Understanding Units of Measure in Construction Estimating

So let's talk a little bit more about units of measure. And the question might come up is, how do you know what to measure something by? It just comes with practice, it comes a little bit research to find out exactly how things are being priced out. But the first step, as mentioned earlier, find out from your suppliers how the material is being sold.

And then also find out from your subcontractors, if you don't already know, how the labor is going to be performed. Because bottom line is, you're going to look at the cost of labor, the cost of material, based on their units of measure. So here we have general conditions.

General conditions is measured by months or weeks, it's duration and time. So whatever it costs for your company to operate that project per month, and then you tell it's going to be a six month project or a 12-month project, that's how you come up with your total general conditions costs. Remember, general conditions is similar, or it's the same as GCs.

Site work and grading typically uses square feet or acres or cubic yards. Reinforcing steel could be one or the other for a unit of measure. It could be either linear feet or it could be priced out by the ton on larger projects.

Understand that when it's priced out by the ton, it's going to say a ton of what? Well, it might be a ton of number five rebar or number four rebar. So more information might be required, but typically that's how your reinforcing steel would be priced out. Concrete footings, again, see that's a volume calculation, so that's going to give you cubic yards.

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Concrete slab is by the square foot. We touched on that as well. Your masonry.

Okay, masonry walls are different depth thicknesses. They go deep into the structure. It could be six inches wide, it could be 12 inches wide.

That doesn't matter because in masonry, it's going to be a square foot cost per square foot of the surface area, and that has to be factored in with the type of masonry that's being used. Is it a six inch wide? Is it a nine or a 12 inch wide? But typically that's how your measurements are calculated with masonry as a square foot. Wood framing and lumber uses board feet as a measurement.

That's 12 inches wide by one foot long by one inch thick. That is considered one board foot. Most of the stores, most of the supply houses that you go to, though, will sell you the wood differently, and it's a little bit easier to work with.

I'll take 20 two by fours or I'll take two by sixes, except they need a thousand feet of those. They can be priced out that way or they can be priced out by the board foot. The board foot itself can actually be a preliminary number overall based on square footage.

It's going to be approximately so many board feet. This will not be part of the estimate, but it's important to understand or recognize BF as in board feet should you ever come across it. Let's talk about plywood.

It's by the square foot, but keep in mind that when you purchase it, you got to purchase it by the sheet. There's a lot of products like that, so there could be a lot of waste associated with it. If you're going to price it out by the sheet, it's still going to be a total of four by eight or it could be a, you know, four by ten or even a four by twelve if you could find it that large.

If you use one unit to measure square feet, keep in mind that you might have to find out how it could be purchased and you have to buy additional feet. In other words, it's going to generate perhaps a lot of waste that you hadn't anticipated on. We'll talk a little bit more about the waste factor as we get into the class, but it's important that you get compensated for every square foot of material or every linear foot of material that might be out there, whether or not it's all installed.

Structural steel, this is the real heavy stuff. This is what we refer to as like the structural element of a building that will be measured in tons, and that's tons per foot. When you have certain size I-beams, those I-beams are going to range in length, but the tons per foot doesn't change unless you get into a larger size altogether.

So TN for tons is not uncommon. It's very typical for structural steel measurements. Sheet metal is by the square foot, but then again understand that a lot has to do with the gauge of material that will be driving the price up.

It's all measured by a square foot, but the price of the different types of sheet metals and thicknesses makes all the difference in the world. Roofing tile, this is a little bit unusual and why this is why I included it as well. Roofing tile is based on squares, not a square foot, not a square yard, but a square of roofing material.

So technically you have a 10 × 10 area as a square, but if you think about it, roofing tile overlaps each other. Well what about all the overlap? How is that calculated in? Well technically the roofing tile for a square already factors in the tile that's going to get lapped over the next layer or the next row. Okay, so theoretically roofing tile is considerably more square feet than a 10 × 10.

Doors and windows, these are priced out and labor is performed based on an each or a count. Plaster, plaster again is another unique one. It's priced out by the square yard and if you're going to ask me how we came up with square yards, I honestly don't know.

It's been around forever. It's nine square feet of surface area that is for your plaster. Although the plaster itself is actually purchased in bulk by certain size sacks that mix with water or it's going to be per cubic yard as well.

So keep in mind that plaster by the square yard is synonymous or very similar to stucco, even gunite, venetian plaster, whatever it may be. It's a different measurement in thickness for each one of them, but at the same time it's still measured by square yards. Metal studs is by the linear foot, but keep in mind that within a metal stud itself there's so many other combinations that have to be factored in, which is the gauge of the stud, the width of the stud, whether it's structural, considered structural or galvanized and so on.

But all studs are for metal framing, for example, they're measured in linear feet. Drywall is square feet and similar to plywood, note that you could have total square feet, but when you purchase the material are you going to purchase it in four by eight sheets, four by ten or four by twelve sheets. Each one of them has different factors as far as how much waste is going to be involved.

So in this particular case you're only going to have exact quantities of surface area for your labor for drywall to install it, but you're going to have to purchase considerably more in square feet and you might look at that and how many sheets you're going to need to purchase that will tell you how many square feet there are. Floor tile is typically by the square foot. Carpet, there's two types of carpet measurements that we may come across.