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DD_BobK DD_BobK is offline
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Default 1/2 inch anchors for hollow concrete block? Must resist pull out.

On May 20, 11:48*am, andyeverett wrote:
A costumer wants 7 foot ceder posts attached to the side of landing
made of concrete blocks topped with brick. A hand rail will be
attached to the posts and a flat ceder board attached to the top of
the posts that will serve as a plant shelf.

I'm not sure if a concrete slab lies under the brick? The landing is
about 30 inches high. What ever anchors I use must resist pull out
forces from the railing and shelf.

Do appropriate anchors exist for what I want to do?

Thanks for any help!


As per the other posts, unless your certain of the design &
constrctuion of the block portion of the landing, attaching a 7' post
to blocks and expecting them to resist side loading could be a recipe
for disaster.

The blocks and landing were probably designed & built with vertical
(gravity) load only in mind. Ungrouted (hollow) cell block
construction is is fine for gravity load but attaching posts / railing
to them is expecting a lot.

You could drill into the side of the landing to probe for whether a
slab exists.
I would recommend embedding a threaded rod with a coupling nut into
the slab & block using an epoxy product like SIKA AnchorFix #1.

Drill a 9/16" hole for the rod & counter bore a hole big enough & deep
enough to accept the coupling nut.
Embedding a rod & coupling nut will provide with a strong & flush
attachment. You can then attach the post with hex bolts. Prior to
attaching the post you could test the strength of the attachment with
a bolt, steel plate & large diameter stub pipe.

Using this setup you can determine if the embed will hold under
substantial force....if you can "jack" the embed out of the stab by
tightening the bolt I would have doubts about using it for a railing.

The attachment at the lower end of the post might be more problematic.

If the post needs to be able to take ~150 lbs lateral load, the upper
attach point needs to take ~500 lbs, the lower attach point a bit less
(depending on the location of the upper attach point)


Long answer for a simple question.... how much can you depend on a
hollow block structure?

cheers
Bob