How to Insulate Your Attic Space

Without attic insulation expect to be hot in summer and cold in winter.

Attics are the major source of energy loss in your home. Heat rises and ultimately goes up and out through the ceiling to the attic in the winter. Yet in summer attics can reach 140 degrees Fahrenheit and heat the ceiling below, adding to the home's heat load and reducing the cooling effect from the air conditioner and fans. The solution is to create a heat barrier, usually in the form of fiberglass insulation--either loose fill or batts -- providing an insulation value of R-32 or better. In addition, prior to adding insulation you need to prepare the attic with a number of preliminary steps. The end result will drastically reduce your heating and cooling costs and add to the comfort of your home.

Things You'll Need

• Insulation (loose fill or batts), enough to cover the attic to an R-32 insulation value
• Vapor barrier (plastic, for loose fill)
• Caulking, high temperature (or furnace cement)
• Caulking, long-life (silicone GE I or II)
• Rigid foam board insulation
• Sealing tape
• Plywood covers for attic openings, bulkheads, and drop ceilings
• Metal flashing
• Hammer
• Nails
• Knife and/or scissors (for batt sizing)
• Rake (loose fill adjustment)

Instructions

Insulating Your Attic

1. Calculate the amount of insulation needed based on your attic square footage and what's needed to achieve an R-32 insulation value. If you have existing insulation, check on its R value and figure out how much additional insulation you will need to go to R-32. If you have vermiculite, it might contain asbestos. Have it checked by a professional and arrange to have them remove it. Loose fill insulation is less expensive, but batts have vapor barriers already in place and install quickly.

2. Duct the exhaust fans to the outside. Cover the fans and seal the perimeters of the fan box to the drywall on the attic side. Seal the chimney and framing using high temperature caulking or cement. Seal the tops of interior walls with long-life caulking for small openings and spray foam or rigid foam insulation for larger openings. Insulate and add sealing tape to your attic access. Air seal and insulate knee walls and vertical walls behind them and in your home. Raise any platforms used for HVAC or hot water tanks in the attic above the ceiling joists to allow proper insulation depth.

3. Cover openings to the attic with plywood. All drop ceilings, bulkheads, and soffits should be covered and sealed to avoid air leaks. Use sealing tape or spray foam depending on the location.

4. Install blocking as required by fire codes. A 3-inch clearance is required for heat-producing items. Add clearances to flues, exhaust fans, chimneys and light housings unless they are rated IC (insulation contact). These are airtight and approved to cover with insulation. Do not block soffit vents or otherwise restrict attic ventilation.

5. Add a vapor barrier on the warm side of the attic with loose fill above. Alternatively, add the batts barrier side down over attic joints facing the ceiling. Make sure all areas are filled or covered completely to obtain maximum efficiency.

Tips & Warnings

• If you live in a warm climate, consider installing a radiant barrier in your attic along with the insulation.

• Note any water marks in the attic and repair any roof leaks before adding insulation.

• Wear a mask to avoid excess dust exposure and protect your respiratory system when laying loose foam or batts.

• Use plywood platforms to stand on when laying insulation, to cover attic joists and avoid contact with the ceiling.

References

• Enery Savers: Attic Insulation