About the Timber, lumber. The hard fibrous lignified substance under the bark of trees and wood size
This project call for 1×6 (150mm x 25mm) The finished (dressed) size as opposed to the nominal size of a piece of wood. and 2×4 (100mm x 50mm) actual size wood – which is usually a rough wood
(not Surfaced; planed; smooth; even surface; gauged., planed, or dimensioned). It will give a bit of a rustic look and be inexpensive. Pressure treated. Refers to lumber that is treated in such a way that the sealer is forced into the pores of the wood. Refers to lumber pressure sprayed with chemicals to lengthen its life expectancy for outside use or inground applications. pine would do.
Would the rough wood pose problems splinter wise?
Not really. The fur (for lack of a better term) on the treated pine is soft and if need be, it wouldn’t take much to sand the parts that matter.
In USA you can get 1 in. x 6 in. boards easy enough (smooth or rough).
In Australia you can get 150mm x 25mm treated (rough Rough sawn; Not gauged, planed or dressed.) pine commonly used as plinth A piece of sawn, or dressed lumber of greater width than thickness. Usually 19mm (3/4") to 38mm (1 1/2") thick and 75mm (3") or more wide..
In NZ you can get 150mm x 25mm treated fence paling (rough sawn).
In most other countries you should be able to source 1×6 (150mm x 25mm) wood without too much bother
in some form or other.
Altogether you will need
Allowing for a little bit of wastage…
• 12 ft (3.6m) of treated 2×4 (100mm x 50mm) actual size Any of the framing wood..
• 72ft (22m) of treated 1×6 (150mm x 25mm) actual size lumber.
Note: treated 1×6 (150mm x 25mm) and 2×4 (100mm x 50mm) actual size lumber usually means (rough) lumber before it has been dressed (surfaces, planed smooth).
When purchasing lumber try to get as long a lengths as possible to minimize waste.
You will also need…
80 of 2″ (50mm) wood screws,
48 of 3″ (75mm) wood screws,
and some glue.