Strongest wood protection?

[Gebbly]

Hi All,
I will be building a wooden workshop this year and have been doing a lot of reading. Something I would appreciate advice on is ways to protect the woodwork from the elements. There seem to be huge numbers of different finishes for woodwork with different strengths and weaknesses but I haven't found any information that meets my exact requirements. What would be the best way of protecting a wooden shed from the elements whilst keeping the wood appearance/colour?
I have used products like http://www.homebase.co.uk/en/homebaseuk/mangers-creotec---light-brown---4l-916434 on fences before and it is reasonable at protection but as I apply fresh coats over the years it slowly tints the wood darker and darker.

Is there anyway of protecting wood that will be outside from the elements without changing its appearance?
thanks for any advice

 

[kevinlightfoot]

Hi I have been using Cuprinol 5 star treatments for quite a few years now with good results.Last year I mentioned this to someone at Johnstones paints and they told me that they did their own equivalent product at a much cheaper price.I purchased some and it appeared to be the same as the Cuprinol.Its longevity I cannot comment on but if it's as good as the Cuprinol then it's well worth a punt,and of course it is clear which I assume is what you are looking for.

 

[yetloh]

I can't comment on the longevity of wood treatments, although it is generally true that sheds will survive unscathed for pretty long periods provided the timber does not stay wet for prolonged periods. This means good gutters, air circulation round it and getting the bottom clear of the ground, When you say you want to maintain the appearence, it is important to realise that any wood will lose its natural colour unless it is coated with something to protect it at pretty regular intervals. Even then, the colour will still be affected by UV radiation.

Jim

 

[RobinBHM]

Unfortunately such a product doe not exist!

The reason is that transluscent stains finishes require UV inhibitors to stop them being broken down by sunlight. there are clear inhibitors but they have a limited life so manufacturers always make stains with a certain amount of depth which helps block UV. In the joinery trade the ubiquitous colour 'light oak' is generally the lightest stain colour which will survive the manufacturers guarantee period.

Also if you use a clear product, UV will quite quickly kill the lignin in the wood leaving the characteristic grey tone, once this has happened it cannot be reversed (although of course the timber can be treated with a stain finish to artificially create a colour.

If you want oak, cedar or siberian larch I believe Sioo is a product that will turn and keep the timber an even light grey colour.

For longest lasting cladding it is important to construct the building with an air gap behind the cladding which allows air to circulate. See tyvek housewrap site for construction detailing.

http://www.sioo.co.uk/wood-protection/products/

 

[RossJarvis]

Hi I have been using Cuprinol 5 star treatments for quite a few years now with good results.Last year I mentioned this to someone at Johnstones paints and they told me that they did their own equivalent product at a much cheaper price.I purchased some and it appeared to be the same as the Cuprinol.Its longevity I cannot comment on but if it's as good as the Cuprinol then it's well worth a punt,and of course it is clear which I assume is what you are looking for.

Have just looked at these. The Johnstones appears to be High VOC, possibly white spirit based and Cuprinol is water based. Have I looked at the wrong Johnstones product? Am looking for something to dip post ends into.

 

[dickm]

Am looking for something to dip post ends into.

Very naughty, I know, but up here in the wilds of Aberdeenshire, the usual mix is dirty diesel/heating oil mixed with used engine oil............

 

[RossJarvis]

Am looking for something to dip post ends into.

Very naughty, I know, but up here in the wilds of Aberdeenshire, the usual mix is dirty diesel/heating oil mixed with used engine oil............

It's tempting, but bearing in mind the amount of cash the client has spent on air dried PAR oak, I'm thinking of something with slightly less "colour" to it. I'm mainly trying to help out where the post goes into the oak cill and may make a moisture trap.

 

[kevinlightfoot]

I think it may be the Cuprinol product that you are looking at may be the wrong one,the one I used was definitely not water based.It was called Cuprinol 5 Star and if memory serves me it was in the regio of 16 pounds for 2 1/2 litres .I think you may be looking at the Cuprinol shades range which is I believe water based and I don't think it would be suitable for your requirements.The Johnstones one is not water based either but I'm sorry I don't know what High VOC means perhaps someone could educate me on the meaning.You do indeed use eithe of the products as a dip for end grain and I think you leave to soak for three minutes.

 

[MARK.B.]

Volitile organic compounds :wink: at least i think thats correct

 

[RossJarvis]

I think it may be the Cuprinol product that you are looking at may be the wrong one,the one I used was definitely not water based.It was called Cuprinol 5 Star and if memory serves me it was in the regio of 16 pounds for 2 1/2 litres .I think you may be looking at the Cuprinol shades range which is I believe water based and I don't think it would be suitable for your requirements.The Johnstones one is not water based either but I'm sorry I don't know what High VOC means perhaps someone could educate me on the meaning.You do indeed use eithe of the products as a dip for end grain and I think you leave to soak for three minutes.

It may be that Cuprinol have changed their formula, the only 5 star treatment I can see on their website is Water Based. (It's called 5 Star Complete Wood Treatment and comes under "eradicators" which may mean it's designed for treating wood which has already started to rot or get worm infestation). Under Wood Preservers they have three products, one of which has some VOCs in it.

I think the Johnstones recommends dipping for 30 minutes.

At the moment I'm looking for something that will least change the natural colour. There is also the consideration of keeping the finish from the start as long as possible which means treating it to some way darker than the original planed finish of bare oak.

 

[No skills]

@ Ross

I've used 3 or 4 brands of the clear wood preservers over the years, all have had the same solvent smell to them and none have done much to the colour of any timber once they dried.

The last one I used was the cheapo non-nonsense brand, it covered and acted in exactly the same way as the expensive ones I've had (green tin for the last expensive one, can't remember the brand (Cuprinol?)) - can't give any more info than that.

Some of them specify that there not for use in ground contact or standing pools of water.

Fwiw

 

[RossJarvis]

@ Ross

I've used 3 or 4 brands of the clear wood preservers over the years, all have had the same solvent smell to them and none have done much to the colour of any timber once they dried.

The last one I used was the cheapo non-nonsense brand, it covered and acted in exactly the same way as the expensive ones I've had (green tin for the last expensive one, can't remember the brand (Cuprinol?)) - can't give any more info than that.

Some of them specify that there not for use in ground contact or standing pools of water.

Fwiw

The cuprinol I used a couple of weeks ago said not for ground contact, but was being used on cut ends of tanalised wood for a rabbit run, hey ho (does anyone actually make a treatment specifically for this? All instructions tell you to treat the cut ends). The Oak jobbie is a porch on dwarf walls so should be well away from standing water and is belt and braces for the lower tenoned joints.

 

[Gebbly]

Thanks for all the great advice everyone.

I learnt from my grandfather many years ago to reapply protection to woodwork every year. So every summer I recoat the fence. So I am happy to also recoat a shed each year if it preserves it.

Kevin > I'll take a look at the Johnstones products and see what they have.

Yetloh > The shed will have gutters and thanks for the tip about good circulation. Regarding being clear of the ground, the construction will be on an area of raised concrete but the "kit" (I'll be getting all the timber pre-cut so its just a put together job) has a row of wooden supports which lay on the ground as a foundation, on top of which, the shed is to be built. I cant help thinking that those wooden lengths will rot over time. Any advice? I'm thinking of perhaps replacing the wooden lengths with rows of loose bricks or breeze blocks (like my grandfathers old shed which is still standing).

Robin > If I am reapplying a coat every year does that open up any possibilities? Would reapplying a translucent finish each year replenish the broken down finish? Or would this still result in discolouration over time? If the UV will kill the colour in the wood would it be effective coating the shed in a light stain to hold colour and then apply the clear product or would the stain fade as well?

Is something water-based always going to be less enduring?

Ross > Would it be possible to coat your posts in 2 different products? On the back of the Creotec bottle I used it said it was good for wood out of the ground but for anything being placed in soil you could paint over it with a bitumous paint. I have some wooden boarders I have put in the ground which I completely coated in Creotec and then painted the backside and bottom (the parts in contact with soil) with the bitumous paint. They seem to be holding up so far. You could paint just the part that will be inside the cill with the less visually appealing product?

No Skills > the products you describe sound similar to the Creotec with the smell and not being for ground contact. The main downside of the Creotec is that although they do a "light" and "dark", even using the "light" after 2 or 3 coats the wood starts turning a darker colour. After all these years my grandfathers shed now looks like its been painted with black paint as it has had so many coats. Can you name drop any products in particular that you were happy with?

 

[ED65]

Have you looked into linseed (raw, not BLO) or tung oil at all? Both were and still are used to finish wood for exterior applications. You would have to be okay with the characteristic yellow tone oiling gives, while tung is usually lighter in colour either one will yellow the wood noticeably. The whiter the wood the more obvious the yellowness is.

They do require regular upkeep but obviously you have no problems with a recoating schedule so worth consideration.

 

[Gebbly]

I had always thought of linseed and tung oil as quality finishes for nice furniture and the like. I hadn't realised they were good protection against the outdoor elements. So simply giving the shed several layers of raw linseed oil would actually protect from rain and rot? And a yearly coating would give as good protection as things like Cuprinol etc?

Thats an interesting idea. A slight yellowing of the wood would be preferable to the darkening to black that years of coats of Creotec give.

Thinking about it the linseed oil would be a nice finish inside as well as out. I really didnt want to paint smelly Creotec inside the workshop but wanted to do something to give the wood some protection inside as well. I will probably be keeping the wood exposed inside rather than putting up some form of insulation. I am looking at getting one of those log cabin type constructions with interlacing timbers and have found a supplier that does wall timbers about 60mm think for some strength. Hopefully they will be thick enough to screw some things to the walls like shelves and brackets.

-- Edit --
I had temporarily forgotten the concerns over linseed oil causing fires. I dont suppose there is a safer alternative?

 

[Gebbly]

I found the following suggestion whilst researching :
"good preservative on all external woods, Barrettine Premier Wood Preservative comes in a clear finish and will protect against Mould, Mildew, Rot and Wood Boring insects. Once this has dried a good quality wood oil such as Ronseal Ultimate Protection Decking Oil"

After digging into just what is in the Ronseal I find "Alkyd acryclic technology in a water thinnable linseed oil". So I guess if someone has a concern about linseed oil they have to be careful not to end up with it with a different name by mistake.

 

[ED65]

I had always thought of linseed and tung oil as quality finishes for nice furniture and the like. I hadn't realised they were good protection against the outdoor elements. So simply giving the shed several layers of raw linseed oil would actually protect from rain and rot?

It's still widely used in the US for log-built homes as one example. With regular upkeep they keep that new, yellow-wood look owners of such buildings are so fond of.

And a yearly coating would give as good protection as things like Cuprinol etc?

Couldn't say it gives as good protection, I think that's unlikely, but it's something. If you wanted to improve resistance to insect attack you could dissolve in some borax, which I think you can still buy in the UK.

I think it's worth bearing in mind that without any further treatment applied to the wood even a cheap shed made from pressure-treated softwood can last 20 years or more.

I had temporarily forgotten the concerns over linseed oil causing fires. I dont suppose there is a safer alternative?

You know that's just any application rags or paper? It doesn't make the building more prone to fire

The only potential risk is if rags/paper soaking in linseed are left scrunched up, lay them flat to go stiff and after that they're no more danger than a printed page from a magazine. But you'll want to brush or roller the linseed on anyway so no worries on that score!

 

[YoungSalt]

Just to confirm, Cuprinol changed 5* about two years ago to be a water based formula...which is a real bummer because it WAS a great product. I'm afraid that as these preservative treatments have no uv protection, I can't see how they would really suit your purposes as a cosmetic finish for your shed. I think you are best off going for a light colour stain, but you need to consider that the way they work is to give a thick solid colour to face the uv exposure degrading the surface too quickly.

 

[Helvetica]

Osmo make a clear, UV resistant matt finish oil. Wisdom would say that a small amount of stain will offer better UV resistance, but maybe not an issue if re-coated annually.

 

[Helvetica]

Alternatively, build the workshop with Accoya, and you could bury it in a marsh and it would be perfect in 30 years.