Are floorboards treated or are they just normal timber?

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Most standard floorboards in residential properties are not treated timber. Also, new floorboards that you will find at big DIY stores and most builders’ merchants, will be standard, kiln dried, untreated timber.

Providing there is good ventilation beneath the floorboards, untreated boards are fine. Ventilation will usually be provided by air bricks

are floorboards treated

Whilst pressure treated boards are not as common, they are available from certain suppliers, you just need to look around a little more. They will be slightly more expensive than standard boards. However, they come with several advantages. These include:

  • Longer life – Due to the process they go through, treated floorboards are much better at protecting against all kinds of rot. This includes more serious dry rot, and the many types of fungus that cause wet rot.

  • Protection from woodworm – Because of the chemicals in the pressure treatment, the timber is no longer edible to wood burrowing insects. In fact it would be poisonous. Therefore, woodworm will not attack treated timber floorboards.

Using treated timber floorboards to prevent rot

You may consider using treated floorboards when there is a risk of high moisture and/or humidity.

Inside a property, places like the bathroom and kitchen could be candidates for this type of treatment in floorboards. These rooms are generally higher humidity, and there is a greater risk of leaks and water damage.

If you are replacing floorboard in an area that suffered with rot, due to excess moisture, treated floorboards could be used as a preventative measure. Obviously, you would fix the issue that damaged the boards in the first place. But there is always a risk of future leaks and just general high humidity.

Another advantage of treated floorboards is protecting the joists below. If your floorboards do become rotten, this can spread to other timbers. Dry rot in particular can be quite aggressive. This can cause serious structural issues to the floor.

With treated timber floorboards this is far less likely, as they don’t rot. Therefore, if your joists did have issues, it would likely be coming from underneath. This would be a whole different problem.

Another time you would be better using treated floorboards, is if they are fitted outside of the main home. For example, in a shed or a garage. Obviously, these structures tend to be more at risk of higher moisture levels.

Protection against infestations

Another reason you may choose to use treated floorboards, is after a woodworm infestation. If you have found woodworm in existing floorboards, you will need to remove the affected timbers, and treat the surrounding area.

Once you have eliminated the infestation, you will need to replace any timber that was damaged and subsequently removed. Depending on how serious the problem was, this could be floorboards and maybe even some joists.

In this scenario, treated floorboards, and treated joists may be a good idea. Whilst the threat has been removed. There is always a chance that it could return. By replacing affected timbers with a treated version, you remove this future threat.

As we mentioned previously, woodworm will not eat a treated timber. Therefore, the new timbers should not be at any future risk of infestation.  

Other moisture resistant flooring

If you are interested in treated floorboard, due to concerns with excess moisture, there are other alternative flooring methods. These are engineered wood products, such as moisture resistant chipboard flooring. Even a decent WBP plywood can be used to replace floorboards.

These types of engineered flooring are not treated in the same way as natural timber. Instead, they are protected by chemicals and glues that are used in the manufacturing process.

Despite the method being different, they can provide a very good alternative to treated floorboards. Whats more, they will usually be considerably cheaper per square meter.

Also, engineered woods are not at risk of wood burrowing insects. Due to the manufacturing process and the chemicals used, woodworm will not be interested in this type of engineered sheet.

The final benefit here, is they are quick and easy to fit. Installing sheets of chipboard flooring or plywood, will generally be much easier than installing individual floorboards.

With that said, there is one main negative, and that is lifting the chipboard or plywood in the future. If you ever need to access pipes or other services below, this can be more of a challenge. Obviously, lifting an entire sheet of plywood, is more difficult than removing one or two individual floorboards.


Floorboards are not usually treated, but you can buy them from certain suppliers and timber manufacturers.

As a general rule, they will be anywhere from 20-50% more expensive than standard untreated boards. However, this can be a small price to pay, if there is a risk of high moisture and rot.

If you have dealt with a problem that damaged the previous boards, using a treated floorboard could be a good idea. For the small extra cost, it will give you additional peace of mind. Plus, it could prevent costly future repair work.

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