I have a predicament, I am putting up a shelf into the wall.

The wall is plaster, and then hollow and then concrete. I have screws with toggle bolts on them.

The 2 inch screw with the toggle bolt was too short to get the toggle bolt inside the plaster to the hollow part.

The 3 inch screw with the toggle bolt is too long because it hits the concrete. But the toggle bolt will reach into the hollow part.

How do I approach this dilemma? Do I need to drill into the concrete somehow? I think my current drillbit is incorrect for doing this, but I'm not sure.

Insight appreciated

  • Are the toggle wings too long to open up inside the gap in the wall? Stick a small object through until you hit the concrete, and mark off the distance. If your measured distance minus the plaster thickness isn't longer than the toggle wings, then you need a different bolt or you need to drill out the concrete. Otherwise, you can do as dbracey suggests and cut the 3" bolt down to between 2 and 3".
    – Doresoom
    Mar 8, 2012 at 19:13
  • what tool would I use to cut the metal bolt? also, even with the 3" bolt I had to wiggle the toggle bolt in one side at a time, because the concrete was too close. I'll measure
    – cqm
    Mar 8, 2012 at 19:15
  • If you have a dremel with a cutoff wheel attachment, that would work. Otherwise a vise and a hacksaw could do it.
    – Doresoom
    Mar 8, 2012 at 20:37
  • 1
    Find a stud, problem solved.
    – Tester101
    Mar 11, 2012 at 13:49
  • @Tester101 That solution is way too simple. We need to add at least 5 steps, one of which requires kayaking to Alaska. :)
    – Doresoom
    Mar 12, 2012 at 15:31

6 Answers 6


Are you comfortable with cutting the bolt to a length between 2" and 3"? That would be simplest.

Another possibility would be to use another piece of wood between your shelf and the wall to create more thickness for the 3" bolts.

If the concrete is actually concrete block, you can drill into that quite easily with a masonry bit from your local hardware store. If it is an actual poured concrete wall, best not to bother.


To shorten the bolts:

A) Take the bolt to a hardware store, tell someone you want the same bolt but in a 2.5" length - this is likely the easiest thing.

B) Cut the bolts:

  1. Thread a nut onto the bolt and spin it back towards the head.
  2. Use a hacksaw to cut the bolt (if you clamp it, clamp on the nut and head - not the threads) - OR - use a Dremel with a cut-off wheel - OR - use boltcutters!
  3. Unscrew the nut from the bolt; this will clean up the damaged threads where you cut it.
  • how can I tell what material it is? I can only shine a flashlight through the hole and see there is something hard there that is not wood. The outside of the building is bricks with concrete in between the bricks
    – cqm
    Mar 8, 2012 at 19:12
  • If there is a big hollow space I don't think you want to screw into the concrete - there will be a lot of shear force on the screw and it might not hold it since it's not designed for a large gap between load and the surface its being anchored to. Cut the screw to the desired length instead and stick with the toggle.
    – Steven
    Mar 8, 2012 at 19:18
  • what tool would I use to cut the screw
    – cqm
    Mar 8, 2012 at 19:26
  • I think he's proposing just making some room for the ends of the bolts, and still using the toggle - not screwing into the concrete.
    – dbracey
    Mar 8, 2012 at 19:26
  • See added lines in the answer above.
    – dbracey
    Mar 8, 2012 at 19:27

What I did when I lived in Virginia was to install a piece of wood that would bear the weight of the curtains so that I could install the curtains at any height of width and not worry about studs!

The beauty of this is the wall doesn't support any of the curtain weight and the whole installation can be removed with very minimal repair to the wall.

I took a 2X4 piece of wood cut to the width I wanted the curtains to extend past the window/door, plus 3 inches.

I painted the wood on 3 sides with the same paint on my wall.

I then located the studs of the window/door frames. I located not only the side studs but the other studs above the window & door frames and marked them, too.

I transferred the location of all the studs marked with a level to the new height I wanted to install the drapes, plus 3 inches, so I could see the transferred marks.

I took the level and drew a light pencil line below where the wood would be installed. I put it below because it's just too hard to see from above when you place the wood on the wall and struggle to attach it! I found that it is best to draw a level line the entire length of the installation or do a snap-line. Otherwise, the line tends to creep up or down, even with a level...!

I positioned the wood so the rod would hang at the right height. You have to determine this by temporarily screwing your rod brackets into your piece of wood on both sides. You should have about 1 1/2 inches left on each side of the wood so it won't split. Be sure to set the brackets in the middle of the 4 inches of wood and at the correct finished width you want the curtain. Figure in how high the curtains and hooks need to be to hide the wood. You may have to use different hooks than planned to get the height to hide the wood. Be sure to adjust the height of the wood placement so the curtains will hang where you want them. Then remove the screws.

Install the wood onto the studs. Put a screw through the wood and in all the transferred stud marks. This strengthens the whole wood installation.

Screw the brackets back into the wood where you temporarily put them, and then into the wall.

Install the drapery rod into the brackets.

Install the curtains.

Erase the stud marks and touch up the paint where they were, feathering the paint out so it is not noticeable.

With 8 ft ceilings, I went just short of the crown molding minus the height of the curtain when it was properly hung with pins on the rod, about 3 inches down. That way the curtains did not interfere with the visual line of the crown molding.

The traditional height for setting a curtain is 4 inches above of the window frame. I wanted to make the rooms seem more impressive so I set the curtain height just below the crown molding.

I also extended the rods beyond the sides of the window frame so the windows appeared wider than they were. This extension on the sides had the added benefit of allowing me to push the curtains back as far as possible while still hiding the side window frames. That allowed the fullest amount of light possible to enter each room. Since the house was an interior townhouse, this was a huge benefit and lightened up the entire house.


I buy 100's of toggle bolts at a time and have for years and years:

The weak link of TB fastening in drywall or plaster is the wall. Because 3/16" TB's slightly exceed the weak link in strength, it's the only size I use. 1/4" doesn't gain much strength and 1/8" can be weaker than the wall.

I always buy TB's with 4" long bolts because the length makes them easier to use, and when you need to shorten them (and that's very common), there're plenty of hand tools that'll cut a 3/16" bolt with ease. Always have your TB fully assembled on the object you're mounting, with a fender washer if needed, and have the toggle screwed onto the bolt past the cut point before you cut. Toggles are not quality hardware and are very unforgiving of buggered up threads.

TB's are not for mounting heavy objects. Shelving should be supported from studs.

TB's can't be used to mount objects that are much smaller in width or height than the width of the open toggle. If the open toggle is 2" wide and say a shelving channel is 3/4" wide, to allow the toggle to fully tighten without pulling through, you have to use a fender washer or similar under the channel against the wall that's close to 2" in diameter.


My sheetrock was close to the outside concrete block wall. A 3" bolt hit the block wall and stood out too much from the bracket I was installing. A 2" bolt wouldn't go in far enough to allow the wings to expand. After some thought I decided to drill a 3/8 inch hole into the concrete block deep enough to allow a 3" bolt to go in far enough so it wouldn't stick out from my bracket. After some trial and error on how far to initially screw the wings onto the bolt, I managed to get it work.


I had similar situation trying to install curtain rod hooks on the wall with thick sheet rock, hollow space and concrete block.

For the screw length issue - The guy at home depot matched the screw from the toggle bolt package by thread count to the sheet metal screws and picked the right length. This gives more choices.

My case was bit worse. I didn't have any screw length for which the toggle will open. The wing length was simply longer the the hollow space. I am posting couple of things I tried just in case.

For half the hooks, I took a sharp chisel and took out bit of inside edge of the sheet rock (through the hole drilled for the toggle bolt) up and down. I took out enough so the toggle will open if inserted vertically. With much difficulty I twisted it around to be horizontal where the sheet rock edge was in fairly decent shape and tightened it.

Since this was getting messier, I tried to cut the toggle wings bit shorter with a snip so it would not get stuck in the sheet rock. Again, after sacrificing few bolts, I had my own custom toggle bolt. It worked - I was able to install rest of the hooks this way.

Not sure how much load capacity I compromised cutting the wings off. Hope it doesn't fall on my head. Not an ideal solution - nonetheless, something to think about if your shelf is not going to be holding all volumes of encyclopedia britannica.


You can cut a slot in the drywall so that the wings don't have to fold. Select or cut a screw to the proper length.

WARNING: This will not be as strong as the traditional installation method.

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