Your Loft

I learned an awful lot about attic insulation while working for an East London loft conversion firm, where we did to loft conversions of all types. One of the first things I realised was lofts are the major source of energy loss in your home. Heat rises and goes up and out through the ceiling to the loft in the winter. In summer lofts can reach 140 degrees F and heat the ceiling below to add to the home’s heat load, reducing the cooling effect from air conditioner and fans. The secret is to create a barrier usually in the form of fiberglass insulation–either loose fill or batts providing a value of R-32 or better. In addition, you need to prepare the loft with a number of preliminary steps prior to adding insulation. The end product will drastically reduce your heating and cooling energy costs and add to the comfort of your home. The methods below will apply

Your Loft

Things You’ll Need:

Insulation (loose fill or batts), enough to cover the loft to an R-32 insulation value

Vapour 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 loft openings, bulkheads, and drop ceilings

Tools You’ll Need:

Metal flashing

Hammer & nails

Knife and/or scissors

Rake (loose fill adjustment)


  1. Calculate the amount of insulation needed based on loft square footage and R-32 insulation value. Purchase the materials on the list from a hardware or outlet store. If you have existing insulation, check on the current R value of what is in place and 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. Batts have vapour barriers 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 loft 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 loft 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 loft above the ceiling joists to allow proper insulation depth.
  3. Cover openings to the loft 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). They are air tight and it is approved to cover with insulation. Do not block soffit vents to restrict loft ventilation.
  5. Add a vapour barrier on the warm side of the loft with loose fill above. Alternately add the batts barrier side down over loft joints facing the ceiling. Make sure all areas are filled or covered completely to obtain maximum efficiency.

Further Tips

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

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

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

Use plywood platforms to cover loft joists to stand on and avoid contact with ceiling when laying insulation.