Every deck is the same machine: a surface that hands its load to joists, joists that hand it to a beam and a ledger, and posts and footings that hand it to ground that freezes 30-plus inches deep. Understand that chain and every line on a deck bid — and every failure you've ever seen — makes sense. Here's the whole structure, top to bottom, with the numbers Colorado adds.
Where does the weight actually go?
Follow a footstep down: decking → joists → beam and ledger → posts → footings → soil. Every part exists to move load one link down that chain, and every deck failure is one link giving up. The diagram below is the whole system in section — the same structure whether the deck costs $8,000 or $80,000.
The ledger: the connection that decides everything
An attached deck borrows the house's structure through one horizontal board — the ledger. It carries roughly half the deck's weight, and it's where industry post-mortems trace the large majority of catastrophic collapses. The failure is almost never the board; it's the details: nails where structural screws belong, or missing flashing letting a decade of snowmelt rot the connection invisibly from behind.
This is also why a “deck pulling away from the house” is a today problem, not a spring problem — our 10-minute inspection guide shows you exactly what to look for from underneath.
Why do footings go 30–36 inches down?
Because that's where Front Range soil stops freezing. Water expands when it freezes, and soil that freezes lifts whatever sits on it — unevenly, every winter. A footing poured below frost depth stands on ground that never moves; a deck block resting on grade rides the frost like a boat. That's the entire argument, and it's why we pour proper caissons even for small and floating decks that could legally skip the permit.
Joists and beams: the span math
A joist can only safely cover so much distance before it deflects — bounces — or fails. The spans Front Range permit reviewers work from (IRC Table R507.6, Douglas fir-larch #2, 16-inch spacing): 2×6 to about 9 feet, 2×8 to 11'10", 2×10 to 14 feet, 2×12 to 16'6". A deck that feels bouncy is usually telling you its joists are at or past these numbers — or that blocking and hardware have loosened with age.
Hardware: the metal that keeps wood honest
Wood moves with every freeze-thaw cycle; hardware is what holds the system together while it does. Joist hangers with a fastener in every hole, post bases that lift the wood off the concrete (posts buried in dirt rot from the bottom, invisibly), tension hardware at guardrail posts so a 200-pound shove goes into the frame rather than the fasteners, and hidden clips that let composite boards expand without popping screws. On a bid, hardware is a boring line. On a ten-year-old deck, it's the difference between tight and wobbly.
What does Colorado add to the design?
Altitude UV about 25% stronger than sea level, which is what kills wood surfaces and why we lead with capped composite. A 30 psf design snow load that sizes every roofed structure — and wind uplift that loads a patio cover upward, which is the load flatland pergola kits never contemplated. Hail that decides roofing materials. And 35–90 freeze-thaw cycles a year working every fastener, which is why an annual ten-minute inspection is worth the ten minutes.
Want this structure under your deck?
Every Haka bid itemizes the anatomy — footings, framing, hardware, surface — so you can see exactly what you're standing on.
Why this matters when you're hiring
Every question in our contractor checklist is really an anatomy question: footing depth, joist spec, ledger detail, hardware schedule. A builder who answers with numbers is describing this page back to you. A builder who answers “per code” is hoping you don't know what code says — and now you do. The cost guide shows what each layer of the anatomy costs, line by line.