The bases for the raised beds were created in three sizes, 8′ x 4′, 4′ x 4′ and 2’6″ x 2’6″.
The frames were made using 12″ x 2″ tanalised timber and 2″ x 2″ site pegs. The timber was cut to length, drilled to accommodate stainless steel coach screws, given two good coats of creosote (yes, I still have a little for jobs such as this) and left to dry for a couple of days before assembly.
As mentioned elsewhere the advantage of this method of construction is that the frame can be assembled, positioned and installed with the top level. It is then a simple matter to take measurements at the base of each side of the frame and cut additional timber to fit where necessary.
The cross members were all cut at 48″ and the side members at 44″ or 92″ depending on the size of bed required. With the 92″ side members an additional site peg was installed centrally on each board to stiffen the frame when installed.
Restricting the width of the beds to 4′ meant that I could weed the middle without standing on the soil. More aggressive forms of maintenance could be carried out with a scaffold board laid across the frame.
I created a simple jig to position a 16mm drill 9″ from each end of the cross members and drilled holes 6″ deep. This allowed the insertion of copper pipe (15mm here in the UK) which could be used to attach the various “hats” and frames as required. Accuracy in the positioning and depth of these holes allowed any pipework structure to be easily moved between the bases as required.
The inside of the cross members also provided a place to attach pipe clips to support the incoming irrigation system pipework.