So, is there a consensus on whether this is a good or bad thing yet? I ask because we're considering timber frame with hemcrete (possibly sprayed) for our new house, being in Essex we're quite near Hemcore, I've spoken to a contractor that really rates it (www.shotcrete.co.uk) and Lime Technology who (obviously) raved about it and even suggested it should be used for the slab.

I'm converting a barn with 600mm rubble stone walls - classed as a new build - and am very interested in using Hemcrete but my architect is concerned that the Building Control people won't go along with it. I've talked to Lime Technologies and they have a LABC certificiate for commercial use but not for residential - yet. I've also read Steve Allin's book on the subject which is well worth looking at if you're interested - but doesn't talk much about u-values or getting approval. Has anyone out there succeeded in getting approval to use Hemcrete in effectively a residential situation? I think I saw was it Gervase mention going through a process but no conclusion... Any suggestions?

Out of interest, lime technologies tell me that a 150mm layer of Hemcrete should bring the u-value to 0.35 which is not the greatest but good enough. The reason I am interested in it is that it seems to solve a few problems - it should be airtight but breathable, it adds some thermal mass, relatively easy to install. relatively green- even if it only sucks up as much CO2 as it took to make the binder.

Thanks in advance.

Tim

My understanding is that hemp shiv (chopped up stems) is a very rapid growing crop, and provides a good mix of bulk and structural reinforcement. The stems are a byproduct of hemp as a crop, so are 'free'. Hemp is a woody plant, rather than a grass, and is used in hempcrete as a part of the structure of the product rather than just a bulking agent.

I think I'm right in saying that hemp as a crop has absolutely nothing to do with drugs - the active ingredient is absolutely minimal in the strains used for agriculture. Nothing 'trendy' about it, it's just a very useful plant.

Tim, I'll be taking a residential extension in hempcrete through planning and building regs this spring. I'll let you know how we get on. If your architect is worried about building control he could always use someone like jhai.

I too am about to begin a new-build using hempcrete and green oak. No problems with getting planning permission for the materials.

I became converted from cob to hempcrete and I'm still convinced that, when it goes up as it's supposed to, it's a great product.

However just as I am about to go on site I've heard of hempcrete failure - in (I think) Suffolk. The suggestion on offer is that the damp climate had prevented the lime from drying out and the hemp had started to rot. A bit worrying for me as Suffolk is relatively dry - though everywhere has been wet these last two summers of course. . My own West Country site is windy and so damp that moss grows,not just on the lower trunks of trees, but on the boughs and branches too.

I understand that there should be a month's gap between the walls going up and lime-rendering - but maybe that's not long enough in wet summers or damp climates.

I doubt whether advice offered by the manufacturers can be relied upon as I gather that their tendency, if anything goes wrong, is to blame the builders for not adhering to the guidelines. I have no idea whether the guidelines include measuring the moisture content before rendering - perhaps they do. But it seems that drying time is an issue.

Hi everyone, this is my first ever post! Interesting to read your posts. Just wanted to let you know i am a builder with experience of three hempcrete builds designed and built by myself, including an extension to a victorian terrace house and a garden office. I am currently setting myself up as a specialist in using hempcrete for new build and period structures repair/renovation. So if any of you require a hempcrete builder please look me up. Williamstanwix248@hotmail.com