Help needed about Tar Paint ? for underground timber

[Quoin21]

I am about to put 4 columns for a water tower on their foundation but being old seasoned timber (300mm x 300mm & rough) it is not impregnated so I need to coat it with something that will keep it rot-free for many years.

I gather there is tar paint but this may be biodegradable so may not last long ?? or could I use the tar used by flat roofers, perhaps.

Does anyone have any knowledge / experience that could help me.

 

[Robbie uk]

Several coats of a good bitumen may probably do it. I did the ends of some fence posts a few years ago and they have'nt rotted yet.

 

[gregers]

soak the ends of the timber in some spirit based wood preserver first,leave it as long as possible to soak up as much as it can,let it dry then do what you say.