Should you shovel your roof? A Q&A with an Anchorage building official.

The roofs of at least three commercial buildings in Anchorage have already collapsed under heavy snow loads this winter, including one off Schoon Street on Monday, with months of winter to go.

No one has been hurt in this winter’s roof failures, but residents are raising questions about if, or when, property owners should shovel their roofs to keep workers and others safe.

So far, more than 7 feet of snow has fallen in Anchorage, and snow depths are higher at this time than last year, which was also a big snow season. Last year, one person died and at least 16 roofs were damaged in partial or full failures, but many of those occurred late in the season after roofs were fatigued for months under heavy snow loads.

According to Anchorage acting building official Ross Noffsinger, homeowners this winter should now be thinking about when they’ll clear their roofs, assuming that the rate of snowfall this year holds steady.

The municipality has previously warned that owners of certain commercial buildings with wooden roof trusses built before the 1990s should clear their roof. At particular risk are roofs spanning large spaces like a warehouse, and with inadequate metal gang plates designed to hold roof beams together.

Noffsinger said roofs in the city are currently bearing 25 to 30 pounds of snow for each square foot. That’s below Anchorage code that typically requires that buildings support a minimum of 40 pounds per square foot. But the collapses this winter and last show that some structures in Anchorage can’t support that much weight.

In a Tuesday interview, Noffsinger spelled out what Anchorage home and commercial building owners should be watching out for through the rest of the season:

ADN: Let’s say that a person works in a commercial building, with a flat roof in particular. What should they be doing to make sure that they are safe?

Noffsinger: We have our snow removal guidance that we issued earlier this winter, and we’ve updated it a few times. We call out a very specific type of vintage of construction and type of roof truss. So I encourage people to go look at this guidance that is posted on our website, and if they think they’re building falls under this guidance, to remove the snow from the roof.

ADN: So that’s the parallel chord wood truss with the (metal) gang plates?

Noffsinger: Yes, and these are buildings that were built between the 1970s and 1990s ranges, and the roofs generally span larger, wide-open spaces.

ADN: Let’s say someone has a building built after the 1990s that is wood with a flat roof. What should those building owners do at this point in the season?

Noffsinger: We haven’t seen any failures in anything built after 1990. We’re kind of thinking that the truss industry learned that trusses were underbuilt and changed their approach by then. Truss plates started growing over time, and they’re considerably larger today than they were back then. So at some point in time, it seems the industry figured out that they had a problem and they addressed it. It appears that way anyway. And that’s why we’re not seeing the failures in the more recent construction — that refers to the failures last winter, and this winter so far.

ADN: Do you feel like Anchorage residents are taking this seriously, or are they not taking it seriously enough?

Noffsinger: So, yesterday, we were over there at Schoon Street. The building is part of what looks like a big continuous building, but there are multiple buildings that look the same, with the same vintage of construction. One cluster was built in 1982, and the other cluster was built in 1985. And I’d say maybe 40% of them had already cleared their roofs. So those people were obviously listening to the message. And maybe for the others, they were on the list to get the roof cleared, too. I mean, obviously, there’s limited resources to get this work done, and it’s expensive. But there are a lot of people out there that are clearing snow from the roofs of these buildings.

ADN: I understand the municipality was concerned that other buildings could face similar problems in the area, since they had the same construction style and vintage?

Noffsinger: We basically went to every business there that we could get into that was open and we let them know that the potential for whatever caused the collapse, the defect, could exist in their roof trusses and we recommended that they get the snow off the roof as soon as they can.

ADN: And the one that collapsed had not shoveled the roof, from what you could tell?

Noffsinger: There was no sign the snow had been removed from that roof.

ADN: We’ve had only three collapses this year and one of them was vacant and waiting to be demolished. So maybe people are taking lessons from last year’s collapses?

Noffsinger: Well, it’s still early. I don’t want to be the bearer of bad news. But we are still early in the winter. If there’s 25 pounds per square foot of weight on some of these roofs, and if it’s allowed to remain there for a couple more months, you know, that’s taking significant risk (for) the target buildings that we’re talking about.

ADN: And what about homeowners who are starting to think about whether they should clear their roofs or not? What should they do?

Noffsinger: That is something that people should be considering at this point, given how relatively early in the winter it is. From my own personal perspective, I’m anticipating shoveling my roof once this winter. And at this point, it’s just picking the sweet spot to do it, so I only have to do it once. I’m thinking I’ll probably be shoveling my roof in February. I’m up on the Hillside, and my house has seen significantly more snow than a lot of the houses down here. But then my house was also built in the year 2000.

ADN: Is your house a pitched roof or flat, and what kind of difference does that make?

Noffsinger: It’s a pitched roof, but at the rate we’re going, I’m going to get over 40 pounds per square foot of snow on my roof.

ADN: So should homeowners be starting to think about when they might want to shovel or not, whether they own a flat or pitched or roof?

Noffsinger: They should be thinking about that. They should be thinking that, “Well, we’re going to get a lot of snow this winter and I’m going to need to shovel my roof. So when should I do it?”

ADN: Initially, you didn’t issue that sort of guidance for homes.

Noffsinger: Yes, we just keep getting more snow. I’ve been driving around town, and there’s a lot of extreme ice buildup on structures. There’s a lot of homes that ice dam very badly that should have been shoveled a long time ago. Those ice dams will just continue to get bigger if they don’t get the snow off. That’s one set of problems, homes where the attics are not very well insulated or ventilated, and hence, those homes are subjected to excessive ice damming. Those homes are kind of in their own class, where snow should be periodically removed.

And then you have other homes that don’t ice dam but they hold the snow, which allows the snow (load) to get really heavy. So if it does keep snowing, I would be thinking at least once this year they’re probably going to need to shovel their roof.

ADN: The length of time a roof is under a heavy snow load is a factor, too, right?

Noffsinger: Yeah, for wood construction, and I’m not talking about concrete or steel. When you subject a wooden structure to a significant load, time matters, basically. The wood will deform under the load. And we think that was a reason why last winter, all the failures all started showing up in March.

And there’s a possibility that that could replay this winter, given we’re kind of in that scenario where we’ve got a lot of weight on our roofs early in the winter.

ADN: And that’s both for flat and pitched roofs?

Noffsinger: Yes. And we’re not worried at all about the steel buildings.

ADN: And nobody has been penalized or received any fines for any of the 16 (collapses) last year, the three this year?

Noffsinger: Nobody has been fined or anything, because no one’s really violated any sort of law or regulation.

ADN: So there’s really not laws that require any kind of clearing every two months in a heavy-snow winter, or anything like that?

Noffsinger: No, because historically, it’s been a non-issue in Anchorage, right? Who knows, maybe the Assembly, the rulemaking body, will step in and create some sort of regulations.

At this point in time, we’re just trying to get a handle on how extensive the problem is in town. We’re actually trying to search our records now and see if we can come up with a number as to how many of these buildings exist and where they are.

ADN: The pre-1990s, parallel truss construction?

Noffsinger: Yes.

ADN: And then once you figure that out, you would send guidance notices?

Noffsinger: That would be our plan. We would start with a friendly letter. And basically, it would be something to the effect, “We think you may have this condition. Please investigate it and let us know.”

If the friendly route doesn’t work, at that point in time, I think the Assembly would adopt regulation to take a more rigorous route.

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Correction: This story has been edited to say that roof snow loads are 25 to 30 pounds per square foot, not 25 to 30 feet.