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Retrofit an Existing Brick Mailbox With a Locking Mailbox

by Matt Prestwich, MailCase Locking Mailboxes

Most brick mailboxes do not have a locking mailbox installed, instead they usually have the common arched-top shaped mailboxes. Since these mailboxes are mortared in the brick column then most homeowners think it is not possible to change out the un-secured arch-top design for one of the new locking designs currently available on the market.

In fact, it is possible. It takes a little work but you can do it as a do-it-yourself project!

Determine if Your Brick Column is Big Enough

The first thing you will need to determine is if your existing brick mailbox is big enough to handle locking designs. The most common type of brick mailbox layout is a square layout with each side of the brick column having two full size bricks and an end brick. The most important factor in determining if your brick column is big enough is the distance between the end-bricks.


The most common brick sizes come in 3 types: Modular Size, Queen Size, and King Size. The distance between the end bricks on most brick columns built with modular brick and a standard layout is about 12" to 12 1/2.". For Queen size brick with a standard layout the distance is about 15" to 15 1/2" and for King brick the distance is about 16" to 16 1/2." Generally, brick mailboxes made with Queen or King size brick and a standard layout will fit just about any locking mailbox design on the market. Brick Columns made with modular brick are a bit more tricky. Only a handful of locking designs will fit it a Modular brick column with at standard layout.

Go out to your brick mailbox and measure the distance between the outer end-bricks as shown in the picture. Then look at the locking mailbox you are interested in buying and make sure the outside width dimension of the mailbox you are buying is smaller than the distance between the end-bricks (outer bricks) on the mailbox. Since your new locking mailbox has to fit in-between these end bricks, the mailbox has to be smaller than the distance between the end bricks (outer bricks).

You will also need to measure the height of the locking mailbox you are interested in buying and then measure your brick column to make sure there is enough room for your mailbox to fit vertically.

Is the Brick Column Hollow or Filled with Debris?

Each mason is different. Some masons believe in building the outer walls of the brick column and filling the inside full of brick, mortar and other debris. Often times masons will dump their extra brick and mortar inside the column to keep from hauling it away. Other reasons for filling the inside is to build up a support for the metal mailbox inside the column. Finally, many masons believe that by filling the inside with brick and mortar they will make it harder to damage the mailbox if it is hit by a car.

However, some masons build a hollow shell with nothing inside. These masons believe that they can save money by using less brick. Also, it can be faster to make a hollow shell brick column.

The best way to determine whether your mailbox is hollow or filled with debris is to pop the concrete cap on the top. This concrete cap is pretty easy to pop since it is only mortared into place. Be careful not to break it as you pop it off. I usually use a 2x4 and wedge it under the cap down to the top of the curb, then gently hit the 2x4 with a hammer close to the curb to pop the top off. Once it's popped, slide it back and see if it is hollow or filled with debris inside.

Cut the Face with Diamond Blade Saw

infflatpanel-concreteIf you don't own one of these concrete cutting saws (chances are you don't) then you will need to rent or borrow one. You can rent one for about $85.00 for a full day. They are pretty easy to use but make sure you find out from the rental place all the ins and outs of using it. I always use a hose to hook up to the saw to make my cuts wet. These saws will cut dry but it is very dusty and hard on the saws. Wet cuts are a lot easier and cleaner to make and it is a lot easier to see what you are doing.

Carefully mark the area on the brick column where you are going to cut (make it about 1/4" lager than the outer dimensions of the locking mailbox you are going to install). If your brick column is filled with debris, then you will want to start the cut right at the very top course of bricks (so you will be removing the top course of bricks). This is so you will have access to chip out the debris. If the mailbox is hollow, then you can leave the top course in place if you want and cut below it (as shown in the pictures in this example).

Start the saw and begin cutting. I usually make a 1/2" deep cut first to get my line straight before cutting all the way through the brick. Go right to the corners of your markings on the brick column but do not go over.

Since the saw blade is round, you have overcut areas where the saw does not go completely through the brick at the corners. It is important that you don't make your overcuts go past the corners where you marked the size of your locking mailbox. If you go over then the overcuts will be visible after you install the mailbox and they will look bad. The problem here is that if you go right to the corners with your round saw blade, then the saw won't go completely through the brick at the corners and you won't be able to remove the cut portion of the brick face.

infflatpanel-concreteThe solution here is to use your reciprocating saw. You will need a carbide blade for your reciprocating saw. Carbide blades can cut masonry. Use the carbide blade on your reciprocating saw to finish cutting out the overcut areas that you couldn't get with your diamond bladed round saw. When you are finished, you should be able to remove the cut section. If you've done it correctly then you should have an exact square, just like in this picture.

Prepare the Inside for the New Mailbox

If your brick column is hollow inside, once you remove the face then you will need to build a wooden platform on the inside on which the new locking mailbox will rest. I usually use Redwood to build this platform.

If your mailbox is filled with bricks, mortar and other debris, you will need to carefully chip this debris out. The easiest way to do this is to use a hammer drill with a chisel bit. You may need to rent this tool or borrow it from somebody if you don't have one Be very careful not to pry against the outer brick when chipping the debris out. The outer walls of the mailbox are weak since you have removed the top course of brick and the cap. If you pry against them they might break of. Chip out enough debris far enough back so the mailbox can fit fully back inside. You will want to have the mailbox protrude out the front of the brick column about 1".

Install Your New Locking Mailbox

The final step is to install the mailbox. For hollow brick columns, the easiest thing to do is rest your mailbox on the wooden platform you built earlier. Most locking mailbox designs come with 4 holes in the bottom for mounting. Use lag bolts and washers to mount your mailbox to the wooden platform. This will securely hold your mailbox into the brick column.

If you had to remove debris and hollow out the area where the mailbox goes, then it is usually easier to hollow out a little bit more debris right below the mailbox. Then get some mortar mix and add water. Create a bed of wet mortar in this hollowed out area and set your mailbox on this bed of mortar. When the mortar sets, the mailbox will be secure.

Use cedar shims to make your mailbox equidistant from the brick (from the end bricks or outer bricks) on both side of the metal mailbox. This will further stabilize, center, and secure the mailbox in the opening.

When the mailbox is installed, then slide the concrete cap back over the top of the brick column and mortar it into place.

You will see an unsightly gap around the mailbox where you made your cuts (you will also see the shims you put in to center and stabilize the mailbox). In the picture at the very beginning of this article you can see the mailbox installed in the brick column. There is a trim around the mailbox. This trim covers the gap and the shims. I make this trim out of Trex brand decking. Rip a piece of Trex in half with a table saw. Then rip it in half thick-wise so you have pieces of Trex that are about 1/2" thick and 1 1/2" wide. Carefully cut and miter the corners and screw the Trex together like a picture frame just big enough to fit around the locking mailbox.. I paint the Trex the desired color and then glue it to the brick column with construction adhesive. If necessary, I use clear silicone to fill the seam between the Trex and the brick to keep the water out.. When it is all done, it looks like the picture at the beginning of this article.

Wow, I know it sounds like a lot of work, and it is a lot of work, but it is easier then tearing down your whole mailbox and re-building a new one. It is also much less expensive and the final results look great!

The mailbox shown in this article is a MailCase Locking Mailbox but the techniques can be used for any locking mailbox brand. Just make sure the mailbox will fit in your brick column before you buy it. Good Luck!

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