This week I managed to find some time to get my first coat of clay plaster on the straw bale walls. I wasn’t sure what to expect, but I was looking forward to not having to wear gloves and safety goggles like I had to with the lime render.
I soaked the clay I had for 24 hours and hand mixed it into the sand per bucket. For my ratio of sand to clay, I went for a high clay content and didn’t worry too much about accuracy or consistency between mixes, as this is the first coat and the primary aim is to get it keyed into the straw well, rather than smooth and crack free. In fact, cracks will help the second course stick well to the first.
My initial reaction is that clay is very fun to work with! It’s messy and sticky, but mixing by hand is nice and relaxing and easy. It’s also very fast, at least for the rough coat I threw on. I managed to get the inside of the studio done in two days, where as the lime render took five days, with help.
I’m letting the render dry over the weekend, and as it’s inside, this is going to be a slower process than the lime render, but once it’s done I’ll get some test patches completed and start thinking about my specific mix for the thicker coats.
By the way, I got my information on clay plastering from here – http://buildnaturally.blogspot.ca/2011/07/clay-plastering-strawbales-first-coat.html?spref=fb
In the weekend just gone, I finished the lime rendering and had a nice relaxing Sunday, knowing all I have left to do is limewashing on the outside!
Meanwhile, I had organised a delivery of one tonne of clay from JJ Sharpe (in Devon) which was due to arrive on Monday, just in time for a new project!
Given the difficulty of access to my street for large vehicles, they brought the shipment in a large van with a tailgate lift rather than a lorry with a crane offload, so during unloading the clay was, rather unfortunately, dumped on the road!
It wasn’t a major concern, as I needed to get it off the road anyway, so I had a spare tonne bag and we (me and my parents) set about loading it into buckets and shipping it up to my shed for shelter. 90 minutes later, we had a victory cup of tea and now I have clay plastering to look forward to!!
I’m busy reading up on mixes now, and I’ve ordered my first tonne of sand, though I think another one or two tonnes might be needed.. I’ll post mixes and results up here when I start, hopefully this will be in half term, which is next week!
I’m getting the final course on the straw bale wall. As it turns out, I’ve probably got about half a ton of lime render that I over-ordered, so I tried a test patch last week on the inside of my tyre wall to see how it would stick.
Here are some photos. As it transpires, the lime render sticks remarkably well to the tyre surface! I’ve also filled the voids between the tyres with a lime/straw mix though in hindsight, the mix in the photo is probably a little lime render heavy as it’s drying quite slowly but I’ll try other ratios in the next few weeks.
The particular ratio of materials in the mix of lime render is not known to me, as I ordered it pre-mixed from Ty Mawr (ask for their straw bale mix), but I know it’s a combination of lime putty, sand, finely chopped straw and hemp.
I was going to plaster with clay between the tyres, but if I’ve got the lime spare, I’m happy to work with that. On searching the internet, there is precious little information about lime plaster and tyres (who would have thought!) that I feel I should try and share as much as I find out on here. If anyone else has tried, or tries this, let me know.
With a yellow wind warning coming our way, and no glass in my window frames still, I thought it might be a good idea to get some window shutters up. I started making them last week, with some spare 6″x1″ board I had from the roof construction. I managed to put all of the windows together with materials I had lying around on site, so they cost me a couple of quid for the hinges and casement stays.
The fixings for the shutters are from screwfix, and they are pretty attractive, especially when you see the price! (link here) Unfortunately, at the time of fitting, it kept slipping out when both the shutters open at the same time, so I had to screw some wood to hold it shut until I can get more time to look at the fittings. Still, the shutter looks pretty good from the back of the house!
In order to give a more structured design to the site. I’m compiling a load of pages on the building. You can follow them in the menu above – under Straw Bale Building.
I’ll try and keep these up to date and with the most relevant information and photos from my posts. Hopefully they can be used as a good source of information for other amateur builders as people look for stuff, rather than going through my blog posts!
Another beautiful day yesterday here in the valleys. Blue skies, warm sun, and a new fence on the front of the decking.
Second coat of plaster is going on too, you can see the curtain I’ve made to shade the wall from the sun. The weather gets cloudier and wetter this week so I can get the front rendered then without worrying about direct sunlight on the walls while I’m in work. Hopefully I’ll be looking at a much smoother exterior render finish this time Friday. Plus I’ll have sorted the clay render out! Fingers crossed..
As the lime plaster goes on in increasing layers, I’m turning my thoughts ahead to the inside and the clay render. Managing time is important to keep things moving and I need to see if I can get the clay render here for my half term so I can take the time to mix up what I need and try it on the walls.
As it is, I’ve come up with a lot of trouble of trying to source clay render for straw buildings. It’s not something that’s obviously available, and you have to bear in mind, lime is the primary material for rendering straw, so when you do a search, most clay that is sold is not advertised as “clay render for straw”.
My lime suppliers at Ty Mawr (www.lime.org.uk) sell a daub, which can be used as a base coat for render, and I also found a number of links at Low Impact’s website (here)
I have found that to save a bit of cash, clay requires a little more work that lime to put onto straw. The easiest place supplying render for straw is Clay Works, however when quoted, their cost of materials was far higher than I was willing to pay – whilst for a home, it might be OK, I’m just building a shed in my garden effectively, so I’m hoping to do this for a small sum of money.
Fortunately, I started phoning people, and got a lot more information when I was able to speak to someone. As a tech geek, I’m so used to finding stuff on the internet, it’s easy to forget that a phone call is faster, and easier to get information. As a result, I’m waiting on quotes for clay powder which should prove much cheaper, and easier to transport, which I can then mix on site to my desired texture and get onto the walls! We’ll see how this goes..
This weekend was a good weekend for getting the plaster on. Still not as warm as I’d like, but at least the freezing temperatures have gone!
We managed to get a first coat over just half of the buiding. The back sides are not covered yet, but I can do them in the week, so it will be covered by next weekend. So far it looks like this:
You can see it’s a little patchy in places, but the second coat should close this up and make it more uniform.
The bulk of the plaster went on well, though in areas where I was using hessian to patch up gaps and bridge areas with wood, it’s a little loose and thin. I’ve draped some geotextile off the roof to shade the building this week and I’m spraying it to avoid it drying out, but there are areas where it has dried more than others.
I need to get some closer photos of areas, but some of the plaster has dried a little flaky and crumbly in some small areas which might need redoing. They tend to be in the areas where the straw is not packed so well, like the joins of the bales, or an area we stuffed with straw.
It’s best to work the first coat in with your hands.
It’s when I encounter slight weaknesses like this that I kick myself for not going on more training courses closer to the build date. I’m going to see how things go on a second coat, and make more effort to work the plaster into the bales on the first coat.
Finding detail on the edge of a green roof and waterproofing it is something I struggled to do easily. I thought as I fitted the roof it would be good to take some photos and show everyone how mine is put together.
The roof consists of 18mm structural plywood, with carpets on top followed by the membrane. At the edge, the plywood overhangs by just over 2″ (5.5cm).
The membrane overhangs by about 6″ (15cm) over the edge, so it can wrap underneath the plywood. In the photo below, you can see I attached some 2″x1″ wood to the edge, which allows the membrane to wrap under and then up, forming a drip edge.
To create a drip edge, some 2×1 is screwed to the edge.
The photo below shows the roof before the drip edge is screwed on.
The plywood has carpet on it before the membrane to ensure no splinters get to it.
Once the membrane is folded over, it tucks up between the drip edge and the truss which the plywood overhangs. The feather edge board then pushes up into the gap and screws on to hold the membrane in place.
The membrane folds over the drip edge and up, and the feather edge board holds the membrane up.
You can see the roof in the photo below with the finished drip edge. The next step will be to trim the membrane hanging from under the feather edge, add a weather board to protect the membrane from the sun, and then add a gutter to catch the water and direct it to somewhere more useful. All should be done this week.
The roof here with the drip edge installed. The membrane needs trimming, and a gutter.
I hope that helps anyone looking at creating a green roof. I would love to hear ideas of other designs and plans. As I develop mine more, I’ll post as much as I can to share more information.
Three things have occurred to me this week;
- I am terrible at blogging about the shed
- I am awful at taking photos and putting them on my posts when I do blog about the shed
- Cats love my shed
I’ve not been very well over the last week, but I’ve recovered this week and I’m pressing on to get the shed roof finished and the inside sealed up from the wind. The timing is a little late, as the weather is warming up, and the winds are howling down the valleys this week. Gales of 40mph are expected on Thursday, and I’m sitting in my house listening to the wind whistling around my windowframes hoping my roof doesn’t come off!
Fortunately, my dad is very into his over-engineering and the trusses are tied down tightly to the building, I’m confident it will hold out, but it is something to consider once I’ve got the roof finished that the wind should be excluded from getting under the roof wherever possible to avoid lifting, which could be catastrophic!
I hereby promise to get some photos taken this weekend and I’ll try and post them on Sunday, when the roof *should* be on and sealed up.
The cat above has nestled into the shed very happily – there every morning and afternoon without fail. In fact I get a nasty look whenever I disturb it! Unfortunately, after this week, it will be difficult to gain entry into the shed so cat fans will be disappointed to hear the eviction notice has been served!