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Insulating old stone building

  • 15-07-2022 9:46pm
    Registered Users Posts: 1

    Looking for advice for insulation for this 200+ yr old stone building for residential purposes. Walls are 2ft thick. A couple of people have been adamant about external insulation but obviously don’t want to ruin one of the buildings best features.

    * can’t get the pictures the right way round


  • Registered Users Posts: 30,964 ✭✭✭✭Lumen

    With external insulation you can enjoy the stone on the inside.

    Presumably you'd need to extend the roof though? There doesn't seem to be much overhang.

  • Registered Users Posts: 2,519 ✭✭✭Yellow_Fern

  • Registered Users Posts: 984 ✭✭✭Still stihl waters 3

    Why can't you insulate from the inside

  • Registered Users Posts: 52 ✭✭Paddy McGinty

    I've renovated an old single-storey stone cottage, same as you describe with walls 2ft thick. Exterior had already been rendered though. Looking at yours I'd say same type of idea should work fine.

    1. Leveled all interior floors, all were concrete and part-screeded but very shabby. Patched up a few holes then covered the lot with floor-leveling compound.
    2. Many old cottages have no ceilings. I went for modern comforts over restoring traditional ways so put ceiling joists in all rooms.
    3. Bought LOTS of 2" x 2" rough sawn timber, 4.8M lengths, to effectively put a wooden box inside each room as follows... (a) Drilled/plugged/screwed a 2x2 batten around floor perimeter of each room, setting each one 2" away from the wall. Very simple to do, just lay a loose piece against wall as a spacer then fix your batten next to it, then remove the spacer. (b) Set your ceiling joists at 400mm intervals, (c) Cut 2x2 vertical battens to run between the top of your floor batten and one side of the ceiling rafter. Fix these vertically by screwing to floor batten and ceiling joist and space them at 400mm intervals around the walls. (d) Regardless of how the vertical battens pan out, make sure you end up with 2 battens almost together in each corner of each room - so you have a fixing point for plasterboard for both walls off that corner.
    4. Obviously you wont run the floor batten across any doorways!
    5. Install any door linings or stud partition frames.
    6. You'll now have the framework in place to screw on half-inch plasterboord on all walls and ceilings but before you do....
    7. Run the first fix for electrical cables, pipework etc, coax, broadband, speakers. Plan it well and you'll end up with a nice neat job.
    8. When you're happy all the above is pre-installed, fill all the vertical voids with 100mm Rockwool insulation or similar. If you use that with standard plasterboard it'll be around half the cost of using say 50mm insulated plasterboard. You'll also find that filling your voids with wool type insulation will eliminate spiders and all the other crawlies that frequent the original stonework.
    9. Plasterboard the walls before the ceiling as that way you'll find it easier to run any other cables or make changes around the rooms before you close it all up.
    10. That 2" void and 2" frame, all packed with 4" insulation will make a massive difference. Fit good exterior doors and windows and your house will be warm as toast!

  • Registered Users Posts: 30,964 ✭✭✭✭Lumen

    Well that's a matter of personal taste, and I guess the quality of the underlying stonework. One of the nicest properties I've ever stayed in was a renovated French farmhouse that had a mixture of bare stone and lime (I think) plaster. Absolutely beautiful.

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  • Registered Users Posts: 812 ✭✭✭bemak

    I don't think stone walls should be externally insulated. this type of construction needs to breathe. the sand and cement render on the outside should be removed to allow this to happen. even if you did insulate the walls externally - I'm not sure how much value you get from it considering the 2ft thick walls will soak up all the heat before it even gets to insulation

  • Registered Users Posts: 5,650 ✭✭✭The Continental Op

    Contrary to common belief most 2ft thick cottage walls are bone dry. The walls are cold so any problems with damp is nearly always caused condensation and lack of heat. I've put pipework and cables through plenty of 2ft thick cottage walls, often total pain as the inner mud and loose stone fill is so dry it just drops down and fills the hole back in. In most cases I'd go for external insulation and perhaps underfloor heating. Internally if the stone work is good I'd leave it as a feature.

    Historically the OP's barn (nice one) would probably have been rendered externally or lime washed every year for donkeys years leaving a thick skin of lime. One old building here had lime wash over an inch thick.

    Wake me up when it's all over.

  • Registered Users Posts: 3,748 ✭✭✭ozmo

    RTE program - think Dermot Bannon - did a cottage once like this and got it to an A++ energy rating or something - got them a huge grant which paid for much of the work. Completely sealed the building air tight - had to be pressure tested to pass - lots of electronics to recirculate air - but almost free to heat once done. Sorry cannot remember details - I dont normally watch these shows but thought it was interesting how they sealed a rough stone building..

    “Roll it back”