Hello,
I’m trying to decide if it’s worth it to go with the foil like radiant wrap vs. Tyvek. The radiant wrap is about $145/1000 sq feet. It doesn’t improve R-value, but it helps reflect back into the living space, supposedly reducing how often your heating system comes on. It’s applied on the outside like Tyvek, but comes in 4’x250’rolls rather than 9′ by 100 or 150′ rolls (which runs from $75 for 100′ – $145 for $150). So it’s a bit more expensive and probably more of a pain to install.
Any lovers or haters of the radiant wrap care to comment/advise?
thanks,
Roger <>< in central North Carolina
Replies
I don't know much about radiant wrap. I would reccommend 30lb felt. It self seals and is a fraction of the price. Tyvek is a fraud IMO. It does not self seal and the million holes from nailing the siding and stapling it on negate any moisture barrier effect you might want. It looks good, goes up quick and is trendy but that is about all.
I would worry about condensation on a foil type wrap. Is radiant wrap supposed to breath?
You are talking about two distinctly different products and applications. We have been using Typar as an exterior house wrap for years. Typar has a UV inhibitor and is supposed to stand up to exposure during construction better than Tyvek. Typar does a couple of things. It provides a water repellant covering for the materials under construction. Often we are using sheet material for sheathing, plywood, OSB. Both during construction and after, the Typar acts a water infiltration barrier. The material will allow water vapor to pass through but not liquid water. The material breathes and that is important on the exterior, under the siding. A moisture barrier on the exterior can trap water vapor in your walls that will condense. Trapped moisture can cause rot, mildew, mold and provide a happy place for insects.
Typar also acts as an air infiltration barrier. When correctly installed, it will help prevent the wind from penetrating your wall. Air penetrating your wall affects energy consumption, heating or cooling.
Radiant wrap is air and water proof. Used on the exterior it can lead to trapped moisture. On the interior wall, under the sheetrock, it can act as a vapor barrier. Interior vapor barriers are needed to keep the walls and insulation from getting wet. We generate a lot of moisture in a home. If it migrates into the wall it will condense, ruining the insulation and causing the other problems with rot. If the wrap is in direct contact with the sheetrock, it can act as a conductor of heat and cold. Most manufacturers recommend using a spacer on top of the wrap, 1/4" plywood strips. The reflective qualities of the wrap are somewhat questionable behind the sheetrock. Foil faced fiberglass insulation used to be common but I haven't seen it for awhile. I would question it's vapor barrier strength because of the four foot width. The seam would have to be sealed.
I think Typar is a good product. It does what it is supposed to if carefully installed. A quality job looks like a well wrapped Christmas gift, straight, tight, folded neatly and all seams taped. I'm hesitant with the radiant wrap. Too much work with the furring strips, electrical boxes have to be mounted out farther and extra furring may be needed for nailing around doors and windows. Doors and windows aren't made for walls that are thicker than 4 9/16" or 6 9/16".
If you want to step up to a more energy efficient wall, you can add an inch of extruded polystyrene, pink or blue, under the sheetrock. This will give you an extra R-5 and eliminate the thermal breaks your framing members cause. It also will quiet your house down from exterior noise. You still have to deal with window and door extensions. Whatever you do, don't put a non breathing material on the outside or you will be in for some serious structural problems later.
Beat it to fit / Paint it to match