Starting from the Cedar Rapids numbers
NOAA's engineering weather data has no Iowa City station. The closest one is Cedar Rapids (elevation 869 feet), about 18 miles north of Iowa City. Every figure on this page belongs to Cedar Rapids, not to a reading taken in Iowa City, yet together they make a useful starting point when you sit down with a siding contractor to talk about what your walls are being built to withstand.
For Cedar Rapids, NOAA lists:
- a 99% winter design temperature of -5°F;
- a 1% summer design temperature of 89°F, with a mean coincident wet-bulb temperature of 74°F;
- about 355 hours in an average year with the wet-bulb temperature above 73°F, and about 1,124 hours above 67°F;
- a 50-year basic wind speed of 90 mph (3-second gust at 33 feet);
- a 100-year rainfall rate of 3.3 inches per hour;
- about 54 freeze-thaw cycles in an average year.
Each line touches a different part of a siding job, so the sections below take them one at a time.
Gusts and the fastening schedule
The 90 mph figure for Cedar Rapids, a 3-second gust at 33 feet with a 50-year return, is the kind of number a manufacturer's wind rating gets compared against. Panels seldom let go in the middle of a wall. They peel from an edge where fastening was light or a lock was never snapped home. Put these to each bidder:
- What wind rating does the proposed product carry, and what nail or screw spacing does that rating assume?
- What fastener, what length and what spacing will the crew actually use?
- How will the top course under the soffit and the panels at each gable end be held down, since uplift usually starts there?
- Are starter strips, corner posts and trim fastened to the same standard as the field of the wall?
A 3.3-inch rainfall rate and the way out for water
NOAA's 100-year rainfall rate for Cedar Rapids is 3.3 inches per hour. Rain on that scale overruns gutters and pushes water sideways into window heads and trim joints. Cladding sheds most of it, but some always reaches the layer behind, and what matters is whether that water can drain back out. Ask each company to describe in writing:
- the water-resistive barrier, lapped so every upper sheet overlaps the one below, with seams taped wherever the maker calls for it;
- head flashing over windows and doors, and sill or pan flashing beneath them;
- a kick-out flashing at each place a roof edge stops against a sidewall;
- gutter sizing and downspout placement, because a downspout that empties beside the wall keeps the lowest courses wet.
Wet-bulb hours and drying time
At Cedar Rapids, NOAA counts about 1,124 hours a year with the wet-bulb temperature above 67°F and about 355 hours above 73°F. A high wet-bulb reading means the air takes up moisture slowly, so a wall that gets damp behind its cladding may need longer to dry. That is a good reason to price a drainage gap. Ask whether the bid includes a rainscreen mat, furring strips or a drainable housewrap, and what each option would add. If wood or fiber cement is going to be painted, ask how the crew will time each coat against the humidity and temperature limits printed on the can.
Fifty-four freeze-thaw cycles at the base of the wall
Cedar Rapids sees about 54 freeze-thaw cycles in an average year, and its winter design temperature is -5°F. Water that soaks into a board end, a cracked sealant joint or a split in trim swells when it freezes, and the lowest part of a wall takes most of that punishment. Ask:
- How far above soil, mulch, a patio or a lower roof will the bottom course sit, and does that match the product's instructions?
- How are cut ends of fiber cement or engineered wood sealed before the boards go up?
- Which sealant is specified, what temperature range is it rated for, and where will joints be left open on purpose so water can escape?
- For vinyl, what expansion gap is left at corner posts and channels on a cold installation day, knowing the same panel has to handle the station's 89°F summer design temperature?
Iowa City in Census figures
The U.S. Census Bureau's QuickFacts gives Iowa City a population estimate of 76,229 on July 1, 2025 (V2025). For 2020-2024, QuickFacts lists an owner-occupied housing unit rate of 47.2% and a median value of owner-occupied housing units of $285,900.
Those are citywide figures. The quote you sign has to describe your own walls.
Matching the cladding to the wall
Choose a material by the upkeep you are willing to do and by what the wall underneath needs:
- Vinyl asks the least of you. It must hang loosely on its fasteners so it can slide as it warms and cools, and thicker or foam-backed panels resist dents better.
- Fiber cement resists rot and insects and holds paint well. It is heavy, its dust needs control during cutting, and its butt joints need the flashing or spacing the maker specifies.
- Engineered wood is lighter and cuts cleanly, but every field cut must be sealed and the bottom edge kept clear of the ground.
- Wood clapboard or shingle can be repaired one piece at a time and needs paint or stain on a steady cycle.
- Steel or aluminum stands up to moisture; ask how scratches get touched up and how dents are handled.
Whatever you pick, ask for the manufacturer's installation instructions and a written statement that the crew will follow them. Warranty coverage often rests on it.
Before the contract: permits and paperwork
Ask the contractor which local permits the job needs. Then work through a few more questions:
- Which permits does the job need, and who pulls them?
- What state license or registration, if any, covers this work, and what is the number?
- Can you show proof of liability coverage and workers' compensation? If you are unsure what to ask for, call your own insurer.
- Will your own employees do the work, or a subcontractor?
- If old painted trim or siding comes off, how will the crew contain chips and dust?
Reading a written quote
A useful quote breaks the job into parts you can check. Look for removal and disposal of the old siding, or a plain statement that new siding goes over it; the product name, profile, thickness and color; the barrier, any drainage layer and every flashing; trim, soffit and fascia; a per-sheet price for replacing damaged sheathing; permits, cleanup and dates; and the product warranty and the installer's workmanship warranty, each on paper. When two totals sit far apart, find the line one bidder left off before you compare price.