On Wednesday, March 5, 2014 7:06:20 PM UTC, Dave Hill wrote:
On 05/03/2014 18:54, stuart noble wrote:

On 05/03/2014 16:01, Andy Burns wrote:

Pete C wrote:



On 05/03/2014 13:08, Nick Maclaren wrote:



Pete C wrote:



Oak will outlive treated softwood by decades.



Sorry, but that is so misleading as to be false.



Oak heartwood will outlast cheaply treated softwood by decades,

true, but oak sapwood will not last that long, and the most

aggressively treated softwoods (the old pressure-creosoted and

tanalised ones) will outlast oak heartwood by decades. What am

an not sure is how effective the tanalisation replacement is.



Sorry Nick, I was only repeating what I've seen on television.



Thanks all, the spec of the oak sleepers allows a maximum of one waney

edge, so could be sapwood, but I prefer the look of oak, will likely go

for it.





In direct contact with soil nothing's going to last that long





Off topic a little.

In much of West Wales the veg gardens are made up into beds by taking

the top soil from the paths and using it to raise the bed height, so

often the beds are 12 inches or more above the path height, this gives

drainage and at no cost .

David @ a rain-free side of Swansea Bay

Yes, that's how I made my 'raised' beds. It's especially useful if your topsoil isn't as deep as you'd like. A certain amount of maintenance is required to keep the soil where you want it.
If the op want's to use oak and can afford it - what's not to like?
I also did several beds like this using larch about 8 years ago and they're still in use by my successors. It's worth taking some time in preparation. Digging the bottom of the intended bed, adding organic stuff, then piling the soil from the paths onto the bed and then installing the boards. If he hasn't got a good cordless drill/driver this is a good excuse to get one.
Rod