DIY Additions - Beware Flat/Low-Pitched Roofs in Snow Areas

Low-Pitched Roofs in Snow Areas

Copyright (c) 2013, Deanna and Jim Gilbert

      Many homeowners in certain areas of Northern Virginia or Maryland opt to install a roof over their patio, build a screened in porch or make an addition to their home.

      Normally the homeowner would get a contractor, who would pull permits and build additions to code.

      In certain areasm, however, some homeowners are "recently arrived," from "warmer climates," and happen to work in the building trades, but do not have their own contractor's licenses.  These "handy" craftspeople unfortunately build additions with nearly flat or slightly sloped shed-style roofs on too many occassions.

      These roofs are then shingled with normal composition, asphalt, or fibreglass shingles intended for sloped roofs. These shingles are not suitable for applications with less than 4/12 slope because they are not watertight; they depend on water running off before it runs underneath the shingle seams!

      For shallowly sloped roofs it is necessary to use a "rubber roof," RV-style, roof with sealed seams that is waterproof!

      Furthermore, when we get the occassional 12" of snow in 24 hours, or sometimes 20" inches of snow in 48 hours the flat roof may be built on a rafter structure not intended to hold hundreds of pounds of snow load!

      If you own a home with a very flat pitched roof on an addition and we get a heavy snowfall you need to have someone get a ladder and shovel it off!  The weight of the snow may permanently damage the structure leaving a visible sag. And the mass of the snow may retain substantial amounts of standing water as it thaws, leading to leaks and water damage inside the house and/or walls, including mold.  Water leaks inside a wall don't always show right away, but they do foster growth of mold. And termites are attracted to wet wood.

      When working with our flipping investors we all to often encounter these poorly engineered additions with the attendant external and/or internal issues.  Sadly, the only way to fix these is to get permits to tear off the roof, build a seriously framed, seriously sloped new roof, remediate any issues caused by water penetration, and refinish.  Or you can just demolish the addition!