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Mainely Roofs

Article written by Jack Carr, P.E., R.S., LEED AP, CRITERIUM ENGINEERS
 
So you missed the Board meeting and you were elected as chair of the Building Maintenance Committee. Now what do you do? Where should you start first? What are your priorities? That’s easy. Ensure the building(s) is water tight and the building envelope is intact after this last winter. So where do you start? That also is easy, as in spring our minds naturally turn to thoughts of… roofs.

Here in New England there many types of roofing materials such as roll and built-up roofing, wood shingles, metal, fiberglass, etc. but for ease of discussion let us focus on high-slope asphalt composite shingle and low-slope rubber membrane roofing. Inspection techniques tend to be generic to all types of roofs.

Most roofs tend to last 20 to 30 years but many factors can cause those estimates to vary. Warranties on roofs should not be confused with how long a roof will survive as warranty is another word for pro-rated insurance. Roof survival is more dependant on the quality and thickness of the material, skill of the installation, ventilation on the underside of the roof, and periodic maintenance than all the warranties in the world.

A periodic inspection by roofing professionals is always a good idea but most roofs can be easily inspected with a little instruction and a systemic approach. The first thing to remember is getting onto a sloping roof or climbing a ladder may be the last thing you should consider. Many roofs can have their condition determined with binoculars and viewing the roof from the proper angle and time of day.

The condition of a roof can often be best determined from inside, such as in the attic. The inspection should include observing the condition of the roof’s underside whether it be metal or wood product sheathing. Old and new leak stains can be noted as well as their locations relative to roof penetrations and other reference points for further investigation during outside viewing.

Attic inspections should also note the quality or lack of ventilation. All vents such as ridge, gable, soffit vents should be clear of obstructions and mechanical vents should be operational. There should be a breeze in the attic on a windy day. It should be kept in mind that a poorly vented attic can reduce the life of a composite shingle roof in half as the excess heat will breakdown the asphalt components of the shingle causing premature failure.

Roofs rarely leak in the open field of the roof unless shingles are blown off. Therefore, the majority of the roof inspection should focus on transition points of dissimilar materials or junctures of roofs and walls such as dormers and chimneys. All skylights, vent pipe, and other roof penetrations should be monitored.

When on the ground, viewing the roof at an angle can easily assist in noting irregularities or the first sign of aging and failure. Conditions to look for include edge curling of the shingles, fish mouths, wavy shingle lines, cracked or missing shingle tabs, and loss of granular particles from the shingle surface. Walking on shingle roofs showing signs of shingle movement can cause severe damage and accelerated roof failure. Debris in roof valleys or condition of the valley flashing should always be noted. Shingles with a southern exposure will fail first. Observing the roof eave edge for damage from ice dam removal, rusting drip edges, and lack of a 3/8 inch drip edge are all signs of early problems. Chimneys without crickets to divert water and ice are more susceptible to water infiltration and flashing failure.

Flat EPDM or vinyl roof membrane roofs are easier to inspect. Parameters to note are the condition of the coatings, punctures, cracking, alligatoring, blisters, fish mouths at seams, blocked drains, and ponding. As an example, often ponding or the dried-up outline of prior ponding can be an indication of water infiltration sources. Roof membranes are designed to allow ponding for only a few days. If ponding is persistent over extended periods, the membrane will deteriorate and seams will fail prematurely.

The heavy snow loads in New England this year were particularly hard on low-slope roofs. Often roofs had to be cleared of snow to reduce dead load. The extra traffic on unprotected membranes can cause severe wear especially in areas where the insulation boards beneath the membrane have their mechanical fastener heads come in contact with the membrane’s underside causing tears.

No matter how many or what type of roof you may be responsible, having a systematic way to keep track of the roof’s condition is invaluable. A maintenance log of leaks, repairs, and observations produces a very organized approach to facility maintenance. A checklist with the issues listed in this article with photos illustrating roof problems can go a long way to keep maintenance cost down and rain out.   


© 2011 CRITERIUM ENGINEERS