The Stem Wall

March 31st to April 4th

After a long winter layoff, building has started on my site again, taking advantage of some warm March / April weather. There has been much planning, preparing and purchasing of supplies, but now it's back to building.

One of my purchases is a forced-action mixer from ebay, and it has had its first outing this week:

    

It's great for mortar, and I'm sure it will be for plaster, but needs a different set of paddles for mixing limecrete, apparently. It has a "Kenwood Chef" mixing action, rather than the normal "Tumble drier" method. It's also a bit of a beast to clean

I am building a stem wall for the bales to sit on, and it will be a wide cavity wall 450mm thick. I am hoping to obtain foamglass blocks for the inner skin, but haven't been able to get my hands on them yet, so I may have to compromise on lightweight concrete blocks. The outer skin will be a mixture of leftover engineering bricks, recycled brick from a garden wall I knocked down last year and flint infil. 

We've been building the corners and the ashlar pillars. Only two of the four walls will contain a flint face, so this is the simple, single-skin brick corner:

This is the doorway in the front wall, showing the ashlar in greyish bricks front, left, and the backing wall for flint in red engineering bricks.

Also, above, you can see a bit of black plastic pipe built into the wall. This will be used much later for compressing the straw with lorry ratchet straps. There will be about 15 of these built in around the stem wall.

It's coming along. Once we have the corners and ashlar finished, the remaining wall sections should go up much more quickly.

April 7th - 11th.

Good news this week: I have taken delivery of some foamglass blocks for the inner skin of the stem wall. They are very lightweight, much less dense than the foamglass gravel in the base.

I was working by myself on Tuesday, and got the remaining corner and ashlar pier finished. (If you're not familiar with the term "Ashlar" - I only heard it a couple of years ago - it's the  brickwork surrounding flint panels in Norfolk flint walls.)

But on Wednesday, I was joined by Guy, my first POOSH volunteer, and the walls have been going up much more quickly. This is partly because there are two of us, but also because we've been working all day, every day. When you are just working by yourself, it's easy to get distracted.

So, here's the front wall:

The 450mm width is made up of 4 components, which from left to right are: 1) Flint panels and ashlar (brick borders). We are going to do these last, but there are a few flints in the far bottom corner of the first panel, where we had some mortar to use up. 2) Support wall for flint made of recycled brick, lime mortar and containing some butterfly cavity wall tiles, which are supporting the flints not for bridging the cavity. 3) Cavity, approx 100mm. 4) Recycled foamglass blocks, 140mm x 450mm x 600mm laid on edge. 

Only two walls are to be faced with flint. On the other walls, the brick will be the outer skin and the cavity will be around 210mm. Also visible in photograph: service pipe for electricity cable, and stainless steel, long wall ties connecting RFG blocks and brick/flint walls.

There's been a change of plan for compressing the straw walls. The RFG blocks looked like they would not support the pressure from lorry ratchet straps, so I am going to put plastic pipe in the top of the wall, so that the compression force will bear directly on the timber base plate. 

Guy, No. 1 bricklayer, at work. There are, of course, not many photos of me at work, as I am usually the photographer.

Here's my delivery method for large and heavy bags of materials, in this case foamglass gravel

1) Get delivery driver to drop bags onto my trailer

2) Drive up garden to where they are needed

3) Tie bags one at a time to tree

4) Drive away with trailer, depositing bags on ground

This foamglass is going to be used to fill the cavity in the stem wall.

April 14th - 18th

I have discovered that you get a lot more work done when someone is helping with a job, especially a job like bricklaying. More than twice as much. Firstly, there's the social pressure of Working All Day; it's much harder to start late or knock off early if there's someone else around who has come to visit specifically to help with the building. But secondly, there are "overheads" in any job - tasks that must be done, but which are not visibly productive: setting out, measuring lime and sand, cleaning the mixer. These take up a smaller part of the day when they are supporting two hands rather than a sole builder.

So, building work has been full time this week, four days of brick (and flint) laying, and one trip out in a hired truck to pick up some scaffolding on loan. As a result the plinth wall is very nearly finished, and the scaffolding is part-erected.

Starting to lay flints whilst Guy completes the brick outer wall.

Last brick!

Thursday night: All bricks and RFG blocks laid

Friday night: The almost-completed plinth wall. Just a few flints to lay on the left of picture

It would have been nice to get finished, but I ran out of lime. No worries - we're still on schedule.

More Preparation. Wood, Ashlar & Cutting Corners

March 30th. I've been getting ready to build in lots of areas.

The cover has come off the limecrete slab and around 20 bales of damp straw fluff removed. All looks OK underneath

I found a source of "SmartPly" OSB, reckoned to be preferable to the standard grade on account of the lower formaldehyde content (Meyer Ltd). I have 16 sheets in the dome for cutting, and 20 under cover for use as the roof deck later.

Cutting corners!

But not in the metaphorical sense. I have been very carefully cutting out square corners from SmartPly sheets to form the corners of the wall plate. Eight of these:

And quite a lot of these straight section, all 450mm wide

It's been very useful having plenty of trestles to support sheets whilst cutting. I made 6 of these from scrap wood during the winter.

Lots of wood arriving: - 

It was a day's work to get the wood up the garden near the site and under cover. Quite a big pile outside......

......and plenty more inside:

Also taking up a lot of time over the last couple of weeks has been the brickwork layout for the stem wall. My layout for the limecrete base last year was not very good, producing a not entirely rectangular base. The diagonals are out by 8cm. I have put up new corner guides for the stem wall that are rectangular, but as a result of the earlier error, they don't sit exactly over the base. I have decided that in the long run, this will be better than having the whole building out. I will have to cover up the foot of the stem wall with plants so it doesn't look too odd; it's a 2cm underhang or overhang at the corners.

I've also been doing detailed planning of the ashlar - the brick corners and pillars that are used in flint walls. 

I've built each one up with dry bricks, photographed it course by course, and produced a plan 

I felt the need to do this because it gives me one thing less to think about when I am laying the bricks.

Completing the Bale Shelter

March 15th. Today is the official start of the building season. It's still a little early for any lime-based bricklaying, but time to get on with some carpentry.

And before I do any large-scale carpentry I am going to need an outdoor store. Time to get my giant tarp out and cover the new dome.

I was going to do this job today, Saturday, but the forecast was a little breezy and I didn't fancy handling 100 sq metres of tarpaulin balanced on a ladder.  But a couple of days ago the forecast was just perfect:

Practically the whole UK was isobar-free. It was a cold night, a foggy morning and then warm sunshine without a breath of wind

The tarp measures 12m x 8m and the dome has a diameter of 7 metres and a height of 3.5m.  I've prepared the tarp with some extra eyelets along one of its long edges. So: chuck it over, and  get the mid-point of the prepared long edge lined up on the large base triangle that I have in mind for the entrance.

Lace up the edge to the struts with shock cord

Tie a couple of bricks on the opposite edge to keep the midline of the tarp under tension,

Work round the base of the dome, tucking the tarp under the bottom struts

Roll up the tarp to make it look a bit tidier; tack down some geotex fabric over the hubs to give the tarp some protection from the edges.

That's it! I've also put some ground pegs along the base, and four stakes inside with tie-downs on the hubs. It's flapping a bit in the breeze today (Saturday) so I plan to make a web or net to go over the top tomorrow, and keep the folds in place.

Information for Volunteers wanting to help with this building project

This post contains information for anyone who wishes to help out with this project on a voluntary basis. It's intended to be supplementary information for "POOSHers"  - sustainable builders and others interested in the subject who are registered with POOSH at www.thepoosh.org. If you haven't come across POOSH before, you should check it out right now. It's just like WWOOF, but for sustainable building, and puts volunteer helpers in touch with host projects.

I intend to restart work on this project on March 15th and I'm posting a timetable below of the types of work that will be going on this year. I will try and keep the timetable up-to-date with changes that arise from the building progress or for any other reasons.

Dates: ( working on most days during the period)	Type of work	Number of POOSHers needed,
March 15  - March 29	Carpentry:  cutting and part-assembling baseplate, wallplate, window boxes temporary roof . Put cover on bale shelter	1 - 2
April 7 – May 8	Bricklaying: Constructing stem wall with recycled brick, flint and lime mortar. Carpentry: completing temporary propped roof Straw delivery Prepare hazel pins Scaffolding	1 - 4
May 26 – June 8	Wall-raising (bales) Wallplate assembled Wall compression	4 - 8
June 9 – June 23	Get the roof on!	1 - 4
July 1 – 20	Overrun period	??
July 29 – Aug 12	Lime Plastering	1 – 8
Aug 26 – Sep 30	Lime & Clay plastering	1 - 8

Calendar View:

The normal pattern of work will be to do some building on 4 weekdays and Saturdays during the highlighted periods above, and to have Sunday and one weekday off. Maybe.

If you would like to come and lend a hand over the summer, please get in touch now via the POOSH network. My project is listed there at http://thepoosh.org/buildproject/richard-roberts/strawbale-workshop, and it is currently the only project in North Norfolk listed on the POOSH project map. (Please do NOT contact me via this blog; I may not see your message.)

Hazel Cutting and Recycled Window Frames

I had an offer to go and cut some hazel not very far away, so Chris and I took the trailer and some tools over. Not the straightest hazel I've ever seen, but I hope it will be OK once trimmed and sorted

Got a trailer load......................................

Stacked it up till I get a chance to cut it.

This is the hazel cutting list, with lengths and diameters

Hazel is needed in a variety of lengths and thicknesses to pin through the bales, hold them securely in place on the stem wall and base plate and to prevent any lateral movement of the bales. More later!

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Also going on this month is my attempt to make some window frames. I have some lengths of wood from door frames removed from the house which I am using. It's good-quality wood, an exterior joinery grade.

Four sections for frame: 

Dovetails on both ends of uprights, cut with a jigsaw:

Not shown: glue, screws, mallet, a few chips to fill the gaps.

A Geodesic Dome Straw Shelter

For the last few weeks, I've been building the components for a 7 metre geodesic dome, which I will cover with tarp to make a shelter for my straw bales next year.

I have decided to make it with "Cundy poles". These are softwood poles, possibly forestry thinnings, that have had the bark removed by machine. The diameter is variable, and they are not absolutely straight, but they look strong, durable (they are generally used as stakes in the ground) and smooth enough to support a tarp without damaging it. They are also much cheaper than machine-round poles.

I've bought 80 poles of 2.4 metre length.

For each of my dome struts, I took a 2.4 metre pole and a couple of 20 cm steel straps, cut from longer sections of builder's strap.

Then I cut a slot in one end, 3mm wide (same as the strap) and 150mm long

Line up the strap on the pole with 3 holes projecting. Mark through 3 of the the other holes for drilling positions:

Keep the pole horizontal, keep the drill vertical

Drill out the pilot holes to 6.5mm

Five poles ready for assembly

The tricky bit: push, or quite often hammer, some 6mm coach bolts through the poles engaging the holes in the straps on the way. No problem, as long as those drill holes all went through parallel

The poles I used have variable diameter, so I had a selection of bolts: 75mm, 100mm, and 100mm all-threaded. Long ends like these ones got cut off with an angle grinder

Then, you do it all again on the other end of the pole. I'm using a jig here, a piece of 6x2 with two nails sticking though upwards, and they were 216 cm apart for the long struts, and 191 cm apart for the short ones. I've already cut the pole to length, and I'm marking up the drill holes on the second pole end to get the strut length  (measured between the outside holes in the steel) accurate.

I made 35 long poles, 30 short poles so this was quite a long job: 130 steel straps, slots, 390 bolts

 Construction, with a little help from my friends.

( I was hoping to have a time-lapse video here, but my camera wasn't up to it.)

So, in early November I had all the parts made and a 7 metre circle on the grass. I'm not going to give you the How-To-Put-It-Together instructions here, just show you some photos, maybe mention some of the issues that came up. It was a great thing to do as a team. I asked eight friends to help, expecting around half to come, but on the day I had seven; eight including me. And they were all needed! There was plenty to do.

We put 10 poles around the base, then joined them up. Next: - the Teeth. Five equilateral triangle constructed on alternate base struts. Each "tooth" is propped with a spare strut for now.

Keeping the props in place, we fill in the gaps until the first level is complete.

Scaffolding platform was essential for the next stages. We are completing the five base pentagons

These are around 3 metres high, and in the absence of any 3-metre props, they are supported for now by ropes on the outside.

Completing the second level. It was necessary to adjust the rope supports to line the joints up

Second level complete!

Happy man! Everything has come out dome-shaped.

Many thanks to Jim, Westie, Sandra, Malcolm, Toby, Andrew & Jess. Great fun, no accidents and a very sturdy-looking dome. Also to Moira, Jean and Chris for "support services" and photography

There was a gale forecast for the evening, so the original idea of getting the tarp on whilst everybody was here had to be scrapped.