Water-based Cuprinol style timber treatmen or oil-based creocote?

[MM]

Now that I have finished my timber lean-to greenhouse (sawn timber, not PAR), should I use water-based Cuprinol or Ronseal (as for fences) or will this, being water-based, cause the wood to swell and possibly deform the frame?

I could alternatively use creosote substitute, namely creocote.

MM

[Bill]

In message , MM writes

I'd always use oil-based now. Cuprinol or equivalent in clear or coloured, or possibly the creosotey type things.

The water based stuff on my shed came off in places, especially near things like knots, and at the bottom, where rain splashes up it is being attacked by various rot and chewing things.

[MM]

Right! It's Ronseal Total/Multi Wood Presever, then! Do you happen to have a can of similar, since on the Ronseal website under coverage it says "look on the side of the can", which is pretty useless information when I'm comparing different products before buying one. I plan to buy the 2.5 litre size. Should be enough for a frame of approx

1.1m x 0.75m x 1.75m, constructed from with 47 x 50mm sawn timber.

MM

[Bill]

I'm not an expert. I actually used Barrettine Clear Wood Preserver on some additions to the shed. They quote 35 square metres coverage for a 5 litre tin for one coat. For the fences I've been using some Creosote substitute, but for where it shows, Cuprinol Shed and Fence Preserver.

I usually brush and dip shed bits, and spill a lot in the process. I usually spray the Cuprinol on the fence, and coverage there depends on how and how often the spray nozzle clogs and misbehaves.

I think coverage is mainly guesswork, and should make large allowance for wastage.

[MM]

Oh, well, 2.5 litres will be plenty for my little project, then!

Creocote (the substitute) was going to be my first choice, but several things came up that made me think again:

1. It was not readily available where I live. Two suppliers had run out.
2. Where it was available it was £7.50 for 4 litres. At Focus DIY it's even more expensive.
3. It is apparently VERY bad for the environment (although I don't see how the spirit-based modern versions like Ronseal Total Wood Presever won't have a similar negative effect).
4. The odour from creosote/creocote is all-pervasive. When I did a fence several years ago you could smell it on the other side of the estate! And it takes days for the smell to subside.

Thanks for your feedback!

MM