Planning estimate · Herriman, Utah
Deck cost calculator
Size, height, material, guard and stairs, priced the way a deck is actually built. The height answer matters more than any other one on this page, because in Herriman it decides the permit and the guard at the same time.
What is behind the number
What decides the price of a deck in Herriman
A deck is priced by the foot, then by everything that is not the floor. The boards are the part people think about and rarely the part that moves the number. The guard, the stairs, the footings and the connection to the house are where a deck quote separates from a rough square-foot figure, and on a Herriman lot the ground itself has an opinion about all four.
The first question this calculator asks after the size is how far it is down to the ground, and it asks for the lowest point rather than the grade at your door. Herriman exempts a deck that is 30 inches or less measured from the walking surface to the lowest grade level around the perimeter, as long as nothing is roofed over it and it is not the required exit. IRC R312.1 requires a guard above the same 30 inches. One measurement, two consequences, and both of them expensive.
Everything else is a choice you can make with the number in front of you. Wood or composite. Wood guard or cable. A 36 inch stair or a wide one. The calculator shows each as its own line so you can see what you are buying rather than watching one total move.
The 30 inch line
Above it: a permit at Herriman’s published $432.39, drawings, a footing inspection, a final, and a guard around every open edge. Below it: none of that. Measured to the lowest grade anywhere around the deck, not to the door.
Footings and what you dig through
Herriman requires 30 inches from the bottom of the footing to finished grade where a deck is attached to the house. On a graded foothill lot with clay that is auger work, and it is priced per hole rather than smeared across the square footage.
How it meets the house
A ledger through-bolted into the rim joist and properly flashed is the normal answer. Stucco or brick veneer has to be cut back so the ledger lands on structure rather than on finish, and that is more work now and far less trouble later.
Guard material
Rails are a bigger share of a deck than almost anyone expects. Wood runs roughly $35 to $55 a foot installed in this region; cable and glass run $140 to $240. On a deck with 40 feet of open edge that difference is thousands.
Stairs
IRC R311.7 caps the riser at 7 3/4 inches and sets the tread at 10 inches minimum, so the height decides the number of steps rather than you. Four or more risers also brings a graspable handrail and a landing at least as deep as the stair is wide.
The frame under composite
Composite boards are less stiff than wood, so the joists come in tighter, and at 12 inches on centre for a diagonal layout that is about a third more lumber and hangers under a surface nobody will ever see. It belongs in the comparison and it is usually missing from it.
What pushes it higher
- Crossing 30 inches to the lowest grade, which adds the permit, the inspections and a guard around the whole open edge.
- A cable or glass guard rather than wood.
- A diagonal or patterned board layout, which brings the joists to 12 inches on centre.
- Stucco or brick veneer where the ledger has to land.
- A hot tub, which changes the framing beneath it rather than just the size.
- A sloping or rocky lot, where every footing takes longer to reach 30 inches.
What brings it down
- Keeping the walking surface at 30 inches or less above the lowest grade.
- Wood or composite guard rather than cable or glass.
- A straight board run parallel to the house.
- Pressure-treated or cedar, if you will genuinely keep up the sealing.
- A 36 inch stair rather than a wide flight.
- Sizing the deck to the furniture you own rather than to the wall it sits against.
Turn the estimate into a real number
Send a couple of photos, rough dimensions, and the height down to the lowest corner. You will get a straight answer about the permit, the guard and what the ground is likely to want, before anyone talks about boards.
What people ask about this
Do I need a permit for a deck in Herriman?
Herriman exempts a deck that is 30 inches or less measured from the walking surface of the deck to the lowest grade level around the perimeter, provided there is no new roof structure over it and it does not serve the required exit. Above 30 inches, roofed, or serving the required exit, you need a permit. The city publishes the deck permit fee as $432.39.
How is the 30 inches measured?
From the walking surface of the deck down to the lowest grade level anywhere around the perimeter. Not to the grade at your back door. On a Herriman lot that falls away toward the foothills those two numbers are often a foot apart, and it is the lower one that decides.
How deep do deck footings have to be?
Herriman sets a 30 inch minimum from the bottom of the footing to finished grade where the deck is attached to the house, and 36 inches to the top of a slab. Footings that stopped short of frost depth are one of the four failures that show up most often on decks of this age, because they heave every spring and nothing above them stays level.
How high does a deck guard have to be?
IRC R312.1 requires 36 inches on the deck and 34 inches on the stairs, with infill that will not pass a 4 3/8 inch sphere, except the triangle formed by the tread, riser and bottom rail, which is allowed 6 inches. The whole thing has to take a 200 pound concentrated load at the top rail, which is why the post connections matter more than the infill does.
What snow load do you design to?
Herriman does not publish one number, because it changes with elevation across the city, and directs designers to the Utah State University snow load website for a specific address. The rest of the published criteria are 30 inch frost depth, seismic design category D, and a 115 mph ultimate design wind speed at exposure C, under the 2021 IRC.
Is composite really more expensive than wood?
To build, yes, and the gap is wider than the boards alone because the frame under composite is spaced tighter. Over ten years the arithmetic changes, because a wood deck wants cleaning, sanding and sealing every two to three years at roughly $2 to $5 a square foot each time. The composite calculator runs both decks side by side and works out the year they cross.
Can you build right up to the property line?
Setbacks are a zoning question rather than a building code one, and they vary by zone and by subdivision, and many Herriman neighbourhoods also have an HOA with its own rules about what can go in a back yard. Both are worth checking before a design gets far. Herriman’s Building Division is on 801-446-5327.
Is this a quote?
No. It is a planning estimate meant to get you to a realistic budget and to show which decisions actually move it. A real number needs someone on the site looking at the grade, the soil and the wall the deck is going to hang off.