Installing Single-Extension Runners: Step-by-Step Guide for System 32 Roller Drawer Slides

September 25, 2025

A single-extension roller runner allows a drawer to extend by roughly 75% and is ideally screwed into place using the 37 mm hole line in the System 32 grid.

Fitting traditional roller drawer runners is one of the most fundamental tasks in furniture making and interior joinery. These fittings stand out due to their straightforward mechanics and excellent reliability. Unlike ball-bearing telescopic slides, a roller runner consists of just two asymmetrical steel profiles per side that glide past each other on plastic rollers.

This guide is aimed at installers and experienced joiners who need to build, replace, or integrate a drawer system precisely into an existing carcase. The focus is on exact dimensional calculations, correct hole positioning, and flawless fixing.

Technical Principles and Dimensional Calculations

Before reaching for the screwdriver, the geometry of the piece of furniture must be completely understood. The smooth operation of a cabinet runner system relies entirely on the required installation clearance.

With a standard roller runner, an exact clearance of 12.5 mm is required on each side. This means that the external width of the drawer must be strictly 25 mm narrower than the internal width of the furniture carcase.

A calculation example: If a carcase is constructed from 18 mm thick chipboard and has an external width of 600 mm, the internal clear width is 564 mm. Subtracting the 25 mm installation clearance gives an exact external drawer width of 539 mm. If this dimension is off by more than 1 mm, the rollers will bind or the runner will have too much play and risk jumping off the track under load. This applies across all dimensions, whether you are using compact drawer runners 250 mm or longer options.

Understanding System 32

Modern furniture carcases are drilled according to the System 32 standard. This industry specification defines the spacing between hole lines. Two dimensions are critical when fitting runners:

The distance from the front-most hole to the front edge of the carcase is always 37 mm.
The vertical pitch between drill holes is exactly 32 mm.
The standard diameter for pre-drilled holes is 5 mm (suitable for Euro screws).

Required Tools and Materials

To professionally install a single-extension roller runner, you will need the following tools and fixings:

Cordless screwdriver with matching bits (typically PZ or TX)
Folding rule and try square
Bradawl or centre punch for marking
Pencil
Euro screws (Ø 6.3 x 13 mm) for pre-drilled 5 mm hole patterns
Alternatively: Chipboard screws (Ø 3.5 x 15 mm or Ø 4 x 15 mm) with flat heads for custom fixings without a pre-set grid
One pair of roller drawer runners (comprising two carcase profiles and two drawer profiles)

Important note on screw selection: Never use countersunk screws with roller runners unless the hole in the runner profile is deeply countersunk to match. A protruding screw head will catch on the runner wheel and permanently damage the plastic. A pan-head or wafer-head screw is the technically correct choice.

Step-by-Step Guide: Fitting Roller Runners

Installation is split into two distinct stages: fixing the runner rails inside the cabinet and securing the matching profiles to the drawer box.

Step 1: Identify and Position the Carcase Profiles

The carcase profiles are the rails with the plastic roller located at the front end. These are secured to the left and right interior sides of the cabinet. Decide on the height at which the drawer should sit. Mark a level horizontal line on the inside of the carcase. If working with System 32, use the existing hole line. The front-most hole of the runner aligns with the 37 mm setback of the front hole row.

Step 2: Screw the Carcase Profiles in Place

Hold the profile in position. The roller must point towards the front opening of the cabinet. Drive a screw loosely into the front slotted hole. Align the runner horizontally towards the back and insert a second screw in the rear third. Use the slotted holes to adjust the height or depth by 1.5 mm to 2 mm if necessary. Only drive screws into the round holes for final fixing once the position is perfectly aligned. Repeat the process on the opposite side at the exact same height.

Step 3: Fit the Drawer Profiles

The drawer profiles are the rails where the roller is located at the back end. Turn the drawer upside down or place it on its side. Place the profile flat along the bottom edge of the drawer side. The front end of the rail (without the roller) must sit flush against the back edge of the drawer front. The rear end of the rail (with the roller) extends beyond the back panel of the drawer. Screw the profile into the timber from the side (and optionally from underneath if the profile has a bottom lip). Use short chipboard screws (such as 3.5 x 15 mm) for this step.

Step 4: Inserting the Drawer

Take the assembled drawer and hold it tilted slightly downwards in front of the cabinet. Guide the rear rollers of the drawer over the front rollers of the carcase rails. Once the rollers engage behind one another, lower the drawer to the horizontal position and push it back into the carcase.

Step 5: Operational Check and Fine Adjustment

Test the action. The drawer should slide in smoothly with light resistance and drop slightly into place at the end of its travel (the self-closing feature created by the drop at the end of the profile). Just like train tracks, any lack of parallelism between the rails will inevitably cause the rollers to jam. If the drawer sticks, check the internal carcase width along its full depth. Often, a carcase bows outwards at the rear due to an improperly nailed back panel, reducing the necessary clearance.

Common Installation Errors

Even with simple hardware, common workshop mistakes can compromise the operation of the furniture piece.

Swapped rails: If the left and right profiles are mixed up, the mechanism will not work. The rollers on the carcase rail must always be at the front and bottom. The rollers on the drawer rail must always be at the back and top.

Incorrect screw heads: As mentioned, countersunk screws in flat pressings cause significant issues. The POM (polyoxymethylene) roller will scrape against the sharp metal rim of the screw every time the drawer opens. Within weeks, the roller wears down and the slide fails.

Ignored installation clearances: If the drawer is made too wide (e.g. only 20 mm clearance instead of 25 mm), it forces the rails apart on insertion, making the rollers run stiffly. If the drawer is too narrow (e.g. 30 mm clearance), the profiles lose lateral support. Under heavy loads, the drawer profile will slip off the carcase roller and drop.

Differences and Upgrade Options

A single-extension runner is practical, but it has mechanical limits. It pulls out to roughly 75% of its length. The back section of the drawer remains inside the cabinet, which can make reaching rear items difficult in deep units (such as a 60 cm kitchen cabinet pull-out).

If full access is required, you should choose full-extension drawer runners instead. These are usually based on a ball-bearing slide mechanism consisting of three interlocking telescopic profiles, allowing the drawer to extend 100%.

There are also clear differences in user comfort. Standard roller runners have an angled drop at the rear that uses gravity to pull the drawer closed over the final centimetres. However, this is not a true soft-close mechanism. For hydraulic damping that cushions the closing action silently, opt for drawer runners with soft-close mechanisms and integrated damper cylinders.

Caution: Soft-close damping systems must never be combined with a push-to-open mechanism (handleless opening), as the two spring mechanisms work against each other.

Weight Capacity and Load Ratings

Roller runners are traditional fittings intended for light to medium loads. The typical dynamic load rating is between 20 kg and 25 kg per pair. This is more than adequate for clothes, cutlery, or office supplies.

If storing tools, heavy files, or pantry goods, plastic rollers reach their limits. Under heavy loads, the wheels deform, the action becomes rough, and the drawer sags. In these scenarios, upgrading to heavy-duty drawer runners is essential. These heavy-gauge, zinc-plated steel ball-bearing slides can withstand loads of 45 kg, 80 kg, or even over 100 kg.

FAQ – Frequently Asked Questions About Roller Runners

Can I simply swap a single-extension runner for a full-extension slide? Yes, this is generally possible, but it will require new screw holes. While the side clearance for side-mounted telescopic runners is often identical (also 12.5 mm per side), the drilling pattern differs significantly from that of a roller runner.

Why does my drawer not close properly over the final centimetres? Check whether the carcase is level. If the cabinet tilts forward, the slope at the rear of the runner will not overcome gravity to pull the drawer shut. Obstructions from screw heads at the back of the runner can also cause this problem.

How do I clean and maintain roller drawer runners? The metal profiles do not need specialised lubrication. Oil or grease will attract dust and debris, eventually turning into a thick paste that seizes the rollers. Wiping the tracks clean with a dry cloth periodically is completely sufficient.

Which runners should I use for very shallow drawers? Roller runners have a relatively tall profile height (typically around 35 mm to 40 mm). For ultra-shallow drawers, ball-bearing telescopic slides with a low profile height (such as 17 mm or 27 mm) are far better suited, as they mount directly to the centre of the drawer side without needing to hook underneath.