Get Real About Roof Tear-Offs

Nov. 2, 2006
Roofing experts weigh in on five questions to ask yourself and roofing professionals before tearing off your old roof

A good roof isn’t optional - it’s a necessity. While a roofing job can be one of the pricier capital expenditures to put a dent in your budget, it is also one that can make or break your building (both aesthetically and functionally).

Many factors assure not only the success of a roofing project, but the long-term return on investment. Here, roofing experts weigh in on five questions you should ask yourself and roofing professionals before tearing off your old roof.

1. How do I determine which roofing system is best for my building?
Because no two buildings are alike, no two will require the exact same roofing system - it all comes down to how the building is used, the climate it’s in, and when the job is going to be performed.

Working closely with a qualified consultant or contractor, as well as product-manufacturer representatives, can help you determine exactly what kind of roofing system will work for your building.

“You know your building better than anyone,” says Larry Stein, a staff consultant at Benchmark Roof & Pavement Consultants Inc. in Cedar Rapids, IA. “Do you have contaminants coming in contact with your roof? Do you have high-humidity occupancy? All of this has to be taken into account during a system evaluation and recommendation. Maybe you need a system with a vapor retarder and insulation. [If so], you need to share this information with your roof consultant or contractor.”

Code issues might also come into play. Do you know your local building codes? How many layers of shingles or built-up roofing can be added on top of a structure before a complete tear-off is needed? Do you know what your roof deck’s structural load is?

All of these factors need to be thoughtabout when you sit down to specify your system. Once you determine which system is best for your building, then you need to work out timing.

2. When is the best time to start a roofing project?
The timing of a roofing project depends on three main conditions:

1) The system being selected.
2) The geographic region and climate.
3) The best time to get the best value from a contractor.

“You don’t want to be putting on a roof system that has significant temperature or weather restrictions if you live in an extreme climate,” Stein says. “There are certain types of roofing systems that do have temperature restrictions.”

Consider single-ply membrane roofing: A popular method of putting it down involves attaching the substrate with an adhesive. Typically, these adhesives have temperature restrictions. “You [shouldn’t] put it down in temperatures below 40 degrees F.,” Stein points out. “You’ll end up trapping moisture between the insulation and membrane.”

Some single-ply membrane systems can be joined by hot-air welding, which, according to Stein, can be a less-risky procedure to use in colder temperatures since the welding machines can be adjusted to accommodate the colder temperature.

Temperature also can affect a hot-applied built-up system - hot bitumen won’t perform adequately in cold temperatures. According to Stein, it is more difficult to maintain the proper mopping temperature at the point of application when the ambient temperature is low.

Application of spray-in-place foam systems also depends on weather conditions. “You don’t want to be spraying foam in high wind or high humidity,” notes Bill Good, executive vice president at the Rosemont, IL-based National Roofing Contractors Association. Stein adds that spray-in-place foam is one of the most sensitive materials in terms of requiring the right atmospheric conditions. “Weather happens; you can get dew in the air and frost that can adversely affect a lot of things,” he says.

Timing is also crucial when booking a contractor. All contractors have a busy season and will often charge a premium for work done during those months. Look at your job and determine whether it’s something that must be done right away or something that can be done when quality contractors are just gearing up or gearing down for the season.

“From a pricing point of view - independent of the roof system selected - if you want to have a safe roof completed during a busy time, the basic concepts of supply and demand come into play,” says Phil Suess, president at DC Taylor Co., a national roofing contractor based in Cedar Rapids, IA. “When you contract in the slow, late-winter or early-spring periods, that is really a good time for value pricing.”

3. Can a new roof be installed over an existing one, or is tear-off a requirement?
In most cases, experts say, you’ll want to tear off the old roof, ensuring a quality job and lessening the risk of failure that can occur if the old roof is not fully attached.

There is, however, a cost incentive to keep an existing roof in place: The contractor doesn’t have to take the time to tear off the old roof and haul away the debris. There’s also less potential for moisture to get into the building (if you’re not tearing off the roof, the deck and material below will not be exposed to the elements). You also won’t have to install additional insulation.

You need to make a careful assessment of the existing roof system before making such a decision. “There is some pretty vital information that has to be obtained before you proceed,” notes Gary Cattel, president at Roof Engineering Inc., Raleigh, NC, and president at RCI Inc. - The Institute of Roofing, Waterproofing, and Building Envelope Professionals (formerly Roof Consultants Institute), also in Raleigh, NC. First, make sure that the surface is relatively dry. Any residual moisture might have a negative impact on the new roofing components. “If you’ve got moisture, you’ve got problems,” Cattel points out.

You also want to make sure that the existing roof is attached securely. If it’s loose or becoming unsecured, the new roof placed on top of it may fail.

Sometimes, a roof might not need to be replaced at all - just simply repaired. “The building owner may think they need a roof replaced because it is leaking, when, in fact, it may not need to be replaced,” notes Eric Hasselbusch, vice president of business development at DC Taylor Co.

Again, it all comes down to a careful assessment of the existing building conditions; a qualified roof consultant or a trusted contractor can help you determine this by inspecting the existing surface and talking with you about all the factors that might affect the roof’s condition.

Examine the reasons for failure and determine if you need to repair the old system or replace it. If you replace it, do you leave the existing roof on or start fresh with a complete tear-off?

4. What steps do I need to take to ensure that I get the best contractor for the job?
No question is out of bounds when you’re interviewing roofing contractors. Roofing jobs are expensive, and you want a roof that holds up to the elements, looks good, and lasts under warranty. “Nothing lasts forever, and roofs are part of that equation,” Cattel says. “But, you can maximize the longevity of that pretty expensive asset by doing it right from the start.”

When the professionals at DC Taylor Co. bid a commercial roofing job, they provide their prospective clients with a checklist to prioritize key criteria that are important when evaluating and selecting roofing contractors. They provide their information in all of the checkboxes and then suggest that the client use this information to assess other contractors during the bid process.

Information on the checklist includes questions about the contractor’s fiscal stability, including requesting financial statements; insurance coverage, including requesting information about levels of coverage and certificates of insurance; how contractors approach creating a safe working environment; and more.

“The owner has the absolute right to ask for as much information about that contractor as he wishes,” Stein says. “There’s nothing wrong with requesting five or more satisfied (or otherwise) clients to talk to. Ask for references for projects that used the same on-site project team that would be assigned to your job.”

Even if you don’t use a formal checklist, other key questions to ask upfront include:

  • How many roofs have you put down like this?
  • What kinds of quality-control measures do you take?
  • How do you approach safety issues?
  • Will the team include a qualified designer to troubleshoot engineering issues?
  • Which industry affiliations or certifications do you have?
  • What does your training program entail?
  • Who would be the foreman on the job? How many jobs like this has he done? Is his résumé available?
  • What are the supervisor’s qualifications? Is his résumé available?

Flexibility is the name of the game. Requesting a certain team can also be worked into your contract before you sign on the dotted line. However, bear in mind that you may not get next-day service. “You might need to wait until the crew is done with another job before they can start on yours,” Cattel notes, adding that building a good relationship with contractors is another way to ensure getting the best team assigned to your job.

5. How should I approach the bid process?
On many jobs (particularly larger ones), it might serve you well to bring a roofing consultant on board. These professionals know the products, can weed out good contractors from the bad, and can also assist you in producing a good set of bid documents prior to starting the contractor search. Pre-drawn specifications can keep the bid process competitive and work to your advantage in pricing.

“A set of bidding documents gives you the chance to get competitive bids,” Stein says. “You can talk to more than one contractor and be able to judge them based on the same scope of work and detailing methods. If you don’t have such a document, you’re relying on the contractor himself to propose a solution, which might not be well defined. Can you be assured he is looking out for your best interests in getting long-term results and value?”

Because roofing is one of your biggest capital investments, the job needs to be done right the first time around. “If you do your homework and find out what the appropriate budget is going to be, talk about the roof systems ahead of time and the timeframe for installing those systems, come up with bid documents ahead of time, and bid at the right time of the year, you can typically lower the cost of your project while ensuring that the job is done right and to your unique specifications,” Cattel says.

Robin Suttell, based in Cleveland, is contributing editor at Buildings magazine.

Intl. Roofing Expo 2007
By attending the Intl. Roofing Expo next March, you’ll discover the latest information on important industry innovations and find the products and devices that can make a big difference to your business. Featuring more than 450 exhibiting booths delivering over 105,000 square feet of roofing products and services, the goods and the suppliers you need to make your roofing projects perfect start here.

Below is a sampling of the seminars you’ll find useful at this year’s event, located in the Las Vegas Convention Center March 6-8, 2007. More information is available at (

Durability and Reliability in Green Roofing Systems
Green roofing is still a relatively new phrase, and the future of green roofing depends heavily on whether these initial systems perform reliably and are durable over the long term. Lessons learned from past real-world roofing and waterproofing projects will be shared to encourage reliable and durable green-roofing systems. Attendees will hear practical case studies of actual examples, supported with photos and illustrations. After attending, you’ll be able to:

1. Compare the advantages and disadvantages of different green-roof membranes.
2. Improve the reliability of details in green-roofing systems.
3. Consider drainage issues in the design of green-roofing systems.
4. Plan for maintenance in the design of green-roofing systems.

The Effect of Reflective Roof Coatings on the Durability of Roofing Systems
This course will bring together certain factors that affect the natural aging of roofing membranes, including BUR, modified bitumen, and EPDM. The primary effect documented is the reflectance and change in reflectance over time of the top surface of the membrane with resultant change in the thermal history of the membrane over time. The rates of physical change are related to thermal history and reflectance. After attending, you’ll be able to:

1. Recognize the effect of reflective roofing on the aging of roofing membranes.
2. Identify the differences in reflectance of different reflective coatings.
3. Distinguish the differences in natural weathering at three different U.S. locations.
4. Identify the physical properties of roofing membranes to understand the aging properties of the membrane.

Roof Deck: Key to Roof System Performance
While installation of roof decks is typically considered beyond the scope of most roofing contractors’ work, most agree that properly designed and installed roof decks are critical to roof-system performance. In this program, NRCA Technical Services Section staff will review roof-deck requirements and guidelines applicable to low- and steep-slope roof assemblies. While most types of roof decks commonly used in roof assemblies will be addressed, specific emphasis will be placed on metal roof decks and plywood and OSB sheathing. After attending, you’ll be able to:

1. Review commonly used roof-deck types.
2. Explain building code provisions applicable to roof decks.
3. Identify considerations for steel roof decks.
4. Recognize considerations for plywood and OSB roof decks.

Roof Fires: Lessons Learned
This session will encompass a presentation of case histories about actual roof fires. Panelists will discuss causes, crisis management, the media, lessons learned, etc. After attending, you’ll be able to:

1. Recognize the importance of communication.
2. Identify the importance of liabilities and employee training.
3. Comply with material safety data sheets.
4. Perform job safety analysis.

Understanding Metal Roofing: Part I
Often billed as “Metal Roofing 101,” this course includes technical information, but is presented in a common-sense fashion that makes the art and science of metal roofing clear, concise, and understandable. Topics to be covered include the history of metal roofing, metals and metallic coatings, metallurgy, galvanic weathering, and material-selection criteria. Also discussed will be fabrication and manufacturing techniques, various seam types and panel profile, in addition to underlayments, the use and misuse of sealants, seam technologies, and the principles of thermal cycling and panel anchorage. After attending, you’ll be able to:

1. Review the history and basics of metal roofing, including material-selection criteria.
2. Recognize fabrication and manufacturing techniques, coating application, and basic metallurgy.
3. Identify the evolution of seams and profiles, and the use of underlayments and sealants.
4. Learn flashing, sealing, joint, and seam technologies, as well as principles of thermal cycling and panel anchorage.

Self-Adhering Products: Best Practices and Common Problems to Avoid
This session will cover the features and benefits of the emerging technology offered by low-slope self-adhering roofing systems and where their application may be appropriate. It will provide best practices for the roofing contractor and why these practices should be exercised. Additionally, the session will caution the roofing contractor on common problems and mistakes to avoid. After attending, you’ll be able to:

1. Pinpoint where self-adhering membranes may be appropriate for use.
2. Determine what common practices are applicable for installing these membranes and what may be inappropriate.
3. Define the limitations of this product category and what pitfalls to avoid.
4. Determine what is different about the installation of these products and where special training may be required.

Roof Edge Performance During Hurricane-Force Winds
This presentation will discuss roof-edge performance observed after significant wind events such as hurricane-force wind speeds greater than 95 mph and sustained winds in a populated area on low-slope roofs. Photographs and detailed reports from the Powder Springs, GA, Roof Industry Committee on Weather Issues (RICOWI) will be discussed, focusing on unbiased investigation into roof-edge performance and failure modes. After attending, you’ll be able to:

1. Learn about ES-1 Roof Edge Standard as required by the 2003 IBC.
2. Calculate the required wind-pressure resistance.
3. Review RICOWI Wind Investigation reports from Hurricanes Charley and Ivan.
4. Discuss edge-failure modes as observed by RICOWI Investigation Teams.

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