Wot you saying Mike - Hemcrete really is .69W/mK? that makes it as conductive as solid brickwork.

Good job nobody reads such documents!

Is it thick, rubble backed, or thin, cut stone all through?

All two skinned, rubble backed, local limestone (South Powys) 500 and 600mm. Cement pointed 30 years ago, fortunately falling out of it's own accord to reveal lime underneath. Refurb to include external re-do of stone work with lime pointing for "fancy" areas and rough cast for rubble gable-ends at back (were once slate hung but cement rendered at same time as pointing).

thick ones like yours (?) think massiveness instead of primarily insulation.

I would stick with massiveness if I thought a) could not significantly improve the rate of conductive heat loss to the walls by adding internal insulation, which could be of virtually the whole outside wall b) insulation would inevitably put the timbers at risk. I have only one opportunity to get it right. Foam would have real advantages (eg detailing round windows, light weight, access to awkward corners) but I recognise the dilemmas. I would really like to try it, perhaps alongside hemcrete. Is that approach practical or is it fantasy? Perhaps a combination of methods is needed.

<blockquote><cite>Posted By: fostertom</cite>State again your concerns and ways and means about joist ends? </blockquote>

OK As I see it from reading/thinking/re-reading, and following this forum and AECB. The joist ends sit in the stone wall (as above, not cared for in best way but still sound structurally). The joists will be presenting cut ends to the wall and will be coldest even before putting in any insulation. So probably already prone to condensation (the old buidings literature documents this site as prone to timber failure). For my house this applies only to first floor so walls pretty dry at this level(solid floors at ground level) and at one end of joists (because two storey part of house abuts gable end of single storey area at right angles). If I put in insulation (any kind) the joist ends will inevitable get colder relative to much larger surface area of walls. If kept dry (hence lime or sheeps wool) or kept warm (Canadian idea) could this protect? Perhaps MHRV with slight negative pressure on living rooms would also help. Definitely no impervious materials to go next to wood or on walls but is semi-permeable foam permeable enough to allow movement of water vapour and surface evaporation via say lime plaster surface? Perhaps hemcrete "better" but certainly heavier, lower u value and more expensive. And my window reveals are chamfered as well as splayed and round topped. Can I cut hemcrete like the foam - probably not?

I doubt that condensation analysis can predict what happens to my joist ends in my house and in my climate/occupation unless the programme used can enter specific data from the particular site in question. So my thinking is "Can I install X in limited area, monitor temperature and humidity behind/on X and at joist ends to measure what happens? Then abandon or proceed on all outside walls according to findings?

Remind us/me - what's osmosis?

I do need reminding - does this apply to liquid moisture? I know it applies to vapour. What kind of force drives liquid to recoil from itself - surface tension? gravity?

No capillary tracts, i.e. interlinking crevices, then no liquid water content can enter a solid - unless it was there already, trapped in non-interlinking voids. Another way might be diffusion through membrane. Ah of course - 'reverse osmosis' - it is about diffusion through membrane.

This is interesting. What kind of materials do you have in mind, hairylime? - perhaps your name's a clue!

Would 'wicking' be another name for it? Of course a wick tends to stay damp, and therefore never allows its source to quite dry out, which it might if it wasn't poulticed with wick material.

Posted By: harrylime just a practical man with a brain.

Posted By: harrylime this technology for many years and have achieved wonderful results.

OK, would you insulate a stone built house internally and if so how?

Here's George Swanson's site http://www.geoswan.com/ - good stuff.

But what you've just described, harrylime, isn't outsulation - but it is the best you can do if extg. external masonry face has to be left exposed. It keeps the whole thermal mass in contact with the interior. It's a Hemcrete technique too. Interesting to find someone who's tried it, and more interesting to get in-use performance data.

Posted By: harrylimeI used a lime putty with a non conductive aggregate (ie silica avoided and dense impervious agg avoided) the whole, makes a material that feels warm at room temperature to touch. I also built iinto the mix lightweight insulating aggregates for low density volume and pump sprayed the mix 4 inches thick.

Thank you for the response - but could you be a bit more specific? I don't know what "non-conductive aggregate" might be. I could guess what "lightweight insulating aggregates" might be but why not tell us?

Posted By: harrylimejust a simple, practical person who observes in detail, the results of his work, over 20 plus years

Sounds like Viktor Schauberger - have you read him, harrylime. might just be contribute to your work.