Edge Distance for Drilling into Concrete

09-22-2011, 01:40 PM	#1
JetMech642 Newbie   Join Date: Aug 2011 Posts: 3	Edge Distance for Drilling into Concrete I will be installing four vinyl porch posts on an existing concrete slab that is 4" thick. The tapcon concrete screws I will be using are 1/4" x 2 1/4". How close can I get to the edge of the concrete without worrying about cracking the concrete?

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09-22-2011, 01:53 PM	#2
sixeightten Framing Contractor   Join Date: Feb 2009 Location: NE Ohio Posts: 872	Edge Distance for Drilling into Concrete I would tr yto stay at least 4 inches away. Only drill as deep as you need to. They make tapcons that are shorter.

09-22-2011, 02:10 PM	#3
AGWhitehouse Architectural Designer     Join Date: Jul 2011 Location: Connecticut Posts: 1,365	Edge Distance for Drilling into Concrete I agree with 4". We have gone as close as 3" with some designs, but unless you can ensure the concrete mix is strong enough I'd stick with 4". __________________ Life's too short...so enjoy it! To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

09-22-2011, 07:00 PM	#4
TrapperL Member   Join Date: Jul 2011 Location: South Texas Posts: 162	Edge Distance for Drilling into Concrete We drill these things weekly and the installation calls for the post to be at the edge of the slab. We drill at 1 1/4" away from the edge. I've never had a slab break in the last decade or so.

09-22-2011, 08:50 PM	#5
Mr Chips DIY Hack     Join Date: Mar 2008 Location: Location, Location Posts: 1,296	Edge Distance for Drilling into Concrete With Concrete Screws you want to maintain an edge distance of at least 6 anchor diameters, but keep in mind your tension and shear values are greatly reduced when you are this close. You need to be at least 12d from an edge to get full tension and shear __________________ Those who can, do... Those who can't criticize on the internet