Which is the best exterior wood treatment?

The sun is out and temperatures are on the rise. This is the time when we venture out to the garden to survey the surroundings, and draw up the list of maintenance tasks.

When talking about exterior wood finishes, there’s always an assumption that it’s about the decking, garden shed or fence. Although these are indeed the most common garden features that need maintenance after a winter of wind, rain and freezing temperatures, wooden window frames, doors and porches should also be checked and given attention if required.

It’s all about the knowledge

A question we get asked a lot here at Wood Finishes Direct is “What is the best exterior wood treatment?”. Unfortunately, there’s no single product that is better than another for every project and type of wood. In fact, deciding what product should be used can be a complex matter. That’s why we invest heavily in the training of our sales and service team, or as we call them, the SAS team. All of our support staff are rigorously trained so that they’re familiar with the products we stock, their properties and their suitability for any number of given scenarios. This means that we’re always able to give expert advice and guidance on which products and brands are best suited to your project .

top-wood-finishing-brands

Just some of the top brands available at Wood Finishes Direct

Exterior wood finishing types

Essentially, there are two types of exterior wood treatments, those that are absorbed into the surface of the wood such as oil based products and those that form a protective coating on the surface of the wood, both of which have their own unique characteristics and benefits.

Penetrative Wood Treatments

Penetrative wood treatments are the type of products that soak into the wood and protect from within such as decking oils, shed & fence treatments. These products are predominantly oil and wax based. They work by penetrating then drying in the surface grain of the timber to provide a tough, durable, weather resistant surface.

The key benefit of this type of product is that they are very easy to apply and maintain. When the finished surface starts to look tired and worn, it’s simply a case of re-applying a fresh coat. No need to sand, strip back or remove the old finish. Wood oils are very forgiving for patch repairs meaning that localised areas of wear are very easy to repair and blend in with the surrounding areas. Leading brands that specialise in these types of exterior wood finishing products include Osmo, Ronseal, BarrettineCuprinol and Holzol.

Exterior coating systems

What was once the realm of paints and exterior wood varnishes is now dominated by an array of ultra modern wood coating systems. Whereas old paints and varnishes had a reputation for cracking, flaking and peeling, modern coating systems have been scientifically developed to withstand the effects of weathering and the constant movement of the timber as a result of moisture and temperature changes.

Modern exterior wood coatings are flexible and durable meaning that they rarely need to be stripped back to bare wood if maintained correctly, a firm favourite for exterior joinery such as wooden window frames and doors. Brands such as Sadolin and Sikkens are designed in such a way that as the top coat wears over time, it starts to lose some of its colour and sheen. This is an indicator that the finish needs maintenance. Surfaces that require maintenance can be restored by following a few simple steps.

  • Wipe down with Methylated Spirit to degrease the old finish.
  • Lightly sand the surface to remove any ingrained surface dirt and debris. This also provides a key for the new top coat.
  • Wipe down a second time after sanding with Methylated Spirit to remove all traces of sanding dust and any residual grease from hands and finger tips.
  • Ones dry, a fresh top coat can be applied to restore the appearance and maximise protection of the timber.

Other brands that specialise in exterior coatings, translucent and opaque include Dulux Trade and Crown Paints. Also see Sadolin’s Superdec Opaque Wood Protection finish.

Any Questions?

If you have an exterior wood care project to tackle and are not sure which product to choose, give our resident wood experts a call. They’re able to provide free, expert wood finishing advice, so that you can make a well informed choice on which products are suitable for your project.

As well as giving advice, support and help, we also like to see the results of completed projects. If you have any before, during and after project pictures, and would like to share them with us and our community, please let us know.

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53 Responses to “Which is the best exterior wood treatment?”

  1. BARBARA Says:

    Hi
    We currently have a dark stain on wood tops and would like a limed light grey effect. Which OSMO Products to use. Also an Indian Sandstone Floor internally which us impossible to clean. How to clean and possible paint to protect for future use in high traffic areas. Also has to be non slip for animals. Kind Regards. Barbara

  2. Sam Taylor-Casey Says:

    Hello Barbara,

    Thank you for your inquiry. You will need to remove the existing finish before you can apply a lighter colour as it is unlikely to work unless applying an opaque finish and this would depend on the current finish of the wood. The Polyx Oils need to soak into the surface of the wood to work effectively and you may have something on the wood that prevent penetration. If you would like to email me with more details about the area to be finished and I would be happy to advice you further.

    I believe that there are some Sandstone sealers out there or a product such as Thompsons water sealer could be used but I am not the best to advice on sealing stone I’m afraid. If there is anything further you would like to ask or you do wish to discuss further you can email me on wood@finishes.direct

    All the Best Sam.

  3. sandra Says:

    My daughter has had an extension and now has large timber posts supporting a canopy over the front door. I thought I would give 2 coats of cuprinol and then use a dark coloured sikkens. Would this be the best way to stain and preserve the wood? Is it ok to use clear cuprinol then a sikkens with a stain or can you suggest something else? Thanks Sandra

  4. Sam Says:

    Hello Sandra,

    I would not recommend the Cuprinol and the Sikkens together. Ideally the Sikkens should only be used with other Sikkens products and for the best finish on new wood the Cetol HLS Plus followed by the Cetol Filter 7 Plus this will give great protection to the wood. If you have a read up of the products and feel free to let me know if you have any further questions.

    All the Best Samantha.

  5. Jon Says:

    Hi
    I have recently built a pergola in my garden. On three sides around the bottom 2.5 to 3 foot I have put a fence topped with some 6×2 timber. I anticipate people to lean on it and rest glasses and cups on it. I’m looking for help to prepare and and choose the right varnish for a natural looking tough easy to maintain surface. I get the image of a good old fashioned wooden bar counter look to it.
    Hope you can help thanks for your time.

  6. Sam Says:

    Hello Jon,

    You could have a look the Sadolin Classic Wood Protection as an option there is a variety of colours available including the Light Oak and Natural. This is a varnish with flexibility and durability for exterior wood. If you have a read up of the product and feel free to let me know if you have any further questions, I am happy to help. Always try a test area first.

    All the best Samantha.

  7. Kath Says:

    Hi,
    We have two old wooden carts which we are in the process of restoring. We are anticipating that they will stay outside from spring to autumn with a variety of flowerpots on them. Any advice on which type of preservative would be best would be much appreciated.
    Thanks
    Kath

  8. Sam Says:

    Hello Kath,

    Thank you for your enquiry, you could have a look at the Barrettine Premier Wood Preservative this will help to prevent mould, mildew and rot. And then to give protection from water ingress and UV a Decking Oil

    Areas of wood with pots on can be susceptible to damage and its worth taking then off periodically to clean the area and remove any dead flower petals or leaves.

    If you have a read up of the products and feel free to come back to me if you have any further questions.

    All the Best Samantha.

  9. Ben Says:

    Hi

    I have made some large raised beds out of Scaffolding boards that I have sanded back to clean wood. I’d like to keep their natural color but properly protect them for as long as possible because removing the soil and treating inside and out will be a nightmare.

    What is the best treatment to use?

    thanks in advance
    Ben

  10. Sam Says:

    Hello Ben,

    You could have a look at the Barrettine Premier Wood Preservative which will help prevent mould, mildew and rot and has wax to make the wood water repellent. Two coats of this will be good and you could follow that up with two coats of an oil such as Decking Oil to improve the protection even more.

    And ideally line the bed with some suitable liner to help protect the wood even further. I hope that helps and feel free to come back to me if you have any further questions.

    Kind Regards Samantha.

  11. daz Says:

    Hi I have just put up a canopy and porch sitting on 5 inch treated posts I want to know the best looking oak stain or oil for the posts and facia board

    Thanks Daz

  12. Sam Says:

    Hello Daz,

    Thank you for your enquiry, could you email me with a little more details, for example what type of treatment is currently on there and what type of wood are you treating. Will be happy to advice on the products that would suit your needs. You can email me at wood@finishes.direct

    Kind regards Samantha.

  13. Diane Says:

    I have a North facing Oak front door, it has been varnish in the past but has not stood up to the weather and is now patchy. What is the best treatment for it now.

  14. Sam Says:

    Hello Diane,

    Thank you for getting in touch. For a door that is particularly exposed you may find it better to apply a product that is quick and easy to maintain over time. Osmo UV Protection Oil Extra is an oil that soaks into the surface of the wood, it helps to make the wood moisture repellent and slows down the silvering process.

    Then a top up of oil annually will help to maintain the protection longer still. You can simply re apply a coat without the need to sand back, just ensure the door is clean and dry. The first application of this will need to be to bare wood, any varnish remaining will prevent the oil from penetrating the wood and protecting effectively.

    I hope this helps and feel free to get back to me if you have any further questions.

    Kind Regards Samantha.

  15. Chris Leach Says:

    Hi I have purchased a wooden framed gazebo it has been stored for three years. I Have no knowledge of wether it has been treated in the past or what with if it has. Can you please advise my best options .

    Thanks
    Chris Leach

  16. Sam Says:

    Hello Chris,

    The first thing to do is carry out a water test. Splash some water at the wood and see if it beads off the wood, if it does then there is likely something on the wood that is still protecting it. If it soaks in ( don’t use too much water ) then you may be able to consider applying a fresh treatment.

    If you do the test and then feel free to email me with the results and maybe a photo of the wood to be treated and I can advice from there. wood@finishes.direct

    Kind regards Samantha.

  17. Geoff Davies Says:

    Hi We have a vertical wooden post at the corner of a porch I would say approx 6inch sq.
    It is old but in good condition and a surveyor recommended we keep it. We are about to have it clad along with the wooden windows to be replaced with UPVC. I was thinking about stripping the paint (which is flaking) and giving the post some sort of protection before they start on the porch. What would you recommend?
    Thanks
    Geoff

  18. Sam Says:

    Hello Geoff,

    Thank you for getting in touch. If the post is exposed to the outside world then a good quality preserver would be recommended Barrettine Premier Wood Preservative offers great protection against mould, mildew and rot. It also contains wax to repel moisture.

    If the post is inside the porch then a couple of thin coats of Hard Wax Oil will give a natural and durable finish to the wood. Always try a test area first and if you have any questions about these products please do feel free to let me know.

    Kind regards Samantha.

  19. Brian Atkinson Says:

    Hi Sam, I have recently purchased an 8′ x 5′ shed as a flat pack, sides, roof and floor, it’s already coated in factory preserver but they recommend it be recoated in more protection. Once the shed is erected and in position, because of limited space, one side will be difficult if nigh on impossible to re-treat, could you recommend a long lasting protection, especially for the side that’s close to the rear of a concrete garage. Cheers Brian.

  20. Samantha Taylor Says:

    Hello Brian,

    Thank you for your enquiry. I can recommend a whole range of products and some will last longer than others. Essentially all treatments will need a top up over time. The one that should be longer lasting is a combination of Classic Wood Protection and the Extra Durable Woodstain these two will give a long lasting protection to the wood.

    It is flexible and water repellent. A test area should be carried out to ensure that there is no adverse reaction to the preservative already on there. If you have a read up of the product and feel free to get back to me if you have any further questions.

    Kind Regards Samantha.

  21. Jim Rooks Says:

    I constructed a pergola and rather that shingle I used fiberglass. I have sanded the fiberglass in preparation of painting with acrylic water proofing and sealer. I worry that some sanded areas may have exposed the untreated wood beneath. Since the resin epoxy is clear it is difficult to pinpoint where the exposed areas may be but primarily on corners. Would you recommend a penetrate to rub over these areas before painting?

  22. Samantha Taylor Says:

    Hello Jim,

    Thank you for your enquiry. For exposed areas of wood you could have a look at the Barrettine Premier Wood Preserver this will help to prevent mould, mildew and rot and it also contains some wax to repel moisture.

    If you take a look at the product and feel free to come back to me if you have and questions.

    Kind Regards Samantha.

  23. Chris Says:

    Hi.Ive just had a new shed put up today .They said it had been treated for rot and fungi but I need too put a water base treatment too water tight it .what would you recommend as also wants it clear or natural wood as dont want a colour.
    Thank you Chris.

  24. Samantha Taylor Says:

    Good Afternoon Chris,

    We often recommend oils for exterior projects as they are not only easy to apply but also easy to maintain and repair. The Log Cabin Treatment is a good option, it is clear and protective, with UV filters to help slow down the natural silvering caused by the sun.

    To get an idea of how it will darken the wood you can wipe a damp cloth over the bare wood. For alternatives or further advice please do not hesitate to get in touch or call one of our friendly team on 0800 7818 123.

    All the Best Samantha.

  25. Col Says:

    Hi,

    I have a large area of planed wood garden border fencing to protect – something like 300 uprights of 4″ x 72″ incl posts. Would you recommend a particular product that is good value for such a large area? thank you. Col

  26. Samantha Taylor Says:

    Hello Col,

    You could have a look at the Barrettine Premier Wood Preservative it great for helping to prevent mould, mildew and rot, And also contains some wax to help make the wood moisture repellent. It comes in a range of colours and is one of our most popular finishes. If you have a read up of the product and feel free to get back to me if you have any questions.

    All the Best Samantha.

  27. mick robinson Says:

    i have built a porch in wet oak and the customer wood like to put a protective coat on preferable to keep it looking light thankyou what wood you recomend please

  28. Samantha Taylor Says:

    Hello Mick,

    Wet or Green Oak has a high moisture content. Because of this we do not recommend applying a finishing product. Many products will not adhere to wet wood and those that do are sealing in the moisture making the wood susceptible to mould and mildew over time.

    People often use green wood in order to get the natural shifting and cracking that comes with the drying out of the timber. As it changes shape and takes on character. Once the wood is dry you can then consider application of a protective treatment and if you would like to email me with details of the colour or finish that you would like our email is wood@finishes.direct.

    Kind Regards Samantha.

  29. Rob Mellor Says:

    Hi Sam,

    My wife and I have recently ordered a Tanalised Timber Summerhouse from Cheshire Sheds. They recommend using a Sadolin wood Protection but they have such a vast range and, when questioned, Sadolin recommended either their Ultimate wood Treatment or Superdec Opaque Wood Protection. Cheshire Sheds recommended a Translucent Protection, to bring out the grain. Also, to add to our confusion, when we went into our local Sadolin Dealer, Bromborugh Paints, they recommended Osmo 420, as a better alternative. Help!!!!!!!!!!!!!!!!!!!!!

  30. Samantha Taylor Says:

    Hello Rob,

    There are so many products out there that is does become a mind field when it comes to choosing what is best for your project. Essentially all those products will be suitable, the Sadolin products are surface sealers, varnish or paint type products that dry on the surface and are fairly long lasting. When they start to break down and peel and flake they need removal in order to re apply new coats. But they have the benefit of lasting up to around 5- 8 years depending on exposure and weather.

    We often recommend Oils rather than surface sealers as they are far easier to maintain over time. They soak into the surface of the wood and will not peel and flake over time. They will simple wear away naturally and give a shorter time span of protection. The benefit comes in that you do not have to strip back the oil that remains, simply ensure the surface is clean and dry and then re-coat. So the Osmo Protection Oil Extra is idea if you would like a natural clear finish to your wood.

    One other thing to consider is a good quality preservative to be applied first, this will help to prevent mould mildew and rot and the Sadolin or Osmo will be a top coat product that will slow down the silvering process and make the wood moisture repellent.

    I hope that helps and I am happy to answer any questions you have, feel free to email me on wood@finishes.direct

    All the Best Samantha.

  31. barry luxton Says:

    hello, I am installing an air dried oak beam 200mm square, across the garden at high level to grow plants across the patio, connect to the kitchen extension, using stainless steel wires, a continental open roofed patio area. It has been suggested to protect this beam with linseed oil. The issue, oak does not allow for deep penetration. How many coats and is it recommended to dilute the first, primer coat?

    Thank you in anticipation.

  32. Samantha Taylor Says:

    Hello Barry,

    Linseed can be used for your project however it will offer limited protection, have a long drying time and require a number of coats to be applied, up to 5. It will then need topping up regularly, around every six months to maintain its durability.

    For Oak I would recommend the Teak Oil from Osmo. It is a thin oil designed for use on hardwoods such as oak. It will make the wood moisture repellent and allow it to silver naturally. It only require two very thin coats to be applied and so a litlle goes a long way.

    I hope this helps and if you have any questions please feel free to get back in touch.

    Kind regards Samantha.

  33. Pauline Says:

    I have two fresh sawn gate posts 200mm square. What would be the best thing to use to protect the posts. I want to try and keep the posts a natural lighter colour. I also have a new shed which has been pre treated. The are a medium brown and would like to make them a lighter colour. Is my only option to use something like Cuprinol Garden shades?

  34. Samantha Taylor Says:

    Hello Pauline,

    You could have a look at the Preservative from Osmo to be applied first, this will help to prevent mould, mildew and rot. Then two thin coats of the Osmo UV Protection Oil Extra this will help to slow down the silvering process and make the wood moisture repellent.

    It will darken the wood slightly to give what we call the ‘wet look’ and you can get an idea of this by wiping a damp cloth over the surface of the wood. It will leave the wood looking and feeling very natural.

    For the shed, lightening wood can be difficult and applying an opaque finish is more likely to get the best result. Cuprinol Garden Shades is a possible option and is available in sample sizes to allow you to try a test area first.

    I hope that helps and if you have any questions please do not hesitate to get in touch.

    Kind regards Samantha.

  35. John Owen Says:

    Dear Samantha ,
    Guidance please ,
    I am about to replace the ,ship-lap T&G ,external wood surround on my bungalow,about 100 m linear length .
    This will be bare wood ,can you please tell me how best to prepare and best finish for this .Dark brown ,mahogany Matt finish preferred .
    Being 78 yrs of age ,the minimum of work and hopefully about 10 yrs life .
    Many thanks ,
    John

  36. Samantha Taylor Says:

    Hello John,

    Thank you for getting in touch. For a long lasting finish you could have a look at the Sikkens Cetol HLS Plus this has a range of colours and you can apply 2 – 3 coats for a semi gloss, natural looking finish. It is brush application and if you are able to apply to both sides before installing this will also prolong the protection to the wood.

    I would expect this to last for a minimum of 5 years and possibly longer, depending on how exposed to the elements it is. A top up coat at the 5 year mark may help to prolong even further.

    I hope that helps and if you have any further questions please do not hesitate to get in touch.

    Kind Regards Samantha.

  37. Michael Says:

    Hi

    I need some advice please. I have just had a new decking built. The actual decking is composite but the sides and railings are a soft wood. Which is best to protect the wood, Osmo or berratine?

    Many thanks

    Michael

  38. Samantha Taylor Says:

    Hello Micheal,

    I would recommend a basecoat of preservative first, this will help to prevent mould mildew and rot. Once this is dry an application of Exterior Oil would be recommended. Oils are easier to apply, maintain and repair over time and for one with not only moisture repellency but also UV protection you could look at the Osmo this is our best oil in terms of slowing down the silvering process.

    If you have a read up of these products and feel free to get back to me if you have any further questions. Always try a test area first.

    All the Best Samantha.

  39. john shaw Says:

    Hi Samantha
    I have read with interest your questions and reply and have a project in hand which i would appreciate your advice The outside wood cladding on my house west facing west of scotland red cedar strip is looking the worse for wear after 30 years flaking and peeling The wood facing is still servicable and i do not wish to go to great expense renewing it Area is triangular approx10m across x5mht Product and application please
    Many thanks
    john

  40. Samantha Taylor Says:

    Hello John,

    Thank you for getting in touch. A good option for an exposed area is some of the products from the Sikkens Range. In particular you could have a look at the Cetol HLS Plus. It is recommended for use on bare wood and so I would recommend removing all the pre existing product, especially as it is peeling and flaking as this will continue to get worse.

    Once back to bare wood 3 coats of the HLS Plus is ideal for use on cladding. It is available in a range of colours and will last around two years with a 3 coat system, before you will need to consider applying a top up coat. For many it will last longer, but 2 years is the guide from Sikkens. Coverage will vary depending on the condition of the timber and so for your slightly aged wood it may be on the higher side.

    I hope this helps and do feel free to get back to me if you have any questions.

    All the best Samantha

  41. Anjila Says:

    I have apple tree slices from the trunk of my old tree .. I’m turning one into an outside stool what would be the best way to preserve this please

  42. Samantha Taylor Says:

    Hello Anjila,

    If the wood has dried out then the first recommendation would be preservative to help to prevent mould, mildew and rot.

    Then a top coat product to seal and help keep the wood moisture repellent, for a clear oil that will help to slow down the silvering effect there is Osmo UV Protection Oil Extra. It will darken the wood slightly to give what we call the ‘wet look’.

    If you are looking to add some colour or something different just let me know and I can make some alternate recommendations. If the wood is freshly cut and has not dried out yet you may need to allow it to weather for a while as treatments are not recommended for woods that have a high moisture content.

    I hope that helps and always try a test area first.

    Kind regards Samantha.

  43. Peter Vaughan Says:

    I have just built an extension which is clad externally in marine ply. The wood does not come into contact with the ground. It is a uniform mid brown colour and I would like to stain it with a colour eg blue or grey. Also, I am unsure whether I should also be using a wood preservative treatment. I would greatly appreciate your advice. Peter Vaughan

  44. Samantha Taylor Says:

    Hello Peter,

    Thank you for getting in touch. Can you tell me if there is any treatment currently on the cladding ? This can have an impact on what I can advise.

    If you are treating bare wood then I would recommend a preservative to help to prevent mould, mildew and rot. And then a top coat product that will make the wood moisture repellent and offer UV protection, Natural Oil Woodstain has a good range of colours to choose from.

    Feel free to email me with an further information or questions at wood@finishes.direct

    All the Best Samantha.

  45. Robert Says:

    I have new fences and a new shed to protect. Do you recommend creocote as a long term solution? Or should I be using a more ordinary preservative such as Cuprinol or Ronseal?

  46. Samantha Taylor Says:

    Good Afternoon,

    The Creocote will help to make the wood moisture repellent. it does not offer protection against mould mildew and rot. For this a preservative is required.

    For the best protection of exterior woods, we nearly always recommend a two coat system, a Preservative first to help prevent mould, mildew and rot. Followed by a top coat product to give moisture repellency, this can be the Creocote or an Oil such as Decking Oil which is very versatile and can e used for a number of exterior projects.

    If you have a look at the recommendations and feel free to let me know if you have any further questions.

    kind regards Samantha.

  47. Mark Belcher Says:

    Hi there

    Just had a new tantalised garden shed fitted. Wondered which clear product I should put on it come spring time?

    Cheers for the steer, Regards, Mark

  48. Samantha Taylor Says:

    Good Morning Mark,

    You could have a look at the Log cabin Treatment This is a clear oil that absorbs into the surface of the wood and helps to make it moisture repellent as well as offering some UV protection. A clear oil will darken the wood a little to give the ‘wet look’ and I would recommend a test area first. Have a read up of the product and feel free to get back to me if you have any other questions.

    All the Best Samantha.

  49. Hi Samantha Says:

    I have just built a large shiplap driveway gate out of pressure treated (brown colour) softwood. I would like to add a clear coat to further protect whilst maintaining the original colouring, and to seal ends and crosscuts made into the timber. The gate is fairly exposed and south facing. Are you able to help. Many thanks Paul

  50. Samantha Taylor Says:

    Hello Paul,

    Can you tell me exactly what is on the wood at the moment ? And then I can narrow down some suitable products for your project.

    Kind Regards Samantha.

  51. Hi Samantha Says:

    Hi Samantha, they couldn’t tell me exactly, but i’ve found out the brown colouring is a dye to indicate it has been pressure treated, and will fade to nothing in a season. So I guess it is just a standard pressure treatment for rot and fungi as found with decking timbers.
    Thanks

  52. Paul T Says:

    Recently had planters installed in garden (pressure treated railway sleepers (natural colour referred to as “green”).

    To maintain current look would like good UV protection to avoid silvering – planters colour looks better after rain so some partial wet look would be a bonus.

    Any ideas? thanks

  53. Samantha Taylor Says:

    Hello Paul,

    You could have a look at an exterior treatment such as Barrettine Wood Protective Treatment this comes in a clear, which will darken the wood slightly, or a coloured finish, the darker the colour the more UV protection it will get.

    You can apply 2-3 coats to build up a protection for the wood and it will help to make the wood moisture repellent. Always try a test area first and if you have any questions, I am here to help.

    Kind regards Samantha.

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