Roofing Calculator Guide: Main Types and How to Use Them for Precise Estimates

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a hand calculator

A roofing calculator is your best bet for figuring out how many squares of roofing shingles you will need for your project. There is a wide variety of these available with just as wide a variety of uses. In this article, we’ll be identifying a roofing calculator effectiveness, and it’s best usage per the categories below.

Roofing cost calculators can be found on most websites with roofing shingles for sale. These roof calculators allow you to insert an SKU number and get an immediate price quote for your square needs. It’s finding out your squares that’s the tricky part!

How to Use a Roofing Calculator

roofers installing solar panels

Flat Roof

Flat roofs are most often seen on commercial buildings. The ideal calculator here is a roof area calculator. Since there is no pitch, there is no reason to use a roof pitch calculator.

Finding the area of a flat roof can be done with any good construction level calculator. For instance, Calculated Industries Material Estimator Calculator allows you to input two quick measurements and gain the area of the roof with just a push of the conversion button. Additional measurements can be quickly inputted for things like roof AC units, area cutouts and the such.

Flat roofs usually need to be tarred and pebbled, with numerous drains and vents checked for blockages. If you have a flat roof with shingles, it is best to speak to a roofing supply company in your area to see if they still stock these sorts of shingles. You usually only find them on older buildings and they are a bit more difficult to discover. Normal roofing shingles have a different tab system and may not line up as well as these specialized ones. If so desired, most flat roofs can be easily transformed into a papered and pebbled roof instead of a shingled roof, usually in the course of an afternoon for smaller buildings.

Short Pitch Roof

Short pitch roofs are usually found on small homes, businesses and tiny structures like dog houses. Roofing calculators, in this case, are usually triple functional computers that can deal with angled calculations. The Jobber 6 is ideal for this purpose, allowing you to input your area measurements then multiply them over your angulation calculation.

When dealing with short pitch roofs, buying an extra square to cover any miscalculation is always advised. These roofs are usually the easiest, quickest ones to scrape and recover if there are not extenuating circumstances. Why? Short pitch roofs usually have the least amount of error in the calculation because you aren’t dealing with a high angulation difference. If you do run afoul of your calculator, don’t feel bad. That’s what the extra square is for. Even professionals make mistakes.

High Pitch Roof

Roofs with a high pitch are usually best left to the professionals. These roofs are not only fairly dangerous to work on, but also hard to calculate based on their valleys and their specific requirements. These range from church steeples to pole barns to large homes with very high ceilings. Though these are by and far not the only high pitch roofs out there, these are probably the most commonly recognized.

Roofing calculators will only get you so far with a high pitched roof. Any roof pitch that is higher than 6/12 is considered a high pitched roof. With 8/12 and 10/12 becoming commonplace in the US over the past twenty years, these roofs are steeper and steeper. But let’s say you want to work with this anyway. Let’s look at how to use a roofing calculator here.

You have an 8/12 roof pitch. This means that for every foot of roof, your roof rises 8 inches into the air. Any roofing calculator that can cope with area measurements can deal with this, but the formula is tricky. Input your area then divide it by 2/3rds. Add on your original area formula. This should bring you to the correct square footage for your roof.

As with a short pitch roof, it is ideal if you buy a few extra squares. Unopened squares of non-special order roofing can always be returned, and it is much easier to return unopened items than to have to run to the store midway through a project.

Odds and Ends

When dealing with roofing, remember to inlay your valleys and peaks in your calculations. This means adding a new shingle for every foot of valley or peak in your calculations. With the average house, this tends to mean that you will go through one or two extra squares of shingles than your average calculator shows to be necessary.

If your roofing project has gutters or artistic flashing, remember that you will likely have to cut shingles around these. Though with a normal roof you desire overhang to help keep the water out of the eaves of the house, one with a gutter spout will do that for you.

Online Calculators

Online calculators are amazing little instruments that you cannot overlook. These roofing calculators are some of the easiest to use, most with numbered steps that show you where and what to measure. If you are a young professional just learning how to calculate a roof cost, or someone looking to perform their own roof maintenance, we highly recommend you to check your calculator’s numbers against one of these.

Also, easily found online are roof truss calculators. These allow you to triple check area and replace trusses as needed in larger building projects or insurance claim projects. Many online calculators have this built into the system, allowing you to see the size of your roof trusses without actually having to expose them. Remember that this is a general size estimate in this particular case and may not be perfectly correct for construction necessity sake. If you are actively replacing roof trusses, it is easier to climb into your attic and measure than to get the wrong sized and angled wood then need to replace it.

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