11:08AM | 07/23/99
Any comments on the comparison between these two? For use in a cold climate, about R25 to R35, in a new construction.


07:10PM | 08/10/99
Member Since: 10/10/98
34 lifetime posts
Polystyrene and the other rigid insulation products are primarily used in wet applications such as the inside/outside of basement walls and floors. It won’t draw out moisture, whereas fiberglass acts as a wick, and in turn will grow mold, begin to smell, and eventually pack down and loose its R-value, forcing replacement. For that reason, polystyrene panels often are shaped to accept firing strips, making basement applications somewhat straightforward. In fact, thicknesses seem to match those of metal studs, such as 1 ½” and 2”.

3 ½ inches of polystyrene has an R-value of 17.5, whereas 3 ½ inches of fiberglass has only R-13. Sounds good, but a 2’ by 8’ panel of 2” thick polystyrene, plus another 1 ½” panel (about 16 S.F.), will cost as much as a whole roll (40 S.F.) of R-13 fiberglass. Moreover, the rigid panels would be very labor intensive to use throughout the entire house, with electrical outlets and the like. For example, since the panels are 2’ wide and the studs, 16” on center, each panel would have to be cut down, creating substantial waste. Consider also, the fact that studs are not always 16” on center, nor are they always straight. Fiberglass batts are 15” wide, and are flexible to imperfections.

The extra cost would probably far outweigh any energy savings, unless you stay in the house for, say, 50 years. Even so, some applications can still benefit from the use of polystyrene besides basements. For example, vaulted ceilings and the like need to have a “breathing” area above the insulation to prevent ice damming and prolong roof life. This limits the amount of insulation in this restricted space. Polystyrene panels could be beneficial in this situation. For most of the house, though, you can get a very close R-value to polystyrene with a combination of fiberglass, reflective panels, and a vapor barrier, for considerably less money.

There are other types of insulation you may want to consider, including several types of foam insulation which are blown in as a liquid, then, when cured, become rigid. If you were thinking of that as polystyrene, well, it’s not. Polystyrene is sprayed into an extruded mold, and the manufacturing process is volatile. Besides, polystyrene is highly flammable and emits toxic gases when burned. One of the other insulation choices is called Icynene, and although typically used in remodeling, may have a spot in your new construction. Check around. Something should fit your plans.

Hope this helps. It would be interesting to hear other opinions and ideas on the subject.



Post a reply as Anonymous

Photo must be in JPG, GIF or PNG format and less than 5MB.


type the code from the image


Post_new_button or Login_button

Making this trio of storage totes is simpler than you might think. Gold screw bolts and spray adhesive hold the fabric cov... Built on a rocky island in the Drina River, near the town of Bajina Basta, Serbia, this wooden house was cobbled together ... Large steel-framed windows flood the interior of this remodeled Michigan barn with daylight. The owners hired Northworks A... Edging formed with upside-down wine bottles is a refreshing change. Cleverly and artistically involving recycled materials... A Washington State couple called on BC&J Architects to transform their 400-square-foot boathouse into a hub for family bea... Similar to the elevated utensil concept, hanging your pots and pans from a ceiling-mounted rack keeps them nearby and easy... Few projects are more fun than upcycling a vintage piece in a surprising way. Outfitted with a sink and a delicately tiled... The thyme growing between these stepping stones adds a heady fragrance to strolls along this lush, low-maintenance garden ... Decoupage is an easy way to add any paper design to your switch plate, whether it is wallpaper, scrapbook paper, book page... Twine lanterns add pops of crafty—but sophisticated—flair to any outdoor setting. Wrap glue-soaked twine around a balloon ... When securely fastened to a tree or the ceiling of a porch, a pallet and some cushioning make the ideal place to lounge. V... Reluctant to throw away any of those unidentified keys in your junk drawer? Hang them from a few chains attached to a simp... A stripped-down model, sans screened porch, starts out at $79,000. Add the porch, a heated floor for the bath, and all the... Salvaged boards in varying widths and colors make up the dramatic accent wall in this attic space. The high-gloss white of... This garden shed has been decked out to the nines. Designer Orla Kiely created the intimate home for a flower trade show, ...
Newsletter_icon Google_plus Facebook Twitter Pinterest Youtube Rss_icon