no brainer to me. Breathable, yet little extra cost, and a 60% reduction in K value for a 50mm bed.

Mmm. Not really relevant whether you are utilising the cellar or not, if it is a source of damp getting into the structure then it's good to try and ameliorate it early. Tanking isn't always the best solution either, on it's own. That would mean the walls would be constantly saturated behind the render and any crack or break at the floor-wall interface even in the floor dpm might create a point of ingress due to extreme hydrostatic pressure and no other exit route.

Drains and lift pumps are the preferred routes as are French drains outside. You can even apply drip membranes to allow moisture to flow down the walls into the drain. Stopping damp in old houses is like stopping excess air movement or stopping wood moving. It's pointless to try and reduce it to zero, that will never happen, you just want to reduce it to acceptable levels.

Remember, the backfill around your footings, or cellar in your case, and in all buildings old or new, is less compact than undisturbed soil and so acts like a sponge. You want to allow that to dissipate as much as possible.

I'm not sure I have much knowledge, I don't actually own a period property myself, although lived in them most of my life, I just work on them and see quite a few each year, so I have got to see a fair few projects. And as I am a nosey bugger, always find out what has gone on! I get to see quite a lot. I always conduct my own unofficial surveys.

 

[Herefordhouse]

Is it realistic to cavity insulate on sandstone?

Thank you for the advice, we will probably do the insulated lime from everything ive read and ill get some advice on what to do with the cellar. We wanted to dig down a foot or so as theres not really enough head height in there currently. So that might actually work for fitting the drains you talk about.

Is floor insulation a good idea?

 

[MatthewC]

I did my own 1860s house back in 2010-11. Do not have a DPC under any circumstances in such a lovely stone house!

I replastered only where necessary but it was extensive. I left plaster where possible: do not lever it off - where it is good, you cut it at a 45 degree angle with a stanley knife with extendable blade, re-plaster the bare bit and I gave it a skim over the top with some fine plaster so you cannot see the join. I will admit that I used plasterboard on the downstairs ceilings. This was because, by the time I realised that replacement was required, we would not have the time to let it go off completely (as you shoulldn't go upstairs above it as that could wreck the bond).

I know what you mean about thermal mass: when it has all dried out the house stays warm overnight in winter and then in summer it is nicely cool inside when it is scorching outside in the sun.

My top tip is to make sure that the ground outside is always at least 6 inches lower than the floor inside. This has worked very well for us. If you have time, see my blog at https://houseintheenchantedforest.blogspot.com/

 

[brianos]

my brain hurts trying to understand what the best approach is for this 1700's stone cottage I've bought in Devon. From reading the posts I can see that you cats know what you're talking about. The below recommendation is what I received from a well respected preservation company in the south west. The quote came to around £4k for DPC course, and £10K for applying the vertical waterproof membrane. From what I've understood from this thread, whilst these recommendations might be belt and braces, they may well be overkill, perhaps unnneccesary, and in some cases, actually create further issues. I'm a bit at a loss as to what to do. In terms of reducing the horizontal penetration, I'm not sure there is much I can do given that the level of the soil outside is higher. Would it make sense to really dig a trench and try and equal it up. In some cases I'm not sure thats possible. What I need is for Tony to get in his car and drive to Devon from Surrey. Problem solved.

From what i've read, the below would create a waterproof bubble, which is fine as long as it can't squeeze its way in anywhere? i.e. would it then come up through the floor? would one have to ensure a tight seal in waterproof membrane between the floor and wall (I havent looked under the engineered flooring yet but its likely to be big flagstones and ting....right? I understand the membrane can be layered on with a thin return covering the floor.

The chap that visited was super knowledgable, super nice and seemed genuine. I want to believe but can't help that feeling that its still a bit of wishful biased thinking on his part with a desire to sell.

I've included the wording from survey below and the picture with legend.

"Rising damp - due to the lack of an effective damp proof course, dampness was found to be rising in the walls hatched red on the attached sketch plan. Meter readings could not be taken in some of the property’s walls due to the presence of kitchen units, bathroom suite, ceramic tiling, furniture, stored items, etc and some of the internal wall surfaces being panelled off/dry lined. However, we have included some of these walls in our estimate. We would like to point out that both rising dampness and penetrating dampness within the masonry, could result in fungal decay (wet and/or dry rot) to the timber fixing battens and any other concealed timbers i.e. timber lintels, joist ends etc. in contact with or built into these walls.
Ground water penetration - dampness was also penetrating on a horizontal plane where ground/abutting floor levels are at a higher level as marked xxx on the attached sketch plan. Our damp proof course will be installed above these higher levels. We feel all internal wall surfaces will benefit from the application of a vertical waterproof membrane prior to replastering (see separate vertical waterproof membrane/replastering estimate)."

Listening on frequency
Brianos

 

[aockenden]

my brain hurts trying to understand what the best approach is for this 1700's stone cottage I've bought in Devon. From reading the posts I can see that you cats know what you're talking about. The below recommendation is what I received from a well respected preservation company in the south west. The quote came to around £4k for DPC course, and £10K for applying the vertical waterproof membrane. From what I've understood from this thread, whilst these recommendations might be belt and braces, they may well be overkill, perhaps unnneccesary, and in some cases, actually create further issues. I'm a bit at a loss as to what to do. In terms of reducing the horizontal penetration, I'm not sure there is much I can do given that the level of the soil outside is higher. Would it make sense to really dig a trench and try and equal it up. In some cases I'm not sure thats possible. What I need is for Tony to get in his car and drive to Devon from Surrey. Problem solved.

From what i've read, the below would create a waterproof bubble, which is fine as long as it can't squeeze its way in anywhere? i.e. would it then come up through the floor? would one have to ensure a tight seal in waterproof membrane between the floor and wall (I havent looked under the engineered flooring yet but its likely to be big flagstones and ting....right? I understand the membrane can be layered on with a thin return covering the floor.

The chap that visited was super knowledgable, super nice and seemed genuine. I want to believe but can't help that feeling that its still a bit of wishful biased thinking on his part with a desire to sell.

I've included the wording from survey below and the picture with legend.

"Rising damp - due to the lack of an effective damp proof course, dampness was found to be rising in the walls hatched red on the attached sketch plan. Meter readings could not be taken in some of the property’s walls due to the presence of kitchen units, bathroom suite, ceramic tiling, furniture, stored items, etc and some of the internal wall surfaces being panelled off/dry lined. However, we have included some of these walls in our estimate. We would like to point out that both rising dampness and penetrating dampness within the masonry, could result in fungal decay (wet and/or dry rot) to the timber fixing battens and any other concealed timbers i.e. timber lintels, joist ends etc. in contact with or built into these walls.
Ground water penetration - dampness was also penetrating on a horizontal plane where ground/abutting floor levels are at a higher level as marked xxx on the attached sketch plan. Our damp proof course will be installed above these higher levels. We feel all internal wall surfaces will benefit from the application of a vertical waterproof membrane prior to replastering (see separate vertical waterproof membrane/replastering estimate)."
View attachment 13106
Listening on frequency
Brianos

So this "vertical membrane" = some kind of cementitious tanking slurry or blackjack bitumen paint layer that they want to slather onto the inside of your walls before replastering?

 

[brianos]

@aokenden --- yeah, I'm not getting initial positive vibes from your initial response ;o) the exact text from this specialist firm is below...


"VERTICAL WATERPROOF MEMBRANE
In certain circumstances it will be necessary to damp proof the walls against lateral penetration of dampness i.e. from high ground or floor levels and from the ground surrounding basements.
Where this is applicable our Tanking process will be carried out using an impervious vertical membrane which will be incorporated into the plastering and applied to the heights specified.
Solid Floors. Damp or damaged floors should be replaced in concrete incorporating a suitable liquid damp-proof membrane to be flushed up the wall to the damp course level.
Dry Lining. Where preferred, as an alternative to wall plaster or where additional insulation is required, dry wall linings may be used. Foil backed plasterboard should be fixed on pre-treated timber battens at approximately 400mm centres. Greater insulation values will be obtained if 25mm or 50mm fibreglass insulation is inserted beneath the plasterboard. The battens and plasterboard must be terminated approximately 25mm and 50mm above the floor. The gap thus formed may be covered using pre-treated timber skirtings.
Condensation. Adequate heating and ventilation must be maintained in order to avoid damage to internal decorations caused by condensation.
Decoration. The use of Non Vinyl emulsion is recommended on all walls treated.
DO NOT USE VINYL EMULSION OR WALLPAPER for a period of six months.
All rainwater goods and plumbing should be maintained in good order."