Culburra Hemp House: Parapet walls and tricky formwork

Last weekend we finished another wall up to ceiling height - the back wall of the main pavilion. This wall abuts the roof over the hallway and I knew it would be a difficult section. The over flashing for the hallway roof is already installed and finishes about 55mm- 60mm from the frame, the same distance that my form work needs to be from the frame. This meant that I had could not fit the form work sheet at the required 55 mm distance out from the frame. I trimmed one of the battens from the hall roof by awkwardly sawing upside down, then fitted the timber form work as close as possible and filled the gap with a bit of left over Jointex (stiff joint) from my concrete slab. The lightness of the hemp meant that the Jointex that was just wedged in place was not pushed out when the hemp was tamped.

Form work around parapet wall

Jointex filling the gap in the form work

Form work well fitted on top of over flashing

Some heavy rain and no downpipes meant that the rain and mud, under where the down pipe will be, splashed up on the hemp wall. The water did not soften or damage the hemp wall at all and it remained as hard and solid as the other walls.

Rain and mud splashed on the external wall

Completing the back wall meant working up to ceiling height. With our experience from the first wall we did this on, we did the last part of the wall in three stages. Firstly filling up to where our arms could just get into the form work, then raising the form work up to the full final height on the outside and just below the bottom of the top plat on the inside. We then filled under the top plate and up to the top of the top plate on the outside of the wall. Finally we moved the inside form work up to ceiling height and filled the remainder of the wall, going over the top of the top plate as the cut away in the eaves rafters has meant that the outside of the wall finishes above the top plate.

Filing under the top plate

As well as finishing the back wall of the main pavilion we did more work on the small sections at the front of the house and around the front door, which is yet to have the roof above it finished.