Most houses built from the 1990s onwards have around 270mm of mineral wool or an equivalent up in the loft, laid loose or as rolls between and over the joists to hit current Building Regs U-value targets. The joists themselves are typically only 100–150mm deep, because they were sized to carry a plasterboard ceiling below, not a storage floor above and 270mm of insulation. Board straight across the top of the joists and you're either compressing that insulation down to the joist depth, or leaving a gap where the boards don't quite sit flush — neither of which is what the person doing the job usually intends.
Raised boarding kits solve this by lifting the deck clear of the insulation entirely, on plastic legs or an interlocking support system screwed to the joists, so the full depth of insulation stays exactly as thick as it was designed to be underneath a floor that's now up above it, not on top of it. The alternative — and it's a perfectly reasonable one for a lighter storage load — is timber battens run across the joists at right angles, which raises the deck by less but costs a fraction of the price. Below is how the two approaches compare, what a compressed 270mm of mineral wool actually loses in performance, and the six products I'd look at.
Worth saying before the picks: none of this turns a loft into a room. These are storage-load systems, not a structural floor — boxes and suitcases, not a home gym.
The one I’d buy
LoftZone StoreFloor 6m² Kit
An aluminium beam-and-support system that clips together on top of the joists and raises the deck fully clear of the insulation underneath, rather than resting on legs dotted individually across the loft. It's the only system in this guide with independent third-party sign-off — BBA certificate 15/5269 — rather than just the manufacturer's own testing claims, which is worth something when you're deciding whether to trust a load figure.
Typically £170–£180 for 6m² (support system only, boards sold separately)
Check price on AmazonHow I judge a loft boarding kit
Whether it actually clears the full insulation depth. A system rated to lift the deck 279mm clear does nothing useful over 100mm mineral wool that's already been topped up to 270mm — check the raise height against what's actually in your loft, not the deepest depth the product is capable of handling.
Independent certification versus the manufacturer's own claims. A load rating published on a brand's own site or Amazon listing is a starting point, not proof — BBA certification is the one genuinely third-party sign-off in this category.
Whether it leaves an air gap, not just a storage gap. Raising the deck also stops moisture from the room below condensing against the underside of cold boards — a system that packs the void solid defeats that even while avoiding compression.
Fit against standard joist centres. Most of what's sold here assumes 400mm or 600mm spacing; an older or non-standard roof is worth measuring before ordering.
Cost against what you're actually storing. A BBA-certified system earns its price for regular storage duty. For a handful of boxes twice a year, timber battens do the same basic job for a fraction of the outlay.
The comparison
| Product | Raise height | Coverage / pack | Typical price | Best for | |
|---|---|---|---|---|---|
| LoftZone StoreFloor 6m² Kit | ~279mm | 6m² (no boards) | ~£170–£180 | Best all-round pick, BBA-certified | View |
| Loft Leg XL 60 Pack | 300mm | 60 legs (pack) | ~£100–£105 | Deep insulation, up to 400mm | View |
| LoftZone StoreFloor Compact-Support x20 | 159mm | 20 supports (pack) | ~£90–£100 | Shallower or older insulation | View |
| Loft Storage Stilts Pack of 32 | Standard leg height | 32 legs (pack) | ~£25–£30 | Budget pick | View |
| Treated Timber Batten 22x50mm 3m Pack of 8 | ~50mm | 24m run (pack) | ~£35–£40 | Traditional DIY method, cheapest overall | View |
| 18mm T&G Chipboard Loft Boards, Pack of 3 | — | ~1.17m² (pack) | ~£25–£30 | The boards themselves, any of the above | View |
The picks in detail
LoftZone StoreFloor 6m² Kit
Best all-round — the one system here with independent certification
Triangular plastic supports sit on the joists and clip to aluminium beams, raising the whole deck around 279mm clear of the insulation rather than resting on individually-placed legs. LoftZone quotes a recommended safe working load of 25kg/m² plus one person's weight, and cites accelerated ageing tests surviving far higher loads — I'd treat that higher figure as a manufacturer claim rather than fact, but the BBA certificate behind the basic system is genuine independent sign-off, which none of the other products here have.
For
- BBA-certified (15/5269) — independent third-party testing, not just brand claims
- Clears a full 270mm of modern loft insulation with room to spare
- Aluminium beam system spans the joists rather than relying on point-loaded legs
Against
- Boards aren’t included — budget for them separately
- The most expensive support system here by some margin
Typically £170–£180 for 6m²
Check price on AmazonLoft Leg XL 60 Pack
Best for deep or topped-up insulation — a 300mm raise
The XL version of the original branded loft leg, raising the deck 300mm clear rather than the standard product's lower lift, and rated by the manufacturer for insulation up to 400mm deep — useful if a previous owner has already topped up the loft beyond the usual 270mm. Each leg screws to a joist individually (screws not included), so it's easy to fit a few at a time. Worth flagging: the Amazon listing states a 50kg/m² load capacity, but Loft Leg's own site quotes 25kg/m² with a caveat to have the ceiling checked by a structural engineer — work to the lower, manufacturer-published figure.
For
- 300mm raise, rated for insulation up to 400mm deep
- Individual legs — easy to fit incrementally, not an all-or-nothing install
- “Loft Leg” is a registered trademark, not a generic product name, for what that's worth on provenance
Against
- Amazon's stated 50kg/m² load figure is double the manufacturer's own 25kg/m² — work to the lower number
- Fixing screws not included
Typically £100–£105 for 60 legs
Check price on AmazonLoftZone StoreFloor Compact-Support x20
For shallower or older insulation — a 159mm raise instead of 279mm
The same BBA-certified StoreFloor beam system as the top pick, but on a shorter support — 159mm rather than 279mm — for a loft with less insulation depth to clear, typically an older house that hasn't been topped up to current 270mm guidance. LoftZone is explicit that this isn't interchangeable with the regular-height support: mixing the two on the same run leaves an uneven deck, so check which depth of insulation you're actually dealing with before ordering.
For
- Same BBA-certified beam system, sized for shallower insulation
- Lighter (178g per support) and lower-profile than the standard-height version
Against
- Not compatible mixed with regular StoreFloor supports on the same deck
- Still needs the matching aluminium beams and boards bought separately
Typically £90–£100 for 20 supports
Check price on AmazonLoft Storage Stilts, Pack of 32
Budget pick — the cheapest genuine raised-leg system here
A straightforward black plastic stilt on the same basic principle as the branded Loft Legs above — a wide foot that spreads the load on the joist, a moulded stem, and a platform top for the batten or board to sit on — at roughly a quarter of the price per leg. It doesn't carry the branded product's manufacturer-published load data or any independent certification, so I'd treat it as a genuine budget option for light, occasional storage rather than a like-for-like substitute for a certified system if the loft's doing regular heavy duty.
For
- By far the cheapest raised-leg system in this guide
- Same basic wide-foot, screw-down design as the branded alternatives
Against
- No published load rating or independent certification found
- No stated maximum insulation depth — measure your loft’s insulation before assuming it clears it
Typically £25–£30 for 32 legs
Check price on AmazonTreated Timber Batten 22x50mm 3m, Pack of 8
The traditional DIY method — cheapest overall, but it still compresses insulation
Run across the joists at right angles and screwed down, a set of battens is how loft boarding was done long before raised-leg systems existed, and it's still the cheapest way to lift a deck above bare joists. Being honest about the trade-off: at roughly 50mm deep, a batten clears nothing like the 159–300mm the leg systems above manage, so it's still compressing anything thicker than about 50mm of modern loft insulation — a genuine improvement on boarding with no lift at all, not a substitute for a proper raised system where the insulation is a full 270mm.
For
- Cheapest way to lift a deck off bare joists at all
- No specialist fixings or matched components — ordinary screws and a drill
Against
- Only ~50mm of lift — still compresses full-depth modern loft insulation
- No load rating — ordinary structural timber, use judgement on span and spacing
Typically £35–£40 for 8 × 3m lengths
Check price on Amazon18mm Tongue & Groove Chipboard Loft Boarding Panels, Pack of 3
The boards themselves — needed whichever support system you choose
None of the leg or support systems above come with a deck — every one of them needs boards laid across the top, and this is the standard product for it: 18mm moisture-resistant chipboard with a tongue-and-groove edge so panels interlock rather than butting against thin air over a gap. At the usual 1220×320mm panel size, a pack of three covers a little over a square metre, so a full loft run needs ordering by the pack rather than as a one-off purchase — work out the area first.
For
- Standard 18mm T&G profile, interlocks properly rather than butting
- Moisture-resistant chipboard, the usual spec for this job
Against
- Sold in small packs — work out your total loft area before ordering, not board by board
Typically £25–£30 per pack of 3
Check price on AmazonWhat actually matters — and what doesn’t
The compression figure is real, but check who's behind it. A widely-cited National Physical Laboratory study found that compressing mineral wool from an installed 270mm down to 100mm cut its thermal resistance from 6.11 m²K/W to 3.09 m²K/W — roughly halving its performance. NPL is a genuinely independent UK metrology institute and the methodology looks sound, but the study was commissioned by LoftZone, a company that sells the product that solves exactly this problem. Worth citing as NPL-tested rather than as fully independent research — the conflict of interest doesn't make the physics wrong, but it's fair to know it's there.
There's no line in the Building Regs that literally says “don't compress your insulation.” Approved Document L sets a target U-value for a loft, not an instruction about boarding technique. The practical effect is the same either way: compress 270mm of mineral wool down to a 100mm joist depth and it won't deliver the U-value the regs are aiming for, even though that specific sentence doesn't appear anywhere in the guidance itself.
Check the joists can actually take a storage load before boarding the whole loft out. This is the bit I see missed most often. Ceiling joists in a lot of houses, particularly anything built before the 1990s, are sized to carry a plasterboard ceiling below and the insulation on top of it — not a floor doing regular storage duty above that. Boarding the full loft and loading it with boxes can, over time, show up downstairs as a bowed or cracked ceiling. If you're planning anything beyond light, occasional items, get the joist spans checked rather than assuming a boarded loft is automatically load-rated for whatever you put in it.
Don't board over the eaves ventilation gap. Cold pitched roofs need a continuous ventilation path at eaves level — BS 5250:2021 calls for a 10mm continuous gap above a 15° pitch, or 25mm at shallower pitches, plus a ridge gap on steeper or wider-span roofs. Boarding or stacking storage right up to the eaves blocks that airflow, a genuinely common way a previously fine loft starts showing condensation on the underside of the roof felt. NHBC's own guidance is blunt: a loft "isn't intended to be a storage area," and restricting airflow to make more of it one can lead to condensation affecting both stored items and roof timbers. Leave the last metre or so nearest the eaves clear whatever system you use. LoftZone markets the air gap under its raised beams as removing moisture build-up on the underside of the boards too, which fits the same principle — but that specific claim is single-sourced to LoftZone itself, not independently tested.
Questions I get asked
Do I need a raised system, or will battens do? If the loft has anything close to the current 270mm depth of insulation, battens at roughly 50mm won't clear it and you're still compressing most of the layer. Battens are a fair compromise over boarding with no lift at all, but a leg or beam system is the only way to clear full-depth insulation properly.
Is “Loft Leg” just a generic name for any raised loft leg? No — it's a registered UK trademark held by Loft Leg Ltd, though in practice people (and plenty of listings) use "loft legs" loosely to mean any brand of raised support, the same way some people say "Hoover" for any vacuum cleaner. Worth knowing when you're comparing products, since not every "loft leg" on Amazon is the branded product.
Can I board right up to the loft hatch and walls? Leave the eaves gap clear as above, and don't block any extract ducting or a cold water tank's access and lagging while you're at it — a fully-boarded loft with no thought given to what else lives up there causes problems that only show later.
Will boarding the loft affect an EPC or a mortgage valuation? Not directly — an EPC assessment records the insulation depth present, and boarding over it properly (without compressing it) shouldn't change that figure. Boarding done badly, with insulation visibly squashed or moved aside, is exactly the kind of thing that can get flagged as a defect on a survey, which is a more likely route to a valuation query than the EPC itself.
I don’t fit loft boarding kits myself, but a properly done PAS 2035 retrofit assessment checks insulation depth and sub-roof ventilation before any loft measure is specified, which is the point at which a badly compressed loft usually gets caught. Worth reading alongside my guide to loft insulation costs if you're weighing this up as one job among several, and best loft ladders covers the access side of the same project. Get in touch for a second opinion, and there are more field-kit guides to work through.
Small print. This guide is general information, not a structural assessment of your specific loft — have joist loading and insulation depth checked before boarding a full loft for storage. Prices are indicative, move constantly and are checked at the time of writing; the linked page always shows the current price. As an Amazon Associate I earn from qualifying purchases.