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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorNoyers
    • CommentTimeJan 11th 2008
    Hi, I am a new member and have been following some fascinating discussions on this great site, I have almost got my head around all those acronyms you are so fond of! I see many references to superinsulation and to "designing out" the need for a heating system but can this be achieved for a 200 year old stone house? External insulation is impossible on many grounds.
    The problems in SW France are: it's too hot in summer and far too cold in winter. The house is on three levels on the side of a hill so the basement has one wall underground; overall plan dimensions 16m x 5.5m.
    Basement: solid reinforced concrete slab floor (new), no insulation under; headroom 1.90m; walls 800mm solid limestone. Floor cannot be lowered as there are no foundations to these houses.
    Ground floor: headroom 2.6m suspended wood floor; ceiling could be lowered. Walls 700mm solid limestone.
    Grenier , room in the roof (2nd floor): suspended wood floor; severe headroom problem (1.4m rising to 2.5m). Walls 550mm solid.
    Roof: about 30 degree pitch, pan tiles, battens (no counter battens) plastic non breathing membrane, rafters 70mm x 75mm at 500 centres (don't ask!) but supported at 1.5m by oak purlins, 250mm x 250mm. Insulation in house currently nil.

    If I was prepared to loose 100 - 150mm from internal walls and 200mm under rafters what would you experts recommend?

    Its been suggested I use Triso-10 (or equivalent) under rafters, perhaps with solid foam sheets beneath the Triso and Triso-10 for all the walls. I can see two problems: do solid limestone wall, with mud interiors and lime mortars count as "breathing" walls, if so how compatible is Triso-10 with this wall construction; SECONDLY the wild life is very active hereabouts, Triso doesn't look very rodent proof.

    Most local French houses do not have rooms in the roof, they leave the idiot English to convert these old ruins. Most "in roof bedroom conversions" are impossibly hot in summer so a priority is preventing heat entering the Greniier (think loft space). All ideas gratefully considered.
    • CommentTimeJan 12th 2008
    Sounds wonderful. When you say SW France, are you south of Bordeaux? Do you have a picture? My first thought is this: Richard, at Construction Resources, showed me a demonstration of how a fibreboard sheet like Gutex (it was Gutex) or Bitvent can withstand the thermal shock of strong sunshine on a surface. It strikes me that once the pantiles heat up in summer, they radiate from the underside and make the space beneath impossibly hot. Even 18mm of eco-friendly fibreboard under the rafters would, on the basis of the experiment I saw, slow the passage of heat into a room considerably. I don't know about the plastic membrane though. I'm sure those more knowledgeable on this site would be able to comment.

    Another thought: the limestone walls will have a certain degree of insulation if they are 800 thick, but in winter, if they're a little damp, it's going to feel unpleasantly chilly. I have sandstone walls (like blotting paper, unlike your limestone) and for that reason, I'm battening out to form a 25mm air gap, then breathable membrane (tyvec or similiar), 75mm sheepswool (or similiar), 18mm bitvent, then lime/clay plaster. My inclination is to keep stone walls breathable, inside and out, keeping the exchange of air and moisture slow. I don't know much about Triso-10.

    Are there, as the name suggests, walnuts about?
    • CommentAuthorCWatters
    • CommentTimeJan 12th 2008
    Check out what local Building Regulations apply. Bound to be different in France.
    • CommentAuthorbillyo
    • CommentTimeJan 12th 2008
    The best for summer heat insulation is wood fibre board, google 'isolation fibre de bois', look for Agepan, Steico, and various others mostly german because they seem to be far ahead of everyone else on these issues, and you will also have to find a supplier in your area, which is easier said than done. Agepan reakon that it takes 8 hours for sun to heat through their 40mm roofing board, not sure of the proof of it though! Most of them also do felxible wall insulation for walls which is very efficient but a bit pricey.

    Your walls definatly need to breathe, if possible repoint them to cut down on draughts (probably a massive task!) and the laeve a decent air gap, and put vents in your new walls to allow circulation.

    What building regs.... :bigsmile:
    • CommentAuthorNoyers
    • CommentTimeJan 12th 2008
    Second attempted answer - first looked garbled.

    Hi Bogmarsh and Billo, Plenty of prunes, duck and walnuts hereabouts. House midway between Toulouse and Bordeaux; this is next door but this one habitable (http://www.lesnoyers.com).
    Thanks for the insulation advice, will look up Agepan panels. Main problem is that day time temps can be over 30C for a week or more with night time lows of 18 - 20C. Result is that night time losses much smaller than day time gains, this equals endlessly increasing temperatures in the bedrooms. A panel with a delay of 8 hours may be insufficient.

    Still like to hear of any personal experiences with Triso (foil) based insulation - anyone?

    CWatters: Building regs? Do they exist in France? You would never guess it looking at some of the renovations I've seen and, regrettably, the worst work I've ever seen was done by an English builder. I think some are hiding over here because the UK media (and courts) would slaughter them if they worked in the UK. Rant over.
    • CommentAuthorPontius
    • CommentTimeJan 13th 2008
    I'm currently doing some research on using lime/hemp (Chanvre in French) as mentioned on another thread. Tradical who make Hemcrete have a depot in Toulouse www.bcb-tradical.fr/index.php I intend using lime to point walls externally and want to preserve permeability. I looked at Tri-Iso 9+ (French version of Tri-Iso 10 I think) but after wading through pages of posts on here and elsewhere decided against it for the roof.

    We also have a solid stone place but for reasons you've mentioned want to preserve the thermal mass aspect. I'm not there yet but it's interesting reading so far!

    (south of Pau)
    • CommentAuthorNoyers
    • CommentTimeJan 13th 2008
    Hi Adrian, Triso-10 is an up-graded version of Triso-9+. Seen some renovations where solution was stone wall, 25mm air gap (sealed). Triso (or cheaper Castorama copy), 25mm air gap (sealed), plasterboard. Certainly the outer skin can breathe but not sure about this system with stone walls.
    The other common solution around here is: stone wall, 75mm glasswool bat with breather membrane on inside, metal lathe (up against glasswool bat to hold it in place), plasterboard. This leaves an air gap inside the metal lathes which is used to route plumbing/electrics. Doubt whether this achieves good R value or allows wall to breathe.
    Interesting challenge these old houses!
    • CommentAuthorTrog
    • CommentTimeFeb 13th 2008
    I am about to insulate my 110+ year old finca over here in Southern Spain with similar temperature problems Summer and Winter. In fact it is supposed to snow next week so I had better get a move on. My north facing wall is stone and covered in asbestos weather boards which are great at allowing the damp and local wild life in. I am going to spray the exterior wall with foam and then render over with water proof mortar. On the inside I am building a false brick wall and lining the inside face with insulation board. The stone work is very rough and not worth exposing nor do I like seeing my breath in my own bedroom in Andalucia. Anyone got any better ideas then post away. :wink:
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