Tanalised Timber FAQs – Everything You Need To Know About Pressure Treated Wood

tanalised timber faqs

Got questions about the timber used in your new wheelie bin storage unit? We’ve got answers! From painting and staining to how timber is treated, we’ve got everything you need to know, right here.

What is Tanalised Timber?

tanalith e

Tanalised timber and pressure treated timber are actually exactly the same thing. They both refer to wood that has been specially treated with a mixture of chemicals to make the timber more durable and long lasting. This treatment is done under pressure which forces chemicals into the wood (thus “pressure treated” wood), and generally involves a chemical called Tanalith E (thus “tanalised” wood). Tanalith is a brand name of the chemical, the actual chemical used in the process may be a relation of Tanalith E, but one that gives the same final result.

Wood that has been tanalised or pressure treated will be more resistant to rot, fungus, mould, and insects, as well as hardier in extreme weather conditions.

How Long Does Tanalised Timber Last?

That’s difficult to say since a lot will depend on how timber is treated. A shed that’s on top of a windy hill in a very cold climate might not last as long as one in the sheltered corner of a garden. But circumstances aside, tanalising timber should mean that the wood is rot proof for a good number of years. In general, we say that the inside of the wood should be protected for about 60 years, and the outside for about 30 years. This is without any extra treatment, staining, or painting on your behalf. Again though, how you treat the wood is going to have an effect on how long it will last.

How Do I Treat Tanalised Wood?

You do not have to treat tanalised wood, though it is recommended for a couple of reasons. Firstly, your timber will last longer if you choose to do some maintenance. Secondly, tanalised or pressure treated wood tends to change colour over time. If you wish to avoid wood turning grey as it ages, then treating it will help.

It’s recommended that you treat your timber with a tanalised timber treatment that you can buy at most DIY stores. This treatment simply paints on over the wood and is simple to use. For the first year of ownership, you shouldn’t need to do anything. After that, an annual coat of treatment will keep your timber looking good and mean that you get much more wear out of it.

Can I Paint Tanalised Wood?

Absolutely! Painting tanalised wood not only makes your garden look great but also gives the timber an added layer of protection, which can only be a good thing. However, you do need to be careful when painting pressure treated timber.

You cannot paint freshly tanalised wood, since moisture in the timber will mean that the paint won’t stick properly. You’ll need to buy some pressure treated wood preservative and paint that on to seal the wood first. These preservatives do vary, so make sure to read the instructions. These instructions should tell you when it’s appropriate to paint on the preservative, how many coats you need, and how long you need to wait before applying paint.

How Can I Tell if Wood is Treated?

There are a few ways to tell if the wood has been pressure treated. Firstly, the wood should be clearly marked as treated with a stamp. This is sometimes cut off when timber is cut down to size though. Secondly, treated wood that’s relatively fresh should have a green tinge to it. This green colour fades over time down to a honey gold, and then a silver grey. But any timber you’re buying that has a green tint to it has been treated.

How Soon Can You Stain Pressure Treated Wood?

There is a lot of debate about how long you should wait before staining pressure treated wood. In general, you’ll need to wait for the tanalith to oxidise and the wood to dry out. This means waiting for at least three days of dry weather (if timber is outside) to allow moisture to escape before painting stain on. There’s an easy test to see if your wood is dry enough to paint. Spill a little water on the surface. If that water soaks in you can go ahead and paint, if it beads on the surface you’ll need to wait longer.

There are exceptions to this rule though. If your timber has been kiln dried after being pressure treated you can stain it immediately (kiln dried wood should be clearly marked as such and will be more expensive than regular treated timber). If you’re looking to paint, then it’s really recommended that you wait for around six months without any other treatment, or that you follow the manufacturer’s instructions when using a treated wood preservative.

How is Pressure Treated Wood Made?

The process of making pressure treated wood is quite a simple one. Firstly, wood is placed in a large tank that is sealed to create a vacuum. The treatment chemicals are then pumped into the tank, and since there is a vacuum these chemicals are forced into the wood to a depth of a few millimetres. The timber is then left to dry.

The chemicals used in the process mostly consist of copper, which provides excellent protection against insects and rot. Any other chemical involved is a “biocide” which means that it kills naturally occurring things, in this case, kinds of rot that copper doesn’t prevent against. All the chemicals used in the process are safe and can be used around both children and animals without worry.

What Type of Paint Should I Use on Pressure Treated Wood?

For best results, you should use a primer before painting. Look for a primer that’s for exterior use and that specifically states on the can that it can be used on pressure treated wood. Once the primer is dry you can technically use any kind of exterior paint that you’d like. Again though, for best results, we’d recommend a latex based paint. Oil-based paints do sometimes have trouble sticking to pressure treated wood, and a latex based paint job will simply last longer.

Does Pressure Treated Wood Need Painting/Staining?

No, not at all. You can safely leave your timber outside without any further treatment should you wish to. However, your timber will last longer if you choose to apply preservatives, treatments, stains and paint. And don’t forget, that wood is going to change colour over time without further intervention. Pressure treated wood is initially green, but this will fade to honey blond, and then a silvery grey colour. If you wish to stop this colour change process, painting or staining your wood is essential.

81 thoughts on “Tanalised Timber FAQs – Everything You Need To Know About Pressure Treated Wood

  1. Richard says:

    I’ve a wooden gazebo which has been treated with Tanatone. The south facing part of the gazebo has faded due to sun exposure. Can you recommend a stain I can use to restore the tanatone colour whilst protecting the wood?

  2. Chris says:

    Hi Sam,
    I have a tanalised timber roof frame in a barn which I have converted to a dwelling. The timbers can be seen in what is a vaulted roof space. The plastered ceiling will be painted as normal and the timbers have been sanded. If I paint the timber with emulsion, gloss or eggshell, is there a risk that any staining could come through from the tanalised timber? E.g. do I need to apply anything onto the sanded timber before the primer? There are no knots but wondered whether the timber being tanalised could lead to any bleeding or staining through to the paint over time? Note, I’m not sure wood staining and oiling tanalised wood would look great inside a home. Any help much appreciated.

    • Victoria says:

      Hi Chris, did you ever find out what to use in this scenario? I am in the same situation but want to keep the trusses looking natural and light – was thinking of using Osmo Oil.
      Many thanks, Victoria

  3. Jasmin Bronkhorst says:

    Hi Sam,
    We recently brought a woodworm infested wardrobe into our brand new build house. Although it has now been removed, quite a few (we found 4 beetles) woodworm beetles escaped into the house whilst the wardrobe was in the house. Unfortunately we didn’t have carpets down at the time so we think the beetles crawled in the gap between the subfloor (chip board) and the skirting boards.
    We have painted wood worm killer on the internal timber that we have access to but we don’t have access behind the wall where they crawled into. Our house has a timber frame and The builder has informed that all the timber used to build my house was pressure treated.
    Will woodworm eat pressure treated timber? Do I need to panic? The woodworm beetles might have layed eggs on the timber within the wall so I need to be sure that the woodworms that hatch will not eat pressure treated timber. Thank you for your help.

  4. Neil McC says:

    Hi, I have recently had my whole back garden walls and fences re-covered in pressure treated wood but I cannot seem to clean off all of the ink stamps. Tried soap, brillo pad, light sanding but still can see the stamp. Any ideas anyone?!

  5. Joe says:

    Just posting this for all those who don’t know, i find this thread very tantalizing indeed :o)

    having been treated with the trademarked timber preservative Tanalith

    1. To excite by exposing something desirable that remains or is made difficult or impossible to obtain: Researchers have been tantalized by the possibility of finding a cure for the disease.
    2. To be strongly attractive to; excite the senses or desire of.

  6. Karen says:

    I’ve recently bought C16 timber for a long shelf in the kitchen (285cm). I’ve now realised is the wrong type of timber to use. Could I still use it indoor? It has lots splits. Unsure how to treat it. Wood filler, Primer, Latex paint, stain?
    Also can i sand the surface?
    Thank you

  7. Julian says:

    Hi, I am thinking of use tanelised 9×2 joists you make up a kitchen worktop. They will plane, sand and oil with Tung oil. Is this a good idea?

    • Sam says:

      It’s certainly an idea, but not one I’d be exploring.

      Tanalised timber is primarily for outside use, or internal but for construction purposes. Not for kitchen worktops.

  8. Tom says:

    Hi Sam, I have made a garden bench using C24 Kild dried timber for the frame and treated softwood carcassing for the seat and back rest.
    Is there a product (preferably an oil rather than paint) that would be suitable to treat for both?

  9. Paddy says:

    What are your thoughts about using tanalised boards: 3m x 224mm x 38mm as decking? Some people seem very worried about warping, but if they were screwed down well (three screws across the width and at 600mm centres along the length), I would think they’d be OK. What do you think?

    • Robert Smith says:

      With wide boards, be mindful of shrinkage/expansion across the width of the board. If you put this many screws through timber that is damp, it will shrink considerably when it dries and could split at the screw holes. You will also need wider gaps between boards otherwise the boards will expand when wet, close the gaps and possibly buckle.

  10. Lesley Miller says:

    I have product code stamped on wooden sleepers which landscape gardener has left visible. Can I remove these.

  11. Abbie says:

    Hello, I’ve used tantalised wood to make a coffee table and applied a medium oak indoor varnish to it. The wood has gone slightly green – is this because its tantalised? Any suggestions on how to correct it? Or is it best to start again with different wood? Thanks.

  12. Ash says:

    I’ve just had some green 2400 x 200 x 100 sleepers delivered and they are soaked through, to the point they look like they are dipped in Creosote. How long will it take for them to completely dry out so i can oil them?

  13. C Barkel says:

    Hi Sam, I’m buying untreated softwood to add to a brown pressure treated pergola. Can you recommend a stain that will be a reasonable match to the brown tanalised look? Thanks.

  14. Suzanne says:

    Hi. I have primed and painted my pressure treated fence and the coloured paint hasn’t taken and rubs off. What can I do to rectify this please

  15. Denis Riddle says:

    I have a boat mooring at the end of my garden, it’s in the river Yare. The mooring is constructed of tanalised timber, do you have any idea how long the timber should last? The river Yare is tidal and although it is technically fresh water, I live at Reedham, which is only a few miles from Yarmouth, so the water can be brackish at this point especially in the winter. Thanks.

  16. georgie says:

    Does tanalised timber split? We had some raissed beds made by a local garden centre. We asked for tanalised timber and paid the premium – but it is now splitting lengthways. It has also splintered -seems like the edges are soft – when i accidently caught it with a trowel it split! Am I expecting too much from this timber

  17. Terry Newbound says:

    Can I use oil.i.e danish on wood logs used as steeping stones in garden.will it effect plants around it.thanks.

  18. Patrick says:


    Are UC4 tanilised pine fence posts not suitable for indoor use, such as a bed frame? If they are, what finish would you recommend?


    • Sharon Griffiths says:

      Can we use clear exterior varnish on our outdoor tanalused shed as we want to keep the natural wood looking colour

  19. kevin greenwell says:

    Hi there, can you tell me once a timber has been tanalised for a couple of days, if it then rains few a days will the chemicals leak out? I have mine over a pond that have just been treated and now my Sturgeon is starting to be unwell?

    Cheers Kev

  20. Dennis Smith says:

    Have a tannalized
    Gate just taken delivery
    What Primer paint would you suggest as it’s going to be painted eventually black
    to match existing
    ? Opaque Dulux water based

  21. Juliano Coimbra says:

    Hi, Sam! Thanks for the good piece of information!
    Should I use gloves, masks or other kind of protection while working with pressure treated timber? I’m planning to build a framed shed in a few months. Kind regards from Brazil!

    • Sam says:

      Gloves are always a good idea when handling it. A mask less so for general handling, but if you are cutting it which it sounds like you will be then a dust mask should also be worn.

  22. Graham says:

    Hi Sam,

    I want to build a long lasting pergola that wouldn’t need any treatment for years – if at all (not worried about colour change). I’m going to use a hardwood that has good longevity. I’ve been told that my local timber merchant could have the wood pressure treated for me. Would that be advantageous? Are there different types or degrees of pressure treatment that increase longevity?

    • Sam says:


      Only softwoods are pressure treated. If you are using a hardwood it won’t be pressure treated.

      For a pergola we would probably recommending using a pressure treated redwood as it’s easier to work with and cheaper. But obviously will need a coat of wood stain to prolong life. But you can of course use hard wood.


  23. John says:

    Hi Sam
    I have some tanalised wood raised planters i want to paint the inside to make them last longer should i use water based or solvent based bitumen paint i only want to apply 1 or two coats. Many thanks J

    • Sam says:

      Do you mean Danish Oil? That’s usually used indoors… I wouldn’t use it on a tanalised timber gate. You should stain them or use something like Hickson Decor Wood Oil.

  24. A Morton says:

    My new picket fence is tantalised,been in situ for six months and it is dry. I want it to stay the same colour, I love it. It seems like a mine field out there. Do I need to use a preservative if so, what would you surgest. Thank you.

    • Sam says:

      It will always fade from the green colour once the chemicals oxidise.

      You can paint it with a wood stain no problem.

      • Robin Towey says:

        I built a car port about 5 years ago using what I thought was tanalised timber. The edges have a 200 X 50 verge which are exposed to make a feature. They were painted with several coats of Dulux shades but the top 50 has split and is now showing signs of brown rot. I want to replace the timbers and I want to have smooth faces. Can this be tanalised and if so will this prevent the problem reoccurring?

    • Sam says:


      Depends how much you take off, the more wood you remove, the greater the reduction in the effectiveness of the treatment.


    • Sam says:


      We wouldn’t recommend it. The treated timber contains copper etc. so it’s not a good idea to spread it on the garden.

      It’s best to be disposed of in an incinerator that reaches high temps.

      • martin says:

        Copper “etc”. So what else does it contain? Specifically, is it safe to burn talanised timber on a domestic bonfire (outdoors), or does it present a health hazard to the person tending the fire, or more generally?
        What is the recommended method of disposal, realistic for something like old garden fencing?

      • Lesley Crimes says:

        Hi, please could you tell me what we can protect our new tanalisied redwood decking with, should we use a sealer, or a deck oil/stain, can we use both, if so, which do we put on first, or is it one or the other.
        Thank you

  25. Godfried Addo says:

    Will the correct application of wood preservatives like Cuprinol extend the life of garden fences and sheds made with tanalised timber?

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