How to Board Your Loft Whilst Achieving Good Insulation

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In this article, I’ll explain how to board your loft the correct way, whilst achieving the recommended insulation thickness.

Boarding out a loft helps increase the amount of storage space within your home. It’s the ideal place to store items you do not need regularly, such as Christmas decorations, collectables, or stuff you cannot store anywhere else.

When it comes to boarding out a loft, there are a couple of ways to do it.

Most people use chipboard (also known as low-density fibreboard). This type of board is made up of sawmill shavings and wood chippings, and is therefore one of the cheaper options.  Chipboard made for loft flooring are supplied in convenient sizes so they fit through your loft hatch. They also slot together due to their tongue and groove design.

There are alternative wooden materials which can be used for loft boarding.  For example, you could use plywood. This type of board is very strong, and is made up of two or more layers of wood veneer that are glued together.  Like many other wooden materials, it will cost a lot more than chipboard.

Overall, chipboards appear to be the most cost-effective option for loft boarding, and the most convenient.

Introduction to Loft Insulation

Loft insulation requirements have dramatically increased throughout the years in the UK, and probably most other countries too.

For example, insulation in household lofts became a requirement for new builds in the 1960s. At the time, the insulation had to be only 25mm thick. Boarding a loft during that time would have been simpler, as you could lay the boards straight over the joists (ideally allowing a 10mm air gap to stop moisture build up).  Loft boarding started to become more difficult in the 1990s, when the recommended insulation thickness exceeded that of the 100mm joists, and became 200mm.

These days the recommended loft insulation requirement is around 270mm, making it impossible to board straight over the joists.

Additionally, squeezing insulation down in order to fit the height of the joist is a terrible idea. Doing so reduces the effectiveness of the insulation.

We tell you how to board your loft whilst achieving the recommended insulation later.

The majority of heat loss from a home is through the roof. Hence you should achieve the recommended loft insulation thickness outlined by the building regulations. A well insulated loft helps keep your house warm in the winter, and cool in the summer.  Remember that a well insulated loft also means a colder loft space, as more heat is being trapped within your home. This means you need to ensure any water pipes in your loft are insulated (lagged).

Any warm moist air that does penetrate though your ceiling into the loft is likely to condense against the cold surfaces within your loft.

To solve such a problem, you should:

  • Ensure the loft space has enough ventilation.  Ideally air should flow from one side to the other via vents within your soffits.
  • Lower the quantity of moist air in your home. For instance, instead of installing recirculating fans in your kitchen and bathroom, you can install the extractor ones.

Insulating and Boarding Your Loft – Step by Step

Health and Safety First!

You must wear the following equipment when insulating and boarding your loft.  Most importantly, it is essential you buy a good quality dust mask such as FFP2 or even FFP3.  Such masks have filters that help block out dust and insulation fibres.

  • Gloves
  • Dust mask
  • Disposable overalls (paper suits)

Loft Boarding Tools and Materials

Before you insulate and board your loft, we recommend you gather the following materials and tools:

  • 100mm glass fibre wool insulation
  • 200mm glass fibre wool insulation
  • Tongue and Groove Chipboard Loft Boards
  • Loft legs
  • Cordless drill.
  • Pozidriv bits.  These bits fit into your cordless drill chuck, turning your drill into an electric Philips type screwdriver.
  • Hammer.  To help you tap the tongue and groove boards into place.
  • Jigsaw.  For cutting boards down if necessary.
  • Workbench.  To help you cut any boards down.
  • Measuring tape
  • Pencil

Step 1.  Plan your Loft Boarding Design

Before I explain how how to board your loft, it is essential you have a plan first.  This is because many people accidentally board over water pipes, gas pipes, or cables.  Ideally you should allow access to such utilities by boarding around them. Therefore, it is a good idea to start drawing a Plan View of your loft area, then plot these essential utilities.

Once you have drawn the shape and location of your loft, you will then need to measure up.  Take the measurements in meters, as this will make your life easier when buying packs of loft boards.  Chipboard loft boards typically come in packs of 3, in dimensions such as 2400 x 600 or 1220 x 320.

Step 2. Review your Current Insulation

The next step is to review the insulation you currently have in your loft. Ideally you should have glass wool insulation between your joists.  Such insulation should be 100mm thick, as this is the typical thickness of joists.

If you currently have insulation between your joists, but looks very dusty and compressed.  Then I recommend you remove it and replace with new 100mm thick insulation. If you do not need to insulate between your joists, go to step 4.

Step 3. Lay Insulation Between your Joists

Joists are typically 100mm thick.  Ensure you have 100mm of glass wool insulation between your joists as shown in the diagrams below.

Boarding a loft fig 1
Boarding a loft

Loft insulation requirements have increased throughout the years. Current regulations require 270mm of wool insulation within your loft space.  By now you should have 100mm between your joists. To achieve more than this you will need to create a raised floor that is approximately 175mm above your joists.  I’ll tell you how in the next steps.

Step 4.  Install the Loft Legs

Once you have your 100mm of insulation between the joists, you can now start installing your loft legs.  Products like loft legs raise the loft boarding above the insulation.  Loft legs are very strong plastic supports that are approximately 175mm high.  They are secured to the top of your joists within your loft via screws. Loft boards can then be screwed to the top of the loft legs, therefore raising your floor level up 175mm.

You should start close to your loft hatch.  A general rule of thumb is to use the joist spacing (for example 300mm in the diagram below, or 600mm, whichever is best for your situation) as your loft leg centres.  Then secure your loft legs to the joists in a grid pattern. Use the diagram below as a guide.

Boarding a loft

Step 5.  Lay Insulation Over the Joists

Once you have installed your loft legs in a grid pattern, you can then lay down more glass wool insulation up to a thickness of 170mm on top of your joists, and in between your loft legs.  Ensure it is laid 90 degrees to your 100mm insulation previously laid. After this has been completed, you can then learn how to board your loft in step 6.

Boarding a loft

Step 6.  Install the Loft Boards

By this step you should have installed your loft legs in a grid pattern, at centres which is equal to the width of your joists.  Ideally your loft boards should be supported at the edges via your loft legs, like the diagram below. Once you have secured your loft board to the legs via screws, you can then slide another board into place.  Make sure the board’s tongue and groove slot together.

Boarding a loft

Sometimes it may be difficult sliding the loft boards into place, due to the tongue and groove connections being tight.  If so, then gently tap with a hammer.

Boarding your loft while achieving good insulation is a brilliant way to create additional storage in your home and save money on fuel bills.  However, to get the most out of the extra storage space, keep it clutter free and organised. You could use plastic storage tubs. They will also keep your possessions out of dust.

Remember to board around essential utilities such as gas and water pipes.  It is essential you can access these in the event of a leak.

Warton Woodworks, the author of this article, are expert loft conversion contractors in the UK.  Visit their blog for more DIY Guides and Tips.

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