# Is there some sort of formula to determine how many bricks I would need to build a completely new structure?

I am looking to add a small ham shack to the property, so I contacted the city's planning department. They said that if the structure was ten feet at most and didn't exceed two hundred square feet in area, and it was kept at least six feet away from the main structure, and three feet away from any property lines, I should be able to carry this out without a permit.

I went over to this place called Mutual Materials where they have an assortment of bricks of different textures, concrete, stones, and other things used in masonry, including mortar for mixing.

When I asked the clerks there how much the bricks would cost, they told me that as a general rule of thumb, six bricks made one square foot. Well, I can see how laying six bricks vertically can make one foot, but I don't see how it would make a square foot unless one were to add five bricks on one side going horizontally, which would mean that you'd need thirty-six bricks in all to make a square-foot wall.

Can this be explained better? I found out that one brick costs \$1.30, so if I can use something to know how much I'd be looking at, that would help a lot.

• What is the surface area of the walls? – Harper - Reinstate Monica May 9 '19 at 14:14
• -1 This is basic maths, not a DIY question. – AndyT May 9 '19 at 14:19
• @AndyT Yes, it basically a geometry question. But there are often "hidden" details that enter into DIY projects - e.g., in this case the mortar (which decreases the number of bricks needed) or in the case of wiring needing to have extra wire at the ends (e.g., if you have 10' between panel & receptacle, you need more than 10' of wire). So asking here is the right thing to do. – manassehkatz-Moving 2 Codidact May 9 '19 at 14:47
• @manassehkatz It's barely a geometry question. Calculating area with rectilinear tiles generally falls under math you learn at about 8-9 years of age in most school systems around the world. Asking here is one option. If OP has kids in elementary school, asking them might be an option too. – J... May 9 '19 at 18:55
• @J... "If I divide the area of this wall by the area of this brick, what number do I get?" is barely a geometry question. "How many bricks do I need?" is more than that. Your elementary school child is probably not going to account for the mortar joint. Or the extra N buried courses you should have (if any). Or the fact that professionals typical add X% for wastage/breakage. Or that if you're making a wall over a certain size, you might want a double layer of brick, not a single layer. Etc. -- That's manassehkatz's point: blindly cranking numbers often misses important considerations. – R.M. May 9 '19 at 20:23

A standard brick is 8" x 2.25" x 3.5". Ignore the 3.5" as that's how thick the wall will be. 8" * 2.25" is 18 sq. in. A square foot is 144 sq. in. (12 * 12). 144 sq. in. divided by 18 sq. in. is 8. But I left out the mortar. It's possible that the mortar on six bricks is equal to about two bricks.

Another way of looking at this is that each brick is two thirds of a foot. So you need a brick and a half to make a foot. If you stack bricks four high, that's nine inches without mortar. Add three quarters of an inch of mortar to each brick, and four bricks is exactly a foot. Now, I think that three quarters of an inch is a bit much, but you also have sideways mortar that I didn't include.

Anyway, if we assume they know what they're talking about, you have one square foot of wall is six bricks. If you want your wall to be seven feet high and ten feet wide, you need 7 * 10 * 6 = 420 bricks. That's \$546.

This answer did the same thing with four 8' tall 14' long walls and got a total of \$3494.40.

I think that the confusion is that you were trying to make a cubic foot wall. But that's not what they mean. They mean that a square foot of wall surface takes six bricks. So when looking at a piece of wall and measuring out a square with one foot to a side, you'll count about six bricks. Roughly four rows of one and a half bricks each.

• Leaving out mortar is a pretty serious oversight. Do the math while adding the thickness of the mortar to the width and height of the brick. – Harper - Reinstate Monica May 9 '19 at 14:13
• The mortar is often as thick as the difference between two times the depth of the brick and the length. That way you can build a nice looking wall end or column. – Phil May 9 '19 at 17:18
• Go out and measure the pitch of bricks (including mortar) in a well-constructed wall. Don't expect it to be any sort of round number in modern feet. ISTR the size of a brick relates to a foot back in 1500 or thereabouts, and never changed thereafter because nobody would want to buy bricks that could not be used to repair walls that already existed. (But Roman bricks are a different size. And many of their brick structures are still standing). – nigel222 May 9 '19 at 18:06

Take the outside dimensions of the proposed project and the brick supplier can tell you how many bricks you will need to complete the project including a percentage for loss and breakage. Done

• How about interior walls that are brick? – Lee Sam May 9 '19 at 12:47

What he's talking about is a unit of area, which measures the surface of something. Take an airplane - the surface area of an airplane is important when you are buying paint for it.

We already have a unit of measure called a foot that measures linear distance. Suppose you make a square, and each side of the square is 1 foot. That's called "1 square foot". We don't mean that the thing has to be square.

The only thing "1 square foot" means is that if you have just enough paint for a 1-foot square, you'll have just enough to paint it.

Here: • The upper left figure is 4.0 square feet.
• The lower left figure is 4.5 square feet (count 'em).
• The circle, well, you have to do some geometry there, but the answer is 7.07 square feet.

So take your shed. Take 1 wall. How wide is it, in feet? How tall is it, in feet? Multiply them and that gives you square feet. Repeat that for each wall, and add them together.

We are overlooking something. At the corners, one wall's brick is also the other wall's brick. But in practice, that will end up being a wash, because you will probably need to cut bricks to make them fit (unlikely your building is exactly the right size to come out evenly).

Example: 14 feet x14 feet =196 square feet of floor space. That is just under 200 square feet.

Each wall 14 feet long 8 feet high = 112 square feet of wall space per side.

112x4= 448 square feet of total wall space .

448x6= 2688 bricks for a 196 square foot structure with 8 foot high walls no windows or doors.

2688x\$1.30=\$3494.40