Roofing ABCs - How a Roof is Constructed

Over the years, roof construction technology has evolved to a point where roof life can last over 100 years.  This is quite an impressive feat when you consider the amount of weather a typical roof can be exposed to.  It must be able to withstand rain, snow, hail, constant sunshine, moss, tree branches and more.  As building professionals have tested what works and what doesn't, they've come up with some very reliable materials and designs that give homeowners added assurance that their roof will not leak and that it will last for years to come.  For our purposes here, we will explain the basic components of a roof to help give you a better understanding of what is protecting you from those summer rain storms day in and day out.

Roof Wood Framing / Trusses

The most important structural component of your roof is the truss or frame.  These are commonly built offsite and then trucked to the home construction site.  The truss is what gives your roof that pointed shape and is also what determines its pitch or steepness.  Depending on the climate in which you live the pitch can be a very important factor in the design of a house.  If you live in an area like Michigan with heavy snowfall, you'll want a roof with a steep enough pitch to allow the snow to slide off of it in the event of a storm.  Otherwise, you'll either need to climb up on the roof and shovel every time it snows or your roof will simply cave in.  Shoveling an icy roof in 20 degree weather is not my idea of fun! 

Roof Deck / Sheathing / Underlayment

So once you have the truss in place, the next step is to build the roof deck.  The roof deck is made of sheathing which is typically constructed of structurally sound plywood or what is called oriented strand board (OSB).  With the roof deck constructed, we starts to get something that looks like a roof that could provide some protection.  The next added component to add to the deck is the underlayment-also called roofing felt.  It is attached to the roof deck for added protection against rain and other weather elements.  This material is usually made up of a thick paper that is coated in asphalt.

Final Step: Adding the Roof Shingles

Ok, so we're onto the step that most people associate with the overall look of a roof.  Adding the shingles are what give the roof added protection but also contribute to its overall appearance and style.  Depending on where you live, there will be certain materials that work best based on weather and surrounding architectural influences.  Most shingles installed are overlapping which means they are attached from the lowest portion of the roof and make their way to the top.  Laying shingles this way ensures that any rainfall will pour down the roof and ideally never penetrate the shingles themselves.  The shingles are attached to the roof in many different ways depending on the material used.  Most are attached with strong nails driven into the roofing deck.  Slate, on the other hand, is often hung like a picture on a wall verses being driven in with a nail.  Regardless of the roofing material you choose, make sure you use a qualified roofing professional for installation.  Poor workmanship will greatly reduce the overall life of your roof. 

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