Hi folks,

Planning a retrofit of a stone farmhouse, considering the box in box approach where you build a timber frame stud structure inside the stone building leaving air gap between timber frame and stone.

Usually I think the windows are set in the timber frame, however this might spoil the traditional look of our farmhouse

 

Are there good examples of how this is built, where could one go and see this kind of building? 

Thanks 

I’m doing work on an old barn that’s being timbered out like you describe 

I can take a few pics if you drop me a reminder 

We had a converted barn in the 90s done that way. And did similar to a house (1830) we did up in 2012. In the house the windows remained in the stone wall - with a small thermal bridge.

Our last house was like this. 200 year old barn and a stick built frame assembled inside. The windows were fitted to the original brick wall like @JohnMo describes. We didn’t convert this barn, we bought it as a new house from the builder. They didn’t do a terribly good job with the insulation detailing unfortunately. There was plenty of it just not well done in places. The window reveals were particularly cold. 

2 hours ago, RoIrl said:

good examples of how this is built

It's what we did. The windows are in the stone which is 600mm thick. The timber internal work is for internal finishes, dpm, insulation: not primary structure. Look back and I may have put some discussions up.

You should either use an utterly expert (in these)  builder, or get reading.

So you've done the right thing starting here. 

We had to do masses of research... some of it is published, some you learn.

 

What stage are you at? What part of the country?

For some bedtime reading look at this thread 

 

 

Where he bought a large derelict stone house and has gradually rebuilt the stone outer structure and built a timber frame house inside it.

Thanks folks, im based in co clare, Ireland and this approach isn't common so any advice or places to see best practice appreciated

On 25/10/2025 at 07:17, nod said:

I’m doing work on an old barn that’s being timbered out like you describe 

I can take a few pics if you drop me a reminder 

That would be awesome, thank you

On 25/10/2025 at 09:23, saveasteading said:

It's what we did. The windows are in the stone which is 600mm thick. The timber internal work is for internal finishes, dpm, insulation: not primary structure. Look back and I may have put some discussions up.

You should either use an utterly expert (in these)  builder, or get reading.

So you've done the right thing starting here. 

We had to do masses of research... some of it is published, some you learn.

 

What stage are you at? What part of the country?

Thanks

We are at the stage of gutting one of the out buildings, the main house we will tackle in a years time

If you had any good reading links of books would be most appreciated 

These kind of details are hard to find

What is the stone construction? Dressed or rubble? Granite/sandstone etc?

11 hours ago, RoIrl said:

That would be awesome, thank you

We would normally frame out in metalBut the client wanted timber

Just now, nod said:

We would normally frame out in metalBut the client wanted timber

We did a structural 2-storey inner timberframe, 50mm away from the old stone rubble walls, with metal-web Posi-joists for the mid-floor (ideally hang these off the inner side of the frame to avoid cold bridging).

 

New slate roof was sat on the old walls at my insistence - the engineer wanted it to sit it on the inner timber frame *.

 

New windows (Accoya d/glazed traditional sash) also set into the original openings of the stone wall.

 

The difficulty with this is the foundations required - have to be very close to the inside of the old walls and, depending a bit on soil conditions, likely to disturb the ground under the old walls if you are not careful. When we dug for the new floor/foundation concrete raft and discovered the old walls stopped not much below ground level the engineer said we should underpin the entire building but then he agreed we could instead just feather the the edge of the internal foundation raft at an angle, away from the old walls. *If the foundations were even deeper, to support the roof weight too, I doubt we would have got away with it.

Edited February 1Feb 1 by Hastings

Airtight build with MVHR.

Structural wall panels were filled with 100 wood fibre, fitted together with expanding foam tape, Intello membrane, then cross-battened 50mm and filled with 50mm wood fibre. One or two needed a pulley to lift.

Window reveals framed out and fitted with PIR, 25, 50, or 75mm depending on available space.

 

@Hastings Great work, love the pulley approach.

My parents ,now late octogenarians converted dilapidated flint stone barn late 90's. Tons of work. Only now, due to feeling the cold decided to insulate the walls with Pavatherm and lime plaster.

Huge difference in comfort and minimal space lost.

They also converted another shed using the approach above, internal timber frame, Pavatherm and lime. 

Keeps them busy!

Edited February 2Feb 2 by Nestor

On 25/10/2025 at 16:42, RoIrl said:

Thanks folks, im based in co clare, Ireland and this approach isn't common so any advice or places to see best practice appreciated

 

Sentimental attachment? 

 

If not I'd recommend knock and rebuild. 

 

Any pics? The construction type will change the advice. 

20 hours ago, Hastings said:

Airtight build with MVHR.

Structural wall panels were filled with 100 wood fibre, fitted together with expanding foam tape, Intello membrane, then cross-battened 50mm and filled with 50mm wood fibre. One or two needed a pulley to lift.

Window reveals framed out and fitted with PIR, 25, 50, or 75mm depending on available space.

 

did you have to ventilate the cavity between the stone wall and timber frame,?

thanks carl

Yes. Building Control specified very small vents every 1.5m, 30cm above ground level, and that the cavity be open at the top to the roof space.

 

I used Manthorpe Refurbishment Drill Weep Vents set into the ends of MDPE water pipe drilled into the walls. Had to buy a 35mm x680mm masonry drill bit just for the purpose. These weep vents are rubbish and fall to pieces within months, due to UV I suppose. Drilling this type of wall seems a bad idea because it disturbs the loose stone fill inside (sometimes jamming the drill bit) and therefore the structure of the wall.

 

The gable end walls were too thick to drill but had a bigger vent in already to feed the woodburner. The woodburner had a duct off the back of it going through the internal wall to the cavity.