A year of siding care in Portland
Siding rarely fails all at once. It loosens at one corner, a seam of caulk splits, a downspout spills onto the same patch of wall, and a few seasons later a board is soft. A short walk around the house a few times a year catches most of that early. This calendar lays the walks out by season, starting with the cold months, because that is when Portland's weather record asks the most of a wall.
The weather figures below all come from NOAA's engineering weather data for its Portland station (elevation 62 feet). They describe that station's record, not a reading from any particular street.
A side note on the city: the Portland Water District's Sebago Lake Water Treatment Facility in Standish began treating water in February 1994, using ozone as its disinfectant. It has nothing to do with your siding.
The figures this calendar leans on
At the Portland station, NOAA lists a 99% winter design temperature of 2°F and about 78 freeze-thaw cycles in an average year. It gives a 50-year basic wind speed of 110 mph (a 3-second gust at 33 feet) and a 100-year rainfall rate of 2.3 inches per hour. On the warm side, the 1% summer design temperature is 84°F with a mean coincident wet-bulb of 70°F, and the station counts about 495 hours a year with the wet-bulb above 67°F and about 74 hours above 73°F.
December to February: cold and snow
With a 2°F winter design temperature at the Portland station, this is the season to be gentle with the walls.
- Keep shovels, snow blowers and ladders off the siding. Cold vinyl cracks when struck.
- Don't let plowed or shoveled snow pile against the wall. Move drifts back from the bottom course when you can.
- Look up at the eaves after a storm. Ice along the roof edge can send meltwater behind the fascia and into the top of the wall.
- Check inside along outside walls and around windows for stains, damp spots or blistered paint.
- Photograph anything loose and save repairs for a stretch of milder spring weather.
March to May: thaw and spring storms
NOAA counts about 78 freeze-thaw cycles a year at the Portland station, and each one works at any joint holding water. Once the snow is gone, look at what the cold months left behind.
- Walk every wall and look for cracked or bowed panels, open corners and trim that has pulled away.
- Run your hand along caulk joints at windows, doors and trim. Replace caulk that has hardened, shrunk or split rather than smearing new over old.
- Find each kick-out flashing where a roof edge meets a wall and make sure it is still there and turned toward the gutter.
- Clean gutters and downspouts, and add extensions so roof water lands away from the foundation.
- Watch a heavy rain from inside a dry window. NOAA's 100-year rainfall rate at Portland is 2.3 inches per hour; overflow, splash-back and streaks under window heads show where water is going.
June to August: cleaning and painting
At the Portland station, the 1% summer design temperature is 84°F, and NOAA counts about 495 hours a year with the wet-bulb above 67°F.
- Wash the siding with a soft brush, a garden hose and a cleaner the siding maker allows. Skip the pressure washer, which drives water up behind the laps.
- Look for mildew or algae on north walls, under decks and behind shrubs, and clean it before it stains.
- Trim plants back so leaves stay several inches off the wall and air can move.
- Paint and caulk inside the temperature and humidity limits on the label, and work in shade rather than on a wall in full afternoon sun.
- Check vinyl for buckling on sunny walls. Panels nailed too tight have no room to move when they warm up.
September to November: closing up for winter
- Finish painting and caulking early in the season, while nights are warm enough for a proper cure.
- Seal gaps around pipes, cables, vents and the dryer duct.
- Clean gutters again after the leaves are down.
- Shut off and drain outdoor faucets, and store hoses away from the wall.
- Move firewood, bins and stored items so they don't sit against the siding all winter.
- Walk the house after the first big fall wind. The station's 110 mph design gust is a reminder that edges, corners and starter strips are where wind pries first.
What a damaged wall tells you
A few small signs usually show up long before major repairs are needed:
- the same patch of paint blistering or peeling each year;
- trim or boards near the ground that dent under a fingernail;
- streaks running down from the corners of a window;
- a musty smell in a closet on an outside wall;
- a panel that rattles or lifts in the wind.
Any of these deserves a closer look before the next season of storms.
When a check turns into a project
If a walk-around finds more than a handful of bad pieces, get written bids from at least two companies that price the same items: removal, the product, the weather barrier, flashing, trim, sheathing repair, permits and cleanup. Ask each one which City of Portland permits the job needs and who will pull them. Ask for proof of liability coverage and workers' compensation, and call your insurer with any questions about your own policy.
Keep a folder
Keep the siding brand, profile and color, your seasonal photos, paint names, invoices and warranty papers together. Matching a replacement panel or filing a warranty claim goes much faster when everything is in one place.