Decking

Frequently asked questions

Why is the ledger the part that actually fails?

Because it is the one connection carrying the whole deck into the house, and the two ways it is commonly built are both wrong. A deck attached to a building hangs off a LEDGER board fixed to the structure, and that fixing takes the full vertical load of everything on the deck plus, in a code that requires it, a lateral tie resisting the deck pulling away. Nailing the ledger on is the first error — nails withdraw under sustained load in a way bolts do not — and the prescriptive guides specify bolts or approved structural screws at a stated pattern for that reason. The second is water: a ledger bolted tight to a wall with no flashing traps every drop running down the face behind it, and the rot that follows is invisible until the deck comes away with people on it. Deck collapses are overwhelmingly ledger failures at a gathering, which is also why some designs avoid the question entirely with a freestanding deck on its own posts.

Does composite decking need less maintenance or different maintenance?

Different, and the marketing claim is narrower than it sounds. A wood-plastic composite board will not rot, will not splinter and does not need oiling or staining, which removes the annual job that makes timber decking unpopular. What it does instead: it expands and contracts with temperature considerably more than timber does, so the fixing pattern and end gaps are specified by the manufacturer and are not optional — a board fixed tight at both ends in winter buckles in summer. It gets hotter underfoot in direct sun than timber. It still grows algae and still needs cleaning, because the film that makes a deck slippery is organic matter on the surface rather than a property of the material. And it is not structural, so the joists and bearers underneath are still timber with a timber's lifespan. The honest summary is a change in the maintenance task rather than its removal.

How do I tell which decking an American drawing means?

By what it is attached to and how it is measured. If the drawing calls up a span rating, a nailing schedule, sheathing thickness or a fastener pattern over rafters or floor joists, it means the structural deck — the sheet material a roof covering or a floor finish is laid over. If it names board widths, gaps, a ledger, posts, footings or a railing, it means the outdoor platform. Two further signals are reliable: profiled METAL deck is always the structural sense, and anything specifying a gap between boards is always the platform sense, because a structural deck is laid tight. The distinction matters commercially as well as technically, because the two sit in different trades and different sections of a bill — confusing them in a takeoff produces a quantity in the right units for entirely the wrong work.