DIY Vermiculite Insulation

Written by jane humphries
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DIY Vermiculite Insulation
Vermiculite insulation reduces heat loss through the roof. (Comstock/Comstock/Getty Images)

Vermiculite is an organic hydrated silicate marketed for many uses, including insulation. The silicate consists of expandable flakes that resist high temperature and mould. Unlike traditional fibreglass insulation, vermiculite does not cause skin reactions or irritation, making it perfect for do-it-yourself home attic insulation projects.

Skill level:

Things you need

  • Patching, filler product
  • Push broom
  • Measuring tape
  • Thin plywood
  • Wood saw
  • L-shaped brackets
  • Wood screws
  • Screwdriver
  • Respirator or dust mask

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  1. 1

    Check the floor in between the joists in the attic to see if any holes or cracks go through the ceiling below. Fill any holes with a suitable patching product that matches the floor substrate so that the loose vermiculite flakes do not fall through ceiling gaps.

  2. 2

    Use a push broom to sweep up dust and debris between the joists. Engage a qualified electrician to reroute electric cables above the expected height of the vermiculite insulation, if cables run on the floor between the joists.

  3. 3

    Measure the width between the joists at the eave ends of the attic. Position the tape measure 6 inches in from the end of the joist so that you leave a ventilation gap for the roof space. Measure the depth of the joists in order to make a barrier to keep the vermiculite in place.

  4. 4

    Using a wood saw, cut lengths of thin plywood to the width measurements you took in Step 3. Cut the width of the wood to the depth of the joists.

  5. 5

    Screw an L-shaped bracket on each width edge of the wood panel, using small wood screws and a screwdriver. Slot each panel into position, 6 inches in from the end of the floor joists at the roof eaves. Screw the panel to the joists via the L-shaped bracket to secure the panel in place.

  6. 6

    Wearing a respirator or dust mask, pour the vermiculite flakes in between the floor joists to the depth of insulation you require. Typically, 4 inches reduces heat loss through the roof by 60 per cent. Use a clean garden rake to spread the vermiculite insulation to a uniform level.

Tips and warnings

  • Do not use vermiculite insulation produced prior to 1990 due to the risk of asbestos contamination. During the 1980s, some mined vermiculite contaminated with asbestos reached the marketplace; modern vermiculite processing undergoes rigorous checks to ensure the purity of the product.
  • Wear a respirator when installing vermiculite insulation to avoid ingesting dust.

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