Creocote Vs Wood Preserver Vs Decking Oil?

Section62

Retrogamer said:

I'm just guessing here with the coats as i gave my fence 2 coats of creocote last september and by the start of the summer this year, it looked like it was almost back to raw wood. I live in the Scottish west coast so it's usually raining a lot and with the older wood not having so tight a grain i suspect it might wash out or fade a bit quicker.

That's a big part of it, which is one of the reasons for my guttering suggestion.  Repeated 'washing' of treated timber will reduce the effectiveness and longevity of most timber treatments.  So a combination of rain and UV will effectively remove or break down the treatment coating on the surface of the wood faster in areas where it is exposed than in areas where it is more protected.

It also matters how deeply the treatment has penetrated into the wood, the deeper the better for durability. In my view waterbased treatments lack the penetrating power of solvent based ones, partly because most timber has some natural water repellent ability. There's also a difference between treating timber on a hot sunny day and an overcast cool day - the depth of penetration of a treatment is affected by evaporation time, so if most of the solvent/water evaporates soon after it is applied, the treatment can't penetrate so far.  Hence two people could buy exactly the same product and use it on similar wood, and a year later report back entirely different outcomes simply down to the weather on the day the product was used.

In my experience the golden brown version of that Barrentine product has remained looking good on shed panels after 4+ years with no interim maintenance.  But I'd put that partly down to me normally only using it during periods of dry weather when the wood is properly dry, only applying it early in the morning or in the evening (and in the shade), and applying two coats by brush (the second as soon as the first is touch dry), and then a third coat a day or two later. I reckon that is the best way of getting the stuff to penetrate as much as you can, short of using pressure treatment.  And using gutters of course.

Section62

Jeepers_Creepers said:

I bought some 'Creocote' a few years back for a fencing too, and was reassured by that almost familiar smell - until I read the small print and discovered it was not a 'preservative' (which is exactly what creosote was), but a 'timber treatment'. It essentially just adds colour and water repellance. It won't actually stop the timber from rotting.

I think that was possibly just a problem with the rules and regulations on biocide product labeling. (in the same way the current 'weed' thread mentions Ammonium Sulphamate being legally sold as a compost accelerator, but 'banned' as a herbicide)

Creosote is manufactured as a product of the tar distillation process, in effect a useful byproduct. One of the issues was the lack of control over what the manufactured creosote contains, given that in the past it was effectively waste material getting only enough additional manufacturing work to make it into a colour-consistent product and packaging it. Creosote contains chemicals which are harmful to health, plus the potential for unknown quantities of 'unknowns'. The petty bureaucrats couldn't think of a way of formulating rules to govern the sale and use of creosote by amateurs, so they 'banned' it.

Creosote works because the distillates of tar are good at penetrating wood and then repelling water. Plus the chemical cocktail it contains is deadly to a wide range of things that attack wood.  Creosotes (the chemical compounds) are part of the same family with toxic qualities which are (or were) used for things like traditional disinfectant, antiseptics, and medicines. E.g. people of a certain age will have some familiarity with coal tar soap.

Creocote is an attempt to replicate the effect of creosote using only refined products with controlled levels of toxic ingredients. Therefore it lacks some of the potency of creosote.  However, it does use diesel as the base solvent, which as a distillate of oil has good penetration and water repellent qualities.  I believe most people who've handled diesel would say that any wood soaked in diesel is to all intents and purposes 'preserved'.  It isn't going to rot easily and most things that attack wood aren't likely to find diesel residue to their tastes.

I've used some creocote on rough sawn wood.  I'd say it isn't as good as creosote, but better on really damp wood than the Barrettine treatments mentioned previously. So for wood in permanent contact with soil I would opt for creocote.

Which according to the Barrettine product safety data sheet is now formulated as an "outdoor wood preservative"....
https://www.barrettineenv.co.uk/uploads/assets/Documents/MSDS/CREOCOTE.pdf

....although the Wickes version is still just described as a "wood treatment".  Maybe all 'creocotes' are not the same.

Jeepers_Creepers

Section62 said:

Jeepers_Creepers said:

I bought some 'Creocote' a few years back for a fencing too, and was reassured by that almost familiar smell - until I read the small print and discovered it was not a 'preservative' (which is exactly what creosote was), but a 'timber treatment'. It essentially just adds colour and water repellance. It won't actually stop the timber from rotting.

I think that was possibly just a problem with the rules and regulations on biocide product labeling. (in the same way the current 'weed' thread mentions Ammonium Sulphamate being legally sold as a compost accelerator, but 'banned' as a herbicide)

Creosote is manufactured as a product of the tar distillation process, in effect a useful byproduct. One of the issues was the lack of control over what the manufactured creosote contains, given that in the past it was effectively waste material getting only enough additional manufacturing work to make it into a colour-consistent product and packaging it. Creosote contains chemicals which are harmful to health, plus the potential for unknown quantities of 'unknowns'. The petty bureaucrats couldn't think of a way of formulating rules to govern the sale and use of creosote by amateurs, so they 'banned' it.

Creosote works because the distillates of tar are good at penetrating wood and then repelling water. Plus the chemical cocktail it contains is deadly to a wide range of things that attack wood.  Creosotes (the chemical compounds) are part of the same family with toxic qualities which are (or were) used for things like traditional disinfectant, antiseptics, and medicines. E.g. people of a certain age will have some familiarity with coal tar soap.

Creocote is an attempt to replicate the effect of creosote using only refined products with controlled levels of toxic ingredients. Therefore it lacks some of the potency of creosote.  However, it does use diesel as the base solvent, which as a distillate of oil has good penetration and water repellent qualities.  I believe most people who've handled diesel would say that any wood soaked in diesel is to all intents and purposes 'preserved'.  It isn't going to rot easily and most things that attack wood aren't likely to find diesel residue to their tastes.

I've used some creocote on rough sawn wood.  I'd say it isn't as good as creosote, but better on really damp wood than the Barrettine treatments mentioned previously. So for wood in permanent contact with soil I would opt for creocote.

Which according to the Barrettine product safety data sheet is now formulated as an "outdoor wood preservative"....
https://www.barrettineenv.co.uk/uploads/assets/Documents/MSDS/CREOCOTE.pdf

....although the Wickes version is still just described as a "wood treatment".  Maybe all 'creocotes' are not the same.

You must be fun in the pub :-)

Interesting stuff - thank you.

ispookie666

+1 for everbuild lumberjack used it on my fence - went through 25L, two coats and garden sprayer.  Then applied decking oil - needed to use a paint sprayer.  Its still looking good 
Thanks to @Jeepers_Creepers

hackeron

Question. I have a shed with OSB3 roof and roof felt over that. The roof felt developed a fault and the OSB3 roof underneath completely rotted as I am guessing it had no treatment of any kind.

I replaced the boards with new ones but to avoid rot in the future, what should I treat the OSB3 with before putting fresh root felt on? - so that at the very least if a leak develops again, I have a few weeks/months to address it before the OBS underneath rots..

I was thinking maybe just creocote on its own and then roof felt over that, but now I'm thinking maybe I need a coat of wood preserver (how about Sika wood preserver from Screwfix?) followed by a coat of creocote on top of that for water protection, does that sound sensible or overkill or totally wrong?

Attached an image of the work in progress repair:

Bendy_House

That's a big shed!

OSB is great stuff, but struggles to cope with damp - and it isn't really designed to. I doubt your OSB actually 'rotted', but just swelled up and fell apart.

So, I wouldn't bother trying to 'preserve' it, and I doubt the stuff would penetrate anyway (OSB has a 'shiny' side, I think?). It's great stuff to use for roof sheeting, but the problem with anything up there is, once the outer covering is breached - be it felt, or EPDM or whatevs - then water gets in and is then trapped between the layer and the supporting sheet, so the water doesn't dry out easily. The sheeting then just swells and falls apart (or rots if it's timber).

So, what to do? I'd just use a good quality felt, and make sure it's put on well. As long as that lasts, the sheeting under it will do so too. If you really really want to, I guess you could coat the OSB with a thick roofing coating/seal, such as Isoflex, Cromopol, Acrypol, or any of the other many 'liquid roof' products which are designed to repair/rejuvenate tired roofs. Once you've done that, you might not even need the felt! (I have used Cromopol to rescue a very old tired flat felt roof, and it seems to be really effective.)

Bottom line; if the outer skin - felt - is fine, so will the rest be.

Retrogamer

Jeepers_Creepers said:

It'll be very useful if you could report back on occasion, please - eg. if there's any changes, when it needs redoing, or "haven't touched it in 10 years - still looks as good as new..."

It's been almost 2 years now and due an update with some pictures soon.
The wood at the back of the shed, which faces the sun most of the time is fully dried out now.
The rest of the shed needs 1/2 coats to get it back to like 2 years ago but the back section with maybe 3/4 coats

ThisIsWeird

Fab. Thanks for the update. Look forward to the pics.

JC, BH, TiW.