How do we insulate our walls? Period Property. Apparently they need to BREATHE!

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Myself and my DD live in a period property which has terrible heat retention. It's just one solid brick wall between us and the elements.

We had a plasterer come out and say that we can't insulate our walls because it will block the walls from breathing, them being in lime mortar and the house being old, the walls need to breathe apparently!

I am wondering if I should get a second opinion or if anyone else on here has any knowledge on some thing that I could do?

I live in a property that is a hundred years old. Walls are damp and plaster needs knocked out, and was advised by damp surveyor to have a damp proof course. But my neighbour who is renovating his property and is also against dpc, has put rolls of insulation wool straight onto the wall, with metal sheets placed on top of this. I assume he will then plaster over the metal sheets.

300 yr old house here. Rubble infill slate walls. Lime render does need to breathe, yes. It’s the best way to avoid damp in these old houses. They do get cold though, don’t they! Best way I’ve found through winter is warm one room and layer up! If you’ve enough money, an aga is great in an old house and keeps it toasty and dry.

Hmm I'd watch the energy usage of agas. Even using agas energy info a traditional mid sized electric aga could be costing you £125 a week in October.

The walls in older houses are different to how we build today and are designed to breathe so you have a plasterer who knows their stuff. Older brick walls absorb water from both sides and then slowly release it over time so if you put modern waterproof materials on the walls, you can upset the balance and this leads to damp and material decay.

Generally dry lining isn't advised as it can cause a lot of problems, English Heritage have good resources on this, but if you decide to go ahead you can use a breathable insulation like woodfibre or Ecotherm and make sure there is a ventilation gap to allow condensation to evaporate. It will reduce the size of your room by about 150mm on each wall however and will cover any historic features like moulding or cornice and will deepen the window reveals. If the building is listed you'll need listed building consent before carrying out any work.

historicengland.org.uk/images-books/publications/eehb-insulating-solid-walls/

Lime does need to breathe and wrong plaster is a big cause of damp. These houses are generally not damp because they lack a damp proof course, they are damp because of undiscovered leaks or wrong plaster/cement being used in modern maintenance.

However there are loads of other things you can do - making sure all windows and doors seal properly, loft insulation, roof repairs, chimney pillow if you aren't using the chimney. These all have a big impact and don't affect the breathability of the building.

Op your plasterer is right, please don't do anything to the walls that would stop movement of moisture. You'll end up causing damp and years of problems. Best things to do - make sure your bathroom has a good extractor fan. Make sure the gutters are sound and clear to keep any rain off the walls. Invest in good, heavy curtains, blinds etc. Insulation in the roof (but not the spray stuff!). What are the windows like?

I'd not advise an aga! We have one and pp above is right, the costs are astronomical but we have no other option.

It is part and parcel of living in an old house, and you'll probably need a few seasons to get used to it and find which bits are most draughty. But old houses have so many benefits it's worth it in my view.

Forgot the curtains! All of ours are down to the floor with interlining.

It sounds like you luckily got an honest plasterer who knows what he is talking about. If you’d got one who doesn’t understand historic houses (or doesn’t care so long as he gets paid) and they’d just slapped insulation on the walls, you could have ended up with serious and expensive problems.

As said, English Heritage may have some ideas.

Ours is old too, brick, but does have a cavity, which someone unwisely put insulation into many years ago- this is now turning to white dust. We're considering having it out, but that's not easy and so far haven't found anyone to do it.
Where the plaster is still lime, we're keeping it and taking off paper and scrubbing off old paste, then painting with breathable clay paint. This has dried out the outer walls in those places close to the floor where the paper was a bit soft at the bottom. I think the paste itself was holding onto moisture- when the paper was off, my hand could feel a stickiness. Once I scrubbed the paste off, the plaster dried out, and even with a damp hand, the plaster felt dry and clean. It's bone dry where I did all that. To be fair, increasing the ventilation in the house had already dried it out a lot ( and made stripping the wallpaper a lot harder!- it was only on the low bits of walls the paper was still soft.).

On those outer walls where the old lime plaster had already been taken off (and walls lined with dot-and dab plasterboard or battened out chipboard), we have stripped back to brick, battened out for ventilation, and then put insulated plasterboard on top of the battens. It seems to be okay so far... Not sure this would work with solid walls though. I'd get an expert on old houses in (we did).

In my opinion there are old houses with reasonable walls and there are places like my previous one, which had walls that were completely unchanged since it was a barn 400 years ago. They were one brick thick and the house was permanently freezing, despite our best efforts with secondary glazing, thermal curtains etc etc. I looked into insulating the walls but concluded that it would be unwise due to the amount of work and risk of damp. The breathable dry-lining materials made of wood made me worry about the fire risk.

I'm afraid my solution was to sell it...