Lime or drywall a Victorian Cottage

[davidt3449]

Hi all

We’ve just bought a Grade 2 listed end terrace which needs a bit of renovation and I’m keen to do things once and do them right. I’ve been trawling the internet for weeks, had a structural survey and an independent damp survey, and I’m still unsure what to do for the best, so would really appreciate any advice or opinions anyone has to offer.
It’s a solid, stone built mid Victorian house which apart from very slight penetrating damp on a couple of through stones and patches under the sash windows, appears to be pretty damp free.
It was ‘renovated’ by the council around 30 years ago and is now a mixture of original lime plaster and gypsum. My plan was to knock off any plaster that’s blown or showing signs of damp and replace with lime. Where the gypsum looks ok, I was planning to leave it.
However, my damp survey has come back saying, don’t bother with a DPC (good, I wasn’t going to), install some air bricks in the sub floor void (sounds reasonable), but put up dry wall on external walls with a waterproof membrane to stop condensation on the inside of the stone. This seems like a modern solution that is asking for trouble? A soon as something fails, you’re surely going to get issues with the stone walls not breathing? I asked if lime plaster was a good alternative but was told that if I’m installing central heating, the lime offers little thermal insulation and the wet air would condense against the cold external walls, leading to a mouldy, cold house.
Does this sound right? I certainly don’t want to compromise the integrity of a building that’s been standing for 150 years, but I’ve got to be practical as well.

Many Thanks
David

 

[Tony.]

I don't understand why a waterproof membrane should be installed.

If appropriate pointing is carried out,outside to ensure no water ingress
Appropriate sub floor ventilation is in place for suspended timber floors.
Appropriate fans in kitchens and bathrooms to take away excessive moisture.
No leaks on existing rainwater goods or sanitary fittings
Ground floor exterior levels are lower than internal

Who know the previous occupant could have dried all their clothes in the room, never opened a window or trickle vent had a tumble drier going in the winter

Personally I would live in the property first and see what needed doing

 

[Zebra]

Whilst I agree with Tony that it may be a better approach to live with it for a while to see whether there is indeed a problem, I also don't think that it is such a bad solution.
Where they're talking about a waterproof membrane, this is on the inside of the stone walls, to stop warm moist air from inside the house condensating on the cold walls. It will not stop the walls from breathing, as they will still breathe to the outside. Indeed, in a recent thread that Penners started, we discussed the risk of such condensation in some depth, and a similar solution was proposed, including adding some rigid foam insulation to make the place warmer. Let's see if I can find that thread. Ah, here it is
https://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=14921
You don't say whether your surveyor's suggestions include some insulation in the wall structure ie insulation backed plasterboard. It might be an idea to try to include some insulation. Of course, there are breathable solutions, but of course there are pros and cons with each system.

 

[Tony.]

My previous comments were based on the fact that the building was grade 2

I read penners thread about his wife's office, i agree that an insulated plasterboard ahould be stuck to the existing walls
I think it was Wookey on the GBF that used an expanding ashesive similar to apply like foam but does not expand so violently, allowing a perimeter bead and dabs to prevent air circulating behind the insulation.

 

[Zebra]

Ah yes, of course, it's listed, hadn't noticed that. Well of course any alterations will be subject to LBC. Perhaps it's worth a chat with your CO?

 

[mims&pip]

In our last house - a two hundred year old, non-listed stone-built thatch - we added insulation-backed plasterboard to some of the walls which had previously been repointed in lime by the previous owner.

For us it was both a time and financial issue - having realised shortly after purchase that the house bought as a huge project was in the wrong location for our requirements, we wanted to complete the work as cost-effectively and quickly as possible without compromising the structure and its breathability etc. We had already completed some lime plastering prior to the *light bulb moment*, but whilst we were in a position to lime plaster the internal walls ourselves, we didn't have the time to devote to this lengthy process. To have employed a company to do the work would have sent our costs rocketing by tens of thousands. Instead we realised that with the lime mortar in place and the fact that the external walls were either bare ashlar stone blocks or (a small area of) limewash, as long as the air could circulate behind the boards, the house should be fine. In addition we added some vents to be on the safe side :wink:

We were pleased with the result and the surveyor instructed by our buyer last October found no significant damp issues.

Obviously the fact that your house is listed, whereas ours was not will have a bearing on the way you are able to proceed.

 

[davidt3449]

Thanks for the input guys.

Yes, I should say that the waterproof membrane suggested was on the inside of the external walls, behind insulated plaster board. I know the stone can still breathe to the outside, but it just seemed like the wrong thing to be doing to wrap the internal walls in a membrane which, to me at least, sounds like it wouldbe suffocating them.

The ground floor is about one foot, maybe one and a half, above the external ground level and there are currently no air bricks.

Having thought about it now, I'm swaying towards lime base coat and plaster where it's blown under the windows and a few other places, but then putting up insulated board on a timber frame, with a waterproof membrane at the sides of the fireplace as this is the only external wall that isn't South facing and it has the worst of the penetrating damp.

Should also add that were doing a full renovation before we move in so unfortunately living with it to get a better idea isn't an option.

Thanks

David

 

[davidt3449]

Apologies but there's a slight delay I my responses appearing here, so I get to see a few more comments before mine appear.

Although it's grade two listed, I believe this is only for the front elevation. I was due to have a meeting with the CO on Friday to verify all this but they cancelled at the last minute.

Thanks for the link to the other thread.

So I i decide to timber frame with insulated plaster board, do I need some kind of vent behind the membrane, to the outside to allow any moisture on the inner stone surface to evaporate, or with it being a single layer, will the wall breathe externally and this is sufficient.

Thanks

David

 

[SilverSaloon]

I'm taking all my internal stone walls back to stone and then having a small void between that and new timber frame, fitted with solid insulation, a vapour barrier membrane, and then plasterboard.

The void carries down from the loft space, behind the walls, down to the subfloor where there are airbricks. The rooms are on suspended wood floors

 

[MatthewC]

Although it's grade two listed, I believe this is only for the front elevation.

Eh? If the house is listed then the listing applies to the entire building and the curtilage (i.e. the garden and walls), and so the entire place is covered by that protection. However, I understand that if the listing description mentions only specific items as being of interest then that might make it easier to get pewrmission to do work on other parts of the building - but you do still need the permission. As has been said here before, so much is at the discretion (or whim) of your CO, which can be either a good thing if they allow you to do what you want, or it can be a bad thing if they don't, as there is no argument when their decision is not based on clear rules.

Having said that, I'm sure one of the forum's COs will be along to correct/amplify it!

Matthew

 

[davidt3449]

I'm meeting the CO on Friday to confirm but I believe that although the entire building is listed, the significant features are external and internal mods should be ok within reason.

So on my west facing gable end, single skim brick (all the other walls are stone), rendered in cement, with slight penetrating damp, is a cost effective and acceptable solution to remove the existing gypsum plaster, put a polythene sheet over the brick, followed by 1x2 treated battens, insulation inbetweeners the timber frame and finish with plasterboard?

To me this sounds like I'll be locking any moisture within the wall but almost everything on the web suggests this is the way to go.

 

[davidt3449]

Sorry, the above post should be solid brick with no cavity, not 'single skin brick'.

 

[TheRoost]

What would happen to moisture at the edges of the polythene sheet though, how do you stop the damp getting inside/how do you seal the edges of the sheet?

 

[xanthe]

I'm meeting the CO on Friday to confirm but I believe that although the entire building is listed, the significant features are external and internal mods should be ok within reason.

I really, really hope you get a good CO - my parents are in the middle of a major battle with their CO over removal of an internal breeze-block wall that was put up in 1968. House is a Georgian farmhouse, and while it's a lovely big house, it has no particularly interesting features and none of us can actually understand why it was listed in the first place.

Some of the things she wants are loopy: one of the issues my parents won on was when they pointed out that the "beautiful arched alcoves" she was waxing lyrical about were actually made of painted cardboard and stuck up with sellotape.

So much seems to depend on their individual foibles and likes and dislikes. Some are wonderful, some less so, and some will agree to things on site and then reject when the paper-work comes through.