Hands-On Experience with New Materials at EBN

EBN office to create work and storage spaces, we jumped at the opportunity to try out a few of the products we’ve been writing about. In partitioning off a small work space in our office, we used Greenwood Cotton Insulation™ for sound control in the stud cavities and tried out the new zero-VOC Benjamin Moore Pristine™ paint on the walls. For a ground-floor storage space partitioned off from a garage, we insulated exterior walls with more of the cotton insulation, then used Stramit compressed-straw panels on Trex^® sill plates for the interior wall partitions. We have a few reactions.

Greenwood Cotton insulation. As described in

EBN (Vol. 3, No. 3 and

Vol. 4, No. 1), this insulation is made from denim textile scrap. It is 75% cotton and 25% polyester.

Our first observation related to lofting. Being used to fiberglass batts, which almost explode with expansion when the bags are cut away, we were surprised to see these batts just sit there; the cotton batts have nowhere near the spring-back properties of fiberglass. Kirk Villar of the company confirmed this and said that you need to shake the batts to get them to loft. He described flicking the batts as you might a blanket. Okay, but the 2x6 batts still didn’t seem to expand enough to fill a 2x6 cavity.

Next, we dealt with cutting the batts. The fibers are a lot tougher than glass fibers, and cutting is quite different. Forget the dull utility knife. Even a new blade has trouble cutting batts lengthwise, though cutting across the width is not as difficult. Scissors worked all right but were a hassle, as we had to make several passes. Surprisingly, what worked best was a circular saw. We used one with a standard blade but suspect that a blade with smaller teeth might be preferable. A battery-powered mini-circular saw that you operate with one hand might be the best solution.

Finally—and much to the material’s credit—after finishing these two projects, we weren’t itchy, we didn’t have to shower, and our eyes didn’t feel as if they had just been in a dust storm. In fact, that benefit may outweigh any difficulty with cutting the material.

Benjamin Moore Pristine paint. We found application of the Pristine flat wall paint (

EBN

Vol. 4, No. 1) to be very similar to that of conventional latex paints—though we weren’t experimenting with out-of-the-ordinary conditions or surfaces. The paint went on smoothly and seemed to cover well.

What did surprise us was a very obvious smell from the paint until it dried. One of the important benefits of zero-VOC paint is that you are supposed to be able to paint while spaces are occupied. Well, we tried that, and one of our staff members, Marianne, experienced a headache (on two separate occasions). Others were not affected—though the smell was evident to everyone.

Stramit compressed-straw panels. The most unusual product we recently tested at the

EBN office is the Stramit EnviroPanel™, a compressed-straw interior-partition panel (see

EBN

Vol. 4, No. 3 and the Construction Detail on page 11 of this issue). These 2¹⁄₄”-thick (58 mm) panels are used as non-load-bearing interior partition walls, replacing 2x4s or steel studs and the two layers of drywall.

Our experience with Stramit was generally quite positive, although the panels are very different from anything we have used before and clearly take some getting used to. For starters, the panels are very heavy: a 4’ x 8’ panel weighs in at 140 lbs (64 kg). So you should plan carefully to avoid moving the panels around more than absolutely necessary. Keep them dry, as any moisture will cause dramatic swelling and delamination.

Our next observation was that the panels are pretty tough to cut. Use a sharp, carbide-tipped blade in a circular saw—preferably one larger than 7¹⁄₄” (184 mm) (which just barely cuts through the panel and may necessitate cutting the bottom layer of paper with a utility knife). Cuts along the length of the panel are much easier than cuts across the width, owing to the orientation of the straw. Be sure to wear a dust mask when cutting panels; a lot of dust is generated!

The H-clips used for joining panel edges work very well, but we were not as impressed with their use at the bottom of panels for securing them to the sill plate. The straw fibers spread out a bit at the top and bottom because the paper does not wrap around to hold them tightly compressed. As a result, we are not as confident that the ring-shank nails supplied by the company will hold securely. The other option, toe-nailing with long (20d—100 mm) galvanized nails, seemed more satisfactory in terms of holding, but you have to be more careful about not knocking the panels out of alignment. The manufacturer addresses this problem to some extent by taping the factory-cut ends, but we found that the tape does not hold tightly. If at least one end of each panel were securely sealed by gluing on kraft paper, more secure bottom attachment could be obtained.

We found the pre-routed wiring chases to work beautifully—standard Romex wire pushed through as if the channels had been greased! We are somewhat concerned about the risk of damage to wires by nails or screws anchored into panels, however, and our electrician expressed some concern about working with the shallow boxes that are necessary.

With the tapered edges, taping and finishing is the same as with drywall. The tapered edges are more pronounced, which is good, as the H-clips and the nails used with them stick out more than drywall screws and have to be covered.

The panels were installed on

Trex^® sill plates, which rested on the concrete floor. Trex, manufactured by Mobil Chemical, is a composite made from recycled polyethylene and wood fiber extruded into lumber profiles (See

EBN Vol. 2, No. 2 and

Vol. 3, No. 1). The Trex 2x4s we used are very heavy, and their structural properties make them unsuitable for many framing applications, but we found them to be very satisfactory for fully supported sill plates. They cut just fine with a circular saw, and we were able to nail and screw through them without problem.