The missing piece- When roofs are done… They are done.

During a roof inspection and I tell the buyer or owner that the roof is done I often get the same response… “Will it last a few years”. My answer is pretty much the same... I can make almost any roof last a few years, it may take a blue tarp, a few repairs and lots of roofing mastic but yes it can be done.

A little more mastic and it is all good

Worn Shingles, the roof is done

Then if you add to the fact the roof was not installed correctly in the first place the “Roof is Done” equation is more important.

Something Missing?

Here we have a roof that is done and worse yet it never have any underlayment installed. Of course the owner did not know this when they bought the home but they will now have to deal with it.

So the codes state an underlayment is required and depending on slope and environmental conditions just how that underlayment is installed.

Proper Installation

2012 IRC-

R905.2.7 Underlayment application.

For roof slopes from two units vertical in 12 units horizontal (17-percent slope), up to four units vertical in 12 units horizontal (33-percent slope), underlayment shall be two layers applied in the following manner. Apply a 19-inch (483 mm) strip of underlayment felt parallel to and starting at the eaves, fastened sufficiently to hold in place. Starting at the eave, apply 36-inch-wide (914 mm) sheets of underlayment, overlapping successive sheets 19 inches (483 mm), and fastened sufficiently to hold in place. Distortions in the underlayment shall not interfere with the ability of the shingles to seal. For roof slopes of four units vertical in 12 units horizontal (33-percent slope) or greater, underlayment shall be one layer applied in the following manner. Underlayment shall be applied shingle fashion, parallel to and starting from the eave and lapped 2 inches (51 mm), fastened sufficiently to hold in place. Distortions in the underlayment shall not interfere with the ability of the shingles to seal. End laps shall be offset by 6 feet (1829 mm).

Proper Installation with Water and Ice Guard

In my area an Ice Barrier is required-

From the 2012 IRC-

R905.2.7.1 Ice barrier.

In areas where there has been a history of ice forming along the eaves causing a backup of water as designated in Table R301.2(1), an ice barrier that consists of a least two layers of underlayment cemented together or of a self-adhering polymer modified bitumen sheet, shall be used in lieu of normal underlayment and extend from the lowest edges of all roof surfaces to a point at least 24 inches (610 mm) inside the exterior wall line of the building.

Now this is from the NRCA (National Roofing Contractors Association) on underlayments.

“Service life: The underlayment should match the primary roof covering's anticipated service life. A heavier, more durable underlayment, such as a double-layer, No. 30 felt or modified bitumen sheet, should be used with more durable roof coverings, such as slate or tile. For roof coverings with shorter life spans, such as 20- or 25 year asphalt shingles, a less durable underlayment, such as No. 15 felt, may be appropriate.

Slope: Steep-slope roof systems rely on slope to shed water. Therefore, the lower the slope, the more substantial the underlayment should be. For lower-slope systems, water won't shed as quickly off the roof, consequently increasing the chance of water infiltrating the primary roof covering layer. This situation necessitates a more enhanced water-shedding underlayment.”

Roofs are often not installed in proper manner because of several reasons; i.e.  poor workmanship, homeowners not wanting to pay the true cost of installation and poor oversight.

“The bitterness of poor quality remains long after the sweetness of low price is forgotten.”

Benjamin Franklin

NCW Home Inspections, LLC  is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…  

Your Wenatchee and Chelan Professional Real Estate, Home and Structural Pest Inspection Service

Instructor- Fundamentals of Home Inspection-  Bellingham Technical College

www.ncwhomeinspections.com                                                   509-670-9572

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