Despite the cladding and flashing not being installed, the builders went ahead and installed the insulation. R4.1 Pink batts to the ceiling, and R2.7 pink sound shield to the walls. This level of insulation gave us a 7.5 star house, so we decided that spending more money to upgrade it to a higher level just wasn’t justified. eg for higher rating on the walls, the wood house frame would likely need to be deeper to fit in the batts – it’s not just the added cost of the insulation. eg R2.7 pink batts 90mm thick, R3.1 110mm thick. The whole structure would have changed. No more 2 x 4s.
The builder told us the insulation would not be for sound, but since Mark is going to use the garage as his wood workshop, we were going to quietly change the garage wall insulation out with a sound deadening one. To our delight, they turned up with the Pink Batt Sound Break. Just as well, because to weather protect it, the installer covered it with silalation foil. All good.
We also planned to fully insulate the garage (the builders were only doing the walls adjacent to the house eg house external walls) to make it more comfortable to work in. And after talking to the builder, we decided to also do the ensuite and bathroom in sound deadening insulation, and somehow that grew into doing the guest/kids wing of the house (added benefit of not losing heat/cold to the wing when not in use), the gym, Mark’s study and then the rest of the master bedroom wall. So the only rooms not to be done were the walk in robe (deadened by cupboards and clothes) and my study room wall – because I don’t care.
The key to the sound deadening is the density of the insulation, unless you’re going for serious acoustic solutions. With a density of 24- 26 kg/m3 the pink batts are pretty good, and we could install it ourselves in the wall cavity, so wouldn’t impact the builders.
To my horror, when we went to buy the insulation, it was out of stock everywhere, and I was told I wouldn’t be able to find it. I finally managed to track some down in North Melbourne, so a quick trip to Melbourne and we were set. As with most building materials, international supply chain issues had led to a shortage, so the locally made Pink batts were also in short supply, replacing imports.
After a weekend of hard yakka, the garage and internal walls of the house are insulated! Nice to have done something to contribute to the build. We did have to pull out some of the insulation the builders had installed, since it was getting wet….