Monday, September 13, 2010

Building materials

One of the things I have most wanted to write about in this blog is selection of building materials. There are so many materials that go into building a new house. I'm sure I won't be able to list them all, but I'll try to cover the main ones, especially those I haven't talked about in other posts.

Our slab has a high proportion of recycled aggregate and uses Boral Envirocrete 60% Slag/Flyash with 100% recycled mesh. This is the kind of stuff that would never have occurred to me and probably wouldn't occur to anyone except a dedicated green builder. Score 1 to Positive Footprints. Creating markets for recycled products is a huge part of closing the loop. Given that about a third of waste in Victoria is construction waste, it's great to know that our slab is partly made of concrete that might otherwise have ended up in landfill.

The structural pine we are using is treated, but not with CCA. It's something else, but I have no idea what. :)

I have just been reading Linda Woodrow's permaculture book, and I've been chuffed to learn that plants really dislike the heat that radiates out of buildings that have a high amount of thermal mass on the outside. I can afford to be chuffed, because we have none! We chose lightweight cladding products for many reasons:
  • Radial sawn timber and Ecoply for their relatively low embodied energy
  • Zincalume for its zero maintenance, long life span and recyclability (in facilities that exist even now, not just in some hypothetical future).
I do love mud brick and strawbale, but the former was beyond our budget, and the sheer square metres taken up by the latter just wasn't going to work on a block of 363m2.

Wall insulation:

Tontine Thermal & Soundbatt R2.5; CSR Bradford Enviroseal Breather Foil. I particularly love the clauses in our specifications that say things like:
"Batts to fit snugly between framing members with no holes or missing sections. Batts not to be compressed. Any batts removed during construction to be replaced."
Maybe that language is standard in any building contract these days, but with our builders, I can feel totally confident that these provisions will be observed.

Ceiling insulation:
Tontine Insuloft R3.5; CSR Anticon 55mm (R1.5) foil backed blanket.

I also like the bit in our specification that says, "During construction the Builder is to limit any thermal bridging between inside and outside as far as is practical." (Thermal bridging is where heat from outside can get transferred in, or vice versa; aluminium window frames are the best example of these).

Our windows are from Mouldright. Crap name, beautiful windows:

All of our windows are double glazed, most have low E glass.

Almost all of our window frames use finger jointed hoop pine. Finger jointing is basically a way of creating incredibly strong joins between pieces of timber. It means you can make quite long pieces out of many shorter ones and so is a very good way of making trees go further. This was the most affordable timber option for us, but while I love finger jointing, the fact that it is hoop pine does represent a bit of a compromise for me.

Hoop pine is plantation grown. Lots of people might think this is preferable, but personally, I've walked through hoop pine 'forests' in Queensland, and I would prefer well managed, selective logging of native forests over a monoculture every time. Here's a nice article that gives some background to explain my preference:

External doors:
Also by Mouldright. Ours are made of recycled Karri. They're gorgeous.

Other timber:
We are using American off-cuts from another job for the timber nosing on our stairs. Our bannister will be recycled jarrah.

See my post of 16 August:

Colorbond, same qualitities as zincalume. We would have used zincalume, but didn't want to reflect that much sunlight into our (hypothetical) neighbours' eyes.

E0 wherever it is used.

E0 MDF is also being used in our stairs. I don't know if Jeremy found these folks on the basis of doing the right thing, or whether he worded them up. Either way, it's great to know that there are people out there doing stuff like stairs with VOCs and recycled materials in mind.

Plumbing stuff:
We've relied on WELS ratings here. We have installed a hot water diverter to reticulate the warming-up water, but apparently they can all be a little glitchy so they've been installed in ways that are easy to get in and fix. We haven't installed a first flush diverter on the rainwater tank, because Jeremy says he's never found one that really works.

Thanks to PF really caring about the little things as well as the big ones, we are using recycled crushed rock as bedding for our sewerage and stormwater pipes.

Modwood. See

Phew. That's all I can think of for now.

As I said in my last post, I'm running out of topics. I do want to post on the different options we had to choose from to boost our house's thermal performance. And I want to write about what this place is actually costing us. I was also thinking that I might go into the design side of things a little more. So that's three more posts!

But my statcounter seems to suggest people are actually reading this blog, so if any of you have questions or things you'd like me to write on, please let me know.

Thanks for reading.


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