Types of hemp for building

Thanks to Deb and Pili for drawing my attention to the need for some basic info. And thanks to all the readers of this blog, which has had over 10000 hits now. The hemp we use for builiding is the centre part of the stem, after the fibres are removed. They're called the hurds. There are three types of hemp for building that I know of. Building type such as St Astier sells, which looks like wood chips, the particles are clean and pretty uniform, and around 1cm. The Horse bedding type is rougher say up to 3cm, but varied and may contain bits of fibre, and the odd seed or leaf. As I understand, this is what's left from a high quality fibre extraction. I use this for building. It binds together nicely, goes on thickly, and gives a prety good insulation. You can work it very smooth, see Neil's work on these pages. alternatively if it looks too bumpy, pop a smooth lime and sand coat over the top. The third type of hemp is a 2mm screened fibre, left over from cloth making I suppose. This is whats in Hempire skim coat. You can use anything in lime plaster that will resist cracking, in the past people mostly used horse hair, but occasionally straw, or jute. Goat and human hair are ok too. Someone tried nettle fibres, with an ok result. Hemp is just todays waste, so this is a handy use for it! Good luck

Hemp and lime plaster with leaves

Here are some photos forwarded from that talented sculptor Neil. He has added various leaves and bracken to his hemp and lime mix. Hope to be linking to his blog soon!

Hemp Plaster on Straw Bale

This is a reply to a query from Deb in Australia, about a mix for straw bales. I don't post a mix usually because it depends on a few things. The exposure and how thick the coat will be; deeper than 1 cm and you'll need hydraulic lime to help it absorb co2 and so harden. I'd suggest either using a Nhl 2, or mixing a Nhl 5 with hydrated lime in 1;5 ratio. If you use hemp to create a smoothing coat, you mix 6 parts lime with water to a cream, add 3 parts ground lime stone, 1 part sand, and as much hemp as you can work with usually 8 parts maybe less. The mix should be sticky. Go over this when its half dry- looks yellow, with a lime and sand layer, one lime to 2.5 sand. Keep misting this as it dries to avoid cracks. If you want to use putty use it in this coat, but be sure to mix it up with the sand 3 months before you want to apply it. I don't use wire mesh on straw bale- you may want to paint on a slurry coat of lime and sand to get started.

Plastering an old stone wall with hemp and lime

Sorry I should have posted these ages ago. Here are Caroline and Shelley wetting down the wall. You can see a platform to help us reach up to the top of the wall. The conduit for the electrics are in place. And the ceiling is plasterboarded. Be careful not to get a cold gap on the wall between the floors. Put a spot board up or have something to stand your bucket on. Hand apply and wooden float as you go. In this room we need 2 coats in places as the walls were very uneven. This wall dried out in a few weeks although we had up to 10cm hemp and lime. Thanks to Eugene and Caroline for their help.

Grouting with lime workshop oct 2009

We will be running a workshop, Grouting with Lime Mortars, with Douglas Johnston (LICW) at the Traditional Lime Company on October 16th, 8.30am to 5.00pm. This will cover the use of lime and natural cements in the grouting and pointing of masonry buildings, bridges and quay walls. The issues of mortar strength, compatibility of mortars with sea water, and grouting techniques will be covered. Cost including lunch €80.00 If you wish to attend could you please confirm as soon as possible as there are limited places. Kind Regards Vincent Coller Traditional Lime Company Ltd. Tel. 059-9151750

Lime plaster on reed over sheeps wool

Hi, This is a photo of Stiofan's self build. The structure is timber frame covered in reed mats, which are great for forming curves. The mats are lime or clay plastered, with ready mix from Otterbein in Germany. If you know a german speaker get them to help you look at all the lovely mixes on offer. As you can see from the photo Stiofan and Christine have used sheeps wool insulation in the cavity.

Natural Building at the Hollies 2009

Hi all, Bumped into Jo Forsythe in Killaloe last weekend. She is teaching at the Hollies this summer, and having had a brief but very interesting conversation with her, I highly recommend popping in to visit. http://theholliesonline.com/courses-2009/

Increase in hemp, decrease in jute

While we all love hemp and the benefits growing hemp can bring, spare a thought for the decrease in jute growing in impoverished areas of Bengal, India and Bangladesh. The market for jute has been waning since the 70's, but some areas have had up to 50% reduction in the last year alone. Maybe its time we all go and buy some new hessian to protect our drying plaster.

Fresco painting on lime plaster

Just realised we've had no pictures for a while, so here's some of frescoes! So easy to do, very little pigment required for a bright colour that lasts. Perhaps better to do it onto a lime plaster skim than direct onto hemp and lime plaster which could be too rough for fine work. The following pictures are of Medieval frescoes in Carcassonne, image of the fresco at Holy Cross, and fresco painting at last years Electric Picnic

Lime course in Letterfract

There will be a lime course by Conservation Letterfract. Please contact Sven or Janet for more details http://www.conservationletterfrack.ie/

First International Hemp Building Symposium Sept 2009

Steve Allin is organising a Symposium in Kenmare 16-18 September. It sounds very exciting, check out his site for more details http://hempbuilding.com/ There are still places for stall holders and speakers, and many people are flying in from all round the world to share their work with hemp. Sadly I can't go! So I hope you'll let me know how it goes.

Learning from my mistakes with hemp and lime plaster

I am about to start hemp and lime plastering in my own home, so I'll be updating this blog regularly on our progress. We have been living in our barn renovation for 5 years so I'm able to see what I'll be doing differently this time. Regular readers will know that I'm not so into the bumpy finish. It gets dusty with a dog and underfloor heating. So I plan on covering up all the hemp and lime with lime render this time. I also hope to use more decorative techniques. There are some places that I would call problem areas, that are prone to too much humidity. We have chosen to use clay beads in the place of hemp low down near the floor, since there is a high water table. They are not so easy to apply, but then maybe I haven't got the technique right yet. Henry Thomson gave me the idea when he said he would recommend them for a lime floor in the place of hemp. Talking of humidity, Steve Allen says in his book that hemp and lime plaster isn't suitable for areas with over 20% humidity. Because we all know lime is good for damp houses, it's easy to make the mistake of thinking lime will fix all damp problems. It won't! A basic check list before you start might be; 1 Remove any cement render or pointing from the outside first. Ed Burn says this is the most important step. If you trap moisture in your walls by stopping it from moving outwards, you will run into problems. 2 Point or preferably render externally with lime. I've seen a lot of damage from weeping stones, and where birds have picked out the old points. 3 Make sure your guttering is good, and leaf free! I have a fault between roofs that has made a whole wall wet. It looks awful, but easy to recognise the real damp from condensation mottling. 4 Dig a french drain around the building. Pretty obvious, to lead water away from your walls. Works wonders. Then there's no need for horrid injections of damp proof courses. That's all for now, more on this soon.

Courses at Ballymaloe with Stoneware Studios this Summer

Hugh Dorian is holding a course a month at the Ballymaloe cookery school in Cork this summer. The first in June is about using lime in renovation. There are also courses in natural plaster finishes and understanding natural paint. Stoneware Studios is in the contacts.

Lime courses 2009 in Ireland

I guess it's that time of year when people start looking for courses, so I thought I'd point you in the right direction, since I'm not teaching much myself this year. Professional plasterers looking to get into lime should contact Ed Burn, at the Traditional lime company in Carlow. He runs workshops every week for professionals, and he has all the materials there to try. I believe the workshops are free! But any of the contacts listed should be able to help. Another one to add is http://homepage.eircom.net/~mcafee/ DIYers are welcome to e mail me, or come and visit here in June. If anyone else would like to offer a bit of hand holding, or pass on advice they wished they were given before they started, please e mail or leave a comment here. Maybe one day we'll get a forum going! I'd also like to add here that I'm getting so many enquiries from plasterers now, I think the world really has come around to using lime, which is great! Also the price has come down for getting someone in, which I'm certainly pleased about. If you're thinking of employing a plasterer, check their mix. Most plasterers would be happy to try using lime, they already have the skill, just get them to have a chat with Ed or Hugh first regarding materials.

Flint and lime

Last year I meet Gerry Williams, the best flint wall builder! Here he is with the ruin he created at a friends garden. He worked with the late John Ashurst, and created the ruinette at westdean college. (John Ashurst's book Consevation of Ruins is top of my wish list at the mo.) Gerry gave me many time and money saving tips for working with lime putty. As far as I know he's involved in some Building conservation courses at Westdean this year. They are aimed at professionals. There are lots of great courses at the neighbouring Weald and Downland museum, in cob, brick, flint, stone, and wattle and daub. I noticed they have used a photo of my pargeting in this years brochure. Thanks guys! Fame at last! see www.wealddown.co.uk The great thing about working with hemp and lime is that any other building technique which uses lime is compatible. There are so many possibilities. If your interest in flint is more about making stone age tools, check out www.beyond2000bc.co.uk, I met them at last years Electric picnic, and wished I had time to give it a go.

Hemp and lime plastering workshops June 2009

I will be hemp and lime plastering here in Clare 8-19 June (except saturday 13th). It will be open house for anyone to come and join in. We'll start at 10 finish by 5. Please bring gloves, something to eat, old clothes to wear, and photo's of your own projects please. If you are traveling far you can camp but let me know in advance. Email phoebeob at gmail dot com

Lime paints

In response to Ray's question about lime paints. I haven't used Earthborn paint myself, but they do seem quite nice. I would be reluctant to use lime wash anywhere apart from externally and maybe ceilings-not that if it's done well over a good background it should be a problem. I have tried St. Astier lime paint, which comes in various colours, as a dry powder. (Save on transporting water) Its probably the next step in durability. Following that I have used Farrow and Ball's casein distemper, they have really inspiring colours, and are easily available. However they are not suitable in areas of high humidity, bathrooms and kitchens, I have learnt by mistake!! The diffusivity is just not high enough. Every additive compromises breathability. Probably the best paint is from Beeke. Aglaia is the internal paint. I have used the external mineral paint, which importantly has a 30 year guarantee, and is applied after etching (with a fluid bought separately). The etching has the effect of opening the sinter skin, making the surface open, so the lime can attach to the plaster. If anyone wants to lime wash over cement that's the only way you'll get it to work. The other thing to bear in mind when choosing natural paints is don't keep them sitting around too long, they can develop moulds. And some natural paints are not lime compatible, choose one's that make it very clear they are for lime. Finally coverage over rough hemp and lime is not great! I've found using a creamy off white the best solution to keeping costs down. Otherwise cover the hemp with a fine lime coat, choosing light coloured sand if possible. Back at the beginning I tried to lime wash first with builder's lime, then used casein distemper on top. The paint has chipped off where a chair back bumps. The inferior lime wash was to blame, not recommended!

Hemp and lime course with Steve Allin

Steve Allin, author of Hemp Building will be teaching a course next month. The days activities will include the theory as to why to use this material, mixing , application and finishes. Hemp Plastering Class with Steve Allin Saturday 14th March 2009 9.30am-5.00pm cost €90 inc lunch venue K.A.T. Gortagowan, Sneem, Co Kerry contact; hempbuilding@eircom.net or phone 064 6641747 Please bring work clothes and strong rubber gloves.

Using hempire's skim plaster

I have wanted to talk about using Hempire for a while. Hempire have 2 ready mixed products, one they call building plaster which slightly resembles the hemp and lime that I mix by hand, and another that has very tiny particles of hemp fibre, that they call skim. Both products were developed for application with a trowel by a professional plasterer. Also it is hoped that by supplying a ready mixed plaster that u values will be easier to work out. It is definitely quite nice to start work without having to get out the mixer, and we certainly saved some time. However I just prefer my own mix to Hempire's building plaster since I find theirs too wet. Just down to personal taste. Where their building plaster came in handy for me was when the job was basically a skim and only need to built out in a few places. Drying times are quite different since this product is based on lime putty. I do suggest making a few experiments. The skim coat is a whole different story. I used it on our on going renovation in Sussex. This cottage doesn't have a single straight wall, and the first plasterers who came to look where of the opinion that everything should be ripped out. Not an option! I had chat with some building conservation experts who advised keeping as much of the original as possible. I'm still finding a little reluctance about hemp and lime in the UK, but I think this is just because it is a new product. But it is certainly an appropriate material. The biggest problem in the cottage was a ceiling with many cracks and a huge bow, and some loose material. It was horse hair and lime on lath. No plasterer would touch it! Also the weather was very hot, the roof space like an oven. I knew from trials that Hempire skim coat just does not crack even when baked in the direct sun. Now I'm not a plasterer, remember, so applying it was going to the problem. I managed though I don't recommend it! To prepare the ceiling the lose parts were screwed back in to place, flaking bits were removed, and one small part was patched with plasterboard. The whole ceiling was thoroughly wetted. I poured off the extra water in the skin coat bag, since mixing it in seemed to be too wet.You don't want the fibres to separate from the lime. Then I gave the mixture a good chop through, don't be tempted to skip even though it's ready mixed. Finishing was a bit tricky. The web site suggests rubbing down. Again make many trials with this. I wouldn't like to have to sand down any rough parts, the dust would be lime and recycled glass. You can see the results. If you are easily disturbed by uneven plaster look away now!! But in fact that is what we wanted, so it would look original. everyone else seems to like it too, and we have been inundated with requests to rent this cottage.

New Irish group for Traditional Buildings

INTBAU is the international network for traditional building, architecture and urbanism. INTBAU Ireland was launched on 28 October 2008 in Belfast. To celebrate this, members of INTBAU Ireland produced an exhibition of classical designs from different parts of the world, including Ireland. The exhibition will remain in Belfast for one week and later this year will be shown in the capital of the Republic of Ireland, Dublin. To see Intbau's work and join look at www.inbau.org