How to Fix a Bowed or ‘Cupped’ Worktop: A Worktop Express® Nutshell Guide
Wood is a natural material and – like any product – if incorrectly handled it may be susceptible to damage. Our wood worktops are manufactured to the highest standard and we do everything that we can to ensure that the items reach you in perfect condition. However in rare circumstances problems can arise as a result of incorrect storage or installation.
Immediately after receipt you should treat DIY worktops (worktops that have not been pre-oiled by ourselves) with at least three coats of Rustins Danish Oil (the end grains will require more) in accordance with our aftercare guide. Once oiled, store your worktops indoors, away from any heated or damp areas, and lay flat with battens separating each worktop.
If your worktop has become bowed, however, then panic not! The damage is far from irreversible; some very simple measures can be taken to restore it to its natural shape.
First, let’s explain why your worktop may be like this, so that you may take the necessary preventative measures in future.
Kiln Dried Worktops
- Our wooden worktops are kiln dried to reduce moisture content to 8 -10%; however this may fluctuate due to the nature and structure of wood (which reacts to its environment).
- Wood expands and contracts with changes in the surrounding humidity and – to a lesser degree – temperature. More humid air will cause wood to expand and drier air will cause wood to contract.
Your worktops will acclimatise to the surrounding conditions and any changes in relative humidity and temperature may cause your kitchen worktop to warp. Worktops should be stored in the area of installation from the outset or, if stored in another area initially, should rest in the area of installation for at least 3 days prior to installation. Worktops transported from a different surrounding and installed immediately are especially prone to movement and warping.
Bowing Once Installed
- On rare occasions timber worktops may bow once installed. Almost always this is as a result of incorrect fitting, which restricts the wood’s natural contraction and expansion. The release of moisture in the room (from appliances such as tumble dryers) and insufficient protection may also cause damage.
If your worktop has been left for an extended period of time before installation, or it has not been stored correctly (laid out flat with battens separating each worktop), bowing can occur. If this is the case, there’s no need to worry; the following procedure should help you to recover its original position.
- Begin the process by oiling your worktops with the recommended Rustins Danish Oil (please see our guide to worktop maintenance for more information). This will seal the timber in preparation for installation. Ensure you apply at least three coats (with 6-8 hours of drying time in between) to the faces, and six coats to the end grains.
- Fix the back end of the worktop to the supporting base units sitting beneath it. Make sure you’re only using the slotted angle brackets –any other fixing bracket will restrict the worktop’s natural movement. Use the slot that runs perpendicular to the direction of the grain pattern (across, not parallel with it).
- Slowly and gently pull the worktop down using clamps and battens. It’s important not to rush this stage – the timber will split if you use too much force – and be patient: this part of the process can take 1-2 weeks.
- Once the worktop has been pulled down, secure the front edge, too. Your worktop should be back to its natural shape now.
Fixing a bowed worktop that has already been installed
Once installed cupping or warping can occasionally occur as a result of the wood reacting to changes in relative humidity or temperature. For example, if the top (as it is more exposed to the environment) reacts more swiftly than the bottom (which is often more sheltered), the wood “cups”. Furthermore, if your worktop has been installed incorrectly – if you have used the wrong slotted brackets, for example, or if the timber does not have sufficient protection – it can bow during its use.
If your worktop has cupped upwards: this may be fixed quite easily by placing a reasonable (but not excessive) weight on the bowed area, causing it to gently return to its natural flat shape.
If your worktop has cupped downwards: this is often due to incorrect installation. Check and make sure you’ve used the correct slot on the slotted brackets that will have fitted your worktops to the cabinets below it. If it doesn’t run perpendicular to the grain width, you haven’t fitted it correctly.
Furthermore, an overhang more than 200mm should not be left unsupported. In some circumstances the only method for fixing a cupped worktop would be to uninstall the worktop and re-install according to the approved instructions above.
And finally… Upon (re)installation of your worktop, make sure you have provided the correct protection: moisture barriers fitted above relevant appliances will prevent changes in humidity from affecting your worktop, and sufficient oiling to the underside of your worktop will also reduce potential damage, too. You should leave at least a 30mm gap between the end cap and a heat source such as an AGA or freestanding oven to protect the end grain from exposure to excessive heat.
If you require any further advice regarding your worktops, please do not hesitate to contact us – we’re always here to help.
Please Note:This guide was originally posted on 20th November 2013 and was updated on 28th March 2018 to include additional information.