Determining a Unit Price for Masonry
Most masons will likely need to figure real costs for work to be done. Here’s how to determine a unit price for masonry.
Being a mason contractor requires many skills. You have to estimate projects, maintain equipment, provide material and labor, and collect your money.
Estimating, for some masons, has become easy. When a project is set up to pay by unit price, you simply tell the contractor how many brick and block you will lay per amount. That is it. If the contractor pays a bit better for each task, it will include extras like quoins, arches and sills.
However, a time will likely come when a smaller mason will need to figure real costs to perform a task. Here is a basic example.
You need to build a brick and block wall that is 50 feet long x 8 feet tall. How many units will you install to build it? Well, by unit price, it may be as simple as $X.00 per thousand brick and $X.00 per concrete block. Do you know how many brick and block you will lay?
The area of the wall is 50 feet times 8 feet which, equals 400 square feet. The number of modular brick is 6.8 brick per square foot of wall (without extras). So, 400 square feet times 6.8 brick per square foot equals 2,720 modular brick.
Now, to calculate the concrete block (Concrete Masonry Unit or CMUs), there are 1.125 CMU per square foot of wall (without extras). Doing the math, 400 square feet times 1.125 CMU per square foot equals 450 CMU.
The materials you install will be mostly on grade, but you will have to construct a hop board or a small scaffold to top out the coursing. This will take a little time. Whether you use a hop board or scaffold, the 8-foot boards you could use generally only give you 7 feet of span due to end lapping.
For a 50-foot span, you will need: 50 feet divided by 7 feet, equaling 8 boards. Triple this for the double hop board and single material board, and you now are moving a minimum of 24 boards. Keep in mind that, if you are using a scaffold, it would legally be 56 boards, two walk boards, and five material boards for each scaffold span. All of this material has to be on the truck, ready to be installed, before any materials can be laid.
How much wall wire is necessary, and how many wall ties do you need to install?
If you see that the wall is 12 courses tall, you can easily figure that the wall wire will be every other course. That would equal six levels of wall wire. Six levels times 50 feet per level will equal 300 linear feet of wire to be installed, or 30 pieces – almost a bundle.
Another way to figure this would be to take the square footage of the wall and divide it by 1.33, which would equal the same number. Let’s just say this is a small residential project and corrugated ties are going to be used. One method of figuring the ties is one tie for every 10 brick.
In this case, that would equal 272 ties, which is a small box of ties plus part of another box. Another way to figure this is to take the square footage of the wall and divide it by 1.45. That should give you an accurate number of ties.
Mortar for the CMU
Mortar is the last part of the estimate to be covered here. Mortar can usually allow for about 140 brick per bag in the wall, and 35 CMUs per bag.
Here is quick way to figure this:
Here’s the math: 8 feet times 50 feet, times 1.125 CMU per square foot divided by 35 CMU per bag of mortar, equals 13 bags of mortar that will be required for this wall. You will mix mud seven times in a two bagger.
Mortar for the brick
To estimate mortar for brick, here is the math: 8 feet times 50 feet, times 6.8 brick per square foot divided by 140 brick per bag of mortar, equals 20 bags of mortar required to lay the wall. You will mix mud 10 times in a two bagger.
This simple wall that you quickly offer unit prices for includes roughly:
- 2,720 brick
- 450 CMU
- 30 pieces of wire
- 272 brick ties
- 24 walk boards minimum
- 33 bags of mortar
Now you can know exactly how much material you’ll install when you figure a small project.
Steven Fechino is engineering and construction manager Mortar Net Solutions. Steven has 35 years of experience in masonry restoration, moisture management and hardscape construction.