The sand/cement (screed) floor is now dry enough to create the floor proper. We’ve deviated slightly from the drawings in terms of construction materials – Jeff describes Howard’s flooring drawing (right) as ‘just a guide’ (I’ll let them fight this out!). So we’ve used the following materials for the floor (from the ground upwards);
screed (with PVA to help it stick to original concrete floor)
damp-proof plastic membrane (stops damp soaking into the rockwool)
compressed rockwool (1 inch)
widthwise chipboard (these last two are for strength as well as isolation)
I’ve just, er, bounced on the floor, and it has that curiously springy solidity that you get in studios – feels like the bass drum/bass cab wouldn’t resonate at all, but there’s a feeling of ‘give’ underfoot.
Here’s a close-up of the membrane/compressed rockwool and first layer of chipboard..
Two and a half metres higher, the roof timbers have been wood-treated (with whatever the modern equivalent of creosote is – I shall call it creosote in tribute to the many Derbyshire chicken sheds I painted with the evil stuff in the 1970s). Artis has now added nearly all the lower-density rockwool – the stuff that actually looks like wool. Rockwool is, apparently, the best material for sound isolation, because it contains a combination of rock and air (as, indeed, will the studio itself ;-). He cuts the stuff with amazing expertise – it’s a millimetre-accurate job because if the slabs are too thin, they fall out of the gap between the timbers; if they’re too thick, they buckle. The control room ceiling is now filled; here’s a picture of it, and of the half-completed live room timbers.
We discovered that the garage was slightly sloping, front to back. No surprise there – it’s a flat roof and the water has got to run off somehow. More mysteriously, the floor was sloping in exactly the same proportion. As I didn’t fancy taking office-chair rides from the control room mixing desk to the sofa (not while anyone was looking, anyway), Jeff suggested that the floor should be completely level. So he’s started at the back of the building where the level is highest, and gradually poured in sand and cement to make a new floor.
On a related note – here’s a link to my favourite application of the moment – the ‘A Level’ is a spirit level for the iPhone. Oh, the lengths to which human beings will go to make a better world…
The roof-raising is now finished – concrete blocks all the way around. The modern blocks we’re using are a lot slimmer than the original (1970s?) ones, and this works in our favour. You can see in the photo how the thin line of blocks at the top is set back from the interior wall, giving us a ‘shelf’ at the top of the lower blocks. This is where Jeff’s going to run the pipes for the (silent) air circulation system.
Meanwhile, the old dividing wall has gone, and the new one is complete. We’re keeping this little ‘stub’ of the old wall as extra support (the rear wall is soil-retaining on the other side) – the stub is going to be hidden by a bass trap in the control room. So the ‘stub’ in the photo is roughly where the left-side monitor speaker will be, in front of the corner bass trap. The music keyboard will go under the window, on the left of the picture, giving line-of-sight communication between keyboard player and vocalist (or drummer). I find this kind of sight/talkback/keyboard communication is really handy when doing a lot of backing vocals (50% of the job is teaching the singer the part IME).
Jeff and Artis are leveling the concrete floors today, but he won’t let me show you a photo until these are complete. Artists, eh?!!
Ceiling now raised by 9 inches. Concrete block going in all the way around. We’re going to keep the whole of the roof (minus the dry rot!). The lintel has also now gone in, above the control room window. There’ll be a row of blocks above this, and the roof timbers will be fixed to the top of the blocks.
In order to accommodate the air handling (and possibly the Sunpipe) we’re raising the ceiling height very slightly. It’s just as well that this was part of the project, because the lifting of the roof timbers showed some unexpected – and unwelcome – dry rot. So we’ll need to replace more roof timbers than originally thought.
Artis has been raising the height of the ceiling using four-inch blocks of wood as spacers – we’ll add a line of concrete blocks at the top soon. Here’s hoping that it doesn’t rain for the next couple of days!
The first thing to go up is the dividing wall – the one-block high line that Jeff’s building at the moment. This is at a slight angle for acoustic reasons, and also to make the control room slightly wider than the live room. The cement mixer here is roughly where the drum kit will be. The main wall in the middle will eventually come down and be replaced by the new one.
In the picture above you can see where the glass wall is going to be. Both rooms will be sealed boxes, and this wall of concrete blocks will provide mass for (mostly low-frequency) absorption between rooms. The physics is all based around the principle that sound travels least well when it has to get through varying densities. So the dividing wall will have a sealed box, then an air gap, then a large mass (these concrete blocks) then another air gap, then another sealed box.
To show the principle further, here (on the right) is one of Howard’s close-up discussion diagrams for the floor, using concrete (floor) ‘jablite‘ (insulation), 2 x ply (flooring) and rubber-backed carpet (click on the image for a larger version).
And here’s the plan – live room shown here on the right of the picture; this shows the angled wall and window position more clearly.
Jeff and Artis, the builders, have made a start. The first part of the project is to move the wall slightly to the left (the live room will be slightly smaller than the control room). So as with all building projects, step one is wanton destruction!