Why estimate tiles and shingles?

Tile and shingle roofers use the age old method of estimating materials based on squares, and have done so for generations. They gauge bundles per square (100sq ft in Imperial) or pieces per square (1 sq metre in Metric), As the method is inaccurate, they use ‘waste factors’ to ensure that enough product gets onto the job site. As a result, roof estimators, who know the cost and inconvenience of ordering short, usually order more product than needed.

Here is why you should estimate tiles and shingles with professional software:

image shows shingle roof

The waste factor method is unreliable

The ‘waste factor’ method is unreliable and not good business practice. Its accuracy depends on

  • how the pieces are laid out
  • whether the offcuts are used or not
  • whether the pieces are interlocking as some tiles are (fixed lap), or have a variable head-lap like a slate
  • the roof geometry.

‘Waste factor’ in Estimating

If you think a standard ‘waste factor’ will help you save time, let’s look at an example to illustrate the point.

Let’s compare two roofs that will have metal tiles installed, both with identical roof areas – 146SqM. We will ‘lay’ the pieces course by course, almost as if we were on the roof.

Roof 1: In this example, the required tile quantity is 390 pieces and there is virtually no waste at all, it all fits. Chances are, a typical ‘waste factor’ calculation would have gotten the job done.

Roof 2: This roof has the same area as Roof 1, but it needs a lot of cuts at hips and valleys. The so called ‘waste factor’ that an estimator would need to include to get this job right is a staggering 39%. As a result, the likelihood of being short on materials on the job is very high. The job needs to go on for longer to make up for the missing materials, eating into the roofing company’s profit and effecting other programmed work.

How can you calculate exact roofing quantities?

Roofers need to receive the exact quantities they need to get the job done in the allocated time and budget. With AppliCad Roof Wizard software, estimators plan the job on a 3-D model of your roof, and run a report that itemises all materials.

The software ‘practices’ the application of the pieces (in our example, a metal tile replica that is 1200 x 300 or 4’x 1’), and shows how the tiles will be laid. It even takes into account of a range of user-defined variables for adding pieces for hips and subtracting pieces at valleys, etc.  

Using these controls, the smart estimator will be able to control the placement of the materials to optimise for the re-use of offcuts thereby reducing ‘waste’ to less than 20% even on a cut-up roof like this one.  This assumes of course that the installer will actually bother to re-use the offcuts.

Simulating the process of installing the product makes the material take-off so much more accurate.

Why AppliCad?

Only AppliCad uses true 3D modelling and simulates piece-material application course-by-course. This is how we can guarantee accuracy of your takeoff, if your plan and live site measurements match. Roofing businesses who use AppliCad software can be confident that they are in control of their margins on a job-by-job basis. They typically also win more jobs, and each job is more profitable because they save time for re-orders or material returns. As a result their service, at competitive rates, will be better for their clients, too.