Ice dam risk in Peru, IN

Will your roof get ice dams in Peru, IN?

10.2 dam days a winter

Moderate risk. On an ordinary house in Peru, conditions for an ice dam come on about 10.2 days in a normal winter, mostly in January and February.

Peru averages 20 inches of snow a year and about 35 days with snow on the ground. Most of it comes and goes within a few days. The conditions that make a dam need all three at once: snow, cold at the eave and heat above it.

What your attic does to that number in Peru

Attic	Dam days	Risk
Air-sealed and well insulated	5.6	Moderate
Typical, some insulation, not air-sealed	10.2	Moderate
Older or poorly insulated, warm attic	16.0	High

Sealing and insulating a typical attic takes out about 4.6 days a winter here. It does not move the risk band, but it shortens every dam. An older house with a warm attic should expect closer to 16.0 days.

What to do about ice dams in Peru

Air-seal the attic floor: the gaps around the hatch, light fixtures, plumbing stacks and the top plates of interior walls. This is the fix that removes the cause, and it usually costs less than a season of contractor ice removal.

Which to spend on first: air sealing or heat cable.

Peru winter, month by month

Month	Snow (in)	Days on ground	Dam days
January	7.3	13.8	4.7
February	4.8	10.3	3.0
March	2.4	2.8	0.5
April	0.4	0.2	0.0
November	1.0	0.8	0.1
December	3.6	7.0	2.0

Peru next to nearby towns

Peru ranks 39 of 88 Indiana cities here for ice-dam days, behind Plymouth at 15.9 days.

Wabash, IN 13 mi, 12.7 days
Logansport, IN 15 mi, 10.4 days
Kokomo, IN 20 mi, 10.8 days
Marion, IN 26 mi, 8.8 days
Huntington, IN 31 mi, 10.5 days

Where these numbers come from

NOAA 1991–2020 climate normals from Wabash, 13.0 miles from Peru. A dam day is a day with snow on the roof and freezing at the eave while heat or sun melts the snow above it. This describes a normal winter, not this one.

Snow-on-the-ground counts come from a second, nearby station, because the closest one does not record them.