Wednesday, 27 April 2016

quick update and sneak peek

You probably noticed that we have fallen terribly behind with uploading new blog posts. Apologies!!

No, we haven't stopped building. Quite to the contrary! Doing work on the tiny house has taken over almost every spare minute of our lives and unfortunately we haven't been able to finish and upload any new posts recently.

We started this blog with the intension of offering some insights into the decision making process around the nitty-gritty details of planning and building our tiny house. When we started doing research on tiny houses last year, we found lots of blogs full of "pretty pictures" taken during and after the construction phase, but a lack of discussion of the specific challenges that come with planning and building tiny mobile homes. So hopefully we'll have a bit more time on our hands to finish off our drafts on topics such as racking and bracing, why we opted for a ventilated rain screen and why we chose sheep wool as insulation.

A little sneak peek: We have finished the outside of our walls now and it's all weatherproof just in time for winter. Phew!

If you are curious to know what we've been up to recently, have a look at our facebook page, where we are uploading short posts more regularly :)

Friday, 29 January 2016

our roof

Our roof has been on for a little while now and this is how we went about installing it:

We decided to go for the “classic cream” colorbond colour, as it seems to perform pretty well in the hot Australian sun. This table shows a comparison of the thermal efficiency of the different colorbond colours, which means how well they absorb radiant heat (the fancy term for this is "adsorptance"). Not surprisingly, the darker the colour, the more heat it absorbs. While we really liked some of the darker colours, we weren't too keen on having a super-hot roof, so we took our pick between "classic cream" and "surfmist", which have the one of the lowest ratings. The only lighter colour there is is called "whitehaven" but it wasn't available through our supplier yet and we also thought the very bright white might be blinding potential future neighbours. The last thing we want is to be an eyesore to anyone!

Up on the scaffold, getting ready for some roofing!

We got our corrugated sheets delivered together with our custom-made flashings and the pile of roofing material looked surprisingly small! After we put the rafters on, we covered the ceiling with a layer of breathable house wrap, which we will be putting around the outside of all our wall frames as well. We thought it would be a good idea to ventilate our roof cavity, so the hot air will not simply be trapped underneath the corrugated iron. To do this, we raised the battens by a few centimetres with little blocks. Even though every single cm in our tiny home will be valuable real estate, we thought that it would be worth "loosing" 4cm in height to hopefully have less heat coming in during summer. We’ll see how well it works. 

Our ventilated roof cavity. From bottom to top, there are rafters
(not visible here), housewrap, blocks for extra spacing, rafters,
anticon and corrugated sheets (also not visible).

We were a little worried about the chance of condensation occurring underneath the corrugated iron in winter, which could lead to issues such as mold or rot down the track. We got a product commonly know as “anticon” (we got the Knauf brand Space Blanket), which seems to mitigate the chance of condensation under the roof. It sits above the roof battens and below the corrugated iron sheets and depending on what brand you choose, it consist of either fibreglass or mineral wool lined with a reflective foil on one side. 
The raised battens should create a big enough cavity below the anticon for its reflective layer to work to its full extend. Wherever the silver foil touches another material, it will just end up working as an unwanted conductor of heat and cold, instead of reflecting the radiant heat. So we took great care that the anticon didn’t sag too much during installation and hopefully it will stay in place over time.

Cutting the anticon to size
A builder friend advised us to make sure to get the first corrugated iron sheet as parallel to the long side of the house as we could (thanks Zev!) and we put a string line across the front of the house to make this job easier. Apparently things can get out of hand pretty quickly if the first sheet isn’t lined up correctly, as any errors made with the first sheet only get worse down the track.

Aligning a corrugated sheet with help of a stringline.
The first sheets are up - time for some rest!

It took us a little while to get our head around what flashings we needed for the roof. We were a little concerned that our low roof pitch could cause rain water to get into our build between the corrugated iron and the gutter, so we decided to install a gutter apron. This should direct rain water that runs off the roof and that might get blown towards the build, straight into the gutter. We’re still not too sure if that was necessary or not though.

For the other three sides, we picked some standard barge capping and used infill strip to stop water from driving rain also insects getting into our roof.

The little bay roof took a lot of fiddling around and even though it is tiny, it took a lot longer than doing the big roof! We think it was totally worth the time and headache though, as we are in love with our bay window already! 

We calculated that the "standard" treated pine fascia boards available would add up to around 70kg, which we decided would be too heavy. So we painted some of the very light weight western red cedar boards we bought for our cladding and to make them stand out by painting them teal. It just made things a little tricky, as they were bevelled, but we are pretty happy with how they turned out! Thanks to Ines and Tabea for your help :) 

The roof from below. The gaps between the rafters will be filled with insulation
Tabea doing some touch-up work on the fascia boards

Barge capping to cover the ends of the corrugated sheets

The little bay roof

A corner of our bay roof

Monday, 4 January 2016

tie-downs and connectors

Before we started working on the roof, we decided to increase the structural integrity of our frame. A lot of it has been learning-by-doing.
After installing some tie-down fittings (e.g. double-sided stud-ties) we found out about even better ones (e.g. hold-down brackets plus bolts). As it didn’t make much sense to remove the fittings that were already in place, we ended up with a bit of an overkill in some areas.

We used:
  • Threaded rod to connect the bottom of the trailer frame to the top plate of our building. Ideally, the threaded rod should have been made of high tensile steel, as that is common in buildings in cyclone-prone areas. However, we couldn’t find the high-tensile rods anywhere in Perth and as we didn’t have time to ship them in, we thought we’d at least use the standard threaded rod. We thought it's still better than using none at all.
  • Hold-down brackets, bolted through the bottom plate and trailer base and then screwed sideways into the studs.
  • Double-sided stud-ties, to connect the top and bottom plates with the the studs.
Hold-down bracket on the left, two double-sided stud ties, as well as
threaded rod connecting top plate to the trailer frame.
Probably a bit of an overkill, but no point in trying to remove the stud ties now...
  • Speed bracing (which comes in long rolls), to reinforce our little wall at the rear. Ideally, this should diagonally connect the top and bottom plates, but the two little windows on that wall were in the way, so we ended up with a bit of a free-style version. We made sure to wrap the bracing around a corner to connect the small wall with the larger walls, and also to wrap the bracing around the trailer base.
Speed bracing on the rear wall.
The bathroom and loft windows
got in the way a bit!
Speed brace wrapped around a corner and underneath
the frame of the trailer. Double-sided stud ties connect the bottom
plate to the studs.

  • Bugle batten screws in a variety of lengths to connect the structurally important stud connections. We became a huge fan and ended up screw-joining many of our noggins with them.
  • Uni-ties to tie down some of the rafters to the top plate, in particular the rafters at the short ends of our roof that might be experiencing strong wind loads.
A uni-tie wrapped around a rafter.

If we had to do it all again, we would use the nail gun just for pinning, simply to make assembly of the frames easier, and then use bugle batten screws to join all connections of the frames. As tie-downs, we would probably only use hold-down brackets (plus the necessary bolts and screws) and high-tensile cyclone rods. If our windows and wheel arches weren’t in the way, we would have used a couple more of those threaded rods going all the way from the top to the bottom. 
The double-sided stud-ties we used didn’t seem to have a very deep grip and also created thermal bridges bypassing the complete wall insulation.
Speed-bracing makes sense in some situations, but bracing requirements of each wall need to be looked at individually and bracing them with structural plywood sheets, either on the inside or outside, should do the job in most situations. 

We chose the connectors and tie-downs to the best of our knowledge (and from the limited range available in Perth...), after researching what is common practise in timber-frame buildings in Australia, New Zealand and the States. We're pretty happy with how it turned out but wouldn't go as far as saying that this was the best way possible. So let us know what you think, what other cool connectors you have seen or used and how you liked them!

Monday, 7 December 2015

rainy days


Don't try this at home...
The unexpected downpours over the last few days have slowed our progress down a little and we have been busy organising and installing tarps. We were a little worried about our subfloor, as we didn't choose a marine-grade type ply. So we decided to "stay and defend" during the bad weather, which meant quite a bit of mopping.

We still managed to build the framing for our bay windows and to install most rafters last week, as well as building our scaffolding. We will be back on site on Wednesday. Until then we will need to figure out some more details regarding our building envelope. We still haven't decided whether to put our bracing on the inside or the outside of our timber frame. Easy accessibility to install plumbing, wiring and installation if putting it on the outside vs. increased airtightness and reduced potential condensation issues with the bracing ply on the inside... we keep going backwards and forwards between the two options.

Here are some pictures that sum up the last week pretty well.
These will be our bay windows!
Thinking about a roof-top pool...

Saturday, 28 November 2015

raising our walls

The crew :)
Today was a massive day - we've raised our walls! Whoop whoop! We've finally made the step from 2D to 3D and the tiny house is starting to feel pretty real now! Check out this timelapse of (almost) the whole framing process, including insulating the subfloor with sheep wool.

Big thanks to our great helpers Selene, Tabea, Pippa and Jamie! Couldn't have done it without you :)

The first corner is up
Decision-making was a truely communal process. We managed to get all walls
more or less level and square with combined brain and muscle power.
Even a broken wrist didn't stop Selene from helping us!
Done for the day

frames and walls

We've spent the last week framing our walls and it's been a huge learning curve. The second-hand nail gun made things a lot easier than nailing frames together by hand. 

We used H2 MGP10, 90x35mm pine at
a 450mm stud spacing for almost all of
our frame parts
Our timber delivery arrived - and
got rained on straight away. 

We've bought a second-hand framing gun and it's the bomb!
Our first two frames still felt a little wobbly after adding the noggins. A builder at a little local hardware shop recommended the type 17 bugle batten screws. We've become a huge fan of them!! They improved the integrity of our frames significantly, so we went on by pinning the frames together with the nail gun and then adding some bugle screws. 

Skew-screwing a bugle screw
into a noggin

A type 17, self drilling bugle screw

We also used double sided stud ties on some of the studs to account for uplift forces that our tiny house might experience. After all, we are building our tiny house to (hopefully!) withstand high wind loads and earth-quake like conditions during moving.

Stud ties
Double-sided stud tie connecting
a stud to a bottom plate

A bushfire came a little too close for comfort 
Tabea is turning into a badass carpenter!
We divided the long sides into three seperate frames, for easier installation
We worked off the section cuts from our SketchUp model to build
each individual frame

Next, we will be putting the frames together and raising the walls!

Thursday, 26 November 2015


The subfloor is finished and we thought we'd let you know how we went about it. 
We installed 120x35 H3 pine joists to support our floor and attached these with joist hangers directly to the trailer. We could have had steel joists welded in when we had the trailer made, but we wanted to reduce both costs as well as thermal bridges as far as we could, so opted for the timber joists for additional support.
Tabea installing a subfloor joist

We then attached 0.4mm galvanised sheets to support our insulation batts. Even though it was extremely awkward, we decided to install the sheets from underneath. This way we can access the subfloor from the outside, if we ever needed to for maintenance. The 0.4mm sheets were the thinnest we could get and while they do feel a bit wobbly, they are sturdy enough to do what we need them to. Working with the galvanised sheets was unpleasant and noisy and we're glad that we picked timber and not metal as our main building material!

Not very pleasant: 
Working with galvanised sheet 
metal in confined spaces

Very pleasant: 
Working with fluffy 
sheep wool insulation

We painted the plywood that we used for the subfloor with a borax solution before installing it. We read that this would deter termites, but hopefully they shouldn't find their way into our subfloor anyway, as everything below will be sealed and out of metal and H3 (external-grade) timber. We're also not sure how effective the borax solution would be long-term, but we had it sitting in the cupboard anyway and it's a natural product, so we thought we'd just do it. Luckily, the termites here are not as aggressive as up north, so we should be fine as long as we regularly check around and underneath the trailer. Fingers crossed.

Borax mixed with hot water
On the photos you might have noticed that our joists are not evenly spaced. This is because we needed extra support in spots where we'll be putting braces and and an internal wall. Other joists had to placed where the standard-sized plywood sheets for our subfloor would meet, so at just under 1.2m apart.

We left 2mm gaps between the plywood sheets to allow for expansion. In hindsight, we should have added those 2mm to the 1.2m joist spacing. 
We then sealed those expansion gaps with caulk, both to increase airtightness at a later stage and because we were worried about rain or bugs getting into the subfloor insulation during construction. Now that the subfloor is finished, we have a clean slate to build our tiny house on!

Cutting the plywood to size.