On furniture and central heating

Posted by on Oct 31, 2013 in Blog | 2 Comments

Sitting at home on our first really dark evening, with the central heating on, makes me think it’s a good time to write about why your solid wood furniture doesn’t like central heating !

The wood in your solid wood furniture is, clearly, no longer alive, but it retains many of the properties of the living timber, particularly its ability to absorb and expel moisture. Even though your furniture will have a finish, whether it be oil, lacquer or polish, this won’t seal the wood entirely. There will also be surfaces that are not finished eg underneath a table top or inside a drawer. This means that your furniture will react to the atmosphere in your home.

The cell structure of timber means that it absorbs moisture during periods of humidity and expels it during warm, dry spells. This process leads to expansion and retraction within the structure of the wood, and this leads, alternately, to swelling and shrinking across the grain. A good example of this is the way our wooden doors and windows stick when we have spells of wet weather.

The same process affects furniture in our homes although, until the days of central heating and underfloor heating, the heat and dryness weren’t of a degree that caused real problems. With modern central heating the relative humidity in your house can drop as low as 10% – the recommended level for furniture is 50%. This level of dryness may lead to shrinkage of about half an inch in a 24 inch solid panel of oak and, conversely, during damp spells, a surface that was perfectly smooth may appear to have tiny ridges (where the wood has expanded).

Fortunately, there are ways that the responsible furniture maker can allow for wood movement during the designing and making process. They can divide large solid panels into smaller units or, where this is not possible, design in a way that will allow the panel to move without distortion. Drawers fitted during humid spells will be made slightly tight so they don’t become too slack in dry weather, and vice versa.

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However, the owner of the furniture also has some responsibility for its care, and there are simple things that can help: checking the humidity in the house and using a simple humidifier to ensure that the level doesn’t drop below 45% for long periods; keeping the temperature at or below 22C (which will also have a good effect on your heating bill !), and trying not to place furniture next to a radiator or other heat source.

The good news is that the timber will settle down, and the expansion and contraction will eventually become less evident. So bear with it –you are the lucky owner of a beautiful piece of handmade, solid wood furniture, and that’s got to be worth something!

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Thankyou, Chris.



  1. Joshua Wooler
    13th February 2020

    Is there any way to prevent the ridges? I always have an issue with oak furniture that I’ve only oiled and not put a film forming coating on. In that case usually within a few days of it going into someone’s house the perfectly smooth surface is so rough! If I raised the grain with water would that solve the issue?

    • Chris
      13th February 2020

      Hi Joshua

      Thanks for the question. To answer it I will need more information. How much sanding do you do before applying the finish? What grit did you get down to? Which oil finish do you use? What aftercare are you recommending? I must admit it is not a problem I have experience so my advice may be a bit limited.



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