As we continue in the dog days of summer, let us pause to consider that winter will come again!

With winter comes unpredictable turns in the weather.  Snow arrives in Florida, ice in the Midwest, and high winds in California. Buildings which function fine 9 months of the year are challenged with sudden weather shifts.  

MATCH ROOF TO REALITY

In surveying the rooftops in Burlington, Vermont (where “Wowuh” went to college; you will find him on Spotify), I found very few flat roofs.  

It snows in Vermont for six months of the year (followed by “mud season” in May, then 4 months of wonderful, then back to winter)!  

Flat roofs don’t shed snow or ice, and the buildup of weight can collapse a roof.  

FLAT ROOF CHECKLIST

The right roof for realistic weather, which is reasonably maintained, will reduce budget reserve requirements.

1. LESS AREA.  Compare the surface area of a sloped shingled vs. flat roof.  There is less area to cover with a flat roof.
2. EASIER ACCESS.  There is no need for multiple ladders to access a flat roof.  Generally, it can be accessed from a hatch in the roof.
3. LESS LABOR. A flat roof can have a membrane rolled out à la carpet or poured like building an asphalt road.  It can be hard hot work, but one that allows for labor-saving techniques per square foot (compared to a sloped shingled roof).  
4. EASIER TO INSPECT.  I have walked flat roofs in August in Florida in a three-piece wool suit when I worked for a subsidiary of Manulife. I was overheated but was able to accomplish my inspection due to easy access.  Do create a pathway across the flat roof (e.g., with concrete pavers) so that non-roof repair personnel (e.g., for HVAC) avoid stepping in the wrong place and damaging the roof membrane.
5. IMPACT OF SNOW AND ICE. This is where flat roofs may be less appealing.  Snow and ice may slide off a sloped shingle roof.  With a flat roof, it is there until it melts. Improper snow removal can damage a flat roof. Heat loss, due to insufficient insulation, can create pockets of water, which turn to ice, which is substantially heavier than snow.
6. CAPACITY. The weight-carrying capacity of the flat roof is a critical due diligence issue in heavy snow areas. Bob Vila notes that wet snow can be three times heavier than dry, fluffy snow (7 vs. 20 pounds per cubic foot). Ice and slush can exceed 50 pounds/ft³. Commercial flat roofs typically support 20–40 pounds/ft³.

BOTTOM LINE.  

I am not a fan of flat roofs, having grown up in Pittsburgh, where the winter freeze-thaw cycle tends to push ice into leaks in flat roofs. Wind can create deep drifts in the corners; snow layers compact over time.

Flat roofs are not inherently good or bad.  They can be less expensive to build and replace, depending on the size of the roof of the prospective building to be built. 

You may also want to walk the interior space, looking for stained ceiling tiles or sagging ceilings, and talking to the tenants regarding their experience in heavy storms.