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Insulation

Best insulation option for 150+ year old solid stone cottage

Anonymous user 28 February 2024 - 4.04 PM

Hi we are renovating an 1800's cottage which is a solid stone outer and all stud walls internally. It's 1.5 story so the bedrooms are partially in the roof. It has minimal foundations but the stone work at the bottom of the cottage goes out and is up to 1m thick in parts. We have stripped everything back so all the stone walls are currently exposed and we have left the vertical studs on the face of them in place (we removed the lathes that were across them.) We've also taken all the ceilings down. The studs on the walls are approx 25mm deep. Before we start to put it all back and get everywhere boarded and plastered etc. we want to put some insulation in but are struggling to know what's best. Have considered foil backed plasterboard but been advised this has no thermal properties only moisture. Have considered insulated plasterboard with polystyrene back but I think would be the most expensive option to do the whole house? And would lose quite a lot of space in the rooms. Looked at Kingspan type board but we wouldn't have the depth of the studs to leave an air gap behind them as recommended. Then other option was to do the bubble/air foil roll but had mixed messages on how it works around sockets etc - builder said we couldn't cut round them and would need to take them off and refit in front of the foil. Were also advised we needed to then put new stud work in front of the foil and plaster board onto them to form a 2nd air gap - which would be costly and take space off the room. The manufacturer said we didn't need to do this but would lose some of the thermal effect by not having an air gap either side. Another seller said we would need SP19+ and would then not need to stud over it. But not sure how it works around sockets etc? Any other suggestions or advice which would be the best, least disruptive and not crazily expensive option? Before we started the work we stayed there for a couple of weeks in January. It was cold when we first got in and when we got up in the morning but it heated up very quickly once we put the central heating on. Now it's warmer it's fine when we go in and doesn't need the heating on but is keeping very cool in comparison to outside temps which is quite nice. It is a 3 bed detached. Would be about 135sqm to insulate walls/underside of roof and about 25sqm of ceiling between the bedrooms and loft. Very grateful of any advice. Thanks

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3 Answers

Grayara Designs

Rating: 5 out of 5555 reviews

Kirkcaldy

Hi Melissa, I have worked on producing architectural drawings for a few stripped back cottages, when it comes to insulating the bare walls I would normally tend to specify Kingspan, they have a useful U-Value calculator on their website that will guide you in the correct direction. Existing stonewalls, DPC strip (if there is a risk of moisture penetration), 25x47mm treated softwood timber battens at 600mm centres, 3mm skim coated 82.5mm Kingspan Kooltherm K118 Insulated Plasterboard (Kingspan Kooltherm Insulated Plasterboard contains an integral vapour control layer. 82.5mm is insulation thickness plus 12.5mm plasterboard thickness.) This would be the typical build up of internal wall insulation and would provide you with a 0.22W/m2K U-Value. I hope this helps.

Answered19 June 2022

Right Price Builders

Rating: 5 out of 5551 review

Plymouth

There is only one proper answer for this, and it is a job you could do yourself with a little patience and a lot of work. You should get back to stone walls, and render with Insulating lime render. This can be rendered in 30mm increments to a maximum of 120mm. Then plaster with CLM 66 lime putty plaster. Then stabilization should be applied about 10 weeks later followed by Beeck mineral paint. This will allow your walls to breathe. Then you need to install french drainage outside to ensure any moisture cannot permeate through your walls. With regard to your lathe, you will need to replace your lathe. This will need to be soaked for 48 hours before Plastering with wood lath render, first a mushroom coat, then a thin coat the next day. Then it will need to cure for 14 days. Then you can use Insulating lime render to obtain your required U-value Plastering in up to 30mm increments. Then plaster with CLM66 lime putty plaster the next day whilst the Insulating lime render is still green as before, making sure you the stabilized after 10 weeks with the fixative solution and then paint with Beeck Mineral Paints. Also if you property is rendered then it must be a lime render, so Insulating lime render again, then promix for the top coats. If your property is of Stone face, make sure it is pointed with lime mortar, preferably CLD28 hydraulic lime. This should then last a lifetime, and will function as it should. The Cornish Lime Company can advise further, and send you the relevant Data Sheets, including AP ratings. Kind regards Mark Kennedy

Answered17 July 2022

BGL home improvements and building services

Rating: 5 out of 55513 reviews

Blackwood

Hello, if you have timber fixing studs in place I would personally consider triso super 10 multi foil insulation. It has a good thermal value however you will need to counter baton to provide a vapour barrier to prevent condensation problems. All installation instruction needed is provided within the manufacturer website. BGL predominantly carry out loft conversion projects building control in Wales are very happy with this product u values are always passed. It's worth having a look. All the best.

Answered6 July 2022