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It is sometimes necessary to drill a hole in the concrete slab of your storage shed. If you have an existing concrete slab that you are building a shed on you will often need to attach the bottom plates of the shed walls to the concrete slab. This is done by drilling holes and installing anchor bolts along the shed wall lines.

Drilling a hole in concrete is as easy as drilling a hole in wood. You just need to have the right drill and drill bit to drill concrete, stone or masonry. The drill used to drill concrete is called a hammer drill. A hammer drill works just like a regular drill except that it also hammers as it drills. The drill bit used to drill concrete is specially made to withstand the hardness of concrete and the hammering from the drill. The best drill bits are carbide tipped, they last many times longer than a regular steel concrete drill bit. The terms Concrete, Masonry and Stone are used interchangebly in this article.

Remember to wear safety glasses and ear protection when drilling concrete!

brief how to

In this article, you will find information about:

How A Hammer Drill Works
Setting The Depth
Drilling The Hole
Types Of Hammer Drill Bits

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Hammer drill
Concrete and Masonry hammer drill bit, make sure it fits the hammer dril.

step 1 How A Hammer Drill Works

To drill a hole in concrete you need to have a rotary hammer drill. A rotary hammer drill works by hammering the drill bit as it rotates. The hammering crushes and chips away the concrete and the drilling lifts the material away from the cutting edge of the drill bit. Most hammer drills have the option to drill only, hammer only or hammer and drill at the same time. These three settings are used in the following ways:

Drill Only: This is used like a regular drill. This can be used, with the proper bit, to drill through rebar or things like tile or other ceramic or masonry products that are very brittle and cannot stand up to the hammering.

Hammer Only: This setting will hammer without turning the bit. This is often used with a spade bit like a chisel to do demolition work like removing floor tile.

Hammer And Drill: This setting is used to drill concrete, stone and masonry.

hammer drill settings

step 2 Setting The Depth

Set the depth of the hole to 1/4" deeper than the concrete anchor will penetrate into the concrete, don't forget to include the thickness of the material that you are screwing or bolting to the concrete. 5 inch anchor bolts are commonly used to attach shed walls to a concrete slab.So for a shed wall bottom plate you will need 1 3/4" for the treated wood and washer and then at least 3 inches into the concrete. There are two ways to judge the depth of the hole in the concrete or masonry. Either a depth gauge or masking tape:

Depth Gauge Most hammer drills come with a depth gauge so you can tell when you have drilled down to your desired hole depth. The depth gauge works by adjusting a rod on the side of the drill so it touches the surface of the masonry or concrete when the drill reaches the desired depth.
Masking Tape: If you don't have a depth gauge you can simply put a piece of masking tape around the drill bit. When the drill bit drills into the masonry far enough so the tape touches the surface of the masonry then you can stop.

step 3 Drilling The Hole

Starting The Hole: Place the drill bit on the mark for the hole and start the drill. Apply pressure to the drill and begin drilling. You may need to restart several times because of the bouncing around of the drill bit.

start concrete drill hole

Drilling The Hole: Hammer drills work best when they are allowed to hammer, when you press down on the drill with excessive weight the hammer part of the process is greatly reduced. Let the drill do the work. The amount of pressure on the drill varies with the size of the drill and the diameter of the bit. Try drilling with different pressures and see what drills through the concrete fastest.

concrete drill pull out

Cleaning The Hole: Withdraw the drill bit from the hole every 30 seconds to lift out the concrete dust. This helps the drill bit cut more quickly thru the concrete. After you get to the desired depth you should use a shop vacuum to remove the concrete dust from the hole or at the very least put the drill bit into the hole several times, turn it on to load it with concrete dust and lift it out of the hole.

concrete drill finish

Hitting Rebar: Sometimes you will hit rebar when drilling concrete. When this happens there will be a noticeable change in the speed that the drill is drilling. Rebar can quickly wear out the concrete drill bit. There are several options when dealing with rebar:

Drill the hole in another location
Use a shorter depth anchor, you may need to use more anchors.
Use a rebar drill bit. These drill bits fit into the hammer drill but you must turn off the hammer function and use the drill only setting.

step 4 Types Of Hammer Drill Bits

Hammer drill bits have splines on them to keep them attached to the drill during use. Since the drill hammers on the back end of the drill bit these splines help for the drill to have a hold onto the drill bit. Because of the extreme stresses put on the drill bit a hammer drill uses a bit that is made from hardened steel and is coated with carbide for extra strength.

sds drill bit end

The most common drill and drill bit system used for home improvement and light commercial applications is SDS plus or SDS max.

sds concrete drill bits

More drill bit information: There are two basic types of concrete hammer drill bits; Multi purpose or Hammer drill. Hammer drill bits come with 3 different types of spline systems; SDS plus, SDS Max and Spline. Without getting into all the details of the way these different bits hook up to a drill the most important thing is that if you buy or rent a hammer drill make sure that the drill bits you get are made for the drill you are going to use.

The most common drill bit used when building a storage shed is the 1/2" size because this is the size of bit needed to drill in holes for anchor bolts to hold the shed wall bottom plates to the concrete slab.