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Screws for decking and sleepers

Updated: October 2026

You are about to drive a yellow zinc wood screw into a deck board or a garden sleeper because it is the box already on the bench. That plating is an interior finish. Screws for decking and sleepers need a coating or a stainless grade the maker rates for wet timber, treated timber, or both. In the [wood screws comparison](/hub/screws-and-accessories/wood-screws) there is one green hex timber screw and no stainless ASIN. None of these listings states BS EN 14592 or UKCA. Products Compared used the amazon.co.uk files from 15 October 2026 and public UK notes on coatings. A qualifying purchase can earn a commission at no extra cost to you. This is not a structural design.

You are about to drive a yellow zinc wood screw into a deck board or a garden sleeper because it is the box already on the bench. That plating is an interior finish.

Our top picks

ForgeFix ForgeFast Elite 5.0 x 80 mm

Best overall

ForgeFix ForgeFast Elite 5.0 x 80 mm
8.3/10about £5.83
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TIMCO TIMCO Index 6.7 x 150 mm, box of 50

Rank 2

TIMCO TIMCO Index 6.7 x 150 mm, box of 50
8.5/10about £13.55
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TIMCO TIMCO Solo 5.0 x 100 mm, box of 100

Rank 3

TIMCO TIMCO Solo 5.0 x 100 mm, box of 100
9.0/10about £4.19
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On this page
  1. 1.Yellow is not an outdoor grade
  2. 2.The hex screw in this comparison
  3. 3.No stainless screw in this set
  4. 4.No structural mark on these listings

Yellow is not an outdoor grade

Yellow, gold and bright zinc are plating colours for dry indoor timber. BuildWiz describes yellow zinc as an interior finish. Ordinary zinc corrodes faster where treatment chemicals sit in the timber. A shed or fence-stake review does not promote that screw to an exterior grade. ForgeFast Elite claims a yellow zinc shield, and one UK review says the box prints internal use only. Other reviews still describe a fence and a gazebo. Those jobs are not an approval printed by the maker. The ForgeFix single sizes and TIMCO Solo are the same indoor finish. Solo’s 5.0 x 100 mm length can reach through a deck board. The finish is still indoor. Brackit and Heifix mention fences on zinc-plated assortments without naming stainless or an exterior organic coating. Indoor sizes stay on the buying guide.

The hex screw in this comparison

The outdoor-shaped listing is TIMCO Index: 6.7 x 150 mm, partial thread, external hex, green organic coating, box of 50, £13.55. The star line is 4.7 from 4,493. UK reviews drive it into sleepers, deck frames and fences with an 8 mm socket. One box contained 45 screws. Sockets wear because the head is harder than the socket. Some comments name 200 mm, 125 mm or 100 mm, so the 4.7 line is the Index range, not a private test of 150 mm. Some buyers used no pilot in softwood. One sleeper job wanted a full pilot. The general rule is on the how to use page. Gorffy and Flintronic stop at 40 mm. A 28 mm deck board uses most of that before any thread reaches the joist.
ForgeFix ForgeFast Elite 5.0 x 80 mm

Testsieger

ForgeFix ForgeFast Elite 5.0 x 80 mm
8.3/10about £5.83
View offer

No stainless screw in this set

There is no A2 or A4 screw among these twelve ASINs. TIMCO’s notes treat A2 as a general stainless grade and A4 as the grade for heavier salt, including green oak. The British Stainless Steel Association makes the same split, with A4 where chlorides are high. This comparison does not sell that screw. TIMCO’s table quotes salt-spray hours for Solo yellow and for an In-Dex organic green range. A dealer page for a different length, 6.7 x 87 mm, cites an older BS EN 14592 line. None of that text is printed on the 150 mm listing or on the Solo listing here.

No structural mark on these listings

Heavy duty in a title is not UKCA and not a structural declaration. Fastener + Fixing’s note is the background: that route needs a UKAS-accredited laboratory and a manufacturer declaration. These boxes do not show it. None of the listings states BS EN 14592 or UKCA. Indoor prices sit on the best wood screws page. For a sleeper or a deck frame, the start inside this comparison is the green 6.7 x 150 mm hex screw, with the short count and the missing standard kept in view. For a treated deck face, or for green oak, buy a box that names the stainless grade. A joist, a stair, a guard or a connection on a drawing needs a professional. A sleeper review is not a design for that joint.

Common questions

What is the green TIMCO screw for?
The Index box is a 6.7 x 150 mm hex timber screw with a green organic coating described as exterior. Reviews use it on sleepers, fence rails and deck frames, with an 8 mm socket. It is partial thread, 50 to a box at £13.55. It is not a yellow chipboard screw, and the listing does not print BS EN 14592 or UKCA.
Do I need stainless for sleepers?
You need a fastener rated for the timber and the weather. A green organic timber screw is what this comparison offers for that shape of job. Stainless A2 is the general outdoor grade in TIMCO’s own FAQ, and A4 is for heavier salt and for timber such as green oak. Those grades are not in this set. Treated softwood sleepers and green oak are different chemical problems. Read the grade on the box you buy.
Will a 40 mm assortment reach through a sleeper?
No. Gorffy and Flintronic list 40 mm as the longest screw. A sleeper is far thicker than that, and a deck board alone can use most of 40 mm before any thread reaches the joist. The Index screw in this comparison is 150 mm. Even then you check that the point stays inside the second piece and that the coating matches the timber.
Do Index screws need a pilot?
The sampled reviews disagree. Some buyers drove them into softwood and sleepers with no pilot. One sleeper job needed a full pilot. If the timber is dense, near an end, or already splitting, drill the pilot. An 8 mm socket that jams is a separate problem: the head is hard on cheap sockets. Stop when the flange is tight, before you crush the surface.
Is heavy duty on a title a structural mark?
No. Structural dowel-type screws for load-bearing timber sit under BS EN 14592, and UKCA for that use is a declared route with accredited testing. None of the listings in this comparison states the standard or the mark. A thick screw and a high star line are shop facts. They are not that declaration. If the joint is on a drawing, the drawing governs.

Related pages

Screws and accessories

Wood screws

Best wood screws: the box to open for indoor joints

Wood screws buying guide for size, thread and finish

How to use wood screws without splitting the timber

Pozidriv vs Phillips: which bit seats in the screw

Sources

Public UK sources on timber fasteners, UKCA, recess types, gauges and stainless grades. Listing prices and star counts are from the amazon.co.uk extracts kept for this comparison on 15 October 2026. Prices move.

  1. BSI, BS EN 14592:2022 (retrieved 15 October 2026)
  2. GOV.UK, designated standards for construction products (retrieved 15 October 2026)
  3. Fastener + Fixing, structural timber fasteners and UKCA (retrieved 15 October 2026)
  4. BS 1210:1963, withdrawn 1 July 2014 (retrieved 15 October 2026)
  5. bolts.co.uk, guide to common recess styles (retrieved 15 October 2026)
  6. B&Q, nails, screws and wall plugs (retrieved 15 October 2026)
  7. Screwsline, metric or imperial (retrieved 15 October 2026)
  8. TIMCO, stainless steel FAQ (retrieved 15 October 2026)