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.

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.

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.

A Weekend in Boston (before the Storm)

Prototype wall by 475 Co. - the wall design I intend to use for John's house. It is air sealed on both sides, but vapor open on both sides so the wall assembly can dry to either direction, inside or outside. The wall components inside to outside will be - drywall, mechanical chase (probably Roxul insulation in the available space in the chase), intello, 6" cellulose insulation, plywood, at least 2" Roxul comfort board mineral wool insulation, the Solitex exterior membrane, rainscreen wall, Hardieboard siding. 

On Monday October 22 there was an announcement on my favorite website (Green Building Advisor - GBA) of a one day conference October 28th in Boston hosted by Passive House New England. I was off for the whole weekend so I talked John into going with me. He was to be the tourist while I attended the conference which had numerous speakers I was really interested in hearing including my course instructor, Marc Rosenbaum, Martin Holladay, editor of GBA, Chris Corson, builder of Passive Houses in New England, and Adam Cohen, designer/builder of Passive Houses in the Southeast.

I got plane tickets - first class for the first time ever in my life because they ended up being about $100 more expensive than the regular tickets if you include the cost of baggage. The real advantage of first class is getting on in a relaxed manner and just having a little space to move. I won't generally go by first class especially if I am traveling by myself, but this time it made sense for a short trip.

The last time John and I made a trip to the Northeast was when we celebrated the end of his chemo and we went to Philadelphia and Washington, DC for a week. We decided to go by train to see how that worked out. It was great on the way up. While we were there Hurricane Irene went through Washington, DC. And we couldn't get the train back because Amtrak was closed. I had to book a return flight to get back home. Serious bummer that we didn't get to take the train back.

When I booked the trip to Boston, we knew Hurricane Sandy was in the Atlantic, but it looked like she was going to basically stay in the Atlantic. As the week progressed computer models showed that the hurricane was going to take a left turn into the northeast coastline. Fortunately this time, we flew up before the hurricane and came back kind of around the hurricane. The flight wasn't even that bumpy. We got lucky.

We meant to do touristy stuff that Friday night, but I had worked all night the night before so I became unconscious when we got to our hotel, the Omni Parker in downtown Boston. It's a great place to stay in Boston. I love it when you can get from the airport to the hotel on the subway. I like that so much better than having to get a shuttle.

Saturday I got up early and went to conference at the University of Mass. The first speaker was Adam Cohen who is a dynamic speaker and very well versed in designing and building Passive Houses. He didn't really talk about humidity and Passive House at this conference, but he came up to me afterward and gave me his card and asked me to email him about that issue. A lot of the comfort issues in the hot and humid South are not really about temperature, it's about humidity. We use a significant amount of energy trying to dehumidify the house in the summer. So I will be taking Adam up on his kind offer and ask him about humidity in a superinsulated house in the South.

The next speaker was Chris Corson is a builder in Maine who built a super-insulated 1600 sqft house for $130/sqft. Amazing.

The last set of speakers was an interesting panel discussion of Passive House which included my zero energy class instructor, Marc Rosenbaum and GBA editor, Martin Holladay.

One of the best things about the conference was the vendor display. I got to talk to someone from 475 building supply co located in Brooklyn NY. I got to see an actual prototype of the wall I want to build.

This view shows the mechanical chase or the part of the wall that will include electrical and plumbing. The wall is air sealed behind the chase so any penetrations, hanging pictures, for example, in the drywall (not shown, it will go on top of these studs) will not penetrate the air barrier. That prevents interior moisture from penetrating the wall assembly causing mold or rot.

The only photos I took were of these wall assemblies. No tourist photos though.

I had a great time. Hope to post more later.






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Lessons from the Shop

I am very glad that we decided to build a shop before we build a house. You learn so much from the building process (even if I wasn’t the one swinging the hammer or nail gun). I think it is especially important if you are trying to build a different kind of house such as a super-insulated one. Here are a few things that I have learned.

Lesson 1 – Get everyone on board. Randy is a good friend as well as contractor. He hasn’t really done stuff like this before, but he is excited about learning and is receptive to these ideas. (He’s now reads Green Building Advisor). Carlton the master carpenter is invested in doing it right. So the 2 main guys are all in.

What I have to do though is show them the significance of every air gap. I plan to do blower door tests on 3 houses – first the Lenore rental house which is a work in progress, my house (which should be done, but I really haven’t finished the attic insulation) and John’s house after we close it in.

My plan is to have them at the house when we do the tests. That makes it tangible. 

The head of the insulation company apparently gets it as well according to Randy. In a previous post I talked about avoiding him because I didn’t want to argue about fiberglass. But he does teach his guys to air seal and understands its importance. Also Randy says he is a nice guy and easy to talk to.

I also plan to invite the guys to dinner and go over the principles that I think are important BEFORE we even start. I’ll pay them for their time. I need the drywall guys there as well because I don’t think they’ve ever attempted an airtight drywall approach before (ADA).

Lesson 2 – Communication is key. It’s really a variation on lesson 1. Sometimes you think and think about a problem, solve it in your mind and assume everyone knows what you were thinking. Example, John planned very precisely where he was going to put his equipment. He drew an AutoCAD plan of his equipment for Don and Buck, the electrical guys. He assumed they would put the outlets about every 4 feet where the equipment was going. They lined up the outlets EXACTLY where he mapped it out on the drawing. See the photo. They put in enough outlets so it won’t be a problem, but it’s not what John envisioned.

Back corner with carriage doors to the side and the fold out stairs  for storage above

Lesson 3 – Ignore John when necessary. My brother was adamant about not giving up square footage on the floor of the shop for either a stairway to the storage area or a small bathroom. Flat out refused. I knew he was wrong, but I could not get him to compromise at all. Everyone who worked on the building was wondering – where is the bathroom? Why didn’t they put a bathroom in it?

John is so happy about all the space.

I should have ignored him on the bathroom issue and at least put in the pipes for a “future” bathroom when they poured the concrete. I can’t believe I didn’t insist on that.

I think John learned something from that as well.

I told him for house, he can do whatever he wants except in matters of energy efficiency. That’s not exactly true but he doesn’t know that yet.

Lesson 4 – You have to be there to oversee the details. The installation of the insulation is the best example. If you are there you can insist on having it done the way you want.

You have to be there to catch little details that matter. 

Here are more photos of the shop. Just waiting on Duke Power to install the power line and for the metal roofing for the awning over the main doors.

Main entrance to the shop. Waiting on the metal for the awning

Beautiful insulated carriage doors built by Carlton and Chris

Stairway to Storage

Front wall of shop

Side wall of shop

Mineral Wool Insulation - Batt installation (and difficulties)

More insulation information.


The insulation guys are at work. First they sealed the 2 x 6 stud bays with a minimally invasive foam, then they started installing the mineral wool insulation. As I mentioned in my insulation choices I talked about the difficulties of installing batts well. Insulation is graded I, II,  or III based on how well it covers the stud bays. Grade I is the best.


A class I installation  - see the picture below from Alison Bailes Energy Vanguard blog





He says that it is one of only TWO class I fiberglass installations he has ever seen as a home energy rater. 


The criteria for a class I installation include:

1. Minimal gaps in insulation coverage
2. Compression or incomplete fill (up to 30% of intended thickness missing)- up to 2% of total area
3. Walls, rim or band joist between floors - enclosed on all 6 sides, in contact with interior or exterior sheathing
4. Ceilings - in contact with interior sheathing 
5. Floors - in contact with interior sheathing (subfloor)
6. Floors over outdoor air or vented - enclosed on all 6 sides

This is from "Insulation Inspections for Home Energy Ratings - Assessing insulation gaps, compression, and incomplete fill provides a way to measure installation effectiveness" by Bruce Harley in Home Energy Jan/Feb 2005 pp 20-23. 


So here is an example in the shop. This photo shows the minimally expanding foam with some pretty well installed mineral wool around the top but not the bottom. 

The next photos show the installation of the batts. 

Neither of these installations is a class I installation for 2 reasons - too much compression and it does not completely fill the stud bay. You will not get the stated R-value because compressed insulation does not trap air as it should. It functions as a solid material that conducts heat. 

What to do about it? Now that's another question. If I was off tomorrow I would get a ladder, put on protective clothing and I'd fluff the stuff up. I'll talk to my contractor and we'll figure it out. 

Insulation Choices

Now that all my Christmas parties are done, I can re-focus on issues about making my houses more energy efficient.

I say my houses like I really own a bunch of property. I have my house built in the 1950s which is less than 2000 square feet but certainly large enough for my cats, 2 doggies, my craft supplies and me. Really my craft supplies and craft magazines take up the most space.

I bought a 1960s house to renovate that is less than a 1000 sq. feet and I rent that out to Kathy and her family. We needed enough space for Kohle, the greyhound, to be able to run.  The house did not have one speck of insulation in the walls unless you count a few widely scattered areas of crumpled up newspaper. It does have some fiberglass batts in the attic that are actually installed better and thicker than the ones in my house.

Ok, so those are my two houses. Well, I’ve been getting into some other buildings that require insulation. One of my family members lives in a mobile home that is less than adequate as a living space. So the first step in getting my brother, John, into a real home is to build a shop. He is a cabinet-maker but he needs space to be able to build cabinets for his new home (and my kitchen, bathroom, my other brother’s kitchen, Kathy’s kitchen and bathrooms, etc, etc.). We (well, really it’s Randy, Carlton, Chris, Don and Buck) are building a beautiful shop for him. We are also using it as practice for the issues you face in building a home.

We are now at the stage for insulation. I thought I would go over my decision-making process for choosing insulation.  I’ll briefly review the choices with pros and cons for the main categories of insulation – fiberglass, cellulose, denim or cotton, and mineral wool.

The shop is on relatively low-lying land in the humid South so moisture control is an issue. Since it is a woodworking shop, fire resistance is also a consideration. I am not considering foam for this particular building so I will not be discussing those choices here, though I will discuss it when we talk about building and insulating a house.

All of these forms of insulation have an R-value (resistance to heat flow) between 3-4. Since they are not very different, the R-value will not be the determining factor.

Fiberglass

1.     Pros – commonly available, cheapest insulation, familiar installation, R value equal to most other insulations except for foam, lightweight, some brands no longer have formaldehyde binder so no off-gassing, sometimes uses recycled glass, resistance to moisture damage and fire are rated as excellent, can be blown in

2.     Cons – high embodied energy in making fiberglass (10 times as much energy to make fiberglass as it does to make cellulose insulation), little recycled content, difficult to install well, more air permeable than most other insulation, prone to convective loops since it is a low density material primarily composed of air, similar problem is “wind washing”, difficult to recycle, cannot compost, questionable health effects from inhaling glass fibers (the fiberglass industry heavily disputes these claims). Itchy unless encapsulated, requires protective clothing

Cellulose

1.     Pros- commonly available, pretty cheap, can install DIY attic installations, R-value similar to fiberglass (generally 3-4 per inch), low embodied energy. No other insulation uses less energy for production. Since it is primarily made out of newspaper, keeps newspaper out of landfill. Ties up some carbon from the newspaper. Borates used for fire resistance and mold prevention are safe chemicals. Can moderate moisture in air. Better air barrier than fiberglass though not rated as an air barrier, compostable.  Good retrofit for insulating intact walls

2.     Cons – holds moisture if it gets wet, fire resistance is less than fiberglass, dense pack installation in walls difficult for DIY (need commercial grade blower, not one from the large stores), wall installation may leave voids, gaps. Can support some mold growth if very wet. No batts available(why don’t we have cellulose batts?), settling can occur if not properly installed, requires dust mask

Denim or Cotton

1.     Pros – very easy, pleasant DIY installation, not itchy at all, somewhat available, R value similar to fiberglass and cellulose, not too expensive, low embodied energy as the material used is recycled, usually pre-consumer though some post-consumer fibers are being used now, no formaldehyde binders, uses borates for mold and fire resistance, sound reduction, no protective clothing required though a mask should be used for cutting the batts, better air barrier than fiberglass though not rated as air barrier

2.     Cons – can be difficult to find, only available in batt form, can’t do a retrofit unless the wall is open, poor moisture resistance, moderate fire resistance, can have gaps, must install carefully behind wires and boxes similar to fiberglass, can be hard to cut (but tears easily)

Mineral Wool – 2 main forms, rock wool from basalt (volcanic rock) and slag wool from blast furnace slag (material that forms on surface of molten metal)

1.     Pros – durable, fire resistant (withstands temps up to 2150 F), no release of toxic gases, will not absorb water, R value similar to fiberglass and cellulose, will not support growth of mold, mildew, bacterial growth, available in batts or blown in, batts are relatively easy to install, a little less itchy than fiberglass, no chemical off-gassing, no fire or mold retardants, no health effects, good sound absorption, better air barrier than fiberglass (though it is not considered an air barrier), can be reused, does not deteriorate

2.     Cons –difficult to find, no local sources, expensive, relatively high embodied energy to produce, requires careful installation like fiberglass to avoid gaps

Conclusion

For John’s shop, I have chosen mineral wool insulation based on its fire resistance, moisture resistance, and sound attenuation. I am not a fan of fiberglass at all and feel that any of others would be superior to fiberglass. Fiberglass just allows too much air to circulate (convection currents, windwashing) through for me to consider that as a viable choice in insulation. I did not choose denim or cellulose primarily because of the moisture issue.

Sources

 “Does Fiberglass Insulation Still Make Sense?” 2004 Fine Homebuilding article http://www.greenbuildingadvisor.com/system/files/sites/default/files/Does%20Fiberglass%20Insulation%20Still%20Make%20Sense_FHB160.pdf

“Installing Fiberglass Right” in Musings of an Energy Nerd, Green Building Advisor July 2009 http://www.greenbuildingadvisor.com/blogs/dept/musings/installing-fiberglass-right

“A Visual Guide to Why Fiberglass Batt Insulation Underperforms” in Alison Bailes blog, Energy Vanguard http://www.energyvanguard.com/blog-building-science-HERS-BPI/bid/47219/A-Visual-Guide-to-Why-Fiberglass-Batt-Insulation-Underperforms

“Should Batt Insulation be Outlawed” in the Green Building Curmudgeon blog, Green Building Advisor http://www.greenbuildingadvisor.com/blogs/dept/green-building-curmudgeon/should-batt-insulation-be-outlawed

“Thermal Control in Buildings” Building Science Digest BSD-011 http://www.buildingscience.com/documents/digests/bsd-011-thermal-control-in-buildings?topic=doctypes/digests

“Insulation Education” by Max Alexander, This Old House Magazine http://www.thisoldhouse.com/toh/photos/0,,20435285,00.html

“How to Make Your Home More Energy Efficient” TLC website http://tlc.howstuffworks.com/home/how-to-make-your-home-energy-efficient7.htm

“What is Wind Washing (and why every homeowner should know)?” by Erik North July 8, 2011 on the Energy Auditing Blog http://www.energyauditingblog.com/what-is-windwashing-and-why-every-homeowner-should-know/

“Fiberglass-Batt Insulation” in How It Works – The Mechanics of Home Building by Rob Yagid in Fine Homebuilding August/September 2011 http://www.finehomebuilding.com/PDF/Free/021221018.pdf

“Heat Transfer Through Insulation” in How It Works – The Mechanics of Home Building by Rob Yagid in Fine Homebuilding September  2009 pp. 16-17 http://www.finehomebuilding.com/PDF/Protected/021206016.pdf

“Insulation Comes of Age” by Alex Wilson in Fine Homebuilding, March 1, 1996,pp 46-53 http://www.finehomebuilding.com/PDF/Protected/021100046.pdf

Roxul Fire Videos http://www.roxul.com/stone+wool/fire-resistance/fire+videos

Quiet Batt Acoustic Insulation http://www.soundprooffoam.com/quiet-batt-insulation.html

“Blown Cellulose Insulations” in John Brooks Real Homes for Real People Blog. http://johnbrooksbuilder.com/articles/cellulose.htm