"Joe J" wrote in message
...
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.

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




Thanks,