How One Remodeler Approaches Insulation Upgrades
Originally published by: The Virginian Pilot — December 13, 2017
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Proper insulation for our homes is an important cost, comfort and ecological consideration, regardless of the outdoor temperatures. But we tend to think more about insulation as the mercury starts to drop and frigid winds pick up. If you are building, remodeling or simply thinking of swapping out existing insulation in those areas of your home that are accessible, you will want to keep reading.
Essentially, you can choose between four types of insulation: two types of batts and two types of spray-in foam, each with benefits and drawbacks. Batts, both fiberglass and cotton, are perfectly sized to fit in the spaces between the standard spacing of wood supports in walls and ceilings. Paper-backed to provide a moisture barrier, batts are an effective and very economical choice, and they’re easy to install, except in odd-shaped spaces. Cotton batts, made from recycled denim jeans, offer the added benefit of being a bit more eco-minded, though at a slightly higher price, while fibers released by fiberglass batts are not healthy to breathe, at least not for the installer. Once they are sealed inside walls, they are thought to pose little hazard.
Open cell polyurethane foam is soft and lightweight and can be blown into the oddest-shaped and hardest-to-reach spaces. Homeowners can expect a better insulation value along with better protection from drafts. They also can expect to pay significantly more. Its cousin, closed cell foam, is denser because of sealed air pockets filled with an insulating gas, which provides greater insulation value and greater moisture protection while actually strengthening the structure. But you can expect to pay even more for these perks. You also can expect to have to cut it away if wires or pipes are added in the future.
There is also rigid foam sheathing or foam board, which is applied to the exterior of the home. Though it is a bit more expensive and not as strong as plywood sheathing (which doesn’t matter if you apply it over the plywood), rigid foam board provides better insulation than plywood alone while doing some heavy lifting against moisture (by preventing both leaks and accumulation) and against air leakage. Rigid foam controls both air infiltration and exfiltration, unlike some house wraps which only guard against the former.
Since it is so important, what exactly is the aforementioned insulation value? R-value refers to the transfer of heat between the interior and exterior of your home, what professionals refer to as thermal resistance. The higher the number, the less transfer because there is greater resistance. With less heat conduction, you can expect energy savings, which are good for your wallet and good for the environment. Today’s homes can achieve an R-value of R-15 up to a R-19 in walls and R-38 in the attic.
Once you understand the science behind this heat conductivity, you will undoubtedly discover that air-sealing your home – creating a tight envelope, as we say – goes hand-in-hand with insulating. That is, R-values alone do not tell the whole story. Addressing both radiation (air moving from a hotter to a cooler material) and convection (the movement of heat and moisture) ensures that your home is the most energy-efficient and comfortable that it can be.
And don’t forget your crawl space. Insulation materials and vapor barriers are also right at home here, whether your crawl space is ventilated or not. If ventilated, you will want to insulate under the subfloor and between the floor joists, while if unventilated, you will instead want to insulate the walls, perhaps with a vapor barrier over the dirt floor.
Though all this talk of R-values, roofs and crawl spaces isn’t terribly sexy, you can further insulate your home with eye-appealing window- and glass-door treatments, such as insulated drapes and cellular blinds. It’s never too late to better insulate.