A brick bungalow with frost on its gray shingle roof and snow along the front walk

Can You Replace a Roof in Winter in New Jersey?

October 3, 20267 min read Filed under Roofing Services

Yes, with care. The thermometer matters more than the calendar.

An asphalt shingle roof can be replaced in a New Jersey winter; the roofing season does not stop when the weather turns. What makes it a good job or a poor one is whether the roofer follows the shingle manufacturer’s cold-weather instructions. Below about 40°F shingles stiffen and can crack, and the strip of sealant that bonds each shingle to the one below it will not activate until the weather warms. Both problems have known answers: keep the bundles warm, handle and nail them carefully, and seal the shingles by hand. The rest of winter roofing is about the schedule, because days are short and snow does not wait for a crew.

This article sets out what changes in the cold, what a winter installation should include, and how to decide between replacing the roof now and getting it through to spring.

What cold does to a shingle roof

Shingles get brittle. Asphalt is flexible when it is warm and stiff when it is cold. GAF says its shingles lose flexibility below 40°F and may crack, and the industry’s own trade body, the Asphalt Roofing Manufacturers Association, warns that in the cold a shingle may crack or, in severe cases, break apart when it is bent or dropped. A crack you cannot see from the ground is still a crack, and it is where the leak starts.

The sealant strip will not bond. Every modern shingle carries a factory strip of heat-activated sealant. In warm weather the sun softens it and the shingle above bonds to the one below, which is what holds the roof down in a high wind. In the cold that does not happen. Owens Corning’s cold-weather bulletin says shingles installed in cold weather may not seal until warmer temperatures arrive, and may take longer to lie flat. Until they do, an unsealed shingle is held only by its nails.

Everything takes longer. Frost on the roof in the morning delays the start, the light goes early, and air compressors lose pressure in the cold, which matters because a nail driven too deep or not deep enough is a defect. None of this rules winter out. It means the job is planned around it.

What a cold-weather installation should include

Drawn from GAF’s cold-weather guidance, Owens Corning’s cold-weather bulletin and ARMA’s recommendations.
What the roofer does	Why
Stores the bundles somewhere warm before use (GAF: 70°F for at least 24 hours)	Warm shingles bend without cracking and lie flat
Carries up only what will be installed soon	Bundles left on a cold roof stiffen again
Clears snow, frost and ice and starts on a dry deck	Nothing should be installed over ice or a wet deck
Hand-seals the shingles with asphalt roofing cement	Holds them against wind until the sealant strips bond in warm weather
Nails every shingle flat, with the compressor pressure checked often	A nail through a shingle that is not flat can break through it
Leaves a slight gap at shingle end joints (Owens Corning: no more than 1/16 inch)	Shingles laid tight in the cold can buckle when they expand in summer
Considers open metal valleys rather than woven ones	Woven and closed-cut valleys bend shingles, which is when they crack
Works in sections, in the warmest part of the day	More sun on each section, and only as much roof open as can be closed that day

Hand-sealing, and why it matters until spring

Hand-sealing means putting dabs of asphalt roofing cement under the shingle and pressing it down, doing by hand what the sun would do in summer. The manufacturers describe it slightly differently. GAF’s guidance calls for quarter-sized dabs under each tab. Owens Corning’s bulletin calls for every shingle along the whole perimeter of the roof to be sealed, with four one-inch dabs on each architectural shingle and two under each tab of a three-tab shingle, using roof cement that meets the ASTM D4586 standard. Both warn against using too much, because excess cement runs onto the face of the shingle and can make it blister.

It is slow work and it costs labor, which is exactly why it gets skipped. A winter roof that has not been hand-sealed may look perfect in January and lose shingles in the first strong wind of March. When warm weather arrives, the factory strips finish the job on their own. GAF says its warranty is not affected by a cold-weather installation as long as all of its instructions are followed, hand-sealing included, so ask for it to be written into the contract.

Underlayment and the membrane at the eaves

Under the shingles, the roof gets a synthetic underlayment and, at the eaves and in the valleys, a self-adhering ice-and-water membrane. Self-adhering membranes rely on a sticky backing, and a cold deck and a cold roll both work against it. Manufacturers publish minimum application temperatures for these products, and below them the rolls have to be kept warm until they go down. The deck has to be dry as well, or the membrane bonds to frost instead of wood.

In Bergen County the state does not require the ice-barrier membrane at all. New Jersey limits that part of the code to areas where January’s average temperature is 25°F or less, which the state says is Sussex County only. We install it anyway, because this county’s houses get ice dams, and a winter re-roof is the one time it is easiest to get right. The full story of what the code does and does not require is in do you need a permit to replace a roof in New Jersey. The short version is that the season makes no difference: a re-roof on a detached house needs no permit in January or in June, and new sheathing needs one in both.

What changes on the schedule

Shorter days. A crew tears off only as much roof as it can cover the same day. In December that is less roof than in June, so the same job takes more days than it would in summer.
Frost and snow. A frosty morning means a later start. A snowfall means clearing the roof or waiting, and nobody should be working on a roof covered in ice.
A dried-in roof every night. Whatever is open at the end of the day is closed before the crew leaves, in every season, but in winter it matters more, because the next day’s weather is less predictable.
Slate and metal. Neither depends on a sealant strip, so the cold matters less to the roof itself. The underlayment and membrane beneath them still have the same temperature limits as on a shingle roof.

Replace now, or repair and wait?

If water is coming in now, do not wait for spring. Get the leak stopped first: emergency roof repair is about drying the house in tonight and diagnosing tomorrow. After that the choice is yours.

A roof that is worn but dry can usually be repaired to carry it through the winter, and replaced in spring when the shingles will seal on their own and the days are long. That is often the sensible route, and we will say so when it is. A roof that is failing in several places, has a soft deck or keeps leaking after repairs is a different case: waiting through a winter of ice and wind can turn a re-roof into a re-roof plus new sheathing. Our roof repair and roof replacement pages cover where that line falls, and a free roof inspection will tell you which side of it your roof is on.

What to ask a roofer about a winter job

Will you hand-seal the shingles, and is that written into the contract?
Where are the bundles stored before they go on the roof?
What happens if snow is forecast part-way through, and how is the roof closed each night?
What are the minimum temperatures for the underlayment and membrane you are using, and how will you meet them?
Is the ice-and-water membrane included, and where exactly does it go, given that the code will not insist on it here?
Will the cold-weather work keep the manufacturer’s warranty intact?

When we re-roof in the cold, we follow the shingle maker’s cold-weather instructions, hand-sealing included, because the warranty depends on it. What a new roof costs here is in our roof replacement cost guide, and the work itself is on our asphalt shingle roofing page.