How to insulate a porch floor

Written by dannah swift
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How to insulate a porch floor
Staple gun (Hemera Technologies/ Images)

An enclosed porch on the back or front of the house will not hold much heat, even if the roof and walls are well-insulated. Cold rising up from the ground directly under the porch floor will make the interior of the porch cold despite wall insulation. Manufacturer Owens-Corning recommends insulating the underside of a porch as you would insulate a crawlspace to keep the interior of the room comfortable in cold months.

Skill level:
Moderately Easy

Things you need

  • Fibreglass insulation
  • Safety glasses
  • Face mask
  • Bread knife
  • Staple gun
  • Nylon straps

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  1. 1

    Cut the insulation if it doesn't fit between the joists. A bread knife is an effective tool for cutting insulation. Flip the insulation so the vapour retarder faces you. Wear safety glasses and a face mask.

  2. 2

    Place the insulation between the floor joists with the vapour retarder -- the paper side -- next to the floor. The insulation should run from one joist brace to the other, or end to end. Don't leave any spaces uncovered.

  3. 3

    Staple lengths of nylon strap horizontally from joist to joist. Placing one strap every 3 feet or so should keep the insulation from sagging.

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