Draught-Proofing Floorboards: A DIY Guide To Insulating Your Home

Dark wood floor boards

Draught-Proofing Floorboards: A DIY Guide To Insulating Your Home

Peeling back a battered carpet to discover a hardwood floor is a moment of great joy. Few floorings will add as much personality and elegance to any room, with just a little loving care.

But, after a while, the beauty of these floors can fade. Wood warps with age, and occasional chips or splinters can leave you with gaping spaces between your boards.

Gaping floorboards are irritating, unsafe and costly. They will swallow dust and dirt, making your room a lot hard to keep clean. They can cause a trip hazard. And finally, these gaps will let draughts in to your house. It allows cold air coming through the floorboards while the warm air heated by your boiler is lost. In fact, the Energy Saving Trust believes that draught-proofing your floor could save you to £40 a year.

The cost of underfloor insulation options to tackle these draughts is usually relatively small. It can be a fiddly job, but it is simple enough to do yourself and the materials are not expensive.

In this post, we’re going to look at the different methods of how to insulate wooden floors to help you weigh up the benefits of undertaking this process.

How to Fill Gaps Between Wooden Floorboards

When it comes to filling the gaps between your floorboards, you can choose between four techniques:

  • Silicone-based filler
  • Pine slivers
  • DIY draught-proofing (StopGap or Draughtex)
  • Mass Filler

Silicone-Based Filler

This is a silicone-based gel or liquid which you squeeze into the gaps between the floorboards.

Pine Slivers

This is where you take small strips or slivers of reclaimed floorboards and hammer them gently into the gaps.

DIY Draught Proofing

This technique involves purchasing a specialist draught-proofing material, something like a thin foam board or matting that you insert between the boards.

Mass Filler

For this technique, you mix sawdust with a glue or resin to create a bulky liquid that your place between the boards, which hardens to form a more robust filler.

shot of peoples feet as they sit on the sofa with wooden floorboards beneath

How to Draught-Proof Using Silicone Based Filler

Silicone-based fillers can be found at most DIY or home improvement stores. These specific flooring fillers have been specially designed to give a long-lasting finish and with a good range of colours so you can match it to the shade or stain of your floors.

These are silicone-based so that they remain flexible to allow for movement of the floorboards. As well as the vibrations of footfall, wooden boards will expand in heat and contract in cold and any filler you use on your floor needs to allow for this.

You run the filler into the gaps using a mastic gun. These don’t always allow for the greatest control, so be prepared for a messier job and some necessary clean-up.


  • Allows great colour matching against the floor
  • A strong compromise regarding cost and quality


  • Can be difficult to control and have a messy finish
  • Won’t last permanently

How to Use Pine Slivers to Draught-Proof Your Floorboards

Pine slivers are probably the pinnacle of draught-proofing techniques for floorboards, fitting in as flawlessly as possible with a very long life. The technique involves buying or making ‘slivers’ of floorboard to slot into the gaps between your existing floorboards. These are gently knocked into place using a rubber mallet, then can be sanded down and stained to match the old boards.

The end result should be a floor that looks as good as new regardless of gap size. No draught should be able to get through and, best of all, this technique should really last.


  • Long lasting
  • High-quality professional finish


  • Expensive to buy the slivers
  • Will need sanding (and possibly staining) to achieve the most attractive finish

How to Draught-Proof Using StopGap or Draughtex

If you can’t afford pine slivers, but still want a longer-lasting and neater finish, a specialist product such as Stop Gap or Draughtex is the answer. Both have been specifically designed to blend invisibly into the floors, and to last for a long time.

Draughtex is a squashy sausage of foam, that you cut to length then push into gaps using a blunt knife or credit card. It comes in 3 thickness options and allows for plenty of movement of the boards, while still maintaining the seal. It only comes in one colour ‘shadow’ which is intended to mimic the dark shadows that sit in the seams for floorboards.

Stop Gap works on a similar principle, though it is plastic rather than foam. When you insert this into the gaps, the v-shaped plastic springs back to fill the gap. The main issue with Stop Gap is it’s ‘neutral’ colour. While it will technically be invisible once applied, this actually means that visually you will still see the gaps.


  • Long-lasting
  • Should leave an invisible finish
  • Available in a range of thicknesses to tackle many gap sizes


  • The range of sizes can make it a lot slower to fit than expected
  • Will not visually hide or minimise the gaps

How to Draught-Proof Using Mass Filler

Mass filler is the most ‘DIY’ approach of all these techniques. That’s because not only are fitting or inserting the filler yourself, your will even create the filler liquid yourself.

You can start with a specialist resins, or even just PVA glue. Mix your chosen liquid with liberal amounts of sawdust to achieve a ‘putty’ consistency. This can then be pushed down between the boards and should harden to plug the gaps.

This is a fiddly, but cheap way of doing it. And, because it’s cheap, it can have mixed results. The resin may not hold for long, particularly on floors that see heavy duty use.


  • Cheap
  • Requires no specialist equipment or knowledge


  • The filler may shrink, crack or fall through the gaps
  • Making the filler mix can be time consuming as you need to get it the right consistency

Having gaps in your floorboards can be ugly and costly. With the variety of techniques available to tackle them, they are also unnecessary. We hope this post helps you weigh up the best option to tackle your boards, so you can recapture the glee you felt when you first discovered your hardwood floor.

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