The figures behind this calendar
Each number used here comes from NOAA's engineering weather data for Cedar Rapids (elevation 869 feet), the station nearest Iowa City, about 18 miles to the north. They are Cedar Rapids readings and are quoted as such. That station lists a 99% winter design temperature of -5°F and a 1% summer design temperature of 89°F with a mean coincident wet-bulb temperature of 74°F. It counts about 54 freeze-thaw cycles in an average year, about 1,124 hours with the wet-bulb temperature above 67°F and about 355 hours above 73°F, a 50-year basic wind speed of 90 mph (3-second gust at 33 feet) and a 100-year rainfall rate of 3.3 inches per hour.
Rather than four seasons, the year below is split into six two-month blocks. Shorter gaps between walks make changes easier to spot.
What to carry on each walk
- a phone for photos, taken from the same corners every time;
- binoculars for the upper courses, so most checks happen from the ground;
- a flashlight for the shadow under soffits and porch roofs;
- a screwdriver to press gently on trim and the lowest boards;
- a notebook or a running note on your phone, dated.
January and February: look, don't touch
The Cedar Rapids winter design temperature of -5°F is a reminder that cold cladding is fragile and ladders on ice are dangerous. Keep this block to ground-level looking.
- Scan for panels cracked by a shovel, a thrown snowball or a slipping ladder; cold vinyl breaks more easily than warm.
- Watch the eaves after a snowfall. Ice along the roof edge can push meltwater under shingles and down inside the wall.
- Keep plowed or shoveled snow from banking against the bottom course.
- Inside, run a hand along exterior walls in closets and behind furniture for damp spots or bubbling paint.
- Write down what you find. Repairs wait for a warmer, drier stretch.
March and April: the thaw walk
About 54 freeze-thaw cycles a year at Cedar Rapids do their work by now.
- Circle the whole house looking for boards that have pushed out, sealant that has split and trim that has pulled away from the wall.
- Press the lowest course and the sills. Softness means water has been sitting there.
- Clean gutters and make sure each downspout releases water well away from the foundation.
- If you want a contractor for anything larger than a patch, start calling now.
May and June: wash and refasten
- Clean the walls with a garden hose, a soft brush and a cleaner the siding maker permits. A pressure washer can drive water up behind laps.
- Check corners, gable ends and the top course for anything loosened over winter. NOAA's 50-year basic wind speed for Cedar Rapids is 90 mph (3-second gust at 33 feet), and wind gets under a loose edge first.
- Find every kick-out flashing where a roof edge stops against a wall, and note any that are missing.
- Trim shrubs so leaves stay a hand's width or more off the siding.
July and August: paint on the label's terms
With about 1,124 hours a year above a 67°F wet-bulb temperature at Cedar Rapids, and about 355 above 73°F, plan painting and caulking around the limits printed on each product.
- Read the temperature and humidity range on the can or tube before you start.
- Work shaded walls, or start early, rather than painting a wall in full afternoon sun.
- Look for mildew or algae on north sides and behind plantings, and clean it off before it stains.
- Turn sprinkler heads so they water the lawn, not the bottom boards.
- After a hard downpour, check window heads and the wall below gutters. The station's 100-year rainfall rate is 3.3 inches per hour, and that kind of rain finds every gap in flashing.
September and October: seal up
- Seal openings around hose bibs, dryer vents, meters, cables and light fixtures.
- Finish any exterior paint or caulk while nights are still warm enough for it to cure.
- Clear gutters once the leaves are down.
- Drain and shut off outside faucets, and store hoses.
November and December: clear the walls
- Move firewood, bikes, grills and bins away from the siding so nothing holds moisture against it through winter.
- Take one last full set of photos before snow covers the lower courses.
- Check that the soffit vents are open and free of nests.
Iowa City by the numbers
QuickFacts from the U.S. Census Bureau counts 30,816 households in Iowa City for 2020-2024, with 2.24 persons per household. It gives the city a land area of 25.60 square miles in 2020 and a population per square mile in 2020 of 2,923.3.
Signs that shouldn't wait for the next walk
- paint that blisters or peels in the same spot every year;
- trim or boards that give under light pressure;
- a stale or musty smell in a room along an outside wall;
- stains running down from the corners of a window;
- a panel that flaps or buzzes in wind.
When it is time for bids
If a walk turns up more than a few damaged pieces, ask two or three companies to price the same written scope. Ask the contractor which local permits the job needs, and put a few more questions to each one: which permits does the job need and who pulls them? What state license or registration, if any, covers this work? Can they show proof of liability coverage and workers' compensation? Keep your dated photos, product names, colors, invoices and warranty papers in one folder, so any repair can match what is already on the wall.