Installing insulation is relatively straight forward for DIYers.

First off it is important to:

  • check everything is safe before commencing. Read and follow the Health and Safety advice in Appendix B of New Zealand Standard NZS 4246:2016
  • Check for existing insulation – If there is existing insulation, you’ll want to check what state it’s in.
  • ensure all insulation (once installed) isn’t squashed. Insulation is most effective at full thickness
  • New Zealand Standard NZS 4246:2016 contains everything you need to know about installing insulation.

Ceilings

Segment insulation

Measure your ceiling joist spacings before you purchase your insulation as you may be able to buy the correct measurement from the hardware store. Always follow the manufacturers instructions.

  • Measure the gap between ceiling joists
  • Cut insulation to suit using a sharp craft knife
  • Fit insulation into the space required.
  • Ensure the insulation fits snug with no gaps and remains as flat as possible.
  • Measure and cut your next piece ensuring it fits snug against the previous piece
  • Cut out sections where clearance from an electrical product is required.

For blanket insulation

  • Ensure all roof space is free of obstacles, all existing insulation is flat, dry and away from old downlights extractor fans etc.
  • Start at the furthest point away from the hatch for convenience.
  • Roll out the ceiling blanket perpendicular to the ceiling joists
  • The blanket can sag slightly between joists.

Wall Insulation

Installation checklist

Check local building consent requirements

Retrofitting wall insulation needs a building consent unless your local council grants you a discretionary exemption. Either way, it must comply with the Building Code. Find out about requirements through your local council.

Council maps and websites – LGNZ website

Ensure your wall cavities are dry

Leaks or moisture issues in wall cavities can be worsened by installing insulation, leading to timber decay and toxic mould growth. To make sure that the outside cladding and flashings are in good condition, and there are no hidden plumbing leaks, consult a qualified builder (who is a licensed building practitioner) or a registered or accredited building surveyor.

Check the building paper in your walls

Building paper (wall underlay) prevents insulation from coming into contact with the outer cladding of your house, reducing the risk of moisture problems that can lead to timber decay and toxic mould growth. You can retrofit building paper, provided your wall is dry – refer to the NZS 4246:2016 insulation installation standard

For segment insulation (follow the manufacturers instructions)

  • Measure the gap between studs
  • Cut insulation to suit using a sharp craft knife (note measure your stud spacings before hand if possible as you may be able to buy the correct width from the hardware store)
  • Fit insulation into the space required.
  • Ensure the insulation fits snug between timber and other insulation with no gaps.
  • Measure and cut your next piece ensuring it fits snug against the previous piece
  • Cut out sections where clearance from an electrical product is required.

UnderFloor

DIY checklist

If you’re going to install underfloor insulation yourself, there are some things you should think about. It can be a difficult, dirty and time-consuming job, and the quality of the job has a big impact on how well the insulation works.

Things to consider before you begin

  • Check your underfloor is accessible – it must be more than half a metre off the ground, otherwise you’ll have trouble getting under the joists and bearers that hold the floor up.
  • Check whether any underfloor repairs are needed – before your insulation is installed. Look for:
    • borer and other pest infestations
    • rotten piles or subfloor framing and any corroded fixings
    • electrical wiring issues
    • drainage, guttering, downpipe or plumbing problems (like water flowing under your house after rain, or from leaking pipes)
    • obstructions (stored timber, rubbish)
    • dampness (mould or mildew, or dirt that stains like mud when you rub it in your hand). Check out countryandcoast.nz/home-dampness/
  • If your underfloor space is open – exposure to wind and weather can impact the effectiveness and durability of your insulation. Consider enclosing the sub-floor perimeter (as long as you have building code-compliant vents), or installing plywood or fibre-cement sheets to the underside of the floor once your insulation is in. It’s worth consulting a qualified builder to find out what will work best for your house. If you can’t enclose your sub-floor space, ensure you choose an insulation product that has been tested for performance and durability in windy conditions.

For segment insulation (follow the manufacturers instructions)

  • Measure the gap between joists
  • Cut insulation to suit using a sharp craft knife (note measure your ceiling joist spacings before you purchase your insulation as you may be able to buy the correct measurement from the hardware store)
  • Fit insulation into the space required.
  • Ensure the insulation fits snug with no gaps and remains as flat as possible.
  • Measure and cut your next piece ensuring it fits snug against the previous piece
  • Cut out sections where clearance from an electrical product is required.

Published by countryandcoast