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Finding solid wall behind tiles to mount pedestal sink!

Finding solid wall behind tiles to mount pedestal sink!

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  #1  
Old 06-19-16, 10:44 AM
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Finding solid wall behind tiles to mount pedestal sink!

Not sure where best to post this, could belong to plumbing, tiles, masonry, carpentry framing...kind of a mix...so here goes.

Started out as a super simple project of mounting a pedestal sink. Which involves anchoring the pedestal to the subfloor and the sink to the wall. This is on concrete slab and an exterior concrete block wall, so my idea is to just mark where the two mounting holes are on the wall and the one on the floor, drill the holes through the wall tiles to the concrete block wall, and the single hole through the tiles to the slab and fasten with 1/4" Tapcon screws. Simple enough.

The first issue I ran into was the really hard and dense porcelain tiles. My masonry bit won't even make a dent. I then switched to 1/4" diamond hole saw bits and they worked much better, but still end up consuming 1 bit per hole, but I got the three 1/4" hole done (one for the floor and two for the walls). Then I switched to hammer mode with my Tapcon bit and drilled into what's behind.

For the floor, I found solid concrete under the tile and drilled my 3/16" hole for the 1/4" screw. No problem.

For the wall, I hit a "wall". You know what I mean, my masonry bit went through different materials as I went deeper and deeper. From the finished porcelain tile, I went through about 4" of "stuff" before I hit the actual concrete block wall.

As best I can tell, behind the 3/8" porcelain tiles laid by the last owner, under that is a 1/2" layer of cement board, behind that is 3/4" of empty space, which is to be expected because it's furred out...then I ran into a layer of ceramic tile, which the bit went through easily but spitting out reddish brown dust, under that I believe a layer of 1/2" sheet rock, then another inch or so of void (furring?), then the concrete block wall. I switched to the longest 1/4" Tapcon bit I have which is 5.5" and drilled until it bottoms out.

So basically, from the front of the concrete block to the front of the finished porcelain tile is about 4" of stuff and voids. The longest 1/4" Tapcon screw is 5". The pedestal sink mounting hole has a thickness of about 3/8", which means the deepest I can sink the 5" Tapcon screw is about 4-5/8"...that is only biting into the concrete block wall about 5/8".

The entire bathroom is tiled wall to ceiling, so I am not going to tear out the whole bathroom to eliminate the extra layers.

Yet I am not too confident about mounting a pedestal sink on a wall using two 5" screws where only the last 5/8" is biting into something structurally solid.

I am aware that most likely this is OK because the weight of the sink is actually on the pedestal and not the wall, and I have even seen some people mounting those sink using toggle bolts on sheetrock...but still I like a more secured solution is there is one.

I have looked at the Tapcon web site and they do have a 6" screw but it's 1/2" diameter. That won't do because the sink mounting holes are smaller than 1/2" diameter, besides, I doubt I can easily enlarge the 1/4" holes I already drilled going through those diamond hole saw bits.

I am wondering are there any products out there, like a bolt hanger for wood, but a long one for concrete? One side can be screwed into the 3/16" concrete block holes, the other side sticks out of the finished tiles by about 1/2" to 1", and I can mount the sink on then tighten down with a washer and nut?

or use the 5" long 1/4" Tapcon screws, just apply tons of adhesve caulk to the back of the sink where it meets the tiles, and let the wall adhesive, the two tapcon screws on the wall and the floor pedestal do their joint duties to hold up the sink?

Or other ideas?
 
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Old 06-19-16, 11:12 AM
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If you do not want to to use toggles (or something similar) you could use 1/4" threaded rod with 1/4" nuts and washers. To connect the rod to the concrete wall use some of this:

Sika 10.1 fl. oz. AnchorFix-1 Anchoring Adhesive-112729 - The Home Depot

OR this:

Quikrete 8.6 oz. High Strength Anchoring Epoxy-862031 - The Home Depot

Leave the rod long to work with it and then cut it off when the epoxy sets. When cutting it off spin a nut on first, cut the rod, then take off the nut to clean up the threads.
 
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Old 06-19-16, 11:41 AM
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Although it may too late for this. You could mount a 1 x 4 across the wall and then mount the sink to it.
 
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Old 06-19-16, 12:08 PM
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I have done a modified version of this on concrete walls when hanging crown molding.

If you already have your holes drilled, take the maximum depth you have - 5 1/2" and insert a 1/4" dowel rod all the way into the hole. Then take a 4" deck screw and drive it through the dowel. The dowel will expand and grab the tile in the first two tile walls. Dowel bites the tile, screw bites the dowel. While I have not done this with such a large format, it works well with smaller screws. May want to start the dowel off with a pilot hole down the center to help guide the screw to the second wall cavity. It is also a good thing to use pressure treated lumber when in contact with block or concrete. So you may have to rip down a piece of pressure treated lattice.
 
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Old 06-19-16, 02:19 PM
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Tolyn, that might work. So basically using this epoxy to anchor a 1/4" threaded rod, and hang the sink on the ends of the rod, then secure with a rubber washer, metal washer and nut.

The only thing is as I squeeze the epoxy into the wall cavity blind I have no idea how much of it is formed across the various layers creating support or if much of it is falling into the cavity bottom. I see I will need to insert the nozzle as deep as possible, then squeeze as much of it as I steadily back out trying to get as much into the hole as possible.
 
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Old 06-19-16, 02:22 PM
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I am not too keen on another layer of 1X4 from the wall...that aside, I am not sure how one would mount the 1X4 to the tiles. I would have a similar problem connecting the 1X4 to the concrete block layers behind it, unless you are talking about using toggle bolts to secure to just the tiles or sheet rock which is what I am trying to avoid.
 
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Old 06-19-16, 02:31 PM
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czizzi, I think I follow your idea. So basically, I "fill" the 1/4" hole with a wood dowel. Then mount the sink, then drive a long deck screw into the dowel, relying on it to expand and grab onto all the wall layers behind it. In a way this is a DIY version of a sleeve anchor.

The problem I see is as you stated, the screw has to be driven centered in the dowel and not go off on a skew.

Furthermore, it would be impossible to "drive" the screw in, as the sink mounting holes are tuck under a recessed cavity under the sink, there is no room to put an impact gun or drill straight. If I do it this way I would have to drive the screws without the sink first, then back them out of the dowel, then mount the sink, then use a socket wrench with a bit to hand crank the screws back in.
 
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Old 06-19-16, 02:49 PM
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The only thing is as I squeeze the epoxy into the wall cavity blind I have no idea how much of it is formed across the various layers creating support or if much of it is falling into the cavity bottom.
You will want to get the epoxy in the hole you made in the concrete. Another option would be put the epoxy on the rod itself and then insert it into the hole.

IMO - I think a Toggler wall anchor would more then strong enough. Toggler Snaptoggle | Anchor Bolts,Toggle Bolt, Toggle Bolts
 
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Old 06-19-16, 03:40 PM
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I went through about 4" of "stuff" before I hit the actual concrete block wall
I agree on using anchors if you have a cavity behind the tiled wall.
The Togglers are strong, but personally here's a link to the strongest anchor I have ever used.

The anchors I reference require the special bit be purchased also. For maximum load, you need to drill a clean 3/4" hole and the special bit does that better than any I've seen.

WingIts World's Strongest Fastener Standard (2-Anchors)-RC-MAW35-2 - The Home Depot
 
  #10  
Old 06-19-16, 04:29 PM
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Check to see if your sink also doubles as a wall mount. If so, there will be a mounting bracket that you can attach to the wall first then mount the sink onto the bracket and lastly the pedestal underneath which then is just decorative and not supportive.
 
 

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