Ventilation, Insulation (and some Frustration)

April 25, 2015

Roxul Insulation

Roxul Insulation

Who helped today:

  • Sheila

What we did today:

  • Insulation Installation

I finally got a little bit back on track with the tiny house today. I have been struggling for the past week to find anything to work on that I can actually figure out how to do. Unfortunately, every time I start something, I seem to run into some kind of problem I can’t solve. By Thursday morning, the list of problems I was trying to solve consisted of over a dozen items. Most of my past week has been spent unsuccessfully trying to solve these problems and very little has been spent actually getting something done. Luckily, Sheila finally helped me to turn that around today.

I can’t say that I actually solved any of my problems today. What I can say is that we found something to work on that didn’t create any new problems. Today, we started working on insulation. It’s the next thing that needs to be done before we can start putting up the interior siding. I still can’t quite button up all of the walls yet because I’m still having a few problems with my plumbing and electrical. However, those problems are mostly localized to a small area of the house and Sheila realized today that those problems should not keep us from working on the insulation and interior siding on the rest of the house. That’s what we worked on today and I am happy to report that we made good progress.

Bird Blocking with Original (Tiny) Holes

Bird Blocking with Original (Tiny) Holes

I started the day by drilling additional ventilation holes in the bird blocking at the bottom of my rafters. Because the Tumbleweed plans specified it, I had drilled some holes in the bird blocking before I installed it. However, the plans did not specify how big to make the holes and I later realized the holes I created were much too small to provide any reasonable air flow. So, I decided to pull off the metal screening I had stapled across the holes, drill some new and larger holes and staple the screening back on. That took a little while because I had to be careful not to drill so far through the bird blocking that I damaged either the roof sheathing or the top of my exterior siding. I only made one mistake with that today and unfortunately broke off a piece of my exterior siding in the process. However, it’s so far up and behind the fascia that you really can’t see it unless you climb up on a ladder and look closely.

Bird Blocking with New (and Improved) Holes

Bird Blocking with New (and Improved) Holes

Screen Re-Attached (to keep critters out)

Screen Re-Attached (to keep critters out)

Next, I drilled more holes in the two by fours struts that connect all of the rafters. That was perhaps the most difficult thing I had to do all day mostly because that would was chock full of nails and screws that were used to attach the roof sheathing and metal roofing panels to my house. To find the nails, I used a combination of things. First, I borrowed some rare earth magnets from my next door neighbors which did a fairly good job of tugging slightly when they got near a nail. Next, I consulted a series of photographs that I took of the outside of my roof sheathing after it had been installed. Between the photos and the magnets, I was able to figure out where most of the nails were. However, I still didn’t get it right 100% of the time and every time I made a mistake, I would hit a nail and damage one of my spade bits. After about three hits, the spade bit was pretty much ruined and I had to pull out a new one. After destroying three different spade bits and after much associated grumbling and cursing, I finally had all the holes drilled on the left side of the house. The right side is a project for another day (one that I’m not really looking forward two).

Rafter Strut Before

Rafter Strut Before

Rafter Strut After (6 holes & one more ruined spade bit)

Rafter Strut After (6 holes & one more ruined spade bit)

While I was drilling holes, Sheila was off at Home Depot and Lowe’s buying insulation materials. I had been planning to use fiberglass insulation, but after doing some research this morning, Sheila convinced me to use something called Roxul Stone Wool instead. Roxul is an interesting product I have never heard of before. It’s created from fibers of basalt (volcanic rock) and slag (leftovers from steel and copper processing) woven together into something that looks and behaves much like wool (although there is no actual wool in it). The end result seems to be an excellent product that gets great reviews. It has an R value comparable to fiberglass, it’s not flammable, it doesn’t rot or disintegrate when it gets wet, it’s easy to cut, it’s not toxic and it doesn’t make you itchy (at least not too itchy). It basically has all of the benefits of fiberglass without any of the unpleasant side effects. After using it for a while today, I have to say I’m pretty much sold. Of all the things I have attempted on the tiny house in the past two weeks, installing this insulation was by far the easiest.

Roxul Details

Roxul Details

Before installing insulation, we installed rafter baffles between the rafters. These are thin sheets of contoured plastic that provide about 1 inch of space between the insulation and the roof sheathing for air to flow, providing a nice ventilation path between all the various holes that I drilled today and the holes I drilled in my roof last year (see my Watertight post for more details on ventilation). If I did the job correctly, all of this work should keep my ceiling nice and dry and the mold safely away.

Installing Rafter Baffles

Installing Rafter Baffles (Provent Ventillation)

Once the baffles were cut to size and stapled into place, then we could finally start with the roof insulation. Installing the Roxul insulation was a relatively painless, three step process. First, we measured the space between the rafters and cut the insulation to size. To cut the insulation, we purchased a little tool that looks like a bread knife and which makes cutting the insulation about as easy as cutting bread (you can save money and use a bread knife instead , if you want to – provided you don’t mind a little extra stone fiber in your meal). Next, we stuffed it into the walls. Finally, we stapled a sheet of 6 mm polypropylene across the outside. The polypropylene is called for in the tumbleweed plans and I wasn’t sure why. However, the guy at Lowe’s said that the polypropylene actually increases the R value a little bit. It also helps to hold everything in the walls. Finally, I’m guessing it protects the walls a little bit from air moisture, which can be a real problem in a tiny house.

Stone Wood Saw (basically a bread knife)

Stone Wood Saw (basically a bread knife)

Installing Roxul Insulation

Installing Roxul Insulation

Together, Sheila and I were able to install insulation between the rafters over half of the loft in only a couple of hours and most of that was figuring out what we’re doing. I’m guessing insulating the rest of the house will go pretty quickly. After that, we can start putting interior siding up which I’m pretty excited about because I think that’s when the inside of my tiny house will start actually looking like a house.

Problems we ran into today:

  • Figuring out what kind of insulation to use. I’m very grateful to Sheila for spending so much time researching online and finding such a great product.
  • Trying to drill holes through the nail ridden struts between my rafters. The whole time I was drilling these holes, I kept thinking how much easier this would have been to do before the struts and roofing were installed. Unfortunately, the Tumbleweed plans made no mention of the fact that these holes were needed for ventilation and I did not figure out that they were required until after my whole roof was put together.

Favorite part of the day:

  • Realizing that I can install the rest of the insulation in my house without too much difficulty and maybe even get started on my interior siding pretty soon. I still have other problems to solve. However, at least now I have something productive to work on when I’m feeling stuck on everything else.
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