Construction Blog


The purpose of this blog

Like most people who have been in this business for many years (forty years and counting), we have lots of opinions, some of them strongly held, about what materials should be used and how the parts go together, which I'll document here on these pages. 

Insulation


Fiberglas Insulation

Fiberglas Insulation is the norm in residential construction. Because it is ubiquitous, it is also the cheapest insulation and can be installed easily, and poorly, by do-it-yourselfers and professionals. The problem with this insulation material is it is difficult to precisely fit in wall cavities that have romex, conduit,  electrical boxes, pipes and framing irregularities.  A second problem has to do with air movement through the insulation. If a wall isn't constructed properly, air can infiltrate the cavity and move freely through the insulation, reducing the R-Value of the insulation.

Fiberglas can be chopped up and blown through holes cut into a netting or polyolefin, stapled and glued to the face of studs. This is called a B-I-B (or blown-in-blanket) system. The advantage to this method is that the fiberglas flows around all irregularities in the cavity, including romex, electrical boxes, and wood framing. If installed too densely, the netting or sheet can bulge out causing the drywaller headaches as he tries to push the drywall tight to the face of the studs. If too fluffy, then air infiltration can still rob R-Value from the insulation.

Fiberglas is also commonly blown into attics as chopped fiberglas. It is important that the installer blow it in so that it is fairly dense, or air infiltrating through the material renders it less effective.

Cellulose Insulation

Cellulose insulation is commonly made from recycled newspapers and treated chemically to make it fire resistant. It can be blown into walls from the outside through holes cut in the sheathing (in existing homes) or from the inside through holes cut in drywall and plaster. It can also be used in a B-I-B system or blown in wet into exposed stud cavities, where it dries over a number of days. Cellulose has about the same R-Value as fiberglas batts. It also has the advantage that it can be installed much more densely, which reduces the impact of air infiltration.

Cellulose can also be used as an attic insulation. When blown into an attic, it tends to settle slightly, compressing in the process and is more resistant to air infiltration.

Foam Insulation

Foam Insulations are products that are sprayed into wall and  roof cavities. They have numerous advantages. They eliminate air infiltration into cavities, they eliminate convective loops within the insulation and they flow around all obstructions within the cavity, completely insulating the spaces they are sprayed into. There are two basic kinds of foam insulations, open-cell and closed-cell. 

Open-cell insulations have an R-Value similar to fiberglas, about 3.5 per inch and are vapor-permeable. The open-cell product we use is called Icynene.

IMG 0837

                                          Icynene in walls and box sills

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                                      Icynene in knee walls and rafters


Closed-cell insulations have an aged R-Value of 6.2 per inch, are vapor impermeable and are much denser and stronger than open cell insulation. The product we use is from Johns Manville and called Corbond. Three inches of Corbond has about the same R-Value as five-and-a-half inches of Icynene, and unless specified otherwise, that is the thickness normally sprayed into a 2x6 stud cavity.


Both kinds of foams are great insulations to use in our structures. They not only save energy, in some cases dramatically so, but also create much more comfortable living spaces. 

Passiv Haus

Several years ago, I learned about the Passiv Haus (Passive House) movement and got pretty excited about it. I bought Katrin Klingenberg's book, "Homes for a Changing Climate" and traveled to their annual conference, held that year at the University of Illinois in Champaign-Urbana. I spent three days in detailed seminars and toured Passiv Haus projects built in the area. If you believe, as I do, that there are limited resources on this planet, then Passiv Haus and building very energy efficient structures make a lot of sense. If you go to web sites to learn about Passive Haus, you'll find a very active and passionate community, but rather small. 

There are a number of problems with Passiv Haus that are stumbling blocks, in my opinion. The first is that it is so difficult to meet their standards and be  certified that it generally requires simple shapes (rectangular), very thick walls (14" to 16" of cellulose in double wall construction, and/or  6" of sheet insulation over the sheathing), thick insulation around and under the foundation and basement floor (in one structure, 14" of styrofoam under the concrete slab was required by their software to achieve passive house certification) and very elaborate, high end windows. 

Elaborate window

This vendor's window  construction has multiple weather stripping, embedded cork, triple glazed windows and thermal breaks.

The end result is close to a net zero energy home with design compromises that would make them unattractive for many people in a market where angles and dangles, hips and valleys and dormers and corners seem to be de rigueur. Many of the homes we toured were rather plain but to be fair, they were the first built in this country and were more proof of concept projects…


Passive Haus 1

….but we did tour one Passive Haus home out in the country that was beautifully done. 

Passive House 2

The second problem is cost. They do cost slightly more than a home with comparable square footage but that cost will be offset by the huge energy savings realized every year. 

Thick walls

       In this photo, you can see just how thick the wall construction is.

To be honest, I haven't built a passive house yet, but I do think we can take many of their principles and methods and apply them to new construction to achieve a much more energy efficient structure and healthy environment.

On Doing the Right Thing

IMG_5061 - Version 2

My brother, sister and I decided to fix up our mom’s home prior to selling it. Our realtor recommended that we remove the ¾ knotty pine T&G paneling in the family room because it made the home look dated. Though I hated to remove beautiful wood like this, we decided to follow our realtor's advice. To our surprise, when we removed the vertical paneling, there wasn’t drywall underneath it, and the rock wool insulation in the outside wall stud cavities was one inch thick, apparently standard back when the home was built.  Some of the people that helped me on this project said to just leave the insulation as is as no one would know or appreciate that we did this, and we wouldn't get our money back. But that’s not the right thing to do. So we pulled out the insulation and discovered several instances where the sheathing had one inch holes left over from the original construction, allowing air infiltration into the stud cavities. We also foamed all the seams in the old Celotex sheathing and also foamed around the perimeter of the stud caviites and then insulated. 

We also decided to paint the basement walls and floors. But they were pretty dirty, so we didn't just wash them, we pressure washed them. It took an entire day for two of us to do the work with soap and bleach. Was it necessary to go to this extreme? In my mind, yes. If the new paint adheres better and longer as a result, then it was worth it.

All this additional work added days and costs to a project which we weren’t compensated for. But when we handed over the keys to the new owner, we knew we did the right thing. 


  (262) 375-2299                             dvanderhoop@mac.com                       © Vander Hoop Construction 2016