Underfloor Insulation Install Guide

How to Install Your Underfloor Insulation


Terra Lana underfloor product is designed for all underfloor ground conditions. However the insulation will not prevent ground vapour rising and potentially causing damage to your home. If the ground is wet, a vapour barrier (250µm polythene) should be installed directly over the earth.

  1. Distribute the bags of Terra Lana product to the areas to be insulated. Leave them bagged until you are ready to install each section.
  2. Split the bags, or pull the Terra Lana from the bag. Run the Terra Lana in a continuous length between the floor joists and over the main bearers. Make sure the white polyester layer faces towards the ground.
  3. Terra Lana is designed to friction fit most joist spacings. Push the Terra Lana lightly up to the bottom of the floorboards, while still retaining its loft. Staple through the bottom layer between 50mm and 80mm from the top of the joist. The idea is to allow the insulation enough space to loft to its designed thickness but still have the insulation in contact with the underside of the floor. At the end of the joists the stapling height should be closer to 50mm below the top of the joist to ensure no air can circulate above the insulation.
  4. Staples should be placed every 10cm or less, while keeping the Terra Lana firm and tensioned. Do not staple directly to the underside of the floor - this will compress Terra Lana and reduce its insulating properties.
    (NB: staples should only be fixed through the polyester outer layer).
  5. Two lengths of insulation can be butt jointed mid-section by pressing the ends together firmly before stapling the new length.
  6. The insulation can be torn across the width of the roll to trim the length to fit firmly against the bottom plate and joist noggings. It is good practice to also staple the ends of the rolls to the bottom plate and joist noggings.
  7. Where the floor joist spacings vary, measure the gap by holding Terra Lana up to the joist and simply rip cross the roll to size, push into place and staple. Repeat until the joist row is complete.
  8. Clearances: Leave a 100mm gap between insulation and waste pipes that penetrate through the floor, and a 200mm gap between insulation and underfloor lighting and heat sources
  9. On completion, remove all plastic bags and leftover material from the underfloor space.
  10. Staple a Product Information and Identification Certificate adjacent to the underfloor access for future reference.

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