And they huffed and they puffed...

We had the strawbales for our house delivered in mid December last year and there was a bit of huffing and puffing getting them unloaded from the truck and stored under cover. Would you believe that we had rain while we were unloading the bales from the truck, thankfully it was only light. On the morning there were 5 of us to unload the ~250 bales so it didn't take too long.

Now we have the bales it was time to start putting them up. There are a few ways to make a strawbale house each with advantages and disadvantages. We chose the framed house with infill walls type of building. One reason was because our outer straw walls are reasonably complex and we didn't want the stress of having to get all the walls up and roof on before rain (this usually involves getting help in to get it done quickly). The downside with infill walls is that you end up with a gap at the top of the wall and roof that needs to be filled (but i'll talk more about this once we work out what we are going to do with our gap).

The strawbale wall is basically made up of a bottom plate, strawbales and then top plate with straps from the top to bottom plate to compress the walls. All our outer straw walls are curved, which adds some extra complexity.

The bottom plate does two things, it raises the bales off the floor to give you a moisture gap and it gives you a solid base to compress the bales against. For the bottom plate we ended up using 90mm x 45mm pine framing timber made up into frames that are 450mm width (the width of the strawbale) and trapizoidal in shape with the long edge 1000mm long (just over the length of  bale). These were dynabolted to the concrete with 4 bolts each so that the frame followed just inside the edge of the concrete slab. Short pieces of strapping were then slid under the frame through notches made before bolting the frame down and the space in the frame filled with 25mm blue metal (bluestone gravel) so that the bales don't sink into the frame.

The door frames were dynabolted to the floor, nailed to the bottom plate and attached to the ceiling with a block that was glued and screwed. The door frames were made up of 2 bits of 90mm x 45mm with noggings (like a ladder) and then a piece of 12mm structural ply glued and nailed to brace it and to give the strawbales a solid end to press against.

The window frames are made like the bottom plates and the door frames, they are designed to sit inside the bales. We will probably attach the windows to the ceiling to add stability to the walls. The windows are curved with the walls. We also designed to windows to fit within a bale width. Later on the door and window frames will be lined (most likely with floor boards).

We have half a wall to finish as of writing this post then we start on filling the gap between the top of the straw wall and the ceiling.

The Design

Well, we've been talking mostly about building the Round Strawbale House so far, but since there hasn't been a lot of building happening lately I thought now would be a good opportunity to show the house design and talk a little about it (I hope to write detailed blog posts in the future about each of the design elements mentioned below).

As you can see from the plan that the house roof line from the top view is a regular decagon. The reason we chose this shape is that we wanted a round house but making an actual round house has it's difficulties, so we squared off the edges and chose the decagon because for the size house it gives a beam length of ~6 metres between the outer posts. Any timber above 6 metres starts to become exponentially more expensive and the bigger the span the bigger the timber cross section. There is a balance between the number of posts required and beam length.

An important design aspect of the house is the sunroom located on the north side of the house. This room covers two outer segments of the building. These two segments are different to the rest of the roof in that they only have roof cladding to just past the inner ring of posts (the overhang will be about 1.2m to shade the entrance in the hottest part of the year in January/Feburary for where we live in South Eastern Australia). This room opens into the living room, one of the bedrooms and the bathroom with the idea of using the sunroom in winter to passively heat the house. The sunroom can also be used to cool the house in summer by drawing air through the house from the south side which will have shade trees.

The next thing you will notice that all the outer walls are strawbale which have a wall thickness of 500mm, this provides a good thermal barrier to reduce heat loss in winter and heat gain in summer. The inner walls are mudbrick and will most likely be between 150mm-200mm, the idea of this is to provide internal thermal mass to keep the house internal temperature relatively stable. The outer walls are all quite curved and do not follow the roof line. This was done for aesthetics, to provide interesting nooks and crannies around the house and because I like to give myself a challenge in building. If you're going to build a round house, might as well make round rooms.


The living room and kitchen are combined into one big room (which is round) in the centre of the house. The idea of this is that the main room in the house is insulated from the outside by the other rooms except to the north which opens up into the sunroom. The kitchen will have a combustion stove that will have the capability to heat our hotwater service and to run a hydronic heating system required. If extra heating is needed then we will locate the radiators for the hydronic heating in the outer rooms. The kitchen shares a wall with the bathroom and is close to the toilet to reduce the plumbing required.

We spent a few days last week on putting up the fascia(6m x 300mm x 35mm) and are currently getting ready to put up the purlins (have got bolts, brackets and timber only need time).

Location, Location, Location!

Location is a very important part of building a house, and probably one of the most important when building a sustainable house  Its also one where some important factors are often ignored. It is one of the cheapest ways to improve your house efficiency since where you place it can have a big impact on heating/cooling. I am going to discuss location with regard to building on a piece of land that is already purchased.

The factors that dictate where you build will change depending on your latitude and local climate. Some common location factors here in Victoria that are usually taken into consideration when building a house are:

1. the view - important to some people, I personally don't mind taking the time to walk to a place on the property to admire the view (on a good day we can see Western Port Bay and Wilsons Promontory National Park), it makes it more special.
2. access to the road - it can be cost prohibitive to build a good long track, but the benefit's are privacy and less disturbance from local traffic.
3. distance to services, ie. telephone and electricity - this can have a major impact on the cost of connecting to public services, running power/telephone a long distance increases the cost of earth works and the cost per meter of cable for power, and could require 3-phase connection depending on load and length of cable. For us this wasn't even a factor since we had decided long ago to run of our own power (solar and wind) and are successfully using mobile broadband and voip for phone.

The major factors that WE used when choosing a location to build our house on the property were

1. has good sun access in the winter (when it is needed, our winters are quite mild with some snow every couple of years) - this is important for passive heating, you do not need to face the front of the house north, just have the big windows facing north (with adequate eaves to shade out direct summer sun).
2. protection from strong winds - this can be negated by planting trees and building shelter around the house, but why do that when you can do the same with less cost by good placement. The last thing you want is to be blown away as you step out of the house. The other thing with an exposed house is that the wind will cool it down, a sheltered spot will naturally have less heat loss.
3. use of natural environment - for us the site has a hill to the east which shelters us from the wind. The other side benefit of having the hill next to the house it that it will be the perfect place to put a water tank on top of to supply the house (by gravity, avoiding the need for electric pressure pumps).

There are other factors that you need to be aware of are the local council building regulation that dictate setbacks from boundaries, creeks etc. This is important to know when buying a property as a spot that you think would be ideal to build on can be excluded by these laws, which usually are very strictly enforced (some for good reason). For us, we are located in an erosion overlay in rural Victoria. We have a creek starting in the middle of the property which has a setback of 100m and a 20m setback from the boundary which severely limits the spotsp where a house can be placed. We picked out several possible house sites at the time of purchase based on setbacks and flat spots that would minimise earth works (and hopefully house footings).

After buying the land we then spent the next few years assessing the different house sites based on weather conditions at different times of the year, during the extremes, summer and winter and the change in autumn where we get strong westerly winds. We noticed that when we got the extreme winds that one of the sites was sheltered (a big plus to that particular site). We were not keen on building near the road as privacy was a consideration but one thing that we noticed was that passing traffic on the dirt road during summer causes a large dust cloud that would cover anything near the road in a thick layer of dust (a big minus for any site near the road).

The extra benefit of the sheltered site is that the hill that shelters the site is ideal to put the solar panels and a water tank on top for gravity fed water. This eliminated the need to run a water pump whenever water is need in the house. Water will be pumped up using an electric transfer pump running straight off the 12V DC battery bank.

The other thing to watch for when choosing a location to build your house are pockets of low land which can trap cold air and frost during winter, the stability of the land. We are building in an erosion overlay and the surrounding area has visible signs of land slippage. This can increase the cost of house footings considerably and the last thing you want is for your new house to be split in half by moving foundations.

My personal 'favorite' biggest house location mistakes are facing a house's main windows west (closely followed by south). Which means you have the hot afternoon sun shining directly in, and the only way to avoid the sun is to block it. Also building on top of a hill where you are exposed to the elements. If you do want a nice view then the choice of property is very important because it's very hard to enjoy the view when the sun is streaming in through your nice big windows on a 40°C day or you get blown away by the wind every time you step outside you house in autumn.

Other important topics of location are with regard to location of windows and rooms in the house which will be discussed some time in the future.

To finish off here is a picture of our house and a description of its location.

As seen from the hill next to the house site

This picture was taken in the morning. You can see from the shadow that west is to the top of the photo (you can see the road which is one of our boundaries), north is to the right, south is left and the photo was taken with me standing on top of the hill to the east of the house.

The 'front' of the house is to the north, where we will locate the sun room for passive solar heating in the winter. The west side has the bathroom, toilet and a short hallway(storage area). The bathroom will have west facing windows but we will have a treed outside area to shade the windows in hot summer evenings(we are may make this outside area accessible from the bathroom). The hallway will have a narrow long window facing south west for light and a view of the paddocks to the south and west (this window will most likely be one that is tinted and has high IR blocking).