A rectangular deck does not suit everyone - in spite of the fact that there is much that can be done to soften or hide the shape.
The requests are for round decks, curved decks, octagonal decks and angled decks. The same effect can be obtained in many instance by a good planting plan. Not easy to visualise for some, so we give examples of decks that have been built to a certain shape - including the most asked for - circular decking. Curved Decking Boards are not available - as yet!
One thing of note. A shaped deck will always cost more than a rectangular deck, and is more difficult with a raised deck than with a ground level deck. Study the curved decking ideas carefully before making a decision.
The main basic problem to overcome in the building of a shaped deck, is the simple fact that all of the construction materials are a/ rectangular section and /b are rigid so as not to be bent - too far! As any good carpenter knows, there are several ways of bending a straight piece of timber to all manner of unlikely shapes. Not all of those techniques are applicable to building curved or circular decking decks! (If they are, then generally the extra cost is out of proportion to the rest of the project.)
The next problem is of how to support the shaped deck frame. Essentially the deck subframe elements are rigidly straight and cannot be 'bent to shape'. Whereas a gently curve of the deck can be accommodated by modifying the shape of the otherwise rectangular base, if it needs balustrades, then these will have to be angled. Balustrades generally do not 'curve'! We have quite a few curved decking ideas on the site for you to study.
The actual finishing off a shaped deck that goes away from straight edges, is that of the fascia. This generally hides the sub frame, but is often more difficult with a rounded or curved deck. The fascia is normally screwed directly onto the endplate joist of the deck. Once the deck diverts from a straight edge - especially if to circular decking, then there is no endplate joist on which to screw the fascia. Simply screwing it into the end grain of the decking is not normally a good idea.
Surprising curves can be attained with the fascia - either by gently bending and screwing into place. A wet fascia is best for this. With a sharp curved edge - or even rounded edge, it is possible to cut a series of cuts into the back of the fascia in order to facilitate quite severe curves - especially where the curved edge is convex rather than concave. (Outward facing rather than inward facing curve.)
A long term problem can arise with this method, for the numerous cuts will negate the preservative treatment inherent in normal deck boards. A degree of protection can be attained by using a good quality timber treatment - allowed to soak into the surface saw cuts with several applications allowed to soak into the timber.
Circular decking is normally a feature for a ground level project, so the problem of suitable balustrades or railing does not arise.
If the deck to be shaped, follows a series of straight lines - such as with an octagon deck, then most of the problems above are not of importance here. Any straight line can have a decking fascia - and normally the provision of an outer endplate joist to whatever shape. Cutting of angles can present a problem for the inexperienced DIY builder - especially on the finishing fascia boards.
In almost all cases with angled decks, the sub deck frame can be constructed as an oversized rectangle, then cut at the corners to give the desired shape. This is much easier than trying to build an octagon shaped sub frame base right off!