Solid Wood Kitchens: Why Does Wood Move?
The wood in our solid wood kitchens is hard-wearing and of high quality, and so of course you’d be correct in assuming that it stays in shape once sawn… which it does, to all extents and purposes! However, all wood retains a lot of moisture after being cut, so takes a while to settle and can shift slightly due to this residual moisture.
Take a house with a wooden front door as an example: many people will find their door sticks in the summer, and then moves more freely during the winter. It’s the effect we were all taught in school – hot things expand and the cold causes them to contract. Whilst this is true of most solids, the moisture in wood causes the effect to be exaggerated, which is why scientists would refer to wood as a ‘hygroscopic’ material – meaning its moisture content is directly related to the humidity of the environment it is in.
Fortunately for Solid Wood Kitchen Cabinets customers, our cabinet panels are superb quality solid oak and are subject to a unique lacquering process, increasing their resilience. If the wooden components in your kitchen do move slightly, you certainly shouldn’t notice it – but here are some key facts as to why this phenomenon occurs at all:
Moisture and Movement
The cellular structure of the tree is what influences this movement for a long time after being cut. The wood of a living tree is inherently very wet, with cells swollen with sap (which is mostly water), and other cells transferring water throughout the tree. These cells will continue to exchange moisture for a long time after the wood has been put to good use, so under humid conditions in the summer these cells absorb moisture, swell and cause the timber to expand. When winter approaches and temperatures cool, the wood dries out and the cells release moisture, shrink and cause the wood to contract.
In freshly cut lumber there are two types of moisture that are retained: ‘free’ water and ‘bound’ water. As the name suggests, ‘free’ water is that which fills the empty cavities between cells, which will eventually dissipate once the wood is fully dried out. The ‘bound’ water has soaked in to the cell walls, and becomes trapped. This is the moisture that causes the fibres in the wood to swell.
Wood never dries out completely, and also never has an entirely stable moisture content, losing approximately 1% of its moisture for every 5% change in surrounding humidity.
There are two different forms of humidity – relative and absolute humidity. Relative humidity is what we are referring to when we talk about humidity in relation to wood. It is the ratio of the amount of water vapour present in the air relative to the maximum amount of vapour the air can hold at its current temperature.
Due to the grain structure of wood, its movement is not only in one direction. When quartersawn it shrinks tangentially (along the curvature of the growth rings), whilst plain-sawn timber shrinks radially (perpendicular to the growth rings). There is no appreciable shrinkage in the direction of the wood’s grain.
External forces can cause wood to move, too. Trees that have grown in an unusual way (i.e. not straight upwards), as well as improper drying of the timber can cause stresses that are released when the timber is cut in to, causing it to react by changing shape.
However, we diminish the potential for movement issues through combining the different types of sawn timber when creating our furniture; this has the advantage of not only balancing structural integrity but also improving the overall appearance of the finished product.
Things to consider
Our kitchen wooden worktops are constructed from well-treated timber that has been prepared in top-of-the-range kiln driers, and hasn’t been dried for a prescribed period of time: the material is allowed as long as it takes for it to dry fully. That said, the wood will still move to some degree, though this is likely to be unnoticeable so long as our recommended maintenance programme is adhered to – so it’s worth bearing the following in mind when building the kitchen of your dreams:
- Our cabinets are made almost entirely from solid wood – save for one part: the back board. This is made from a manufactured composite that will not expand or contract, precisely because the structure of wood requires some flexibility: this board allows for the natural expansion and contraction of the timber in a way that a solid oak backboard could not.
- Solid wood worktops should be installed as soon as possible following delivery. Try and organise a delivery date that will coincide with the rest of your kitchen being fitted, though if this isn’t possible, make sure your worktops are first oiled, then stored on a flat surface, raised off the ground by batons. If you have multiple worktops to store, separate them with further batons to allow the air to circulate freely around them.
- When your worktop is being installed, ensure there is a 3-4mm gap between it and any adjacent walls or units. This is commonly known as an ‘expansion gap’ and will allow the worktop to expand and contract over the course of the year with the changes in humidity.
- Consider affixing moisture barriers on the underside of the worktop where any appliances are being used. This will stop any rising damp from washing machines or dishwashers impregnating the timber.
- When fixing worktops to cabinets, or cabinets to walls, ensure to use the correct ‘stretcher’ brackets, which allow the worktops to move whilst remaining well attached. These brackets should only ever be fitted in the correct orientation to allow you to use the slot which runs perpendicular to the width (across rather than parallel to the grain).
All of our assembly instructions are available online, if you would like further information on how to install our cabinets successfully.
Though wood is naturally bound to move a little throughout its life, there’s absolutely no reason that this should affect your wooden kitchen; indeed, with proper installation and maintenance you’ll enjoy your wooden kitchen components for a long time without any trouble.
To discuss the topic of this information guide further, please feel free to contact us – we’re always happy to hear from our customers.