Most internal door handles are secured with either countersunk wood screws, M4 bolt-through fixings, or a combination of the two. The right choice depends on the handle’s fixing holes, the latch or lock behind it, the door construction and its thickness.
Do not select replacements by length alone. The thread diameter, thread pitch, head shape, fixing centres and available clearance through the latch must all match.
A typical lever handle has several different pieces of metalwork that can look like “fixing screws”, but they do different jobs. The main screws or bolts attach the backplate or rose to the door. A smaller grub screw may secure the lever to the spindle. The square spindle operates the latch, but it is not a fixing bolt.
New door handles will normally be supplied with suitable fixings. Replacement screws become more complicated because apparently similar handles may use different metric threads, screw centres or concealed fixing arrangements.
Which fixing does your door handle use?
| Handle type | Usual main fixing | What must be checked |
|---|---|---|
| Lever handle on a rose | M4 bolt-through fixings are common; some designs use wood screws into the door | Rose fixing centres, door thickness, threaded lug position and clearance holes in the latch |
| Lever handle on a backplate | Countersunk wood screws, or bolt-through fixings where the handle and latch are designed for them | Backplate screw-hole spacing, screw-head diameter and the location of the latch or lock case |
| Mortice door knob | Wood screws through the rose; some modern sets accept through-bolts | Clearance around the larger knob spindle and the body of the mortice latch |
| uPVC or multipoint-lock handle | Metric machine screws passing through the door into the opposite handle | Screw diameter, screw centres, door profile thickness, PZ measurement and spindle length |
| Rim knob or rim-lock furniture | Wood screws into the door and, depending on the design, screws associated with the rim lock | Door thickness, rose position and whether the screw could foul the lock case |
| Pull handle | Through-bolts, concealed rear fixings or back-to-back connector bolts | Door material, handle fixing centres and whether the bolt heads must be concealed or security protected |
Wood screws: suitable for face-fixed handles
Traditional backplate handles, mortice knobs and some lever-on-rose designs are face-fixed with countersunk wood screws. These bite into the timber of the door rather than connecting the two handles together.
The screw head should sit neatly in the countersunk hole without projecting above the plate. If the head is too large it will not seat properly; if it is too small it may pull into or through the fixing hole. Decorative brass screws can also be softer than steel screws, so the correct pilot hole and a well-fitting screwdriver bit are important.
How long should door-handle wood screws be?
Use the longest screw that can obtain a sound hold without reaching the opposite fixing, entering a glazed area or damaging the latch or lock. There is no single correct length for every handle.
- On a solid timber door, the screw should penetrate sound timber rather than only a thin surface layer.
- On a hollow-core door, the handle must be positioned over the timber lock block. Ordinary wall plugs are not a satisfactory substitute in a thin door skin.
- If handles on both sides use face screws in matching positions, overly long screws can meet in the middle and force each other off line.
- A screw beside a mortice lock must not enter the lock case or interfere with its internal mechanism.
The pilot hole should be approximately the diameter of the screw’s solid core, not the full width across its threads. Dense hardwood usually needs a slightly more generous pilot hole than softwood. Mark the required depth on the drill bit with tape so that you do not drill through the door.
Do not drive fixing screws with excessive force. A powered driver can strip the timber, snap a decorative screw or distort a thin backplate. Drill the pilot holes accurately, start each screw by hand and complete the final tightening with a hand screwdriver.
Bolt-through fixings: the stronger option for many lever handles
A bolt-through fixing passes through the door and connects to a threaded lug, sleeve or corresponding part on the handle fitted to the opposite face. M4 is common on internal lever furniture, but it is not universal. M5 and other proprietary sizes are also used, particularly on entrance-door and multipoint-lock furniture.
Through-bolts are especially useful on frequently used doors because the load is shared between both handle assemblies. They are less dependent on the holding strength of a few short wood screws and are unlikely to loosen simply because the timber around a face screw has worn.
The arrangement varies by manufacturer. Both screws may enter threaded posts on the opposite rose, or the fixings may alternate direction around the spindle. Follow the handle’s drilling template rather than assuming that every bolt goes in from the same side.
The latch or lock must allow the bolts to pass
The most commonly overlooked compatibility issue is the latch. A standard latch case may obstruct the bolts running between the two handles. A bolt-through latch has clearance holes positioned around the spindle follower so that the fixing bolts can pass through without touching the mechanism.
Never drill through a latch or lock case to create your own clearance. Swarf can enter the mechanism, and drilling may damage springs, followers or internal levers. If the existing latch blocks the required fixing route, replace it with a compatible bolt-through model.
How to choose the correct bolt length
Measure the actual door thickness with the handles removed or loosened. Internal doors are often around 35mm or 44mm thick, but paint, veneers, fire-door construction and previous alterations mean nominal dimensions should not be relied upon.
The required screw length is not necessarily identical to the door thickness. It also depends on:
- how far the threaded receiver projects into the door;
- whether the screw head sits in a surface plate or a recessed fixing plate;
- the amount of thread engagement required by the manufacturer;
- whether the bolt is designed to be cut or snapped to length.
The bolt must engage sufficiently to hold securely, but it must not bottom out before the rose or backplate is clamped against the door. If a handle remains loose even though the screw feels tight, a bolt that is too long may have reached the end of the threaded hole.
Only shorten bolts designed to be shortened. Break-off screws have defined sections for this purpose. If cutting an ordinary machine screw, protect the thread with a nut before cutting, file the end square and then remove the nut to help reform the first thread. A damaged first thread can ruin the receiving lug.
Measurements to take before ordering replacement fixings
- Actual door thickness, not its nominal size
- Fixing-hole centres, measured centre to centre
- Outside diameter of the existing machine-screw thread
- Thread pitch or a confirmed manufacturer specification
- Screw length and the correct method of measuring it
- Head style: countersunk, raised countersunk, pan or another profile
- Head diameter and the type of screwdriver or hex key required
- Available clearance through the latch or lock case
For countersunk screws, length is normally measured from the top of the head to the tip because the head sits within the material. For most non-countersunk screws, measure from beneath the head to the tip. When identifying a machine thread, do not force a “nearly correct” screw into the handle: similar-looking metric threads can damage a threaded post within a few turns.
If you are replacing the complete handle rather than just a missing screw, measure the backplate, spindle and existing fixing positions as well. Our guide to How to Measure Replacement Door Handles explains the key dimensions.
What are the small grub screws for?
A grub screw is the small headless screw normally found in the neck of a lever or knob. It locks the handle onto the square spindle; it does not secure the rose or backplate to the door.
When fitting the lever:
- Pass the spindle through the latch follower and centre it so that both handles have adequate engagement.
- Fit the levers and check that they return freely without rubbing against the roses.
- Where the spindle has a flat face or groove, align the grub screw with it.
- Tighten with the correctly sized hex key. A key that is too small will round the socket.
A lever that pulls off while the rose remains firmly attached usually has a loose, missing or damaged grub screw. A rose that moves against the door indicates a problem with the main wood screws or through-bolts instead.
Fixing a door handle without distorting it
- Check the latch first. Operate it with the spindle before fitting the handles. A stiff or incorrectly positioned latch should be corrected before it is hidden by the furniture.
- Mark from the actual handle or supplied template. Keep the spindle level and do not rely solely on old screw holes, which may already be off centre.
- Drill square to the face of the door. Angled holes pull through-bolts sideways and can prevent the rose from sitting flat.
- Fit all bolts loosely. Start every thread by hand before tightening any one fixing. This prevents cross-threading and allows both handles to align.
- Tighten gradually from side to side. The handle should be secure, but overtightening can dish a rose, pinch the latch follower or mark a veneered door.
- Test before fitting concealed covers. Operate the lever repeatedly and confirm that it returns to horizontal without binding.
For a complete fitting sequence, see How to Fit Internal Door Handles Using a Door Handle Pack.
Common fixing problems and what they mean
The screw turns but never tightens
A wood screw may have stripped its hole, or a machine screw may have the wrong thread. For a damaged timber fixing, remove the handle and repair the substrate properly before redrilling a pilot hole. Do not keep fitting a progressively larger screw if its head will no longer seat correctly in the handle.
The bolt is tight but the handle is still loose
The bolt may be bottoming out in a blind threaded lug, or a spacer, fixing plate or concealed rose component may be missing. Compare the parts on both sides and check that the backplates are clamping the door rather than merely tightening internally.
The lever becomes stiff when the bolts are tightened
The fixing holes may be out of line, the rose may be distorted or the spindle may be pressing sideways against the latch follower. Loosen the bolts slightly. If the handle immediately operates freely, check alignment rather than leaving the assembly loose.
The concealed rose cover will not clip or screw into place
Check that the countersunk fixing heads are fully seated and that the fixing plate is flat. A projecting screw head can prevent a cover from engaging even when the handle itself appears secure.
The handle repeatedly works loose
Confirm whether movement is at the lever, the rose or the latch. Tightening every visible screw may hide the symptom temporarily without addressing a loose grub screw, stripped timber or an incompatible bolt that has insufficient thread engagement.
Special cases: external doors, uPVC doors and fire doors
External and uPVC door handles
Handles for multipoint locks commonly use metric screws passing through the door profile. Screw-centre dimensions and door thickness vary, and the spindle-to-cylinder measurement must also match when replacing the handle set. On an external door, fixing heads should normally be accessible from the secure internal side rather than exposed outside.
Do not substitute ordinary wood screws for a handle set intended to clamp through a uPVC, composite or aluminium door. The load must be carried by the designed fixing points without crushing or distorting the profile.
Fire doors
A fire door is a tested assembly. Use door furniture, latches, locks, fixings and any required intumescent protection that are suitable for the door’s fire rating and fitted in accordance with the relevant manufacturer’s instructions. Avoid enlarging holes or changing fixing methods merely to make an incompatible handle fit.
When a complete handle pack is the safer purchase
If several parts are worn, missing or incompatible, assembling a handle from unrelated fixings can cost more time than replacing the set. A coordinated pack can include the handles, spindle, latch, hinges and suitable fixings, reducing the risk of finding that a bolt-through handle will not work with the existing latch.
See Door Handle Packs vs Buying Separately for help deciding which route is appropriate, or view the Door Handle Packs collection. If the handle itself needs replacing, the All door handles collection provides options for different fixing arrangements and door styles.
In practical terms: use the fixings supplied with the handle whenever possible. For replacements, identify the fixing system first, then match the diameter, thread, head, fixing centres and usable length. Where through-bolts are required, confirm that the latch or lock has correctly positioned clearance holes before drilling the door.
