Footings to fascia — what each component does, why it's there, and which ones actually fail. If you've ever nodded along while a contractor said "ledger" or "stringer," this is the page that fixes that for good.
A deck is built from the ground up, and it carries load in the opposite direction — from the surface down into the soil. Reading this list bottom to top is the order a crew builds in. Reading it top to bottom is the path your weight travels every time you step outside.
Click any numbered part of the deck to read about it
Concrete piers poured into holes dug below the local frost line — commonly 30 to 36 inches along the Front Range, deeper in some mountain jurisdictions.
When saturated soil freezes it expands, and a footing sitting above that zone gets pushed upward every winter. That's frost heave, and it's why some older decks develop a slope or a bounce. Building departments inspect footings before they're covered, which tells you how much they matter.
Galvanized or stainless brackets that anchor the post to the footing while holding the wood about an inch up off the concrete.
That gap exists because concrete wicks moisture, and a post sitting directly in it will rot from the bottom up. A soft or crumbling post base is one of the most common serious problems we find on older Colorado decks — and one of the clearest signals to stop using the deck.
Usually 4x4 or 6x6 pressure-treated lumber, occasionally steel on larger structures. Posts carry compression load straight down into the footings.
Taller posts also need lateral bracing, because an elevated deck has to resist sway as well as weight. That's a big part of why tall decks cost disproportionately more than low ones.
Horizontal members running post to post, collecting load from all the joists bearing on them. Either built up from multiple boards fastened together, or specified as solid or engineered lumber.
Beam size is driven by span — the further apart the posts, the deeper the beam has to be. A beam can sit on top of the posts or bolt to their sides, and that choice changes the deck's finished height.
The repeating framing members supporting the decking boards — typically 2x8, 2x10, or 2x12 depending on span.
Spacing is the number worth knowing: 16 inches on center is standard for most wood decking, while 12 inches on center is frequently required for composite and always for diagonal layouts. Going from 16 to 12 adds roughly a third more framing lumber, which is a legitimate reason bids differ.
The board attaching the deck to your house. It must be through-bolted or lag-screwed into the home's structural rim joist — never nailed — and properly flashed so water is directed away from the joint.
Improper ledger connections are the leading cause of catastrophic deck collapses nationally. If you can see nail heads instead of bolts where your deck meets the house, that deck needs a professional evaluation.
The surface you walk on, and the only part most people ever really see. Structurally, boards are a surface rather than a structural element — they transfer load to the joists and don't span anything meaningful on their own.
Boards are installed with deliberate gaps for drainage and for thermal movement. Composite and PVC move noticeably along their length, and correct gapping is a specification, not a matter of taste.
Typically required once the walking surface sits more than 30 inches above grade, and commonly 15 to 25 percent of a deck's total budget.
The guard posts do the real work and must be bolted through the rim joist. No opening may allow a 4-inch sphere to pass through — that governs baluster spacing, cable spacing, and the gap under the bottom rail.
Everything in this section is invisible on a finished deck. It is also where nearly all the safety lives, and where a low bid usually gets its savings.
Concrete piers poured into holes dug below the local frost line — commonly 30 to 36 inches along the Front Range and deeper in some mountain jurisdictions. The frost line matters because when saturated soil freezes it expands, and a footing that sits above that zone gets pushed upward every winter. That is frost heave, and it is why some older decks develop a noticeable slope or a bounce over time.
Footing size is determined by how much load it carries, which depends on beam spans and joist spans. Building departments inspect footings before they are covered, which is a good sign of how much they matter.
Galvanized or stainless brackets that anchor the post to the footing while holding the wood roughly an inch up off the concrete. That gap exists because concrete wicks moisture, and a post sitting directly in it will eventually rot from the bottom up. A soft, crumbling post base is one of the most common serious problems we find on older Colorado decks — and one of the clearest signals to stop using the deck.
Usually 4x4 or 6x6 pressure-treated lumber, occasionally steel on larger structures. Posts carry compression load straight down. Taller posts also need lateral bracing, because an elevated deck has to resist sway as well as weight — this is why tall decks cost disproportionately more than low ones.
Horizontal members running post to post, collecting load from all the joists that bear on them. They are either built up from multiple boards fastened together or specified as solid or engineered lumber. Beam size is driven by span: the further apart the posts, the deeper the beam has to be. A beam can either sit on top of the posts or be bolted to their sides, and each approach changes the deck's finished height.
The repeating framing members that support the decking boards, typically 2x8, 2x10, or 2x12 depending on span. Spacing is the number worth knowing: 16 inches on center is standard for most wood decking, while 12 inches on center is frequently required for composite boards and always for diagonal board layouts.
Going from 16-inch to 12-inch spacing adds roughly a third more framing lumber and labor. It is a legitimate place for bids to differ — but if one bid specifies 16-inch spacing under composite decking that the manufacturer requires at 12, that is not a savings, it is a warranty problem waiting to happen.
The rim joist(or band joist) caps the ends of all the joists around the deck perimeter, tying them together and giving the fascia something to attach to. Blocking is short pieces installed between joists mid-span to stop them twisting under load. Blocking is easy to skip and frequently is — but on longer joist spans it is a meaningful part of what makes a deck feel solid instead of springy.
If you only remember one section of this page, make it this one. The ledger is the board that attaches the deck to your house, and improper ledger connections are the leading cause of catastrophic deck collapses nationally. It is a small detail with enormous consequences.
A ledger must be through-bolted or lag-screwed into the home's structural rim joist, in a specified pattern with specified spacing. Nails are not acceptable — they pull out under load in exactly the way bolts do not.
It also has to land on actual structure. A ledger fastened only to sheathing, siding, or brick veneer is attached to nothing that can carry a deck full of people.
Flashing is metal or membrane installed to direct water out and away from the ledger connection rather than down behind it. Without it, water runs into the joint every time it rains or snow melts.
What follows is slow and hidden: the ledger rots, the house rim joist rots behind it, and the fasteners lose their grip. By the time there is a visible symptom, the damage is usually extensive.
Look at where the deck meets the house. If you can see nail heads instead of bolt heads, or there's no flashing visible at the joint, that deck needs a professional evaluation. This is not a wait-until-spring item. Deck repair services · 303-781-3325
Some decks avoid the ledger entirely by standing on their own posts with no attachment to the house. This adds a row of footings and posts, but it removes the highest-risk connection on the whole structure and sidesteps any question about what the home's rim joist can carry. On some homes — particularly those with stucco, stone veneer, or uncertain framing — it is genuinely the better engineering answer.
The boards themselves come in wood, composite, PVC, and aluminum — covered in depth in our decking materials guide. What matters structurally is that boards are a surface, not a structural element. They transfer load to the joists; they do not span anything meaningful on their own.
Boards are installed with deliberate gaps between them, for two reasons. First, drainage — water needs somewhere to go rather than pooling on the surface. Second, movement: every decking material expands and contracts with temperature and moisture, and composite and PVC move noticeably along their length. Manufacturer gapping specs exist because a board installed tight to its neighbor in February has nowhere to go in July, and buckling is the result.
Boards typically run perpendicular to the joists. Running them diagonally looks great and visually widens a narrow deck, but it lengthens the effective span, which is why diagonal layouts require tighter joist spacing. Picture framing means running a border board around the perimeter so all the cut ends are hidden — it looks considerably more finished, and it requires extra blocking underneath to support that border, planned during framing.
On decks wider than the longest available board, you either butt boards end to end in a seam or install a breaker board — a board running perpendicular through the field that gives every run a clean termination. It turns an awkward necessity into an intentional design line, and it needs framing support underneath.
Hardware is the least glamorous part of a deck and one of the most consequential. Modern pressure-treated lumber is corrosive to ordinary steel, so the coating on every screw, bolt, and bracket is a functional specification rather than a detail.
Galvanized brackets that support joists where they meet a beam or ledger. They must be filled with the correct structural nails — not deck screws, which are not rated for shear in this application.
Connect posts to footings below and beams above. Post bases hold the wood off the concrete; post caps keep beam-to-post connections from shifting laterally.
Through-bolts and engineered structural screws carry real load — ledger connections, beam-to-post joints, and railing posts. Rated, stamped, and not interchangeable with deck screws.
Screws driven down through the top of the board. Fast, strong, easy to service — but you see every screw head, and in freeze-thaw climates they can back out over time.
Clips that sit in a groove milled into the board edge, leaving a clean surface with no visible screws. Standard on most composite installs and worth the upcharge for the finished look.
Hot-dip galvanized is the baseline for contact with treated lumber. Stainless costs more but resists corrosion best, and is worth specifying near hot tubs and in coastal-grade exposure.
Putting dissimilar metals in direct contact — a stainless fastener through an ordinary galvanized bracket, for example — can drive galvanic corrosion, where one metal deteriorates faster than it would alone. It's why hardware gets specified as a system rather than picked piece by piece off a shelf.
Railing is typically required once the walking surface sits more than 30 inches above grade, and it commonly represents 15 to 25 percent of a deck's total budget. It is also the most visible design decision on the whole project.
The most affordable and most traditional look. Straightforward to repair one at a time. Wood balusters need refinishing along with the rest of a wood deck.
Powder-coated, slim, essentially maintenance-free, and they read visually lighter than wood. A popular middle ground that pairs well with composite decking.
Horizontal stainless cables tensioned between posts. Nearly disappears against a view, which is why it dominates mountain builds. Needs sturdy end posts and periodic re-tensioning.
The most transparent option and excellent as a wind block on exposed sites. The most expensive, the heaviest, and it will show every fingerprint and dust storm.
No opening in a guard may allow a 4-inch sphere to pass through. It exists so a small child cannot slip through or get their head trapped, and inspectors literally test it. It governs baluster spacing, cable spacing, and the gap beneath the bottom rail.
Worth knowing: a guard and a handrail are different things. A guard prevents falls from an elevated surface. A handrail is the graspable rail alongside stairs that you actually hold onto. Stairs above a certain number of risers require both, and a handrail has specific shape and dimension requirements so a hand can properly close around it.
Stairs are the most labor-intensive part of most decks and the most common place inspections fail. The reason is precision: stair geometry has tight tolerances, and the math has to be right before anything gets cut.
Codes require riser heights within a flight to be consistent within a very small tolerance — typically about three-eighths of an inch between the tallest and shortest. That is not bureaucratic fussiness. People climb stairs on autopilot, and their feet learn the rhythm within two steps. A single riser that is half an inch off is a genuine fall hazard, and stair falls cause serious injuries.
This is why the bottom step matters so much. If the landing pad settles even slightly, that last riser changes height and the flight goes out of compliance. It is also why stairs get rebuilt rather than patched more often than homeowners expect.
North-facing stairs hold snow and ice long after the rest of a deck has cleared. Riser lighting, textured or grooved tread surfaces, and adequate tread depth genuinely matter here — they are safety features in our climate, not upgrades.
A finish board covering the rim joist around the deck perimeter. It is cosmetic — it hides framing lumber and gives the deck a clean finished edge — but it also shields the rim joist from direct sun and weather. Fascia is normally matched to the decking material.
Material closing off the open space between the deck and the ground: lattice, vertical boards, or panels. It keeps animals from nesting underneath, hides the framing on a low deck, and neatens the whole appearance. Skirting still needs ventilation — sealing the underside of a deck completely traps moisture, which is exactly what you do not want against wood.
On elevated decks, a drainage system installed between or beneath the joists catches water passing through the board gaps and channels it away, turning the space below into usable dry patio. It is dramatically cheaper to install during the original build than to retrofit later, so it belongs in the design conversation early.
Stair riser lights, post cap lights, and under-rail strips are inexpensive while the framing is open and wire can be run freely. Adding them after the deck is finished means fishing wire through completed construction, which costs several times more. The same applies to outlets, hot tub circuits, and speaker wiring — decide before the boards go down.
A filled hot tub with people in it can weigh several thousand pounds concentrated in a small footprint — far beyond standard deck framing. It requires additional footings, heavier beams, and tighter joist spacing directly beneath, all planned in advance. Adding one to an existing deck always requires a structural evaluation first.
After three decades of repairs across Colorado, the failure points are remarkably consistent — and notice how many of them are connections rather than materials.
The deck is visibly pulling away from the house · a post base is soft or crumbling at ground contact · the structure moves noticeably when people walk on it. Any of these means structural failure in progress, and none of them get better on their own. Call 303-781-3325 for a same-week inspection.
The vocabulary you'll hear on a job site and in an estimate, in one place.
The ledger is the board that attaches your deck to the house, and it carries a large share of the deck's total load. It must be through-bolted or lag-screwed into the home's structural rim joist and properly flashed so water is directed away from the joint. Improper ledger connections are the leading cause of catastrophic deck collapses nationally — usually because the ledger was nailed instead of bolted, was never flashed, or was fastened only to sheathing or siding rather than actual structure. If you can see nail heads instead of bolts where your deck meets the house, that deck needs a professional evaluation.
Sixteen inches on center is standard for most wood decking. Twelve inches on center is frequently required for composite decking and is always required when boards run diagonally, because a diagonal layout increases the effective span each board has to cover. Joist spacing is set by the decking manufacturer's specification and by code, not by preference. Tighter spacing uses roughly a third more framing lumber, which is a legitimate reason bids differ — but installing composite over 16-inch spacing when the manufacturer requires 12 typically voids the warranty and produces a deck that feels soft underfoot.
Footings must extend below the local frost line, which commonly means 30 to 36 inches along the Front Range and deeper in some mountain jurisdictions. The exact requirement is set by your local building department and is not something to estimate. The reason is frost heave: when saturated soil freezes it expands, and a footing sitting above that zone gets pushed upward each winter. Over several seasons that produces a deck with a visible slope, a bounce, or gaps opening where it meets the house. Building departments inspect footings before they are covered, which tells you how much this detail matters.
A guard is the barrier preventing people from falling off an elevated surface — it is what most people mean when they say "railing," and it is typically required once the deck is more than 30 inches above grade. A handrail is the graspable rail running alongside a staircase that you actually hold while climbing, and it has specific shape and dimension requirements so a hand can close fully around it. Stairs above a certain number of risers require both. They serve different purposes, and passing inspection means getting both right.
Two reasons. Drainage: water needs a path off the surface rather than pooling against the boards. And movement: every decking material expands and contracts with temperature and humidity, and composite and PVC move noticeably along their length. Colorado's daily temperature swings make this more pronounced here than in milder climates. Manufacturer gapping specifications exist because a board installed tight against its neighbor on a cold February day has nowhere to expand on a hot July afternoon, and the result is buckling. Correct gapping is a specification, not a matter of taste.
Often yes, and it can save a substantial amount of money. A properly built substructure with sound footings, a correct flashed ledger, and healthy framing frequently outlives two or three generations of decking boards. The catch is that the frame has to be genuinely sound, and that requires inspection rather than assumption — we check footings, post bases, the ledger connection, joist condition, and hardware before recommending a resurface. Joist spacing also has to suit the new material, since switching from wood to composite sometimes requires added framing. If the structure passes, resurfacing is usually the smarter project.
Hidden fasteners are clips that seat into a groove milled along the edge of a decking board, holding it down without any screw heads showing on the surface. The result is a noticeably cleaner finished look, and it is now standard on most composite installations. They cost more in both material and labor than face-screwing, and individual board replacement takes a bit more work later. For composite and PVC decks most homeowners consider the appearance worth it. For pressure-treated wood that will be sealed and refinished repeatedly, face-screwing is often the more practical choice.
We'll inspect the parts you can't see — footings, ledger, post bases, hardware — and tell you straight what needs attention and what doesn't. Free, and there's no pressure attached to it.
Deck Doctor Inc. · Family-owned since 1993 · 6,073+ projects · BBB A+ Rated · Licensed & Insured · No payment until the job is complete
