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Your Best Estimate

Effective construction estimation helps save materials and money

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Construction estimating helps contractors control costs like materials, time and labor on their projects. Contractors prepare bids or tenders to compete for projects using a cost estimator that determines costs and prices. A cost estimator will typically use estimating software to estimate project bid price, which will become part of a resulting construction contract. While there are many facets of construction cost estimating, this article focuses on materials.

Correct estimating is vital to reducing construction material waste. Correct estimating ensures accurate material deliveries to prevent downtime from shortages. How exactly does an estimator estimate the cost of metal construction project materials? The process is complex, and far more detailed and intricate than could be covered in this article. However, learning the basics about cost estimating for metal construction materials can help non-cost estimators understand what is involved.

Reid Ribble, CEO, of National Roofing Contractors Association (NRCA), Rosemont, Ill., says to avoid metal construction material estimation problems, it helps to start out by choosing the right metal roof for the building. “Next, design a layout in the estimating process that provides clarity on how the roof system will be installed,” he adds. “Taking these steps before a roofing installer even shows up on the job can go a long way to having an accurate estimate of labor and material.”

The Square

Anyone familiar with construction has heard about the square; it’s an imperial unit of area used in the United States construction industry and was historically used in Australia. One square is equal to 100 square feet. It does not matter how you arrive at 100 square feet:

• 10 feet x 10 feet = 100 square feet or 1 roofing square

• 5 feet x 20 feet = 100 square feet or 1 roofing square

• 2 feet x 50 feet = 100 square feet or 1 roofing square

The traditional method of metal construction estimating was to guess the number of squares for a roof, guess the length of edges such as ridges, hips, valleys, gutters, etc., and then put a base dollar rate per square for materials. This was a dollar rate per foot for trim and a dollar rate per square for labor. However, Ray Smith, managing director of AppliCad Software, Jupiter, Fla., believes such an approach does not account for complications such as extra fitting out around roof features or changes of roof pitch, nor does it account for reuse of offcuts to save waste and increase profit.

“Estimating based on squares is how people used to do it and how they might still estimate materials such as shingles,” he says. “Serious metal roofing companies (manufacturers or contractors) use programs such as our Roof Wizard software because nothing is a guess and everything can be checked and re-checked easily and quickly. All output is automatic once the dress rehearsal is done on the CAD model. [It is] fast, accurate and repeatable. Repeatable means that you can get six people to do the same take-off and you will get six answers that are the same. All reports are designed by the operator to suit the needs of the business and are generated automatically.”

Again, successful estimating aids in the correct ordering of the number of metal construction squares and other materials. In his 40 years of working on metal roofs, Larry W. Johnson, roofing and sheet metal operations manager, Chamberlin Roofing and Waterproofing, Dallas, says the biggest waste he has witnessed has been in over ordering panels (or flat stock) for a project.

“Knowing how to estimate panel length is key, especially on hip or valley areas. If the estimator isn’t well versed in computing increasing (or decreasing) panel size on cut-up roofs, it can be a huge accident waiting to happen (profit wise). If you aren’t experienced in this, the very best option is to wait until you have an opportunity to physically measure the actual roof surface itself.” Smith cautions that estimating metal roof materials is not like estimating shingle roof materials. “If you’re a bundle or two short of shingles, you just whip down to the nearest hardware store and buy another couple of bundles and finish off the job,” he says. “If you have ordered too many, the supplier will take them back and give you a credit. If you screw up a metal roof take-off, then you are in a very bad place. If your panels are too short, then that is a catastrophe; you can’t stretch metal panels. If the panels are all too long, then you waste time with extra cuts and you have increased the waste (material that you have paid for that ends up in the trash) and reduced your profit margin. It also means that your job was over-priced, even if you convinced the customer to pay for it.”


Estimating Software

It would be impossible to look at material cost estimating without looking at today’s software technology. Doing job-costing calculations used to require hours of manually inputting data on columnar sheets of paper (spreadsheets). There was a lot of room for error.

Job-costing software streamlines, eases and speeds the bidding processes. After inputting the requisite data for a project, estimating software does the calculations saving time, allowing bids and formal proposals to be presented to potential customers quicker. Many metal construction estimating software programs can seamlessly integrate with other business management software for inventory control and contractor payments. Some can even export the panel cutting list to the controller of a rollforming machine for automated manufacture, reducing errors and increasing efficiency.

“Software should allow the user to define any unit types such as any weight unit associated with any length unit,” says Paul Plummer, president, Coon Creek Software, Minneapolis. “Software should also track weight by length unit and type, and total by estimate/job so the estimator knows how much shipping capacity is needed.”

“Estimating software, when used properly, can help greatly in reducing over ordering or under ordering when making your cut list for a roof,” Johnson says. “[Software has] formulas in place to calculate panel lengths for you, based on roof pitch, panel width, valley and hip lengths, etc. However, estimating software is not perfect and will never replace experience when it comes to controlling costs.”

Brendan Doyle, president of Brendan Doyle Associates, Fernandina Beach, Fla., says reroof estimating software can play a major part in an efficient business model for a metal reroof contractor. He believes some of the attributes of an effective estimating software program should be:

• Allows an accurate and complete bill of materials to be priced in a timely manner for the reroof estimate

• Includes manufacturer specific comprehensive parts packages for roof and trim

• Should be intuitive to use and must be able to handle complex geometry, while generating effective preliminary plans for presentation purposes

• Generates standard details in AutoCAD and PDF format: these can be used to rapidly put together a product specific set of installation drawings

“[Some] software permits electronic order entry; the project parts list is transmitted directly to manufacture, and typically, it can be delivered in two or three weeks from order entry,” Doyle adds. “This is crucial in the short‐cycle aspect of the metal reroof market. In turn, this ensures quick turnaround time for working capital, good cash flow, etc.” AppliCad’s Roof Wizard software generates accurate estimates for all roofing and cladding, with particular emphasis on metal panels, trim and accessories. However, “We prefer that we do not estimate anything,” Smith says. “That implies a guess. We prefer to use the term take-off so that we get accuracy in estimating. The software allows an operator to create a 3-D model using very basic parameters, starting with perimeter measurements and a roof pitch. Materials defined by the user are applied to the model for the installation. From that, a full material list is extracted, a client proposal, supplier orders, installer’s pay summary, detailed panel and trim cutting lists, including all accessory items such as clips screws, adhesives, and even fall protection, fabrication and installation guidelines.”