Anybody with a circular saw and a trailer can put up a sign that says deck builder. Illinois doesn't require a special state license just to build decks, so the only thing separating a good one from a bad one is what they know about footings, lumber, and local code, and whether they're willing to tell you the truth about it before you sign anything.

Ottawa sits on ground that was glacial till before it was anything else, and under the topsoil most lots here have a clay subsoil that holds water. Clay swells when it's wet and shrinks when it dries out, and a deck footing sitting in the wrong spot or poured too shallow will heave with it. That's not a maybe. That's a few years out, when your deck starts pulling away from the house or one corner sits an inch higher than the rest.

Ask how deep the footings go

In this part of Illinois, frost depth is generally figured around 42 inches. Footings that don't go below that will move every winter as the ground freezes and thaws underneath them, and LaSalle County gets a real freeze-thaw cycle most years, not just one hard freeze in January. A builder who tells you 12 inches is plenty, or who wants to pour on top of the existing patio slab without digging down, is telling you what's fast and cheap, not what holds up. Ask for the footing depth in writing before the concrete truck shows up, and ask how many footings a deck your size actually needs. A 12x16 deck isn't held up by three posts stuck wherever they're convenient.

Ask what's attaching the deck to the house

Most deck failures that make the news aren't the decking boards giving way. It's the ledger board, the piece bolted to the house that the whole structure hangs off of. It needs to be lag-bolted or through-bolted into the rim joist, not nailed, and it needs flashing behind it so water doesn't get trapped between the ledger and the siding and rot the house framing from the outside in. If a builder is vague about how they're flashing that connection, or says they'll just caulk it, that's worth stopping and asking more questions about. Caulk fails. Flashing, installed right, doesn't depend on staying sticky for twenty years.

Ask about joist spacing too. Composite decking generally wants joists 16 inches on center, sometimes closer depending on the board, and running composite boards at an angle usually tightens that spacing further. A builder who frames everything the same way regardless of what decking is going on top hasn't read the manufacturer's span tables, and those tables are what your warranty depends on if the boards ever sag.

Ask about the permit, don't assume there isn't one

A lot of homeowners think a deck is small enough to skip the paperwork. In Ottawa, a deck attached to the house generally needs a building permit regardless of height, because it's structural work tied into the house itself. The usual process involves an inspection of the footings before they're poured over, and often a second inspection of the framing before the decking boards go down and hide everything. A builder who tells you not to bother with a permit is either trying to save a week of schedule or doesn't want an inspector looking at the footings. Either reason should bother you. If you ever sell the house, an unpermitted deck can hold up the sale or get flagged at inspection, and a buyer's inspector will absolutely check the ledger and railing even if nobody else ever has.

If your lot backs up to a drainage easement or you're near the Fox or Illinois River, grading matters more than people think. Decks built low to the ground on a lot that doesn't shed water well will sit in standing water after a heavy spring rain, and posts set in wet ground rot faster no matter what lumber you used.

Ask about railings and spacing, not just looks

Code generally calls for a 36-inch railing height on residential decks, sometimes 42 inches depending on how high the deck sits and local amendments, and the gap between balusters needs to be small enough that a 4-inch sphere can't pass through. That number exists because of kids getting stuck or falling through wider gaps, not because anyone likes measuring spindles. A builder who eyeballs railing spacing instead of measuring it is cutting a corner that an inspector, or your own kid, will find eventually.

What should make you walk away

  • A bid that's dramatically lower than every other one you got, with no explanation of what's different about the materials or footings.
  • No mention of a permit, or a builder who says they'll "handle it" without telling you how.
  • Pressure to pay most or all of the money upfront, before any lumber is on site.
  • Vague answers about ledger flashing, footing depth, or joist spacing. These aren't trick questions. A builder who's done the work has the numbers ready.
  • No proof of insurance. If a worker gets hurt on your property and the builder isn't insured, that liability can land on you.

Older homes closer to downtown Ottawa often have additions, poured patios, or buried utility lines that a newer subdivision lot won't have, so a good builder walks the yard and asks questions before quoting a price off a photo. A deck on a 1920s foundation isn't the same job as one going up in a subdivision built in the last fifteen years, and the price difference between two bids sometimes comes down to exactly that kind of homework, not just lumber grade.

None of this is complicated once you know to ask. Get the footing depth, the attachment method, the permit plan, and the insurance in writing, and most of the bad builders filter themselves out before they ever pick up a shovel. If you want a second opinion on a bid you've already got, or you're starting from scratch, you can look at our deck builder work at Elevate Deck Company and see how we handle the parts most people never ask about.