Treated timber sub-frames are used for both in most applications.

Sub-Frame       A Deck25 deck sub-frame must be designed and built to last.  This includes treating and sealing the part of the post that is in contact with the ground and up to 100mm above ground level.  The ground air interface is where treated posts are most susceptible to rot.  Galvanised steel post anchor systems are excellent.

Joists   Joists will rest on a primary bearer or purlin system.  Joists must be spaced at 300 centres (250mm apart).  This generally only means an extra 4 or 5 joists over a deck which means very little cost, but makes a massive difference in terms of strength, eliminates bounce and increases the loading capacity of the deck dramatically.

Balconies, roof gardens and marine decks are constructed differently but joists should be no more than 250mm apart, self draining rubber shoes are recommended to elevate the sub-frame, ensuring that water flows freely below the joist or counter-batten frame system.