What size Tapcon concrete screw do you use to fasten a 2×4 to concrete? I will give you the answer straight away but please read on for some helpful tips for using Tapcon anchors. The correct length for fastening a 2×4 to concrete, block or other masonry material is 2-3/4”. From there you have a couple options. First off you have a choice of diameter. Tapcon comes in either 3/16” or ¼” diameter. I would recommend the ¼” size as it is less likely to snap and offers more holding power. You have two head styles to choose from, either flat or hex head. You may prefer the hex head where your application allows as the head won’t strip. The latest version of the screw are now star drive so stripping the head really isn’t a concern. Some situations require a flat head (countersunk) head screw, for instance if you are fastening a 2×2 furring strip to the wall and you are going to lay drywall or paneling over the top.
Some have a love hate relationship with Tapcon screws. Problems with installation usually happen when either the wrong length of anchor is used or if the hole is drilled the wrong size or not deep enough. The proper installation of Tapcons starts with the correct size. To find the right length Tapcon for you application, add 1” to 1-1/4” to the thickness of the material you are fastening. So for instance our 2×4 is 1-1/2” thick. If we add an inch we come up with 2-1/2” which size isn’t available so we jump up to the 2-3/4”. Drill bit diameter is set by the anchor diameter. A 3/16” Tapcon will use a 5/32” bit where as a ¼” Tapcon will use a 3/16” bit. Usually you will find a bit packed with the anchors. It is just a straight shank hammer drill bit so you may want to purchase an SDS hammer bit if you have a SDS hammer, they drill much faster. The last consideration is drill depth of the hole. You need to over drill the intended penetration of the anchor to allow a place for the dust. Try for ¾” to 1”. It also helps to pull the bit in and out a couple times as you drill to get some of the dust out. So again for our 2×4, our Tapcon is going 1-1/4” into the concrete so we want the hole to be 2” to 2-12
When the correct anchor is selected and installed properly, Tapcon are a great fastener. They have a coating that makes them acceptable for treated lumber and easily removable if you make a mistake. They are readily available, inexpensive and require just a hammer drill to install. Follow the installation directions above and you will really appreciate these handy little anchors. If you are interested in a faster option than Tapcon check out our post on framing your basement with the Ramset Cobra Plus.
Proper Installation Of Tapcon Concrete Screws
Benefits Of The Tapcon Anchor
