Walls with starw bale insulation

So this March I have been back working on the house alone, this suits me as there is lots of little things to think about and ideas to try out.
We actually only have one exterior wall that goes all around the house, it is 26.4m long and 3m high. The straw bales need some kind of stabilizing, this can be done two ways, they can be pinned down the middle of the bale with really long dowels which stop the bales from sliding against each other. Or they can be stabilized using external pinning, which I had thought to use 3"x1 1/4" (75x32mm) timbers every 35cm, these are nailed to the base and the top of the wall, one on either side, and tied together through the bales with twine.

Base of wall

First to carry the straw bales 4"x2"s spaced the same width as the bales are nailed to the floor joists.

Top of wall with structural beam on left

The top is a lot slower as a birds mouth cut needs to be taken out of the roundwood rafters. And then a timber is fixed from the inside top piece to the roundwood beam of the structural frame.

Top from the outside

Then the external pinning 3"x1 1/4" (75x32mm) is nailed top and bottom. These make building the straw bales a lot easier as there is a surface to place the bales against.

10 bales standing in place, feels good to be looking at them!

 We made a trial of placing the bales, each one is tied by the strings to the outside as they are laid. Only 9 fit in leaving a 230mm space for the last 300mm bale, then the bales are compressed using heavy duty ratchet straps until I was scared about the ratchet failing from the pressure! The last bale just fits in with a bit of shoving and pushing and the straps are released.

We now have a precompressed bale stack, looks like it works. Yay!

 I want to add some extra stability to the walls as I noticed there was some movement when we finished the structural frame. This stopped when we put temporary 5"x1" X braces between the posts. Our engineer Esa suggested doing a yurt wall type lattice. We will probably be doing this, I just have to decide if it will go on before or after the bales. Easier to do the bales first but then harder to do the lattice, or easier to do the lattice first and harder to do the bales? I'm going to do some trial sections to try it out.
I realized the last bale can only be fitted from the inside because of the sloping roof, so that's decided then we will build the lattice after the bales.

Views from above

We had a reporter and photographer come to make an article about our project. The photographer had a copter/drone that he took these winter pictures with.

A picture of our place from right above. The blue circle is our house (covered with a tarpaulin), next to it building wood under cover, to the left of it some trees, the outside toilet on the edge of the few trees, all the way to the left the piles of fire wood. Closest to the top of the picture a pile of building wood and close to that the play house. To the bottom of the photo there is the driveway up to our yard. To the right (south) of the house there will be our garden with berries. Picture/Kuva: Aleksi Jalava/Iltasanomat

 

Picture taken from the south so here you could see our well and garden if it wasn't covered with snow. To the right here is building wood under cover.  On the east side of the house you can see the completed tin roof. The rest of the roof is covered with a tarpaulin and the sides are covered with recycled plastic to keep the snow out of the house for the winter. To the east we have young spruce forest on a uphill, to the west we have really young mixed forest with mostly birch on a downhill. Picture/Kuva: Aleksi Jalava/Iltasanomat

 

 Picture taken from the north. In the background you can see my dads vegetable farm. When we are in our yard we are not able to see the fields through the skinny forest. Picture/Kuva: Aleksi Jalava/Iltasanomat 

This picture is taken last summer from the roof of our house. It shows the few trees we have between the house and the fire wood piles.

 This is taken towards north. Playhouse and in distance building wood.

And this is taken towards south. There is our water well surrounded by earth that our helpers moved to make the ground higher because the ground around the well was in a depression. So now the rain water does not run down hill straight to the well and will hopefully flow away because of the uphill it meets before the well. You can also see the area that will be our back garden.

How far we got on the roof in 2018

So we continued on working right up until Christmas again last year in an attempt to get the roof finished before the winter, but as you will see it did not quite get there. All of the major structural stuff is done but only one third of the roof is covered with used corrugated galvanized sheets. We chose to use the metal sheets as they have a lot less work involved than the aspen shingles we were planning on. 

 Scale model of roof

I changed the shape of the dormer windows to better suit the metal roofing sheets, thus avoiding lots of joints between different roof surfaces meeting. I made a scale model of the roof to try out some ideas and decided on this shape which divides the roof into three somewhat flat surfaces. All the cuts on the sheets are at about 45 degrees which reduces waste. So we end up with pointy topped dormers instead of the more curvy eyebrow shape .

Our minimalist scaffold with dormer roof windows to the sides

First we fixed the soffit boards to the overhanging part of the roof. These are 1 inch sawn boards with natural edges, we first scorched them with a propane blow torch to give some more resistance to insects and rot protection, and they look nice too. Then cut and nailed them all around the roof. They will only be seen from underneath.

Soffit boards with wind protection layer above

Next the dormer windows, fixed on to the wall beam a 5"X6" frame carries the central rafter which is the same design as all the other rafters. Then 4"X2" jack rafters run at right angles from the central rafter to meet the main roof surface. Then we built a small stud wall each side to make the space for the insulation and to give intermediate support to the jack rafters. The jack rafters we needed to fix temporarily because they had to be lifted for the wind protection membrane to run underneath, this was a bit awkward and slow, I would have liked to avoid this but could not come up with a better solution.

Dormer window from inside

Jack rafters

Then we get to start covering up! Wind protection membrane, 2"X2"s fixed horizontally at 800mm centers, 2"X2"s vertically along the run of the rafters, these make up the recommended 100mm ventilation space. Then water protection membrane, 2"X1"s vertically, 4"X1"s horizontally spaced to suit existing holes in second hand roof sheets, and finally cut and screw on the corrugated galvanized roof sheets. Yay!

 

 Membrane layers and ventilation space

Nearly ready for metal roof sheets

So we got one of the three main sections finished and the tarpaulins covered the rest of the roof. We put up a plastic wall to keep the snow out and then took a long rest!

House from the east