Drawer construction and runners

At a glance

Rated loads are examples from manufacturer pages and catalogues, in kilograms per pair, not a survey and not a recommendation. Sources and what was not read are set out below.

Why two quotes for a drawer differ

Two quotes for the same drawer can describe different things. Five decisions sit behind the price, and each can be written down: the corner joint, the box material, the bottom, the runner, and the load the runner is rated for. A quote that names only ‘soft-close drawers’ has settled none of them.

A drawer is also the part of a piece of joinery that moves most. It is opened and closed more often than a door, it carries its own weight and its contents at the end of a lever, and it is slammed. Each of the decisions below changes how it will behave after a year of that. The studio coordinates drawer construction through partner workshops; the partner states what it builds, and the specification at the foot of this sheet asks it to.

A quick look at a drawer on a visit. Pull it fully out and turn it over. Are the corners interlocked or only butted? Is the bottom let into a groove or fixed underneath? Does the box sit square and run without rubbing? Is the runner marked with its maker and a rating? Press the front down gently: a runner that is too light, or fixed at too few points, shows it.

The box: joints, materials and the bottom

The joint is the first thing to ask about, and the least visible.

The corner. The Wood Handbook is plain that a plain end-to-edge-grain joint is difficult to make capable of carrying appreciable load, and that such joints should be designed with interlocking surfaces so that edge grain bonds to edge grain: its examples are dowels, mortise and tenons and rabbets, and its Figure 10-8 lists the dovetail and the lock corner among the end-to-edge-grain joints. It adds that wood swells much more across the grain than along it, so these joints should be protected from changes in moisture content in service. That is the reasoning behind the table above. It is not a ranking: we read no test of one drawer joint against another, so the page does not rank them.

The bottom. A drawer bottom is a loaded panel. Its sag follows its stiffness, thickness and span, in the way a shelf’s does: the shelving span and deflection sheet gives the arithmetic for a shelf resting on two supports, and a bottom held in grooves on three or four sides behaves better than that, but we give no figure for it. The EN 15338 runner test, as printed in a 2025 test report to the 2007+A1:2010 edition, includes a limit of one seventy-fifth of the shortest inner dimension for the sag of the drawer bottom after loading for 15 minutes (clause 6.3.2). That is a runner-test criterion, not a design limit for your bottom. A solid-wood bottom is let into its grooves so that it can move, which is the floating-panel principle on the timber movement sheet; a plywood bottom can be glued.

How heavy is the drawer? The runner’s rating counts the drawer itself, so its own weight matters. Our arithmetic, for a box with 15 mm sides and back, a 6 mm plywood bottom and a 20 mm oak applied front (oak at the Wood Handbook’s specific gravity of 0.68, plywood at about 700 kg/m³):

So a plain drawer box weighs a few kilograms, and the drawer front is part of that. A rating of 40 kg is the drawer plus its contents, not the contents alone.

Runners: types, mounting and rated load

The runner decides how the drawer feels, how far it opens, how much width it takes and what it can carry. The table gives what the pages and catalogues read say, with the loads they list.

What the rating means. There is no single definition, and that is the point. One runner maker says its load capacity to EN 15338 is the weight of the drawer itself, including its front panel, and its contents, at a reference length of 500 mm, and that the capacity may vary at other lengths. A catalogue from another maker says its figure is the maximum load per pair of runners at 80,000 cycles, for dynamic stress, valid when every mounting hole is screwed, and measured as a sample at 450 mm rail length and drawer width. Write which definition you mean, and ask for the data sheet of the runner chosen.

The same runner is rated differently at different lengths. One heavy-duty side-mounted runner is listed at the loads below, with a lower starred figure that we read as applying to a drawer 1,000 mm wide. The runner family is nominally a 100 kg runner; at 400 mm it is listed at 65.

Class is not capacity. A runner page can show both a load capacity and a load class: the concealed runner read at 350 mm is listed at 40 kg capacity and 50 kg class. Specify the capacity at the length you will use. Soft-close and push-to-open are features of the runner, not of the drawer: the concealed runner read is listed as compatible with a push-to-open system. Ask for them by name.

Tests, standards and what a rating proves

Two documents are often confused. A runner test (EN 15338) tests a runner, with a drawer in a test frame. A storage furniture test (BS EN 16121 with BS EN 16122, or BS EN 14749 for domestic and kitchen units) tests the piece. A pass on the first says nothing about your drawer box, your fixings or your carcase.

What a runner test covers. The maker’s own summary lists a wear test (the fully laden drawer must still work after a defined number of opening and closing operations), a retention-on-opening test (the loaded drawer is opened abruptly several times), a horizontal load test and a vertical strain test with the drawer fully open, an impact test in a test frame, and a corrosion test (72 hours of condensation water). A test report to the 2007+A1:2010 edition shows more: the loading capacity M and the number of durability cycles are both ‘specified by applicant’ (60,000 cycles in that report); the static vertical and sideways forces are set from M; the sag of the front must not exceed 4 per cent of the extension length; and the opening and closing forces must not exceed 50 N for a capacity under 40 kg, or 12.5 per cent of capacity at 40 kg and over. We did not read the 2024 edition, so the page does not say which of these still applies.

What the manufacturer chooses. The load and the cycle count in a test are the applicant’s choice. Catalogue figures of 80,000 cycles and test reports of 60,000 are therefore not the same claim. The rating on a data sheet is the manufacturer’s, tested to a standard, which is better than an unstated one but not the same as a drawer proved at your load.

For heavy use, such as a hotel desk drawer, a reception counter or a cutlery drawer in a restaurant, ask whether a test report exists on a drawer built as specified, and under which standard. If none exists, the specification should say so, and the risk sits with whoever accepts that.

Writing the specification so quotes compare

To make quotes comparable, ask each partner for the same eight items, in writing, for each drawer type on the schedule:

• Joint and construction: corner joint, glue, pins or screws, and how the front is fixed to the box.
• Material and thickness: sides, back, bottom and front, with the species or board type and grade.
• Bottom: thickness, how it is held and whether it can move.
• Runner: type, extension, mounting, soft-close or push-to-open, the maker and reference.
• Rated load and its definition, at the length used, and the weight of the drawer itself.
• Contents load you expect, in kilograms, so the partner can compare it with the rating.
• Inside finish and lining, and the sealing of the inside.
• Adjustment and gaps, and who adjusts the fronts on site (see joinery tolerances and scribing and shadow gaps and flush trim).

The sheets on sheet materials and MDF explain the board properties that feed the second item, and the furniture strength standards map places the storage standards among the others.

Drawers [150] mm high internal. Box sides and back [15] mm [birch plywood, B/BB grade] with [through / half-blind dovetail] corners, glued. Bottom [6] mm [birch plywood] let into grooves on all sides and [glued / left free to move], [lacquered / sealed] on the inside to [ ]. Applied fronts [20] mm [species / finish], fixed from inside the box. Maker to confirm the construction of each drawer type before manufacture.

[Full-extension concealed] runners, [soft-closing], tested to EN 15338, with a rated load of not less than [40] kg per pair at the [500] mm length used, the rating being defined as the weight of the drawer including its front and contents, fixed at every hole provided, for [ ] kg of contents in addition to the weight of the drawer, which the maker is to state. Runner maker, reference and data sheet to be submitted for approval before manufacture.

Maker to supply the runner maker's EN 15338 data sheet and, for [heavily used / contract] drawers, a test report on a drawer built as specified [to BS EN 16121 with BS EN 16122], or to state in writing that none is available. Fronts adjustable [3] mm in height and [1.5] mm sideways after installation.

Standards and sources

• BS EN 15338:2024 Hardware for furniture. Strength and durability of extension elements and their components: status only; not read.
• BS EN 16122:2012; BS EN 16121:2023; BS EN 14749:2016+A1:2022: storage furniture; statuses only; not read.
• USDA Forest Products Laboratory, Wood Handbook FPL-GTR-282 (2021): Chapter 10, pp. 10-16 and 10-17: joints.
• Runner makers' data sheets and catalogue pages: manufacturer statements; names in our notes file.
• Make Bespoke Studio journal: Types of furniture joints: the wider guide to joints.

Questions we are asked

Why do quotes for the same drawers differ so much?

Because they often describe different drawers. The corner joint, the box material and thickness, how the bottom is held, the runner type and maker, and the load the runner is rated for can each differ, and a quote that says only 'soft-close drawers' settles none of them. Ask every maker for the same items in writing.

What load rating should a drawer runner have?

Write the contents load you expect, add the weight of the drawer itself, which can be a few kilograms for a plain box and more for a wide pan drawer, and check that the runner is rated for that at the length you will use. Examples read here run from 6 kg for light roller runners to 100 kg for heavy-duty ones. The runner maker's data sheet governs.

Are dovetails always better than other drawer joints?

We found no test of one drawer joint against another, so the page does not rank them. The Wood Handbook says plain end-to-edge-grain joints are difficult to make strong and should be designed with interlocking surfaces, and lists the dovetail among the end-to-edge-grain joints. Ask the partner which joint it uses and why.

Is a steel-sided box system better than a timber drawer?

They are different products. A steel-sided box set comes with its runner and a stated load, 30 or 35 kg and 50 kg in the two sets read; a timber box is made part by part. Neither is better in the abstract: choose by load, look, inside finish and what the partner can evidence.

Does EN 15338 prove my drawer is strong enough?

No. It tests a runner, with a drawer in a test frame, and its scope says the results apply to the element tested and are only a guide to the performance of furniture. Whether a drawer as built passes a storage furniture standard is a separate test report.

What is the difference between soft-close and push-to-open?

Soft-close is a damper that slows the final part of closing. Push-to-open lets a drawer without a handle open when its front is pushed. Both are features of the runner or box set and should be specified by name; the concealed runner read is listed as compatible with a push-to-open system.