Renovating the house

Fact sheet for our house

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We’ve had a number of tours visit our house, most recently, a group organised by Marrickville Council. While we haven’t done anything truly extraordinary, I know from personal experience that the most helpful thing can be sharing the little details, such as what materials to use, where to source supplies, or what contractors to use.

So to help with this, we provide visitors with a fact sheet (PDF), containing a summary of what we’ve done. Hopefully you’ll find it useful too!


Constructing our chicken coop

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Our three girls, happily clucking around the chicken run.

With the house renovation essentially finished, our attention has turned to the garden. The highlight so far is adding chickens to our family, an essential part of any inner-city permaculture system.

The photos in this post show key steps of the construction process. This is one massively over-engineered chicken coop, which all comes down to the mindset you have when starting the project. If you’ve come from a bit of light DIY, then you build something simple. If you’ve come from six months of building a house, as we have, then you build … a small house.

The upside is that, following the grand tradition of backyard coops, it does mean that all the left-over building materials can be recycled into the coop. It should also last for a while 🙂

A few construction notes:

  • The coop sits on a base frame of recycled hardwood, 500mm above ground level. This gives some protection against rats, termites and general rotting. It also gives the girls somewhere to shelter from the sun and rain, and they spend a lot of time napping under the coop.
  • The coop is quite high, for no real reason other than avoiding the need to crouch when cleaning it out.
  • The nesting boxes are made out of recycled eco-ply from the kitchen, and they give easy external access (for when they finally decide to start laying!).
  • An old curtain rail provides a roost, and they happy put themselves to bed each night.
  • The coop is connected to a chicken run beside the fence. By working against the boundary, only two new fences needed to be built.
  • Learning from the nuns next door, the run is built like fort knox, to protect against foxes (oh yes!), rats (heaps) and scavenging birds. This includes aviary mesh on the sides (tucked underground and weighed down with old concrete garden edging), and chicken wire across the top. Every gap has been plugged to the best of our ability.
  • The feeder and water are all suspended off the ground, again for proof against rats.
  • While we lock them up in the coop each night, the run is secure enough to leave them out if we have to go away for a week.

We now have three chickens happily clucking around. Two Isa Browns, and a “something else” (inherited from relatives). No eggs as yet, but the Isa Browns are still very young, and the older bird was moulting when we got her.

And now for the construction photos…

The base of the coop, with recycled hardwood legs and a floor of reused yellow tongue construction flooring. 1.2m x 1.2m
Framing for the walls, just like a house 🙂 Made of reused 90×45 oregon and pine.
The coop moved into place beside the fence, before it gets too heavy! The back wall has gone on, and the first window constructed.
We had left over insulation, so might as well use it!
The construction of the nesting boxes, made from eco-ply. Apparently you need one per five chickens, so we have room for the flock to grow!
The outside being clad in Weathertex watherboards, to match the house. Ok, we know that’s going overboard!
Almost there! Just the inside walls to be done, reusing some left-over plywood sheets.

Contructing a reverse brick veneer wall

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Layering of the reverse brick veneer wall -- 9 layers in total!

A key part of the design for our house extension was increasing thermal mass, which helps to keep the house cool in summer, and warmer in winter. Two major elements contributed to this: the rammed earth wall and a reverse brick veneer wall.

Of these, we were expecting that the rammed earth wall was going to be the wacky-difficult-to-build element, but it proved easy. In comparison, I’d been reading about reverse brick veneer walls for ages in the green community, and was aware that they are widely used in places such as New Zealand.

And in general, they are simple: you put the single brick wall on the inside, where it provides valuable thermal mass, and you put the highly-insulated wood frame on on the outside. In otherwords, the reverse of a traditional brick veneer construction.

Surprisingly, however, when it came down to finding out exactly how to construct the wall, I came up short. I could find no clear diagrams on the web, nor was this type of construction covered in the books I had on hand. No builder I talked to had ever done one.

So we worked it out ourselves, and in the interests of sharing our experiences, this is what we did:

Layering of our reverse brick veneer wall

From the inside to the outside:

  1. Gyprock. Traditional plasterboard inside wall surface, nothing unusual there.
  2. Single brick wall. This is constructed in the usual way, and isn’t load-bearing. It’s anchored to the wood frame via brick ties (lots of them!).
  3. Air gap. This is one of the key elements of the insulation, just like a normal cavity brick wall.
  4. Wood frame (4a) and bulk insulation (4b). The wood frame is completely run-of-the-mill, and is a load-bearing structure. Inside the frame, we put Grenstuf R2.5 wall batts, which provides the bulk of the insulation.
  5. Reflective insulation. Air-cell Permishield provides a layer of reflective insulation, helping to keep radiated heat off the inside layers.
  6. 20mm batons. The reflective insulation only works when there’s an air gap, which we created via batons nailed through to the wood frame.
  7. Gyprock Fyrchek MR. Unfortunately our side wall was closer than 600mm to the property boundary, making it necessary to meet fire rating standards. Thus the layer of fire-protecting Gyprock.
  8. Wallwrap. Strictly speaking, the Gyprock Fyrchek isn’t weatherproof, despite the “MR” rating. So we added a cheap wallwrap, as per Gyprock’s installation instructions.
  9. Weathertex weatherboards. Finally, the outside cladding!


Some notes

  • This is a lot of layers! There were a few different combinations possible, particularly relating to the Air-cell Permishield (inside the stud wall, air gap inside or outside). I think we made the right decision, but your circumstances may vary.
  • The requirement to have the wall fire-rated added a bit of complexity.
  • This type of wall is thicker than a traditional double-brick wall (with or without a cavity). So be warned, and factor this into your designs from the outset.
  • Make sure you seal the top of the wall (against the weather) as well as the bottom (against bugs). All the air gaps could otherwise cause problems down the track…

The good news is that this type of construction really isn’t any more effort than a traditional brick veneer, and it should pay us positive dividends for the lifetime of the house. As opposed to “normal” brick veneer, which is perhaps the most foolish possible building technique for the Australian climate…

Kina sea-urchin light

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We recently purchased a Kina light for our newly-renovated dining room, “Kina” being the Maori name for the local sea-urchin. It was designed by David Trubridge in New Zealand.

The light came as a flat-packed kit which reduces freighting, and only took an evening to assemble. It is made from plywood from sustainably managed plantations, and the inner surface is painted orange (other colours are also available).

It makes a great centerpiece above our dining table and when the light is on it throws patterns across the room. Due to the story behind the object + the environmental aspects + the design I’d have to say this is one of the best furniture purchases we’ve made for our new extension.

More photos of our eco-kitchen

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Thanks for the positive feedback on our kitchen — we like it too! For those who want to see more, here are some further photos of the kitchen, providing a more complete view…

The main work area, with a gas stovetop, and a rangehood that exhausts sraight outside
Double sink and a view outside to the garden and neighbouring trees
Two ovens: a conventional electric oven (below) and a combined steam/conventional oven (above)
The breakfast bar, with three LED pendant lights
View into the kitchen, with the rammed earth wall on the right

Details on our eco-kitchen

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Key elements of our eco-kitchen (click to see larger version)

Our kitchen has ended up a little out of the ordinary. Starting from a clear focus on low chemical use and simple materials, we’ve made a few decisions that might be interesting.

The key points on our eco-kitchen:

  • We’ve completely avoided using melamine-covered particleboard (“whiteboard“), as this  emits huge amounts of volatile organic chemicals (VOCs), is considered industrial waste when the kitchen is taken apart, and can’t be recycled. This is truly nasty stuff.
  • Instead, we used an E0 FSC-certified birch eco-ply from Finland (of all places!). “E0” indicates the lowest level of VOC emissions, and this ply has every certification going. It’s also a truly beautiful material.
  • The inside of the cupboards are protected with shellac, a lot friendlier than many of the artificial sealants.
  • The benchtops are unsealed solid kauri, with experience in other kitchens showing that while they wear and mark over time, ongoing gentle cleaning keeps them looking beautiful.
  • The cupboard fronts are solid kauri, painted with low-VOC Haymes paints (no two-pac polyurethane coatings here!). In addition to being much better for the environment, the semi-gloss paint gives a much softer and warmer feel to the kitchen.
  • The walls and ceilings are also painted with low-VOC Haymes paints.
  • The floors are solid kauri floorboards, with a tung oil finish (no polyurethane finishes again).
  • LED lights are used throughout, including the downlights in the ceiling and the strip lighting under the upper cupboards.
  • The large servery window (which can be opened onto the deck) and the upper window behind the cooktop both bring in lots of natural light, reducing the need for artificial lighting.
  • The moving glass is double-glazed, while the fixed glass is triple glazed.
  • The fridge (brought from our old house) was purchased as the only 5-star efficient fridge at the time, slashing our electricity bills.
  • There is an under-floor vent beneath the fridge to draw in cool air (increasing efficiency by up to 20%), with a wall vent that goes into the pantry cool cupboard (more on this in a future post).
  • We chose a water and energy efficient Miele dishwasher, installed new as part of the fitout.
  • We have an on-bench compost bin, collecting scraps for the big compost bins and worm farms outside. There is also a recycling bin inside one of the cupboards.
  • There’s a walk-in pantry beside the kitchen, which is cool and dark (also to be covered in a future post).

We love the kitchen, and it’s both practical and beautiful (we think).

As it turned out, commercial kitchen companies couldn’t cope at all with our requirements. So we had it made by a local craftsman, Ian Thomson (see his website for more on this work).

While it isn’t a cheap option by any means, we’d highly recommend going down the route of a bespoke kitchen, as it gives the time and opportunity to really refine what will be delivered.

Six types of insulation in our new house

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Our six-month renovation process finally draws to a close, and now that I’m not working so hard on the house, I can catch up on our blogging about the key environmental details.

A good starting point is a summary of the insulation that went into the house: walls, roof and floor.

Our insulation choices

  • RoofPolyair Multi, a multi-layer combination of reflective foil, foam and bubble wrap. 9mm thick, it sits directly under the corrugated iron roof.
  • CeilingR4.0 Greenstuf batts, which are conventional insulation batts but made out of recycled plastic rather than fibreglass. Manufactured in New Zealand.
  • WallsR2.5 Greenstuf wall batts, fitting into the standard studwork walls. Then R1.6 Air-cell Permishield wall wrap layered under the outside cladding, with a 20mm air-gap to allow the reflective layer to work properly.
  • FloorR1.5 Greenstuf underfloor insulation rolls, under the wooden floorboards (the house sits on piers, as is typical in Federation houses in Sydney).

So that’s six types of insulation from three different manufacturers. In each case, we looked at a range of options, and picked the one we felt would give the best outcome for a reasonable price. While there are undoubtedly a large number of possible ‘right’ choices, it shows that there isn’t a one-size-fits all product (or even manufacturer).

How does this compare to typical insulation?

This is a lot more insulation than a typical Australian house (although only a fraction of what would be installed in colder European or North American climates).

It greatly exceeds what we were required to do according to government regulations (BASIX), but more on that in a future post…

How much did it all cost?

The total spend on insulation was approximately $3,800, for a 100m2 extension. That probably seems like quite a lot, but it all comes down to the payback period.

The house had underfloor ducted gas heating when we bought it, and this will be extended to the new portion of the house. The better insulated the house is, the more warmth it will retain, and the lower our gas bills. But exactly how big a saving — hard to tell.

What we can be confident of is this: we don’t have air conditioning, and we won’t be needing it. So that’s an up-front saving of $3-5k in avoiding the purchase of an aircon unit, and then the yearly savings on electricity from that point onwards.

So the payback period: immediate. A sensible use of our money, we think.