morehawesTiny House Construction – Week 1
Posted on 01/02/2016 under My Tiny House Project
This trailer needs a house on it
Getting set up
Waking up on the morning when I took possession of the barn (where I will start the build) it felt like my first day of school, or a new job. When I mentioned this to Carly over breakfast she commented that really it was both! There are many reasons why I want to build a tiny house, a big one of them is to try out a different kind of work, to get away from sitting in front of a computer. I was excited, I am excited. I am building in a barn because it rains a lot over winter in the Pacific Northwest… and it’s January. Once I was able to get in to the barn and assess what I needed to do to get set up, I found that it was a little more than I had expected: the lights didn’t work, the roof leaked more than I had anticipated (luckily it had rained the night before so I knew where the worst leaks were) and the gate which needed hanging to secure the space turned out to not be big enough to space the width of the barn. Luckily I figured something like this might happen.
The barn ready to go
Who needs a ladder when you have a van?
Tarp set up to redirect one of the worst leaks
Finally moving the trailer out of the driveway
Build Day 1
I woke up early so I could get a good start to the day, having planned for a slow start on day one. The barn is conveniently located very close to a local builders merchants/lumber yard so this was my first stop of the day. I filled the van with 2x6s and started preparing to build the framing which would make up the house floor.
I raised the trailer up on it’s levelling jacks ready for work
Blocking which will support the subfloor
Build Day 2
Then weather today couldn’t have been more different than the day before, with clear skies and sunshine. I was thankful to have Carly helping me again today, so we again achieved more than anticipated. I managed to finish the three floor blocking sections and with Carly’s help we did half of what will act as the insulation support. I decided to raise the floor blocking about an inch and a half off of the trailer base as I was concerned in the potential for it sitting in condensation on the cold metal (the trailer is sealed at the bottom by a galvanised bottom pan). The insulation I am using is water resistant, but I didn’t like the thought of it sitting in water, and as my dad taught me: “if you are going to do something, you may as well do it right”. As the blocking is suspended I used joist hangers to make up the blocking, this also meant that the insulation would have an air gap underneath it with nothing to support it.
Carly finishing of attaching the insulation supports to the first of three blocking sections
Build Day 3
Today started with visiting shop after shop to gather materials and equipment for the build, which I am learning always takes longer than I think it will. I had to do some non tiny house related tasks this morning (the house isn’t going to pay for itself you know), so I was very eager to get working on the house in the afternoon. Looking forward to putting in hours of hard work on something you are enjoying it a nice feeling indeed, and not one I have felt for a while.
Buying insulation. I should have chosen a bigger cart
Using clamps to hold the blocking in place so holes can be drilled to attach it to the trailer
Build Day 4
I woke up with something called ‘thermal bridging’ on my mind, I guess this is my life for the next year. My trailer is metal, but I am building a wooden floor in it. Wood transfers heat quite well, so this connection will act as a cold spot in the house, sucking out the heat, known as a thermal bridge. To stop this, you need to put something between the two materials to avoid direct contact. I had seen some videos on how to avoid this, which involves adding a tin layer of insulation was added but I for some reason had decided this wasn’t necessary. This morning I decided it was, so I had to scramble to find the materials I needed. Luckily I found some underlay that I thought would do the job, and upon taping it to the trailer I was happy with the result.
Blocking in place (again), this time with extra insulation
Showing the foam underlay which prevents the metal and wood touching
I am so enjoying this blog!! It is so interesting and brilliant!! You kids are awesome!! I can’t wait to come see it myself. Big hugs and much love. xoxo
Thanks Ruth, yes it has been great fun so far. I’m looking forward to having an extra pair of hands to help out 🙂
Joe
Looks awesome Joe! Wow can’t wait to see it in a couple weeks. I think any time different materials meet like wood on steel is a great place for condensation, so a great idea to separate them. Do you put a vapor permeable membrane on the subfloor that allows the condensation in the vapor to permeate out should it get in there somehow? If you have a vapor impermeable membrane any water that gets in there, even with an air gap could cause mold in the insulation I would think? It needs somewhere to escape but it ideally never gets in there in the first place I suppose. Good call on the thermal bridging too, whenever I read about energy efficient house design it seems like the best bang for your buck in terms of savings is adding an unbroken wall of insulation to either the interior or exterior wall to cover up those wood studs which suck heat out. All the best!
Thanks Brady. After reading up on this I’m not planning on having a vapour barrier between the insulation and the subfloor, but instead allowing the components to breathe. The trailer is mostly sealed from below, but does have some air holes which should allow air to circulate. There is then an air gap between the trailer and insulation, so it won’t be sitting in any condensation. The insulation is also meant to be water resistant, so in the event that there was some kind of flood in the house, it should be able to escape out of the holes in the trailer and then dry out. I saw some people (like Tiny Nest) use a vapour barrier underneath the subfloor to protect against leaks from above, but to me that seems like it would trap the water in the floor in the event of a leak. That is my thinking at least. Please do let me know if any of that sounds off as it’s hard to get definitive answers when you are building an unconventional house!
Joe
Great to see that you’re on your way at last, but I’m a little confused about this thermal bridge thing.
There may be a point about wood being a “poor” insulator and creating a bridge, when talking about a well-insulated exterior stud wall but that isn’t the situation here.
Left uninsulated, the steel trailer frame with its large sheets acting like radiators would certainly have drained heat out of your house at a great rate of knots. But your wooden floor frame and insulation should reduce that immensely. Compared to steel, wood is in fact a very good thermal insulator, (Steel conducts heat about 500 times better than wood), so I doubt that adding a few millimetres of underlay will have changed the thermal situation very much. On the other hand, it won’t have done any harm either. 😉
Bottom line: I think your first instincts were right.
MOG
Thanks for your input Dad. While I am no expert, as I understand it having an unbroken wood-on-wood connection from the inside of the house to something very cold on the outside is a bad idea. Perhaps there is some nuance that I am missing, and therefore didn’t include in my write-up. From my research and also speaking to a couple of people much more in the know, breaking this kind of metal-wood, or even concrete-wood connection is a ‘thing’.
I can foresee many more of these kinds of decision down the road, where I need to defer to what I find in my research as I am unable to make the call alone. This is made more complicated by the fact that there is nothing ‘standard’ about these houses, so information can be scarce. When it comes down to it I’m going to err on the side of caution and see how it goes. I think this will end up with an over engineered house, but also a big bag of knowledge and experience for next time (if there is a next time).
Joe