Insulating old house

Common topic on here. If the walls are built predominantly of stone you'll need to apply a breathable insulation internally like an insulating lime render or hemp. There are many voices proclaiming which works better so you'll have to decide on what the best option is for you. I looked into hemp recently and if you have enough room to apply it to the internal face of the external walls it looks to be a very good product. Any breathable solutions require a lot of prep (if the walls are stone internally). You need to take off the internal render before applying any of the products mentioned. You're wasting your time otherwise in my opinion. A lot of people would have put up insulated slabs onto stonework and they'd swear by it but it's just a problem waiting to happen.

If the walls are blockwork internally you could look at slabbing it with insulation backed plasterboard. I would leave a cavity behind between the slabs and the walls to allow air to circulate. You'll need to add vents to assist with this also.

The quick win is the attic insulation. Just make sure the roofspace is well ventilated to avoid condensation etc.

Floors are trickier. It's very costly to put in a new slab and I often wonder if the cost is worth it considering the improvement in performance.

Good windows, installed properly to avoid draughts will also improve the perceived comfort levels.

If the walls are stone on the outside, I'd consider putting in a french drain to help take the water away from the base of the walls.

Good rainwater goods are vital if you want to avoid water ingress.

bemak

How do you propose to create a cavity between the walls and the proposed insulation, for air to circulate.

We renovated an old limestone building and what we did was build stud partition walls inside. We put rigid insulation in the partition walls and left a gap between them and the original stone walls. When the roof was replaced vents in the soffit allows air to circulate. The downside was we lost a few inches of room space but house is very warm.

i would always put dpc between the battens and wall to reduce the risk of rot as much as possible.

the battens needn't be continuous either so you don't necessarily need to vent every cavity.

Bemak

if there is dampness on the inner face of the external walls caused by rising damp, it needs to be investigated to reduce or stop it if possible.

if it is caused by ingress of rainwater then that should be investigated and stopped.

A new floor could be installed. Kept approx 70 mm from the walls below floor level, to form a cavity between the edges of the 150 mm floor and external walls.

The DPM /Radon is brought up the side perimeter of the concrete floor and folded on to the to the top surface of the floor.

Construct a metal Stud Partition on top of a DPC on top of the DPM/Radon. This can be a 100 or 150 metal Stud Partition, which is approx minimum of 50 mm away (cavity) from the external walls, to be fitted in accordance with the manufactures instructions.

This cavity between the external wall and Stud partition must be adequately ventilated in accordance with the Building Regulations.

Fit approved Insulation in to the metal stud partition in accordance with the manufactures instructions, Fit Services etc. and fix Airtightness membrane, and fix plasterboard slabs and apply skim of plaster.

There will also be a need to attend to many other details of items of works.

Any damp - don’t use timber. ☹️☹️☹️

Yes bemak, every house is totally different.

For many past projects, I advised the clients to demolish the old house and construct a new building.

Very old houses were built in different eras with different requirements etc.

Most were not constructed to get the best benefits of the Sun or views

Carrying out major changes to old houses, has a lot of unknowns and is usually unquantifiable by Quantity Surveyor etc and is very expensive.

The Layout and room sizes are not suitable for todays housing needs.

in many cases it is best to demolish them and construct a new building to the Clients design, because they are making their biggest investment.

You would be advised to get a condensation risk analysis carried out based on the proposed insulation build-up. I'm sure you don't want mould build up in your building fabric and eventually making it's way inside.