We needed something to connect the big glass doors with the pond, so we built an oak terrace cum patio.
It was to be an irregular shape because of the pond, so we drew it exactly, levelled the ground and dug nine post holes, into which were inserted short lengths of 100×100 mm fence posts, bedded in concrete.
The four showing at the front were oak, and the rest were standard treated timber. When all the posts were in, we screwed the outside joists onto them, using heavy duty exterior screws. This was easy for the softwood, but the oak posts at the front had to be drilled out very carefully. All joists were 150x50mm treated timber. The longest one by the brickwork was 3.6 metres.
The books advise maximum spacing of posts of 1200 mm and of joist centres 400mm, and we stuck to that (in fact less in this case for the joists because of the shape of the terrace). Before the inner joists were fixed, we put two pairs of bearers across from front to back to spread their weight, maintaining the same 1200 mm spacing.
Once the whole frame was in and fixed we could start contemplating the oak planking. This we bought from an excellent supplier in Corby, Northants, called UK Oak , though for small quantities their fixed minimum delivery charge is quite high so we went 70 miles to collect with an estate car. (Their service is good – there was a small problem with the order when we arrived, so they ended up delivering it to us free a couple of days later). We went for smooth rather than ribbed, since oak has a good natural non-slip surface if it is scrubbed regularly.
The planks were fixed with stainless steel screws, also supplied by UK Oak, and then extra planks were used round the outside to cover up the grain ends where the planks were cut and to hide the cheap softwood frame.
Finally, a small (1800x500x120 mm) frame was built for a step by the window, and planked in a similar way. Gaps between the planks for drainage were 4.5 mm (calculated to avoid having to cut a plank lengthwise, and controlled using a thin template) which is just enough to lose something small and valuable through them. But the design and the use of stainless screws allows planks to be removed again, just in case! The terrace is too low to get underneath to retrieve things.