When winter packs a wallop, the snow is a burden on more than your lower back; it’s also a heavy load for your roof to bear. Clearing it is important to prevent your roof from sagging, buckling or even collapsing, but the process may involve more than just taking a shovel to the problem.

Protect your roof, your house and yourself with these do’s and don’ts.

The do’s

Assess which parts of your roof need to be cleared. According to Michael O’Rourke, PhD, professor of civil engineering as Rensselaer Polytechnic Institute in Troy, New York, some roofs are more vulnerable than others, so you can save time and work by prioritizing.

“Roofs that are above a heated space tend to have less snow,” says O’Rourke, author of “Snow Loads,” a book about how to prevent roof damage from heavy snow. “An unheated garage is more likely to have problems than a heated house,” he says.

Related: Prepare Your House for Winter Storms

Look for clues inside your home to understand what’s going on outside. O’Rourke suggests keeping an eye on ceilings and walls inside the home for indications of roof problems.

“Look in the attic,” says O’Rourke. “If you see sagging or hear cracking, then it’s a good idea to get someone [a professional] in there.”

Most home roofs can support 20 pounds per square foot of snow before they become stressed, according to the Insurance Institute for Business and Home Safety (IIBHS). But how much weight your roof can handle depends on when the roof was built and what materials were used, O’Rourke says.

Since it isn’t practical to measure exactly how much the snow weighs up there, it’s hard to know whether the amount of snow is putting too much pressure on your roof. But generally, the more snow you see, the heavier the load. “The first foot may be fluffy, but every foot after that puts more weight,” says O’Rourke.

Rely on licensed, insured professionals to clear the roof. In cases of heavy buildup, throwing salt on the roof isn’t going to cut it. Using a roof rake, if not done properly, could damage the shingles on your roof. And breaking ice dams yourself with sharp objects could damage your roof, gutters and siding.

“Hire somebody that knows what they’re doing,” says O’Rourke. But beware of scams. Legitimate roofing contractors should be able to provide local references, licenses, written labor and manufacturing warranties and proof of workers compensation and general liability insurance, which includes fall protection.

The don’ts

Don’t use a ladder to get to your roof. If you have an inclined roof and need a ladder to reach it, you’re better off calling a licensed and insured roof contractor, says O’Rourke. “A steep sloped roof sheds snow, so problems are less likely to occur anyway,” he adds.

When it comes to snow buildup, “flat roofs are the bigger problem.” While flat roofs can be easier clean off once on top, O’Rourke suggests only doing it yourself if you’re able to access the roof without a ladder.

Don’t ignore ice dams. Ice dams occur when water pools on the roof from melting snow. The water then refreezes into chunks of ice and icicles at the edge of your roof. The dams can clog gutters, too, which can back up water onto the roof, according to IIBHS, which offers tips for safely preventing ice dams in the first place.

“Roofs are intended to shed the water and not hold it,” says O’Rourke.

Ice dams can damage the roof and even seep through to cause soggy or leaky ceilings and walls.

Related: How to Walk on Ice Without Falling

Lara Salahi is a multimedia journalist who specializes in health and medical news.