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How to Blow In Insulation

Blow-in fiberglass loose fill insulation provides an affordable method for shielding your home from hot and cold temperatures. An attic that is under-insulated or uninsulated reduces the energy efficiency of your home’s heating and cooling system. Insufficient insulation could also increase the risk of moisture condensing in your attic and cause ice dam buildup on your roof. The materials and equipment needed to learn how to blow in insulation are available at home improvement stores.

How to Blow In Insulation Step-by-Step

  1. Measure the width and length of the attic space.
  2. Multiply the figures to find out the square footage.
  3. Determine the R-value needed for the space so that you know how much insulation to buy.
  4. According to Energy Star, the Delaware Valley falls into insulation zone 4.
    1. An attic without any insulation needs an R-value of R38 to R60.
    2. An attic with 3 to 4 inches of old insulation needs new material with an R38 value.
  5. Consult blow-in fiberglass insulation packaging to learn how much to buy to fill the space and reach the necessary R-value.
  6. If old insulation is present, assess whether you can keep it.
    1. Remove any old insulation if it’s moldy or extremely deteriorated.
  7. Seal air gaps with caulk around pipes, exhaust vents, and electrical boxes.
    1. Use spray foam in gaps too large for caulking.
  8. Run a bead of heat-resistant caulk around heater flue.
  9. Use sheet metal to construct a wall around flue to prevent contact with new insulation.
  10. Cut metal with tin snips and bend bottoms of pieces.
  11. Staple bent bottoms of metal pieces to attic floor joists around the flue.
  12. If recessed lights are in attic space, confirm that they are rated Type-IC.
    1. If not rated Type-IC, build a protective box with drywall pieces so that 3 inches of air space surround a light fixture.
    2. Connect drywall pieces with drywall screws.
  13. Seal seams of drywall box with spray foam.
  14. Now that the attic is prepped, you can finish the steps for how to blow in insulation.
  15. Nail or tape wooden sticks or rulers to some floor joists to serve as depth guides when blowing in insulation.
  16. Open insulation packages carefully because material will expand.
  17. Load the blower according to its directions.
  18. Connect the hose to the insulation machine mounted on the lower level near the attic access.
  19. Pull the hose into the attic.
  20. Have a partner turn on the machine and load insulation as needed while you work in the attic.
  21. Start in the farthest corners and work your way toward the attic access.
  22. Spread insulation evenly up to desired depth.

Tools & Materials

  • Measuring tape
  • Caulk gun
  • Insulation blower
  • Tin snips
  • Stapler
  • Drywall (sheetrock)
  • Plywood to place across joists while you work
  • Power drill
  • Protective dust mask
  • Safety glasses
  • Long-sleeve shirt and pants
  • Work gloves

Insulate Your Attic During a Roof Replacement

A roof replacement provides an excellent opportunity to insulate an attic. We can easily add insulation to your attic while redoing your roof as we will have easier access to all areas under your roof. The PJ Fitzpatrick team uses high-quality Owens Corning Loosefill Insulation. Talk to one of our insulation specialists to learn how much insulation your home needs. Contact us for an attic insulation or roofing estimate today.

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