Every Michigan thaw brings the same phone call: a brown ring spreading across a bedroom ceiling,
or water running down the inside of an exterior wall, days after a snowfall nobody thought twice
about. The homeowner assumes the roof has failed. Usually it has not.
An ice dam is a ridge of ice that forms along the cold edge of a roof and traps meltwater behind
it. That trapped water sits on the shingles, works its way under them, and finds the ceiling. The
damage is interior, the cause is almost always heat escaping from inside the house, and the fix is
rarely a new roof.
How an ice dam actually forms
Three things have to be true at once. There is snow on the roof, the upper part of the roof
surface is above freezing, and the lower part — the eave, which hangs out over unheated air
— is below freezing. Snow on the warm section melts, the water runs down, and it refreezes
when it reaches the cold overhang. Repeat that over a few days and the ridge of ice grows tall
enough to pond water behind it.
The U.S. Army Cold Regions Research and Engineering Laboratory pinned down the temperature band
where this is worst: below about 22°F, icings rarely form and attics ventilate easily; above it,
the melt runs faster than the refreeze. It is the days hovering right around 20°F, with snow on
the roof, that build the dams — not the coldest night of the year.
Snow itself makes the problem worse, because snow is insulation. Roughly R-1 per inch of it. With
a foot of snow on the roof, researchers calculated you would need something like R-45 in the
ceiling below just to keep the deck cold enough not to melt it.
The cause is heat loss, not the roof
This is worth stating plainly, because it decides who you should be calling. The National Roofing
Contractors Association — the roofing industry’s own body — puts it this way: ice dams
are primarily caused by heat energy leaking through inadequately constructed thermal and air
barriers.
In other words, warm air escapes the living space into the attic, warms the underside of the
roof deck, and melts the snow sitting on it. Building scientists who have measured this find that
air leakage matters more than insulation depth — gaps around ceiling penetrations,
recessed lights, bath fans, attic hatches and chimney chases move far more heat than conduction
through the insulation does. One field study recorded a ventilated attic sitting at 55°F while
it was 22°F outside.
Ductwork run through an attic is the worst offender of all. If your heating ducts are up there
and leaking, ice dams are close to guaranteed.
Michigan has a built-in insulation gap
Here is a local detail most homeowners never hear. Michigan’s residential code requires about
R-38 of attic insulation, and it allows as little as R-30 where the insulation crosses the top of
the exterior wall — which is precisely the spot above the eave where dams form. The Department
of Energy recommends R-60 for our climate zone.
So a house can be fully code-compliant and still be underinsulated exactly where it matters for
ice dams. If your home was built before the modern energy codes — and most housing in Wayne
County and the city of Detroit was — the gap is usually wider still.
One thing Michigan does get right: the state’s residential code already requires an ice barrier
membrane at the eaves, extending at least two feet inside the exterior wall line. If a contractor
presents that as an optional upgrade on a roof replacement here, it is not. It is code.
Are icicles a warning sign?
Often, yes. A roof that is genuinely cold underneath does not produce much meltwater, so it does
not produce many icicles. A long row of them along a gutter usually means heat is escaping into the
attic and melting snow that then refreezes at the edge. Sun contributes too, but researchers are
clear that sunshine makes icicles while building heat makes the large, damaging dams.
What to do while water is coming in
Do not open the ceiling. This is the single most common mistake, and it is
counterintuitive enough that it is worth explaining. Cutting into a leaking ceiling lets warm indoor
air up against the roof sheathing, which accelerates the melting that is feeding the dam. You make
the leak worse.
Catch the water instead. If a section of ceiling is bulging with trapped water, make the smallest
hole that will drain it and put a bucket underneath. The ceiling comes open properly after the
event, not during it.
Then get the moisture out of the structure. Water that has run through a roof deck and attic
insulation is not clean, and saturated insulation does not dry in place — it needs to come out.
Wet ceiling wiring matters too: the standard residential cable used above ceilings is rated for dry
locations only, and electrical industry guidance is that soaked cable and recessed fixtures should be
replaced rather than dried and reused. A wet ceiling is not a cosmetic problem.
Removal: what damages your roof, and what does not
Almost every quick fix circulating online will cost you shingles.
Chipping with hammers, chisels, axes or picks. GAF names these specifically as
things that damage the roof. Worse, shingles get brittle in the cold — the same manufacturer
warns they can crack, break or delaminate when handled below about 40°F. So the conditions in
which people reach for a hammer are exactly the conditions in which shingles break. One documented
case saw a building owner clear snow rather than fix the ventilation for four winters running, and
ended up needing a new roof because the removal work destroyed it.
Pressure washing. The asphalt roofing trade association is blunt: never pressure
wash an asphalt shingle roof. It strips the granules and shortens the roof’s life.
Chemical de-icers, calcium chloride and ice-melt tablets. This is the advice we
most often see repeated, and the manufacturers disagree with it. GAF recommends against chemical
de-icers because they damage roofing, siding and planting. IKO goes further and says ice-melt
tablets may void the shingle warranty. Restoration engineers advise against applying salt or
calcium chloride to a dam at all.
What is left is low-pressure heat and patience — and prevention before the
season. From the ground, a roof rake used on the first three to four feet above the fascia genuinely
helps, and the roofing association notes plastic tools are less likely to damage the roofing than
metal ones. Do that carefully: OSHA documents a fatality from a rake contacting an overhead power
line and recommends keeping ten feet clear of them, and snow sliding off a roof can bury someone
standing underneath.
Heat cables: the experts genuinely disagree
You will find this recommended confidently in both directions, so here is the honest version.
GAF and IKO both consider heat cables an acceptable measure. The National Roofing Contractors
Association advises against them — a live electrical conductor exposed to weather, fasteners
that penetrate roofing, no protection at all if the system fails, and, in their view, a workaround
that adds energy cost without addressing the cause.
Research also shows cables melt a channel only a few inches wide, and the sawtooth pattern of
melting can create secondary dams further up the roof. If you use them, they are a tolerable
stopgap on a problem roof, not a substitute for sealing the ceiling.
The fix that actually lasts
In order of effect: make the ceiling airtight first, then insulate it properly, then ventilate the
attic so any remaining heat is flushed away. Air sealing comes first because air leakage moves more
heat than anything else, and a blower-door test will show you where. Insulation added on top of a
leaky ceiling is money spent on the symptom.
Does insurance cover ice dam damage?
Interior water damage from an ice dam is generally covered by a standard homeowners policy. The
national average settlement is around $8,000 — and it is worth knowing that figure reflects
interior damage only, not exterior repairs.
Two Michigan points worth having. You have the right to choose your own restoration contractor,
whatever your carrier suggests — the state’s Department of Insurance and Financial Services
says so directly. And when you report the loss, describe it as water damage rather than
flooding; DIFS specifically warns that “flood” carries a narrower meaning that points toward an
exclusion.
What we do, and what we do not
We are a restoration contractor, not a roofer. We do not steam ice off roofs. What we handle is
everything the water did once it got inside: drying the structure and the wall and ceiling cavities,
removing saturated insulation and wallboard, documenting the loss for your claim from the first
hour, and rebuilding what has to come out — drywall, insulation, paint and trim — with
one licensed Michigan builder accountable for the whole job.
If water is coming through a ceiling right now, put a bucket under it, leave the ceiling alone,
and call us. We answer 24 hours a day and we are on site across Metro Detroit and the Blue Water
Area within the hour.
Related reading: frozen and burst pipes — the
other way Michigan winters put water inside a building, and one where the flooding starts when the
ice thaws rather than when the pipe breaks. See also our water damage
restoration and storm damage services.
