Tapcon screws & concrete block?


I'm going to be building some heavy duty shelves in the basement, attached to concrete block. The horizontal supports will be 2x4s, with 5/8 material for shelves. My plan was to attach the 2x4s to the block using tapcons. Pre-drill through the 2x4s, then since the longest length tapcons I can find are 2 3/4, I was going to counter sink them into the 2x4 about 1/2". Here is the question. Am I better off going into the block, or the mortar joint? I've got a hammer drill, so that isn't an issue. I'm thinking into the block, rather than the mortar, would be a stronger fit. Each set of shelves will be 8' long, 2' wide. I was going to use 5 tapcons per 8' section into the wall. Open to suggestions. I've built these same shelves every house we've lived in, but in the garage attached to the studs. First time trying with concrete block.
Thanks,
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Another option would be to attach a few verical 2x4s to the wall (which will only require a few tapcons and therefore a few holes in the blocks) and attach the shelves to them. Less damage to the walls and easier to move the shelves if you ever need/want to.
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Attach some 2x4's vertically. Or hang the shelves from the sill plate and the floor joist above.
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Concrete blocks these days are not the robust castings of some years ago. Given their delicate nature, the less you depend on Tapcons (as good as they may be) the better off you will be. Consider the suggestions above, and also generous use of construction adhesives.
Joe
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What the other said, plus:
If you make the vert. 2x4s as long as possible, and let the bottom rest on the floor (mebbe with a metal spacer for moisture), theoretically you would just need one small screw at the top. Of course you'd use a substantial screw at the top, but you'd need less-substantial screws further down, as they are more for stability.
You could also use a butterfly anchor, but you'd have to make sure you're hitting the hollow of the block.
What I've done, for very heavy shelving loads, is drilled *thru* the concrete block, and nutted threaded rod from the other side -- if you have access.
Another neat option is this:
If the *opposing wall* is accessible, theoretically you wouldn't need any screws at all. Put up the vertical 2x4s, and *wedge* them with horizontal 2x4s, along the ceiling, to the opposing wall. Small rabbet joints, etc would make this very secure.
Any screws/adhesives would be just for lateral-type stability, not for structural strength. I've actually done this a number of times, works great. Plus, the horizontal wedging 2x4 is available for hanging all kinds of stuff, etc. In which case you might want a vertical 2x4 on the opposing wall as well.
These types of methods greatly reduce uncertainties/loads on existing structures, and place the load/stresses almost totally on the shelving frame itself, mostly in the form of compression. Tension/bending (like anchoring to walls) is always dicey-er. Doable, of course, but dicey-er.
--
EA



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wrote:

Yeah, sorry I forgot to mention that the 2x4s should at least rest on the floor so that they are taking the weight and not the anchors. I would at least put one anchor at the top and one at the bottom so there's no chance of the the 2x4s shifting and leaving the weight on the anchors.
Personally, I prefer to build self-supporting units so I can put them wherever I want, but that's substantially more work to make them stable.
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Self-supporting shelves that are attached to the wall for safety or stability purposes are much better than something built in that requires structural support for each shelf via additional fasteners...
~~ Evan
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Existential Angst wrote:

All that is needed is one 2x4 across the top front of the verticals, said 2x4 being held into place by fastening vertically into the trusses/joists above. Of course, one *does* need to have the trusses going in the needed direction :)
--

dadiOH
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Joe J wrote:

Sounds good to me, going into the block not the mortar. I built mine the same way. Only thing is my block was filled with concrete every 2 feet so it would actually be difficult to get a Tapcon to strip. If none of your blocks are filled, just go easy and not too much pressure with the hammer drill. And if you get one here and there that don't hold well, just drill again a few inches over. Or, I hear people have very good results with loose holes by inserting a piece of 12 or 14 gauge copper wire then screwing the tapcon in again. So hopefully you have some extra romex around.
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