Best Practices With Insulation Installation
I have found that insulation of an attic space is not the number one thing buyers ask about. We have a very mild climate here with wet but not freezing cold winters and warm but seldom very hot summers. However, if buyers are concerned with heating bills they may want to know about the home’s insulation. Jay Markanich has written a blog about the proper way to insulate a space.
It isn't often that I am able to write something about best practices with insulation installation. So here it is!
This is a new house, abandoned mid construction, then purchased and construction begun anew. The buyers are saavy enough to act as their own GCs. That is not recommended for most people. They seem to have a handle on it.
As GC, selecting the proper subcontractors is crucial to the process.
It could be said that the best (new) form of insulation is sprayed foam. It is, however, very, very expensive. Even when it is used minimally to seal air flow through places like rim joists, it still increases costs dramatically.
There are many advantages to using sprayed (blown-in) cellulose insulation. It is a recycled product, is permanent, has no gaps or holes, and retains an R-value of about 3.3 per inch for the long run. It is nothing more than chew-up newspaper and can be treated with boric acid so bugs will not eat it. Also, its treated to make it non-flammable.
But look at this! When a stick'em is added to the cellulose, it can be sprayed into vertical wall cavities, and will not sink over time. Gravity still works, however, so there are places where it needs support. Supported well, it will last forever. I seldom, seldom see this insulation technique here and it is great to see! In fact, to me,
its use is a
Best Practice
Consider these photos and the best practices employed.
The exterior walls are framed with 2x6" studs.
The sticky insulation is sprayed into the space, brushed off mechanically so it's flush to the stud, and covered with drywall.
It dries, is permanent and will not move.
The brushed-off insulation is simply swept up and can be used in another application.
The vapor retarder is on the exterior wall, a form of plastic wrap, in this case Dupont.
This allows the wall to "breath" with humidity getting out, but wind and moisture are sealed from coming indoors.
This thickness of insulation provides an EXCELLENT R-value!
In addition, all exterior gaps between studs are sealed with caulking, the small gaps around windows and doors are sealed with an open-celled foam, and here insulation is sprayed over the window header to give it some R-value kick. Bare wood is not as insulative as the insulation alone.
Where floor joists are parallel to an exterior foundation wall, the cavity is completely filled with cellulose.
It is supported so it will not move.
Notice the hole cut into the mesh. The supportive mesh is stapled into place (see the staples every inch or so?).
Then a hole is cut to accommodate the nozzle of the sprayer.
Insulation is then sprayed until the cavity is completely filled and insulation begins to spit out of the hole.
In time, when this basement is finished, a stud wall will be in place and this mesh covered with drywall.
Where floor joists are perpendicular to the rim joist needs to be insulated as well.
In this location there is a cantilevered overhang.
The entire cantilever is insulated, of course, but the mesh is stapled three feet or so into the house, so that the blown-in cellulose extends that far inside.
This is excellent coverage.
This is certainly a best practice.
Even large areas under floor joists, where either insulation or sound blocking is needed, can be covered with mesh.
See the various holes cut?
Each long cavity can be filled with insulation.
It is not heavy and the mesh can handle it until, one day, drywall is installed.
This insulation and mesh can handle an outdoor application too.
This small area is the exterior wall where the front porch attaches to the house.
The insulation and mesh protect an area over the indoor ceiling drywall, but under a clerestory window.
This exterior insulation and mesh will be covered with something so it is not exposed directly to the air.
Even a thin sheet of masonite is enough to help it to maintain its R-value.
Interestingly, from the front, the house appears to be a ranch design. The garage to one side is almost as wide as the house.
I loved seeing another clerestory window over the garage!
It is not functional except to provide natural light to the garage. But from the outside it adds spectacular symmetry to the house. In my opinion that was very Jeffersonian to do!
My recommendation: when we see best practices employed, we should note them! It is wonderful to see. And to be able to blog about!
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia
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