More progress than expected was made this weekend after some luck with Freecycle, Gumtree and Ebay.
Guessing there were people in the area with surplus concrete blocks, gravel and hardcore/sand, I hit the web. Lots turned up but only a few were suitable candidates. I used my Friday morning to collect three items and picked up the last on Sunday.
In the end I ended up with:
Total estimated saving of £200
I also put the 2-4 tonnes of soil (estimate) that I moved to the front of the house on Freecycle and a friendly couple in a ‘73 VW camper van turned up to take two trailer’s worth away. This was another saving over having it removed for ~£100.
I need another 10 or so blocks, as does a friend who’s helping with the build, well he needs nearer 40. So I’ve followed up with another offer for 50 blocks delivered for fuel cost only.
Still looking for:
The fun part on Sunday came when I tried to level the first blocks. Using a blob of mortar and a fair bit of tappety-tapping I managed to get a block on the pathway level, with the help of a friend. Using his laser-level (also have a string and string level to check that against, no batteries required!) we got another block lined up to it. This block was in a shallow pit, lined with the hardcore/sand mix. Then the rains came so we called off play.
But I have the method now, so will set about levelling up as many as I can this afternoon after a freelance work session.
Now there was the question of whether or not I should have moved 30 barrows of soil, or just raised the front end of the office up, but I didn’t like the idea of it sitting 2ft off the ground, plus that would have meant losing height as the regulations say 2.4m to the eaves, 3m to the roof pitch. Which will be our front. So at least this way it’s nestled into the garden that bit better.
Adjusting the design, with said friend’s help, we’ve managed to lose a row of blocks, with the 6x2s now being supported on 4 rows instead of 5, with the reasoning being that the same rafters can support room-weights in a house on just 2 supports, one at each end. With a bit of tying and noggings it should be a very solid framework to start from.
We may be at the stage of ordering the timber for this weekend later in the week, all being well. Meaning the build can start in earnest. I just have to sort out the drainage around the back and side of the office, which means at least a tonne of gravel and membrane, before building the base.
I think I’ve found the solution to the moisture question set out in the last part… the section will go, from inside out:
As simple as that. Adding a moisture barrier before the rockwool on the inside would stop the building from breathing, if I’m not mistaken, and cause condensation on the inside of the wrap. Still in two minds about the inner wall - plaster looks nicer, but OSB is much more useful and robust to drill into and attach things to. I’m now wondering what painted OSB would look like…