How to Board a Loft Without Crushing Insulation

How to Board a Loft Without Crushing Insulation

The complete guide to creating safe, usable loft storage while keeping your insulation fully intact.

View Loft Stilt Packs

Why This Matters: How Insulation Actually Works

Loft insulation works by trapping millions of tiny pockets of air within its fibres. Those air pockets are what slow the movement of heat from your home into the cold loft space above. The deeper and fluffier the insulation, the more air it traps — and the better it performs.

When you lay boards directly on top of insulation, the weight compresses those fibres flat. The air pockets collapse. The insulation can no longer do its job properly, and heat escapes through your roof at a much higher rate.

⚠️ Flattened insulation can lose up to 50% of its thermal performance. That means higher energy bills and a colder home — even though the insulation is still there.

The solution is simple: raise the boards above the insulation so it is never touched. That is exactly what loft stilts are designed to do.

Step-by-Step Guide

  • 1

    Measure Your Loft Space

    Note the length and width of the area you want to board, and measure the spacing between your joists. Standard UK joist spacing is 400mm or 600mm centre-to-centre. This tells you how many stilts and boards you need.

  • 2

    Check Your Insulation Depth

    Measure how deep your existing insulation is. The current recommended depth for UK lofts is 270mm of mineral wool. Make sure the stilts you choose will raise the boards clear of the insulation with a small gap to spare.

  • 3

    Fit the Loft Stilts

    Clip each stilt onto a joist at the correct spacing intervals. No cutting or drilling required — they press firmly into place. Work across the area systematically so you do not have to move over unboarded sections.

  • 4

    Lay the Loft Boards

    Place your loft boards across the stilts. They sit flat and stable above the insulation, creating a solid, level platform. Use tongue-and-groove boards for a tighter, more professional finish.

  • 5

    Fix the Boards with Screws

    Secure each board to the stilts using 4.0 × 30mm screws. Drive one screw per stilt per board. This locks the platform firmly in place and prevents movement or creaking when you walk on it.

  • 6

    Leave Access to Cables, Pipes and Tanks

    Do not board over electrical cables, water pipes, or cold water tanks. Leave a clear gap around them and ensure you can still reach them for maintenance. If cables run across joists, route boards around them rather than trapping them underneath.

What You Will Need

Loft Stilts DIY Pack

Loft Stilts DIY Pack

Clip-on stilts that raise boards above insulation. Available in 32, 64, 96, 128 and 256 packs.

From £49.00
OSB Loft Boards

OSB Loft Boards 1220 × 300mm

Tongue-and-groove OSB boards for loft use. Available in packs of 6, 12, or 18.

From £44.99
Screws 4.0 x 30mm

Screws 4.0 × 30mm

Purpose-made screws for fixing boards to stilts. Packs of 200, 400, and 1000.

From £12.99

Common Mistakes to Avoid

Boarding Directly onto Insulation

The most common mistake. Even lightweight boards compress insulation over time. Always use stilts to maintain the full depth and effectiveness of your insulation.

Using the Wrong Screws

Standard wood screws are too long and may split the stilt or board. Use 4.0 × 30mm screws specifically sized for loft boarding to get a secure fix without damage.

Blocking Ventilation

Lofts need airflow to prevent condensation and damp. Do not board right up to the eaves — leave a clear gap of at least 50mm at the edges to allow air to circulate freely.

Covering Cables and Pipes

Trapping electrical cables or water pipes under boards creates a safety hazard and makes future maintenance impossible. Always route boards around them and leave clear access.

Frequently Asked Questions

Can I board over loft insulation?
You should never lay boards directly on top of insulation. Doing so compresses the insulation and significantly reduces its thermal performance. The correct approach is to use loft stilts, which raise the boards above the insulation so it remains at full depth and full effectiveness.
How many loft stilts do I need?
As a general guide, you need one stilt per joist crossing point. For standard 400mm joist spacing and 1220 × 300mm boards, a 32-stilt pack covers approximately 3.6m². Measure your loft area and use our pack chooser to find the right quantity.
What boards should I use?
We recommend 1220 × 300mm OSB tongue-and-groove loft boards. They are designed specifically for loft use — strong enough to bear weight, light enough to handle easily, and sized to work with standard joist spacings. Avoid using standard chipboard or MDF, which are not suitable for loft conditions.
Do I need to add more insulation first?
If your insulation is below the recommended 270mm depth, it is worth topping it up before boarding. Loft stilts make this easy — you can add insulation first, then fit the stilts over the top without disturbing it.
Is loft boarding a job I can do myself?
Yes. Loft boarding with stilts is a straightforward DIY project. You do not need specialist tools or skills. Most homeowners complete a full loft boarding job in a single day.

Get the Right Loft Boarding Kit

Stilts, boards, and screws — everything you need to board your loft properly, in one place.

Get the Right Loft Boarding Kit

Related Loft Guides & Products

Browse All Loft Storage Products →