How To Fix Loose Screw Holes | 8 Methods of Fixing Stripped-Out Screws
A loose screw is a problem that everyone faces time and again in their households. There are many factors which can cause a loosely fitting screw. Frequent use of furniture, for example a door handle, door hinges, wooden chair, table, wardrobe, cupboard and drawers will lead to wearing out of the screw hole. As pressure is applied on the screws over time, lateral forces will compress the inner surfaces of the hole, increasing the diameter and loosening the screw. Frictional forces will also cause some erosion on the inner surfaces of the hole, chipping away some tiny particles and increasing the diameter of the hole. Loose screws are encountered everywhere, even on rarely disturbed furniture such as shelves and wall fittings, as well as installations like gutters, downpipes, eaves board and fascia board. Whereas moveable objects like chairs, door handles and hinges are subject to kinetic forces as well as static forces, permanently fixed objects like wall fittings are mostly subject to static forces like gravity and weight. For example, a wall fitting such as a bathroom wall cabinet is often fixed on the wall bearers using screws. The forces acting on the screws in this case are gravity plus the weight of the bearers, wall cabinet and its contents. Of course, if the windows are open or if the wall cabinet is exposed to weather elements such as wind, these elements will exert some kinetic pressure on the cabinet, which in addition to static forces will affect the screws.
Deterioration of the substrate is another reason why screws loosen up. A substrate is the surface on which a screw is fixed e.g. a wooden board, block or cross-section. Steel screws are often screwed on a wooden substrate. Wood deteriorates with time, it also expands and contracts. This can affect the screws, causing them to loosen.
There are 10 ways of fixing a loose screw.
This method is useful if the board is way thicker than the length of the new screw. As an example, if a 20mm long screw is stripped-out and loose, replace it with a 40mm long screw, but you have to make sure the thickness of the board is greater than 40mm, e.g. 60mm. A longer screw works because it penetrates deeper into the board, creating brand new, tighter threads in the wood.
A typical screw for a door handle is 2mm thick. Examine the loose hole to determine its increased diameter. Get a new screw is slightly thicker than the increased diameter. Let’s say the hole is 3mm in diameter, get a new screw which is slightly thicker, i.e. 4mm. A thicker screw will hold tightly in place creating new threads in the wood.
Plastic Screw Anchors
Plastic screw anchors are often used in drywall/plasterboard panels to hold screws tightly in place. Plastic anchors are small hollow cylinders which are inserted inside the hole. They are about the same length as the screw which is going to be driven in. Insert the anchor inside the hole making sure that the top flange is flush with the surface and supported by the board. Your plastic anchor must have an outer diameter which is equal to the hole, not smaller. Anchors are suitable for narrow holes where the hole is not too wide, that is where the hole diameter has increased by a small amount. If your anchor is thicker than the hole, use a drill bit which is the same size as the anchor.
Put the clamped part in place, aligning the holes and then drive in the screws with a screwdriver inside the anchors. Note that your screws must be paired with the right anchors, which means you must have the right size and specification. As an example, 4x30mm screws are paired with 6x30mm anchors. In this case 6mm is the outer diameter of the anchor below the flange and 4mm is the diameter of the screw as well as the internal diameter of the anchor. This kind of pairing ensures the screws are tightly held in place as they press and wedge against the anchor. The anchor itself presses and wedges against the hole creating a tight grip.
A wooden toothpick or wedge can be used to tighten the screws in place. The wedge reduces the diameter of the hole so that the screw can fit tightly. Insert the wedges inside the hole so that they are tightly packed, break off the protruded parts then drive in your screw. The hole can be filled with glue before packing it with wedges or toothpicks, but in this case you will need to wait for the glue to dry first before you drive in the screws.
Epoxy Resin and Hardener
This viscous solution is made by mixing Epoxy Resin and a Hardener. The hardener acts as a catalyst which accelerates the setting / hardening of Epoxy resin. Without a hardener, Epoxy resin would take a long time to set. Thoroughly mix equal volumes of Epoxy resin and hardener (1:1 ratio). Make the existing hole wider by drilling with a larger diameter bit. Fill the hole with the resin mixture. Lubricate your screw by dipping it inside a lubricant. Insert the screw vertically inside the resin by screwing it in. Compact the resin around the screw, adding more resin if needed. Leave the solution to harden for 3 to 4 minutes, then slowly take out the screw by unscrewing it. This is where you must pay attention. Don’t pull out the screw, unscrew it. Unscrewing the screw leaves a nicely threaded hole which is precisely the same diameter as the screw. Leave the threaded resin to dry and harden for at least 24 hours. Take your screw and drive it inside the hardened hole.
An alternative method of fixing is allowing the Epoxy Resin mixture to dry and harden. Afterwards you can drill through the hardened epoxy resin and drive in your screws.
Expanding Foam Sealant
Expanding foam sealant is a solution that is used to fill gaps, holes and cracks in construction work, renovations and repairs. This sealant has extremely high adhesive properties, it can’t be removed when hardened. It will stick to most types of materials like brick, wood, stone, metal, plastic and glass. When applied in holes and gaps, it will fill the voids, spreading and taking the shape of the hole. It is mouldable within 5 to 15 minutes of applying it and will harden in 60 minutes. Trimming should be done after 60 minutes in the hardened state, and not in the mouldable state.
Start by drilling to make the hole a little bit larger. Fill the hole with expanding foam sealant. Lubricate your screw by dipping it inside a lubricant. Wait for 5 to 15 minutes before inserting the screw inside the sealant. Insert the screw vertically inside the sealant by screwing it in. In this case compacting the sealant around the screw is not required because the sealant will expand on its own as it hardens, squashing the screw. Slowly take out the screw by unscrewing it. This is where you must pay attention. Don’t pull out the screw, unscrew it. Unscrewing the screw leaves a nicely threaded hole which is precisely the same diameter as the screw. Leave the threaded sealant to dry and harden for at least 24 hours. Take your screw and drive it inside the hardened hole.
Wood Shavings, Sawdust and Glue
Wood shavings or sawdust can be mixed with glue, and then packed inside the hole. Allow the packing to harden, drill through and then drive in your screws. Plastic screw anchors may be needed.
Rubber Powder and Glue
Rubber powder is an alternative to sawdust and wood shavings. Mix the powder with glue, and then pack it inside the hole. Leave the adhesive solution dry and harden, then drill through and drive in your screws. Plastic screw anchors may be needed.
Hardwood glue for tiles creates a very strong bond with the surface. It can be drilled when hardened. Fill the hole with glue, leave to dry and harden. Drill a hole and drive in your screws. Most types of industrial adhesives such as gorilla wood glue, wood putty and epoxy resin can be drilled and screwed when hardened.
Wood fillers such as Ronseal and Polyfilla are another alternative for filling in holes. They form a tough bond which can be drilled and screwed.
Glued Dowel or Hardwood Plug
This is one of the familiar methods for filling screw holes to allow for re-screwing. A cylindrical hardwood dowel or plug will be needed. Drill a hole which is larger than the worn-out hole. Get a wood dowel or plug which has the same diameter as the drilled hole. Dip the dowel in glue and insert it inside the hole. Alternatively, fill the hole with glue and insert the dowel. Hardwood plugs are available from building hardware stores and retailers. The top face of the dowel/plug must be flush with the board or surface, and you must trim off any overflowing glue. Allow the glue to dry and harden for at least 24 hours, then drill through the plug/dowel and drive in your screw.