Thursday, 25 December 2014

Strawbale house, latest

This is the house as it was at the end of 2013. Externally, it was virtually finished - at least to look at. What it still needed was a few coats of limewash on top of the final coat of lime mortar. For this I used hydraulic lime, mixed with water to a consistency that was thin enough to apply easily with a masonry brush; it quickly soaked in, and I realised afterwards that maybe I should have sprayed water on the wall first. The first coat turned out to be brilliant white. For the second coat I used a different bag of lime, which when mixed looked earth-coloured, but on the house it dried to a pleasant cream. The idea is to apply 3 or 4 coats and then add some pigment; we thought we'd try to match the tone of rose-coloured granite in the walls of Mill House.

Moving inside, the first job was to finish the insulation. Putting slabs of Kingspan between the rafters was not a pleasant job. The aim was to make a tight fit so that the material would stay in place until the plasterboard was screwed on. Inevitably it had to be trimmed to fit in situ, and that meant a shower of insulation dust on the face. 

Between the ring beam on top of the straw bale walls and the sarking was a big space that had to be filled with insulation, and then laths fixed between verticals. Lime mortar was applied, so the internal walls were covered from the lower ring beam up to the eaves beam. 

The end gables above the ring beam were just stud partition walls, and they needed insulation too. I had bought a cubic metre bag of fleeces from Donald Ingram and decided to insulate the walls with the wool. First I cleaned it, in batches, soaking several times in warm water and detergent (getting rid of some of the lanolin), rinsing, draining and leaving to dry in the sun (conveniently, in the conservatory and the greenhouse). Surprising how dirty sheep are!

The dry wool then needed teasing out by hand, before packing the wool into bags of plastic netting, spraying it with a solution of borax (supposed to deter insects) and then suspending the 'cushions' in the spaces in the wall - hoping there wouldn't be too much settling with time. After that, a layer of OSB (oriented strand board, or smartply), 50 mm of Kingspan and plasterboard.

Dry-lining the ceiling was a job I was not prepared to tackle myself. Gordon, who was in charge of the work, was impressive; he would support the plasterboard against the rafters with his back, and aiming the screw-gun over his shoulder, fix the board to the rafters in no time. (The screw-gun inserts the screws to just the right depth in the plaster - so difficult to achieve by hand.) I did do the painting - and with the wooden beams against the white ceiling the look of the interior was transformed.

We laid a network of plastic pipes for the underfloor heating, pinned down on the slabs of Kingspan insulation. The weekend before the screed was due to be laid, there was heavy rain, and - to my dismay - the next morning the insulation was squelching underfoot. I went ahead with the screed for the rest of the house. It was pumped into the house as a liquid, and levelled by a man wading through it with a rake.

As for the kitchen, I had to remove the insulation from the perimeter, take down the wooden panels that I'd lined the walls with, and think again. A thick application of Cementone waterproof quick-setting cement, about 30 cm up the walls and onto the floor, plenty of cement behind the posts, and then a liberal coat of bitumin paint over the lot seems (as at mid-December) to have solved the problem, but when the weather is better we will have to excavate around the outside, lay a land-drain, and seal the outside of the walls with bitumin to be sure. Only after a severe testing from a heavy rainfall will I dare to lay screed down there.

Once the screed was down in the living room area, I could prepare for installing the wood-burning stove. I bought a slab of reclaimed Caithness flagstone from Howard Owens, who has a fine collection of stone and timber in a field near Cullen. (It has a square hole cut in the middle, apparently once a window; in Caithness, it's normal to see fences between fields made of slabs of stone, and apparently they made shelters with it too.) Howard trimmed one side to fit the curve of the fireplace. I bedded it down on slightly runny mortar, and filled the hole with mortar. A few weeks later the stove - which I bought three years ago - was fitted. It looks great. I fired it up, and it looked just like the picture in the brochure.

Meanwhile, Sam Green has been installing the electrical system bit-by-bit, and Nick has started on the plumbing. With the stove operational, the house is warm enough to be able to work comfortably on the inside during the winter.

The storage area over the hallway is finished, with a clever design of spring-assisted loft ladder, book shelves on each end wall, and a double faced book stack across the middle (suspended from the roof beams to take the weight off the floor). The hallway itself is almost finished; I laid Kährs Swedish engineered oak flooring, with a clever interlocking system that is much easier than tongue-and-groove. The outside walls are lime-washed and have a pleasant natural cream colour. This is now my office, with a desk, filing cabinet and computer. 

A satisfying project during the early part of 2015 has been constructing a staircase to the gallery over the kitchen. It has to be a spiral staircase, to fit the space available, and Duncan (the architect) gave me some basic advice. The treads are fitted between a post on the narrow side and a wooden panel on the outer side. Strictly speaking, it is helical rather than spiral, and (here my DNA background comes in useful) it starts as a left-handed helix and then half way up turns into a right-handed helix. 

I used Oregon pine (otherwise known as Douglas fir), reclaimed from a distillery and bought from Howard Owens. The beams – about 22 cm wide and 8 cm thick – were the base of a fermentation vessel, and were joined together by wooden pegs. I sliced them both ways to make 4 planks from each, and planed them; there was a wonderful fruity fermentation smell from the cut surfaces.

Each tread has a different shape and size. I made a template from rough wood for each, to fit between a slot cut in the post, and an aluminium angle screwed to the wooden panel. Planks were cut to length and laminated together (using my new toy, a biscuit jointer). [This cuts slots in the faces of two pieces to be joined together, into which are inserted the biscuits – specially made pieces of wood that look just like biscuits – before gluing the planks together.] 

Seen from above, the (bisected) pegs are visible - revealing the history of the wood.

The gallery was virtually finished by fitting the glass balustrade - difficult to photograph as it is transparent, so I left the plastic spacers on. The clamps - satin stainless steel finish, from Raymar Industries, are a neat design and work and look well. 

Outside, a small deck, made of larch (the same boards as were used for the sarking). The part nearer the house was laid in May, and by August (when the rest was laid) has weathered to a pleasant grey.

Inside, the the Kährs engineered oak floor has transformed the space into a real room. I made good use of a beam of pitch pine that I had lying around for 20 years or so; I sliced it up, and managed to get enough pieces to assemble (using the biscuit method for the top) into a (very heavy) table that fits perfectly with the rest of the room.

When the stove was installed, I planned to spray the stainless steel flue with black paint to match the stove, but the man at Stovesonline recommended waiting; the flue would soon turn a pleasant shade of bronze. Which indeed it has.