This is my first post here so please be gentle with me!

We have recently acquired a traditional, stone-build c1850 Northumberland farmhouse. The building is effectively empty, having been unoccupied for over 12 years, and in need of complete internal renovation. The good news, therefore, is that there are no practical restrictions as to how we can go about modernising the place, but the bad news is that we are very new to all of this and could do with some advice.

The external walls of the building are thick stone and in very good condition. None of them are cladded (externally) and there have been no previous attempts at damp-proofing. Some of the internal wall surfaces are really quite damp, but in most cases this can be traced back to something fairly obvious, such as earth piled against the exterior.

We had in mind insulating the place well with internal wall insulation and using low-energy heating. I.e. going down the lines of an ‘eco-home’, but the more I read, the more I worry that we could do more harm than good by adding internal insulation to the walls etc. and potentially causing a damp problem. With that in mind, is there a balance that can be struck between insulating the house well but at the same time allowing it to breath? Are there methods of insulating that ‘breath’ well enough for this to be feasible? Our surveyor recommended that the whole place be membrane-sealed, but this would not seem to be the best approach from what I have read?

Any advice welcomed!

Thanks,

Nick

Comments
  • Tim Pullen

    You are right to approach this with caution. As you have guessed the wall works by being allowed to breath and there are plenty of choices of breathable insulation – hemp, wood fibre, sheep wool, flax, for instance. All of these can be placed directly against the wall. You will then use a breathable wall board such as Fermacell and a breable paint for internal finish.

    Or use an insulated plaster – a hemp/lime mix usually – directly to the wall. Apply 40 or 50mm in 3 coats to get a reasonable level of insulation.

    Alternatively build an internal stud wall at least 50mm off the stone wall and insulate that with Kingspan or Celotex, ensuring that the cavity is ventilated.

    Obviously DO NOT try to install any form of damp proof course to the walls. It will only serve to make damp prolems worse as they will prevent moisture falling out of the wall.

  • Tim Pullen

    I should have mentioned, an alternative would be to not install any insulation to the walls but install a low running cost heating system, like a log boiler. The building works by allowing air to move from the inside to the outside, thereby pushing any moisture in the wall to atmosphere. That is helped by putting a lot of heat in the house, maintaining a higher internal temperature and encouraging that air movement. It also allows the natural thermal mass of the house to be fully used, as it was intended. You would then focus on insulating the floor and roof.

  • Mark Brinkley

    There are two widely different ideas about how buildings such as this should be renovated. One is that it should be "tanked" and insulated with whatever comes to hand. This works fine as long as the "tanking" is carried out perfectly and remains that way for the forseeable future. It’s like a swimming pool in reverse. The other is to accept the so-called "breathing" method which is more expensive but is likely to last longer, as it doesn’t depend on the waterproofing working perfectly, but builds in a safety element by allowing moisture trapped in the walls to evaporate. This is what Tim is suggesting.

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