Tangled Up in Blue - Blue Jean Insulation, that is

Stacks of UltraTouch Denim Insulation from Bonded Logic

I've been working a little bit each day on the insulating my attic before it gets too hot to work up there. If you have been reading my blog, you would know that my absolute favorite insulation is mineral wool insulation, the two main brands are Roxul and Thermafiber. It's made from either melted volcanic rock - basalt, specifically, or from slag, a by-product of making steel so you could imagine it is fire-resistant. It is also relatively dense insulation and reduces transmission of sound. BUT if you are going to spend hours and hours crawling around in the attic with this type insulation, you have to be prepared to ITCH. I just could not face that. I had enough of it last year on John's house.

So I picked denim insulation. The best deal I could find was from Home Depot online. I ordered 2 pallets for 24 bales of UltraTouch insulation. Each bale covers 48 sq ft. It's 5.5 inches thick for an R-value of 21. It took about 2-3 weeks to arrive and was delivered to my home for a charge of $55 which I thought was a bargain. It has been a delight to work with. It's easy to tear and install, doesn't itch at all, but it is very dusty. Despite wearing a mask when I am up there, I still sneeze some blue fibers out afterwards.

Here's the current state of insulation.

You can see that insulating at the far end of the rafters will be a serious pain. I need to install some baffles so the insulation won't get into the soffits. That I dread as well.

To show you the effectiveness of this layer of insulation look at the before and after infrared photos of the ceiling fan in one of the bedrooms.

Before air-sealing and insulation above the ceiling fan

After air-sealing and insulation above the ceiling fan

I think the purple area (the cooler temperature) on the ceiling after the insulation was installed is where a beam crosses the ceiling joists. I thought I stuffed the insulation underneath there, but apparently not. I will go back and get it. That's a significant advantage of having my Flir One infrared camera. It is nice to be able to check of your work.

Insulation - My Favorite Thing

You know I love insulation, even more than air sealing. I even dream about insulation, mostly because my home is cold and I dream about being warm and snug in my own home. That problem will be improved on very shortly.

Anyway back to the insulation at hand, several years ago I bought a little house that we've partly renovated that Kathy lives in. In fact when I started this blog, the first stuff I wrote about was what we were doing at that house. There is a very solid, little concrete block building in the backyard (about 12' x 25' interior dimensions) that has been mostly used to store things. Since the home is so small at about 900 square feet, we decided to renovate this building to make it livable and give Kathy and her son just a little more breathing room.

Carlton has done most of the work. First, he studied the building carefully and felt confident that there weren't any water issues and that the block walls and roof framing were solid. Then he installed some windows to bring light into the space. Then framed the floor and installed 2 doors - one so you can go into the building from the driveway without having to open the gate to the fence. We may build a garage someday, so this door would open into the garage. Finally, Carlton installed a layer of foam insulation board on the interior of the walls, then framed the walls and insulated them with 3.5" mineral wool and installed drywall. That's where he stopped, now it's my turn.

Carlton was able to insulate a large portion of the ceiling with the Roxul mineral wool left over from John's house, but he ran out before he could insulate it all. I told him, "No worries, I'll finish it up." If you recall from last summer I spent HOURS and HOURS under John's house air sealing and insulating the floor of his house. It is tedious doing this work overhead. I also got tired of the itchy, scratchy sensation from the Roxul. It is supposed to be less obnoxious that fiberglass, but I wouldn't know as I've never installed fiberglass insulation before. In any case, I did not feel like suiting up to avoid the itching. So I ordered from Soundproof Cow once again and got some denim insulation.

My plan was to use these flexible metal tension rods to hold the 2 layers of 3" denim insulation in the 24" on center ceiling bays.

Don't do it. Don't buy those things. They will flop down and hit you in the head and they won't hold anything. You can see the scratches on the rafter on your right where they kept falling down on me. I had to come up with a new method to hold up the insulation.

The solution? An insulation corset.

I didn't want to use staples because it's hard for one person to hold the insulation up, pull the string tight and staple all at the same time. Also I don't have John's pneumatic staple gun set-up and regular staplers hurt my hands. (Youngsters, you will be amazed at what hurts you when you get just a little older - say, in your 50s.) So I hammered in some roofing nails because they have big heads on them and would hold the masonry string well. I chose masonry string because I figured it would pull taut and hold pretty well. I think it looks pretty good. Above shows the first layer of the 3 inch deep insulation.

And here is the full bay of insulation. I'm pretty happy with it. I will probably cover the seam between the Roxul insulation and the denim insulation with a band of the Roxul Rockboard that is left over from  John's house.

Denim insulation is a challenge to cut. It will not cut with a utility knife. Often people just end up tearing it which works pretty well though you won't get a good edge. I kind of do a sawing, tearing motion with a drywall saw.

Below you can see what the edge looks like.

So that was my insulation adventure today. I have 5 more 24" bays to insulate and 8 narrower bays. Tomorrow some more insulation will arrive. It is planned for my house, but I will use a few bales of it on this building.

I have not yet expanded on the topic of how much insulation should you use beyond the code requirements. That is coming as well.

Thank you for taking a look at my blog. I hope you are warm and comfortable.

Door installation with Exterior Insulation

I don't have a big readership of my blog which is fine with me. I mostly put the construction stuff out there to help anyone else who might be trying to build or renovate a better, more comfortable, more energy efficient house. Every once in awhile I get a question about the actual construction of John's house and I certainly want to help if I can.

One reader asked a question about installing the doors with the exterior insulation, the Roxul mineral wool Comfortboard. Here's the question:

Hello, wanted to say great job on the house! 

Im currently gutting a 1930's bungalow down to the frame & sheathing & am planning to add roxul comfortboard to the exterior. I see you went with the approach of mounting the doors and windows to the outside of the now-thicker walls. The windows are easy, but I'd like to see or hear about how you did the doors. Did you fir out the door opening, mount the door to the outside of the thicker wall, then trim the difference inside? If so, does this stop the door from swinging open fully? Thanks for any input on this detail....there is so little info online about the door installs on these exterior insulation jobs.

From looking at the photos the doors were installed on the outside of the thicker wall and trimmed out on the interior. It probably does prevent the door from opening more than 90 degrees. Here are some photos that might help explain it better than I could.

Back Porch Door with Polyiso around the edges, taped

Back Porch Door Opening

Front Door Framing with tape before installation

Close-up view of door framing

Installed Back Porch Door showing the thickness of the wall

Front Door Sidelights installed

Another Porch Door fully opened - looks like it opens just past 90 degrees

The only 2 articles I could find that address this issue are listed below. Green Building Advisor (GBA) is the single best place to get information. You do have to sign up to ask questions, but it costs nothing as a regular member and you get great advice from people who know their stuff.

Here is a similar question on GBA to the one you asked:

http://www.greenbuildingadvisor.com/community/forum/energy-efficiency-and-durability/37017/window-and-door-installations-thick-walls

This is an article in Fine Homebuilding where they address your question when double stud walls are used:

http://www.finehomebuilding.com/design/departments/energy-smart-details/windows-and-doors-in-double-stud-walls.aspx

So I hope this is helpful.

Crawlspace Insulation

Crawlspace insulation under enclosed porch

The current project on the perpetual house (perpetual building mode, that is) is insulating the crawlspace. Anything in a crawlspace is a pain, but insulating in a crawlspace is particularly painful - insulation in your eyes, breathing insulation, insulation on your skin, etc, etc. I wear a mask, glasses and a Tyvek suit to make it a little less onerous.

We are doing this ourselves because we can and our labor is free. We is me and Rich, my brother-in-law. Also I believe that no one else will do the same quality work. I don't know that to be true, but I suspect it is true based on the insulation work I've seen done in the past by others and the fact that no one else cares as much as I do and no one else is as willing to do this painful job as I am.

Ok, so here is the plan for insulating under the porch - the floor joists are 8" which works out to a 7.5" space for insulation. I have 2 different kinds of insulation that could be used for this area: -
5.5" Roxul mineral wool insulation which is listed as R-23
2" Roxul Rockboard insulation (about R-8).

For the 7.5" space, we installed the 5.5" Roxul first and the 2" Rockboard to finish filling up  the joist bay. The 5.5' Roxul batts were easy to apply, but the 2 ft wide Rockboard was a pain. We had to cut it to fit each of the floor bays which ranged from 21" to 23" wide. Then we had to wedge that stuff in. It was awful. I don't find Roxul to be as horribly itchy as fiberglass, but it does aggravate me, especially when I have to wedge it in with my shoulder and the stuff is going down my neck. Some of it was a little loose so we put strapping across it to hold it until I install the DA vapor permeable membrane from 475 Building Supply.

Larger view of the crawlspace insulation under the enclosed porch. Strapping is to hold it in place until the DA vapor permeable membrane is installed by stapling it to the floor joists. 

Lynn warned me about critters under the house, but other than the Carolina Wren nesting on one of the piers that we are having to work around, and an occasional wasp, critters have not been a problem. There is a dead critter present though. You might be able to see on the pier on your right. See the close-up below.

A little dead bat. I keep meaning to take it down, but I really don't want to touch it even with gloves on. 

I have to fill 2-3 small gaps where we did not abut the Roxul Rockboard together very well and I need to foam the gap between the floor joists which you can see above the bat. That is the space between an open part of the porch and the area below the door to the enclosed porch. 

Well, that's where we are today. I am off tomorrow so I will work on insulating the rest of the floor under the house. It is forecasted to be a tiny bit cooler tomorrow - in other words, it is not supposed to reach 90 tomorrow. Little blessings. Thank you for reading.

Insulation in Kneewalls

Kneewalls are a challenging part of a home because they are a little bit hard to build and insulate. We chose kneewalls because of the expanded space and better, though challenging, insulation.

Here is a drawing from Shelter Kit showing the kneewall extension. So rather than having the rafters meet the floor joists directly, there is a extension of the wall that supports the rafters. This gives you more usable space.

Shelter Kit - Drawing of Kneewall 

The next drawing shows the increase in space in the upstairs with kneewalls.

Comparison of space with and without kneewalls

The difficulty arises with the funky cavities made by these kneewalls. How do you insulate this space?

Dormer framing with wall framing behind it

I posted a question on Green Building Advisor about it because I just didn't think the insulation company would be able to blow-in cellulose effectively in these spots. I decided to fill them with Roxul mineral wool insulation and then I'll cover that with the Intello Plus smart vapor barrier. Then we will insulate with the cellulose over that. Does that seem like a lot of insulation for this area? Well, it is, but this is what I call "a vulnerable area" a seam between sections of the house (the roof, the wall and the rim joist below) that is very prone to air leakage. 

Also the details of adding exterior insulation to this short section of wall would have been very challenging. So we omitted it from this section of wall. And we built this wall before I started going crazy about air sealing so the inside of this cavity is not air-sealed as almost every other cavity in the house is. The outside is taped though. 

Now you can see my efforts at insulating the kneewalls. This might not meet Grade 1 insulation standard, but the voids are filled. Remember that there will be at least 5 inches of cellulose interior to this insulation to make sure the wall is well insulated.

Intello Plus membrane will be stapled between the Roxul mineral wool insulation and the dormer wall framing in front. That space will be filled with dense-packed cellulose.

Bedroom kneewall stuffed with Roxul mineral wool insulation.

Cozy Mineral Wool Sweater on the House

John's house has a number of uncommon features that are designed to make the house more efficient and more resilient, better able to withstand weather and time. I'd like to talk about a couple of those details, the mineral wool exterior insulation today and the function of the rainscreen in another post.

Here is our cozy Mineral Wool Sweater before the addition of the rainscreen.

The most time-consuming of these two features is the exterior insulation and all that installation details that entails. So we (I say we, but it is, of course, Carlton and his crew that have done this) covered the entire house with a cozy mineral wool sweater, so to speak. This 2 inch thick sweater of insulation  (total R value of 8) provides an uninterrupted layer over the house that is insect, fire, water resistant and helps maintain the desired interior temperature with much lower energy use. It reduces thermal bridging - the transmission of heat through the parts of the building that are more conductive such as the wood studs and beams. Remember the R-value (defined as resistance to heat flow) for wood is about 1 per inch whereas most insulation ranges from 3 to 6. 

This is a drawing of a thermal scan showing where the heat loss occurs in a normal stud framed house. You can see that more intense heat loss occurs through the windows but a significant amount happens through heat flow across the wood studs. In the average home built with 2' x 4' or 2' x 6' framing, approximately 25% of the exterior is wood which means LOTs of thermal bridging.

Here is an actual thermal image showing the interior of a house where you can clearly see the wood studs and bracing in the wall. The deep purple is probably due to air leaks through the intersection of the studs in the corner. 

From Erik North's Energy Auditing Blog

When I re-sided my house about 3- 4 years ago , I covered the entire house with Polyisocyanurate foam sheets (polyiso for short) to reduce the thermal bridging. I chose polyiso because it has the highest R-value for common insulation materials and was relatively easy to install. Also that was early in my studies on energy efficient design. Disadvantages of polyiso are that it is made from oil, somewhat flammable, insects love to nest in it, and it has "global warming potential" from the blowing agents used in the making of the foam. So at that early stage in my studies, that's what I chose. 

After realizing that there are many other options out there, we chose Roxul Rockboard 80 for John's house. It's much more of a pain to work with because it itches (some people aren't bothered by it, but I try not to touch it without gloves on) and the sheets come as 2' x 4' rather than 4' x 8' for foam sheets. Truthfully, I did not calculate the cost difference because I was set on Roxul and was not going to consider foam. I feel that this is the proper choice for John's house based on fire, insect, and water resistance. 

Later in the construction process, we will do an energy audit so we can see how effective the cozy mineral wool sweater actually is.

Back to Reality - Homebuilding, Work

This week has been a serious back to reality week. I was exhausted after coming back from Oregon last week. I slept like crazy. Going to bed early and everything. I had wonderful days at work, busy, but not overwhelming. I have to take my Pediatric Emergency Medicine recertification boards this week. Pretty scary. I studied some, even in Oregon, but you can't study enough to feel comfortable. I am pretty anxious about that. And then there is the house which is going really well. That's mostly what this post is about.

You may recall the we are using an exterior insulation called Roxul. I looked for Roxul Comfortboard  but was unable to find it easily. I could have gotten it from one of the big box home improvement stores but it would take 6 weeks or so to get it in. I did find Roxul Rockboard online from ATS acoustics, an acoustic supply house. Their lead time was about a week. I posted online at Green Building Advisor (my favorite website) to see if Roxul Rockboard and Roxul Comfortboard were equivalent and Albert Rooks of Small Planet Workshop (where I am getting a lot of my air sealing supplies) said that they were. The compression resistance of both products is 743 psi so the products were very similar. I ordered from ATS despite very high shipping costs, but we were able to get the product in one week.

Carlton and Chris and Myron have been installing this material on top of the very well air-sealed exterior for the past week when I was gone.

Front view of the house with the installed 2 inches of Roxul. Foam was used around the windows so we could make sure that we airsealed well around the windows. The rainscreen  which goes on before the siding has not been applied to this area of the house.

You can see the rainscreen has been applied to the back side of the house. The fixed transom window is above the stairway. I know it looks a little funny, but it is about all that would fit there. We were going to put a window in the bathroom, but decided against it because that can cause all sorts of problems with mold and rot. Since we are trying to build a highly efficient, long-lasting, resilient home, it does not make sense to put a window in the bath/shower area to catch water and cause rot in the wall. So it looks a little strange, but it is on the back of the house. To bring light into the bathroom, we will install a sun tunnel on the roof of the dormer.

Driveway, gable end side of the house. Again, the rainscreen has not yet been installed on this side. You can think of exterior insulation like a sweater for your house. There are essentially no thermal bridges on the outside of the house to conduct heat in or out of the house. So the insulation inside can do a much better job maintaining the desired temperature. The comfort level of the house is going to be amazing, I think.

See what a great job they have done installing Roxul Rockboard 80.

You can see the rainscreen details a little bit better in this photo. There is a small air gap around the windows to allow any moisture in the siding to evaporate which will significantly prolong the lifespan of the siding, the sheathing below the insulation and even paint on the siding.

Well, that's where we are this weekend. Next week Carlton and Myron will work on the soffits and more rainscreen on the gable ends. Then I don't know what is next. I have to figure out penetrations though the wall. Most electrical and plumbing should be through the floor (which brings its own set of problems), but there are still some things that will have to go through the wall. I need to make sure that is planned for now.

Carlton's helper, Chris, was switched to the day shift so he is no longer able to help in the mornings before he goes to work. That is kind of sad, because he has been a very good worker and great help to Carlton. We will miss him.

Porches are framed

The guys have been working really hard and have framed all the porches. We are going to use the porch roofs to help get the roof sheathing on. The roof pitch is kind of steep. It's a 12:12 pitch which means that for every foot out you go, it goes up 1 foot. This is not really a typical pitch in the Southeast. It is more common for areas with a significant snow load. Since the kit is from New Hampshire, that's why it's so steep. The steep roof pitch does make for a very attractive house shape though.

So since the porch roof pitch is much shallower, you can stand on it to get the plywood sheathing on the main roof. It makes it much easier.

Windows have been ordered.

I have not ordered the Roxul insulation yet. I need to figure out surface area of the house so I can get an accurate estimate of how much I need and can compare prices.

John and I went to the bank to apply for the construction loan on Friday. I have a whole list of things I need to get to them to help our application go through:

1. Current photos of the house - where we are in the construction process
2. A "Spec sheet" - what goes in the house such as flooring, trim, countertops, siding, metal roof, etc. This list is supposed to be very specific. Randy is going to send me a sheet so I can see what all is included and modify it.
3. Paid invoice of the cost of the kit from Shelter Kit
4. Description of the "green" features of the house
5. Floodplain information

Here's where we are as of Friday:

The porch roof sheathing is not on yet; hence, the tarps. We continue to have record-breaking rain here - as in more rain than has EVER been recorded in July.

Proposed Wall assembly

Here is a drawing of the proposed wall assembly.

The R values (resistance to heat flow) of each layer of the assembly are outlined below:

2" x 6" stud wall = 5.5 inches x 3.5 R value/inch = 19.25
2" layers Roxul Comfort Board* = 2 inches x 4.2 R value/inch = 8.4
1.25" layer of Roxul Comfort Board or insulation in service chase = 1 inch x 4.2 R value/inch = 4.2

Total R value = 19.25 + 8.4 + 4.2 = 31.85

*I just looked at the Roxul website and the thickness of the Comfort Board is listed at 1.25", 1.5", 2", 3" so we may have an R-value about 2 higher if we use 2 layers of the 1.25" board.

Also we will probably use HardiPanels rather than HardieBoard sheathing.

3 postings in a 24 hour period. Pretty impressive, huh? I even skied a little bit today. Last day of skiing is tomorrow which always makes you a little sad.

Challenges in Designing an Energy Efficient Home - Exterior Insulation

I am trying to finalize plans for John’s house. I have to order the kit by January 31^st for delivery in April. I backed up the start date to April just because I’m not ready AND I might be taking boards in March. I do not need to be trying to build a house and studying for boards in the same month. That would absolutely drive me crazy.

Today's topic will be exterior insulation.

Exterior insulation is used to prevent thermal bridging. I learned in my Net Zero energy class that for a standard 2 x 6 wall insulated with dense pack cellulose you lose 25% of the insulation value from thermal bridging through the wood studs because the R-value of the wood is only about 1 per inch. There are a number of strategies to prevent thermal bridging, but exterior insulation outside of the sheathing makes the most sense to me.

Polyiso covering house from the Building Science Case studies

When I installed new siding on the my house, we covered the sheathing with Tyvek housewrap and then  2” polyisocyanurate (polyiso) foam to give me an uninterrupted R-value of 12 around the house. My house looked similar to the house above before the siding was installed. The advantages to using polyiso foam are that it is relatively easy to find, lightweight, relatively easy to install using cap nails, good R-value of about 6 per inch, uses more environmentally benign blowing agents than EPS or XPS foam. There are some serious downsides to polyiso though– ants and termites can tunnel through foam. They don’t eat it but they love to nest in it if it is wet. Although polyiso is less flammable than EPS and XPS, it is still flammable. But the most important disadvantage is that it is derived from petroleum. For those reasons, we’re going to use a different product on John’s house.

I’m voting for Roxul ComfortBoard which is made from volcanic rock. I've talked about Mineral wool insulation before when I talked about insulating John's shop. Below is a photo of exterior insulation with Roxul ComfortBoard.

Roxul ComfortBoard

I’m choosing this because it is non-combustible, does not rot, insects cannot tunnel through it, cannot get moldy, vapor permeable, water resistant. It is probably harder to install the polyiso and it is itchy. I’ve ordered Roxul batt insulation from a local store when I was working on the Lenore house so I think I can get the ComfortBoard which is a compressed version of the Roxul batt. R-value is about 4/inch. Cost is supposedly similar to the foam.

Schematic of Roxul with rainscreen to allow rain to drain from behind the siding. This keeps the wall sheathing drier as well as allows the siding to dry on both sides prolonging the paint and the siding. This photo is from Builder Online  in a slideshow on 10 Hot Products from Greenbuild 2012.

Using exterior insulation solves the thermal bridging problem, but it brings a whole new set of challenges - detailing around the windows and doors, and what to do about the roof overhangs. I hope to cover some of those issues in the next post.