Your Roof Needs a Solid Foundation, Literally 

Just like a building needs a solid foundation, so does your roof.  Roofs consist of several layers.  The sheathing is the bottom layer and is nailed to the rafters.  A good shingle roof should have three layers: sheathing, covered by some kind of roofing felt, with shingles on the exterior.  

Chances are your shingle roof might have more than just three layers.  Building codes generally allow homeowners to apply a second layer of asphalt shingles over the existing one to seal leaks, but on older homes, it is common to find three or four layers of roofing over the original. Roof maintenance sometimes involves re-shingling, but it is an ineffective solution if the foundation of your roof is not in good condition. Don't let the cost of a new roof scare you - it should be covered by your home insurance policy.

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Asphalt shingle roofs have a lifespan ranging from 18 to 30 years.  Warranties for roof shingles themselves are about 10-15 years.  The average age of homes in America is 35 years, and in Connecticut, homes are even older. 

Year Built


West Hartford, CT

Average in US

1999 to 2005

2.91%

13.71%

1995 to 1998

1.84%

14.31%

1990 to 1994

1.84%

14.31%

1980 to 1989

4.84%

13.87%

1970 to 1979

7.41%

16.17%

1960 to 1969

13.15%

11.70%

1950 to 1959

26.39%

11.08%

1940 to 1949

15.26%

6.02%

1939 or Earlier

28.20%

13.15%

Information from www.bestplaces.net

The statistics for West Hartford are pretty representative of the rest of the state.  In West Hartford 70% of homes were built in the 50s or earlier. Roofing materials have evolved since then.  Your roof is likely old, and the original building method is probably antiquated. 

Board Sheathing 

tongue and groove sheathing board

Sheathing in old houses was typically made of straight-sided lumber butted together, or tongue and groove boards.  We can call this type of sheathing 'board sheathing.'  If your roof was built in the 1950s or earlier, this is almost certainly what you have. The problem with this type of sheathing is that wood can shrink and expand. 

Wood naturally contains moisture so as it heats up it expands, and as it cools, it shrinks.  Over time the wood can lose moisture and shrink 5-10%, creating '' gaps.  Some materials can be installed on old board sheathing that is still intact, such as wood shingles and some seam metal roofing systems, but asphalt shingles need a solid foundation.  Contact a roofing expert to discuss your options for installing new sheathing.

Solid Sheathing

Solid sheathing is made from plywood or oriented stand board (OSB). 

 

plywood cross grain sheathingPlywood is made from thin sheets of wood that are glued together so that orientation of the wood grain in each layer alternates.  Cross graining provides dimensional stability to reduce expansion and shrinkage.  Plywood was not used in residential construction until the 50s.  OSB was not developed until the 70s.

image via Pancelcenter

OSB sheathing OSB is made of rectangular wood strands that are glued together.  It is becoming more and more widely used, as it is one of the most cost effective roofing materials.  

 image via woodbusinessportal

Experts and Fiderio&Sons work with CertainTeed, which offers roofing solutions for pretty much every need.  CertainTeed shingles also come with one of the best warranties. Learn more about roofing in general, or specifics about sheathing materials. 

What to Look for When Selecting Solid Sheathing:

  • Grade:  Make sure it is rated 'Exposure 1' or exterior grade

  • Span Ratings: Distance from the center of one rafter to the center of the next.  The farther apart, the thicker you need. If anything, go thicker!

  • Number of Nails/Staples required

  • Spacing: Panels for OSB should be spaced with a minimum gap of 1/8gap between all butting edges

  • Ventilation: building codes suggest a minimum vent area of 1/300 of the total ceiling area. 

Important Installation Considerations

As the name implies, OSB is oriented: the grain is on the length of the axis, and thus should be applied perpendicular to the rafters.   For plywood, the face grain should also run perpendicular to the rafters.

Solid Sheathing is manufactured to increase dimensional stability and resist warping and buckling, but they are still susceptible to some shrinking and expanding.  The roof of your home is exposed to the most extreme temperature changes, so it needs room to shrink and expand.  Make sure solid sheathing is installed with manufactured spacing clips to prevent the need for roof repair down the road.  Beyond warping, your roof needs have proper ventilation anyway!   

Before shingling, make sure the roof surface is dry, and shingle as soon as possible after sheathing.

We are one of the best roofing and siding contractors in Connecticut. Call us to learn what your options are for removing, replacing, or recovering your old sheathing.