Need to improve the insulation for your home? Some tips:
Are you planning to improve the insulation in your home -- maybe one room or the entire house? Here are some tips:
(1) The basics: There are two key factors - insulation R-value and air leaks. Insulation effectiveness is measured by the R-value. Foam board provides R-4 to R-6 per inch of thickness. Roxul rock wool delivers R-4.1 per inch. Fiberglass and cellulose offer R-3.5 per inch. Almost as important: your air leaks, especially up from your home into your attic. No matter how effective your insulation is, air leaks steal your money.
(1) Start by sealing your attic: Heat goes up and the sun comes down. So the best place to start is your roof / attic. Most homes have a standard "ventilated" attic with visible gable vents on the sides, soffit vents along the bottom edge of the roof, and maybe a ridge vent at the peak. Start by sealing every air leak from your house into your attic. Recessed ceiling lights are Culprit #1: install a Tenmat cover over every light can and seal the edges with DAP 230 sealant. See: Tenmat Model # FF130E Hoe Depot Internet # 204286308 Store SKU # 1000012747 and DAP 230, Home Depot Internet #100035980 Store SKU #284425 Great Stuff foam is good to fill larger gaps and holes -- but do not use it near anything that gets hot, e.g. a recessed light, chimney or exhaust vent. For gaps near a hot surface, fill the space with Roxul rock wool, then cover it with fire resistant sealant, e.g. 3M Model CP-25WB+, Home Depot Internet #100166701 Store SKU #163096 For the large gap next to an interior chimney, bridge the gap with aluminum flashing (available at Home Depot) nailed to the joists, and seal the edges with 3M. Your goal: block every air leak into your attic -- which rob you of heating dollars and comfort. Your money is literally flying out of your gable vents all winter.
Key tip: You can do this work yourself, but if your attic is filled with fiberglass or vermiculite (looks kind of like big bits of cat litter), be sure to wear a good dust mask, e.g. 3M Model # 62093HA1-C, Home Depot Internet #202080148 Store SKU #674580 -- NOT a cheap "dust mask" with a rubber band. Also wear a cheap Tyvek painter's suit and gloves, e.g. Model # 09961/12HD, Home Depot Internet #203555482 Store SKU #692106. Get one with elastic cuffs. The goal: keep the microscopic, VERY itchy and carcinogenic fibers away from your skin and out of your lungs. Trust me!
(2) Upgrade your attic insulation: Now that you carefully air-sealed your attic, it is time to seriously upgrade your insulation. If you climb up into your attic, chances are that the 2x6 ceiling joist bays are filled with insulation - probably fiberglass. That gives you R-3.5 per inch, for R-19.25. In the northeast, our attics should be R-38 to R-60 -- at least double what you probably have now. Here are some options:
> If your attic is NOT used for storage: Hire a contractor to add 6" to 12" of blown-in cellulose, which will simply be applied over your existing insulation. Blown-in cellulose provide R-3.5 per inch. If you are adventurous (and have someone to help you), Home Depot rents blowers for cellulose. See: Green Fiber Model # INS541LD, Home Depot Internet #100318635 Store SKU #211904 and Cellulose Insulation Blower rental, category #10 group #166. An important tip: Nail a bunch of yard sticks to your joists, before you (or your contractor) begin to blow in cellulose -- to accurately measure the depth. After the joist bays are covered, it is impossible to gauge the depth unless your yard sticks are in place beforehand.
> If your attic IS used for storage: You can upgrade insulation and improve your air seal. First, install two 2" layers of Foamular 250 foam board on top of your joists (and over existing insulation). Carefully seal all of the joints and edges to block air leaks, with DAP 230 and the 'Window and Door' version of Great Stuff. Install the second layer at a 90 degree angle from the first, and seal all of the joints and edges to block air leaks. Then install 3/4" plywood over the top. Mark the center line of the ceiling joists on the foam board, so you can use 6" screws to fasten the plywood to the joists. See: Foamular 250 Model # 52DD, Home Depot Internet #202085962 Store SKU #307101 This will add R-20 insulation, plus a more effective air seal. Note: Foam board is flammable and emits toxic gas when it burns, so it MUST be covered by an approved 'thermal barrier' in any living space, garage, basement or attic storage area. The standards are 1/2" drywall and 3/4" plywood.
> Do you need to install new roofing? STOP! This is also the IDEAL time to upgrade the insulation for your home. First, install Grace ice and water shield on the roof deck, at least 3' from every edge and every valley. (We covered our entire roof.) Then install 2" thick Foamular 250 foam board on top of the roof deck. Foamular provides R-5 per inch of thickness, and does not absorb water -- a key factor with roofs. Seal all of the joints and edges to block air and water leaks; DAP 230 works well when the weather is warm. Otherwise use DAP 3.0. Depending on the type of roofing, you can then install PT 1x strapping or 1/2" outdoor-rated plywood, e.g. Plytanium, as the nailing surface for your new roofing.
(3) Exterior wall insulation: If you are installing new siding, this is an IDEAL time to upgrade the insulation for your home! First, wrap your house with Tyvek house wrap -- which blocks water leaks and reduces air leaks. Carefully tape and seal all of the joints and edges. Then wrap your house with 2" thick Foamular 250 foam board, or 3" (double layer) of Roxul Comfortboard. Both options will give you R-10+ for your entire home, block condensation on your sheathing, and block the "thermal bridges" created by all of the exposed studs, joists and sheathing. Foamular will also help you air seal your walls, but foam is flammable. Roxul Comfortboard cannot air seal, but is not flammable. Your choice. If you install Foamular foam board, carefully seal all of the joints and edges to block air leaks. DAP 230 is good for joints and small gaps. The 'Window and Door' version of Great Stuff spray foam is good for larger gaps.
(4) Air seal your exterior walls: No matter which insulation option you choose for your exterior walls, you can add a final layer of water / air protection with Henry Blueskin VP100. We wrapped all of our walls with Blueskin, after the steps noted above.
(5) Insulation for your interior walls: If you are going to launch a serious remodeling project and plan to remove drywall, you can significantly improve insulation. Fill the open stud bays with Foamular XPS foam board or Roxul. Foam board offers the ability to air seal, but is flammable. Roxul provides nearly as much insulation value, but no air seal. (We used Foamular on a recent project; a photo is attached.)
(6) Insulate your basement floor: The best option is XPS foam board which provide R5 per inch. XPS does not absorb water, which can be important in a basement. Foamular 250 product also provides good 'compressive strength' -- which is needed under floors. See: Owens Corning Model # 24DD Internet # 100320335 Store SKU # 52802 Be sure to carefully seal all of the edges and joints to block air leaks. A generous layer of DAP 230 sealant works well.
If there is any possibility of a water leak in your basement, start with DriCore panels -- which have a rubber layer on the bottom with channels for water to flow through to a drain. Then add the foam board on top, followed by 3/4" plywood as the subfloor for your laminate flooring. See: DRIcore Model # CDGNUS750024024 Internet # 202268752 Store SKU # 361018 Make sure you have drains for the water to flow to and a dry well and/or sump pump. We recently used this combination for the basement of a home in Massachusetts and it was very effective. Rain leaked through a window during an unexpected downpour, and DriCore saved the new floor.
(7) Insulate around hot surfaces: If you need to insulate and air-seal near a hot surface, e.g. a recessed light, exhaust vent or chimney, special materials are required. Use Roxul rock wool to fill gaps; it is made from rock with a melting temperature above 2,000 degrees F -- ideal for any hot surface. To air seal on top of Roxul or a hot surface, use 3M Fire-Barrier Sealant, Model # CP-25WB+, Home Depot Internet #100166701 Store SKU #163096. NEVER install foam board or any type of Great Stuff spray foam near any hot surface.
A 'caveat emptor' warning: Have you seen magical claims for "reflective / radiant barrier" insulation products? They look like shiny bubble wrap or aluminum foil, with amazing R-values. Surprise! The actual R-value is ~R-1, and the claims are based on a sealed air gap that you must build when you install it. The air gap provides almost all of the claimed R-value. Plus, reflective / radiant products are not effective in winter because cold cannot be 'reflected' and the warmer air inside your home is not radiant. Reflectix claims R-7 for a cathedral ceiling in the summer, for example, but only R-1 in winter in the northern USA.
Standard insulation is always more effective, with one exception: If you have ventilated attic and a hot summer, you can lay a radiant barrier down on the attic floor and reduce heat flux from the summer sun by ~24%. This will reduce your HVAC costs by 3% to 4%. Dust will accumulate on the shiny surface, however, so you will need to shake it off from time to time. Otherwise, always use standard insulation.
In summary, the devil is in the proverbial details with insulation. There are many variables and product choices. We have been pleased, however, by the noticeable improvements in our homes.
Let me know if you have any questions: MarkAllenHays@Gmail.com
I do not have any connection to Home Depot or any insulation products manufacturer or vendor, (except as a Home Depot Pro Desk customer).