How To Insulate Your Home

How To Insulate Your Home

Difficulty level: Low

These tasks should be fairly straightforward, whether you have experience doing DIY or none at all.

Before you get started on any of our ‘how to’ guides, please take a moment to read through our DIY safety tips.

1. Draught-proofing your home

External doors

  • Make sure your front door only has a 2mm or 3mm gap at the top and sides and a 5mm gap at the bottom.
  • For extra protection use self-adhesive foam or flexible vinyl strips to seal around the edges and top of the door frame.
  • Bring in a draft excluder to stop cold air slipping through the bottom of external doors. These plastic or metal strips have a rubber seal or rows of nylon bristles as barriers against those icy draughts (fig. 4). To be effective the seal or bristles must overlap the door frame.
  • Buy draft excluders in wood or metal finishes to match your door.
  • Cold air creeping through your letterbox? Get a letterbox draught excluder.

Skirting boards

  • Clear flexible sealant does the job on skirting boards. Squeeze sealant between floorboards and the base of the skirting. Work along the board in a smooth, continuous motion.
  • For gaps over 5mm, pin strips of quadrant-shaped moulding over them (fig. 5).


  • Suspended wooden floors in older homes are trickier as they need air flowing underneath them to combat condensation and rot. But you can make ground-floor rooms warmer and more energy-efficient – simply fill spaces between boards with a clear flexible sealant or insert thin strips of wood into larger gaps.

2. Insulating under a new floor

  • If you’re laying new flooring, why not insulate at the same time? Lift the floorboards and fit glass mineral wool insulation between the floor joists.
  • You’ll recoup the cost of this in just a few years with lower energy bills.

Lifting your floorboards

  • Lift boards with a thin bladed cold chisel and club hammer. Lever them up, working along the board to prise away all the nail fixings.
  • To stop insulation dropping through the joists, simply staple plastic garden netting between the joists at the bottom of each side. Or you can nail lengths of roofing batten along the sides of each joist (fig. 6).
  • Lay rolls of loft insulation or rigid pieces of wall insulation between the joists.
  • Once the entire floor is covered, re-lay the floorboards. Replace damaged sections and nail firmly to stop any squeaking or movement.
  • Don’t leave wide gaps between the boards – see advice on floorboards in Section 1.
  • Use a nail punch to push the nails below the surface of your floorboards.

3. Insulating your windows

  • Double glazing isn’t cheap but the effect is fantastic – you’ll halve heat loss through your windows instantly.
  • Your shorter-term fix is secondary glazing fitted to the inside of window frames. These units come as kits.
  • Fill gaps around the secondary glazing frame and your window frame with flexible sealant



Writer and expert