Avoid Roofing Pitfalls

Common roofing mistakes made on the jobsite can jeopardize the quality and durability of typical, asphalt shingle roof installation. Eliminating just these five “hot spots” could make all the difference in the world. These are common sense approaches builders should use to work with their roofing trades.

Follow all manufacturers’ installation instructions

A shingle is not a shingle is not a shingle – installation protocols (and possibly code requirements) can vary significantly from one type/style/brand of shingle to another. Unfortunately, despite manufacturer installation instructions consistently being printed on the paper in which they are wrapped, instructions often get overlooked or discarded altogether during the construction process. Most roofers assume they know how to install shingles and don’t need to read the instructions included. But starter course instructions, nailing pattern requirements per shingle, and even roof coverage area can be vastly different for one style versus another. Failing to follow instructions precisely can lead to durability problems and/or void manufacturer warranties, leaving builders bearing the full cost of any needed repair or replacement.

SOLUTION: Take the time periodically to read the instructions that come with each delivery of roofing materials yourself. Quiz your crew or the crew foreman. Regardless of how many times they’ve installed those materials previously, they may have been doing something wrong all along and just didn’t know it. Also, be sure all current installation instructions are on file with the jobsite superintendent and affixed to the scope of work given to the roofing trade crew leader. Regularly take stock of installation instructions on file on the jobsite to be sure they are the most current and accurate for the type and style of material you are using.

Plan the work and work the plan

A builder’s goal with any element of a job should always be to do it right the first time to avoid costly delays. One of the keys to “doing it right the first time” is to create a comprehensive job plan for every type of work to be done on the site, including roofing. 

SOLUTION: Some of the most straightforward, but critical, elements of a roofing work plan should include the following: 

• Carefully lay out the job before it begins. Every crew on every job needs to place evenly spaced chalk lines along the roofing underlayment to give the installer a visible guide for every course to avoid an unacceptable, inconsistent finished look.
   
• The builder or the designer must decide on valley style and ridge and gable end treatment and be explicit in those details on plans and/or scopes of work before roofing begins. Better to make sure everyone is on the same page ahead of time than to waste valuable time with questions or corrections as the work progresses.
   
• Periodically confirm the take off and make sure there is a sufficient quantity of the same “dye lot” on the job and ready to use. Running a few square feet short at the end of the job and “filling in” with shingles that don’t quite match is a rookie mistake that reflects poorly on your reputation for quality. Extra quantities can be returned but ordering extra later can have risks of delays and mismatched colors.

Get the fasten-ating details

You always specify what shingles are to be used on a roof, but do you always specify the type and gauge of fasteners for those shingles? If you don’t, you should. Specifying and ensuring use of the correct fasteners is important. Incorrect or mis-sized fasteners can lead to wind damage, reduce the durability of the roof surface, or can result in a red tag by the code inspector.

SOLUTION: The type/gauge/brand of fastener needed for your job is called out in the manufacturer’s instructions and/or in the local building code. You may also have a personal preference for either nails or staples based on past experience. Make sure any preferred or required fastener detail is included on the approved plans and specifications for a given project and that those details are also included in the roofer’s scope of work. If staples are to be substituted for roofing nails, be sure the acceptable wire gauge and staple length are clearly stated as well.

Ready, aim … adjust nail guns properly

While it is the contractor and not the builder who owns and uses the nail guns on a jobsite, ensuring they are adjusted to the proper settings to maintain adequate and consistent fastener penetration throughout a job is very important. Too little pressure leaves the crown of the nail or the staple too high and makes a bulge in the profile of the shingle; too much pressure and the nail or staple can crush the shingle or even be driven through the shingle. Overdriven fasteners tear the fabric of the shingle and reduce holding power and durability.

SOLUTION: If a nail gun or automatic stapler is to be used, make sure the air pressure adjustment is correct. And, because the air pressure can change over the course of a day, the compressor needs to be checked periodically to keep the pressure within an acceptable range. Be sure these pressure checks are documented by the trade contractor and that your trade partner or site supervisor have a record of proper adjustment throughout the course of the work.

Look at it on the (roof) level

Sure – a city or county inspector will ultimately come around and conduct an inspection of your building, including the roof. But that inspector will rarely, if ever, get up on the roof to have an up-close-and-personal look at the quality of the job; what looks good from the ground may not look so great up on the roof and vice versa. On the other hand, it’s risky to rely solely on your roofing material installer for your inspections – while the installer is right there in the heart of the details, he lacks the objectivity you need. 

SOLUTION: While you should always try to have problems addressed and solutions implemented before a final inspection, it’s best to have a third-party inspect the roof both from the roof and from the ground to ensure that both the quality of workmanship and aesthetic details are where you expect them to be. Some key components of that inspection should include the following:

• Make sure any holes in shingles created due to the installation of cleats or other temporary framing members are not simply filled with roofer’s mastic. Shingles with holes need to be replaced.
   
• Step in a valley yourself and make sure the paper and the shingles are secured to the roof sheathing, not suspended above it. A roof valley will seem like a safe place to climb if the homeowner or a contractor he/she hires should ever need to go onto the roof (although your homeowner manual undoubtedly suggests that the homeowner should stay off the roof altogether), and having someone’s foot poke right through the valley during one of those treks makes you look pretty bad.
   
• Look for any reverse shingling, especially near a chimney or a plumbing stack. Water flows downhill and shingles need to let it flow, not catch it.
   
• Look up through the trusses or ceiling framing from the underside of the roof to confirm whether nails or staples were used in compliance with your specifications. This part of the inspection can also confirm proper spacing and sufficient quantities of fasteners used.
   
• If corrections are required, write them down and agree with the roofing contractor on when a follow-up inspection can be scheduled. Don’t assume the corrections will be made – always re-inspect. Document this and all other final inspections and make sure both you (the builder) and the roofer sign off on that final report.

Specific scopes of work and inspection checklists are two key elements of a documented quality management system adopted and implemented by quality-minded builders across the country. Contact Home Innovation Labs for more information on implementing quality management systems for both builders and trade contractors.

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