Drilling tapcons into hollow blocks

[MiamiCuse]

Is there any special tricks in using Tapcons on hollow concrete block walls?

I want to secure copper pipes, PVC drain pipes etc... onto my block walls using those copper straps. I am using 1-1/2" Tapcon screws and drilled a hole then when I feed in the screws it reached bottom and spins. The straps are still secured in that I can't pull them out, but I would prefer I can drive the screws in and be tight and snug.

The block walls are built with the typical 8" thick hollow blocks with a web in the middle. I think if I drill into the solid part of the block it's better but most times this is not practical as the pipe may be a vertical run from floor to ceiling and I want to secure it in say three spots and they are all in the thin part of the blocks.

Is there a trick? Will a specific size and length work best, reading the Tapcon website it says it needs a minimum embedding depth of 1" to a maximum of 1-3/4". It looks like the blocks are about 1" thick. When I drill them sometimes it punches through and sometimes it does not. I am just not doing something right so I stopped before I drilled too many holes.

Thanks in advance for any suggestions.

[Oren]

Try shorter screws?

Are the screw threads the full length of the screw shank?

[Chip C]

I don't think hitting the hollow part of the block is the problem. As the box says, the 1" thickness of the block ought to be enough to get the screw snug. If the screw is turning freely, then you've stripped the threads that the screw has cut in the concrete, it's really got nothing to do with whether the tip has entered the hollow void.

I'd say your drilled holes are too large. Are you using the specified bit for that size of tapcon? (Some packages include a bit; all of them tell you what size to use.) I've used tapcons occasionally and I often find that the bit wanders or precesses enough that it creates a bigger hole than it ought to. So maybe try a slightly smaller bit.

Chip C Toronto

[Colbyt]

Use the shorter screw and make sure you have the proper bit used in a hammer drill at moderate speed.

For your situation the 1 -- 1-1/8" would be the correct choice.

Sometimes you are hitting a core and other times you are not.

Colbyt

[Michael Dobony]

It is better to drill into the mortar between the blocks.

[MiamiCuse]

I know I am using the correct size bit because the bit came with the screws.

I also don't think I am "stripping" the threads at all, because I can back a screw out and then use it in another spot and it would work.

It's a hit and miss, and misses more than hits.

Thanks,

[EXT]

Not really, drilling into the mortar is easier but the mortar is not hard enough to support much weight not hold many anchors. Most Tapcons will not hold in the mortar but will just enlarge the hole and fall out. The Tapcons I have purchased in the past only called for 1" to 1 1/4" penetration into the concrete not up to 1 3/4".

[Michael Dobony]

Drilling into the hollow area often breaks the inside of the hole, reducing the bite of a Tapcon. Mortar will hold tapcons very well for the OP's intended use. If you have trouble with enlarging the hole you can use an expanding rivet type anchor or use foil to get a grip.

[DerbyDad03]

re: "I also don't think I am "stripping" the threads at all, because I can back a screw out and then use it in another spot and it would work."

The issue is not with stripping the threads on the screws, but with stripping the hole.

Once that happens, there is no way to make the same size Tap-Con work in that hole again. Once you've spun one, forget that hole and move on.

If you absolutely need to place a screw in that location, fill it with epoxy or something and start over.

You have to extra careful when using Tap-Cons in block walls. You have to get a feel for the speed of your driver so that you drive them fast enough so that they bite and become snug, but not so fast that you strip the hole.

Here's an FAQ on tap-Cons:

[hrhofmann]

It sounds like the hole is a little bit too big for the tapcon. I would put some epoxy on the female portion, place it in the hole, and then wait for the epoxy to set and then insert and tighten the screw.

[Oren]

What if one whittles a wooden peg, inserts it and snug's the screw?

Cheaper than epoxy?

[Steve B]

Yes. As with anything, understand the enemy. Take a block of the type you are going to drill into, and observe where the thick parts are, and that is where you want to drill in for max strength. Typically at the ends and the middle.

If the block was grouted solid, as some are in block walls, you can drill most anywhere and hit solid meat. A simple tap will either ring hollow or solid to tell you where the cells are grouted or not.

There is no trick. If you drill into the thin part, you will either blow a hole, or have a weak spot and your fastener will pull out. Just like regular walls. You can either hit a stud, or hit air.

Which one do you want to hang your Picasso on?

Steve

[Oren]

Drilling a pilot hole into a block cavity will not cause it too "break" inside the hole every time.

The OP was smart to ask his question. It amounts to a simple tap into the wall, cavity or not.

Rivets are not worthy, for this task?!

...short screws...

[dadiOH]

Save the Tapcons for something else and use short lead anchors and regular fasteners.

[Michael Dobony]

No, maybe not every time, but much of the time. It is more reliable to drill into the mortar than the block.

For holding a pipe strap? Have you looked at rivet type expanding tip anchors? They have a pretty good holding power. You put it in all the way into the hole and drive the pin in with a hammer. The end expands considerably and creates quite a grip.

[Red Green]

"dadiOH" wrote in news:cZxan.225540$ [e-mail]:

That's what I use. Wondering if anyone was gonna mention it. Thought maybe because of lead they were now frowned upon or illegal.

Google lead anchors if unfamiliar with them.

[DanG]

You can add a piece of #12 electrical wire (leave the insulation on) and reinstall the Tapcon, it will hold quite well. This method works just as well using drywall and other screws in CMU walls. It does a tremendous job holding concrete forms to a slab with double head 16's also.

[Tony]

The blue screws sound a little long. Do the threads possibly go through the block and all you have is the smooth shaft in the block?

(more below)

Try easing up on the drill pressure so hopefully it won't punch a hole through, if these blocks are more of a problem than most, try turning off the hammer action on the drill when getting close.

*And here is the trick my brother recently taught me!* Remove the loose blue screw, get some scraps of 14-2 romex and insert a short length of 14 gauge copper wire (stripped). Reinsert the screw again with the copper wire in the hole. It really worked great for me! He said if it doesn't hold, don't bother with 12 or 10 gauge wire, drill a new hole.

[mkirsch1]

You're stripping the HOLE, not the screw.

If you are using a cordless drill to drive the screws, you need to loosen the clutch up so it clicks before you strip out the screw.

[mkirsch1]

Do you even know what you're talking about?

What female portion? Tapcons drive directly into the concrete.