Render Update

Well, we finally finished the first coat of render on the outside of the strawbale walls on new years eve and we are pretty happy with the result. Our technique in mixing the mud and applying changed as we went along.

We actually ended up taking longer in putting the mud on the walls by about halfway around and taking time in making sure the render penetrated the bales for good adhesion. This was done by pushing the mud into the bale wall with thumbs and fingers, I would estimate that we got around 50mm penetration and you can tell the difference between the earlier walls and the later walls. The other advantage of working the render into the straw was that the render mix changes as it is worked, it is actually hard to explain but it is certainly noticeable when doing.

In mixing the mud we ended adding the sand and then clay and then water to a wetish mix (not too wet) and then mixing the sand, clay and water with a shovel. Once mixed only then add the straw which dries the mixture slightly. We also often left a wheel borrow load of mixed sand, clay and water without straw overnight.

The next step is to build and install the window and door frames. For this we are using 140x35 hardwood planks for the window frame and 140x45 for the door jam sourced from a local sawmill. We are using 4 edge joined to make a single ~560mm plank. The planks are joined with floating tenons at about 200mm spacing and glue, the boards are clamped using homemade threaded rod clamps. I did initially use some Irwin Quick Grip clamps but while being quick were not able to apply the required pressure, while the cheap homemade threaded rod clamps apply more than enough.

Because the walls are curved the upper and lower planks have to be curved, to do this we make the plank as above. Once the glue is dried (left overnight) the outer curve is marked through the center of the board and a jigsaw is used to cut it, the two pieces are then swapped and joined. Once the join is dried the inner curve is then marked and cut. You just have to make sure that the initial plank width is the desired width plus the difference between the inner and outer curve. You can see one of the curved pieces in the picture below.

I have currently joined enough timber to make two door jams and one window and hopefully in the next week I will put together the first window frame.

As we put the window frames and door jams we will also be able to apply the next coat (may end up being final if good enough finish) of outer render which should come upto the frames with a ~10mm overhang. We are hoping this coat is easier to apply, at least there wwill nt need to be any working the mud into the bales.