How to Fill a Tub Spout Gap

Written by heather lamborn
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How to Fill a Tub Spout Gap
Bathtub diverter spout (water image by Joshua Peterson from

You can fill a gap behind a tub spout with silicone, but take care to keep the job neat. It would be best to try to fix the gap problem before resorting to caulking. Review the fixes before trying to caulk the gap. If the fixes will not work, or if they seem to be too difficult, then caulk with silicone. Even if a fix works, you may want to caulk a remaining small gap.

Skill level:
Moderately Easy

Things you need

  • Caulking gun
  • Silicone for Kitchen and Bath
  • Allen wrench
  • Tubing cutter
  • Nipple

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  1. 1

    Fill a gap behind a bathtub spout only as a last option. There are slip on spouts and threaded spouts. Only the threaded bathtub spout has the possibility of not being adjustable. Determine the type of spout before going any further.

  2. 2

    Look for a set screw under the spout near the wall. If there is a set screw, then the spout is a slip on type. The screw is usually a hex screw. Use an Allen wrench to loosen the hex screw, and try to slide it in or out, using a slight twisting motion as you push or pull on the spout.

  3. 3

    Push the spout with a gentle twisting motion to see if it will press tightly against the wall. If is does, tighten the hex screw and you are done. If it will pull out but will not push against the wall, the copper pipe is too long and must be cut.

  4. 4

    Pull the spout off the wall with an easy twisting motion. Open a tubing cutter until the roller blade fits over the tube. Tighten the blade until it presses against the tube, and begin rotating the cutter. As you turn the cutter, tighten the blade until it cuts through the copper.

  5. 5

    Slip the spout over the copper tube. The tube enters a gasket that will seal the tube inside the spout. Push the spout against the wall and tighten the set screw. If there is no set screw, the spout is screwed onto a threaded pipe. If the gap is 1/4 inch or more, unscrew the pipe from the wall.

  6. 6

    Protect the spout finish with two turns of duct tape, and use a pipe wrench, turning counterclockwise.

  7. 7

    Thread the spout in a bit farther if the gap is less than 1/4 inch. Wrap the spout with two or three turns of duct tape to protect the finish. With a pipe wrench, grip the duct tape portion of the spout, and tighten without applying excessive force on the wrench. If the spout will not tighten a full turn, the spout must be removed.

  8. 8

    Check the pipe or tube coming out of the wall. If it is a 1/2-inch copper tube with a threaded male adaptor on the end, use the tubing cutter to cut off the adaptor. Purchase a slip-on spout and slide it over the cut off copper tube. Push the spout against the wall and tighten the set screw to hold it in place.

  9. 9

    Remove a steel pipe, called a nipple. Tape a piece of thin cardboard or heavy paper to the wall to prevent damage. Grip the end of the nipple with the pipe wrench and rotate counterclockwise. The nipple may extend only a 1/2 inch from the wall, so be careful not to crush the pipe.

  10. 10

    Purchase a nipple 1/2 inch shorter than the one removed. Wrap three or four turns of Teflon tape around both ends. Screw the spout onto the nipple as far as it will go by hand. Insert the nipple into the wall and turn the spout by hand. Wrap the spout with duct tape for protection and continue turning the spout with the pipe wrench.

  11. 11

    Remove the short nipple and insert a longer nipple that is the same length as the one that was replaced if the spout goes to the wall but seems to turn almost hand tight. You will have to caulk the gap.

  12. 12

    Caulk the tub spout if all else has failed. If you were able to make the spout fit pretty well, you may still want to caulk around the spout.

  13. 13

    Caulk around the spout with white bath and kitchen silicone caulk and a caulking gun. The silicone caulk will go on messy, so have a bottle of rubbing alcohol and a rag handy.

  14. 14

    Wipe neatly around the spout with your finger after applying the silicone with the caulking gun. Clean your hands with rubbing alcohol quickly, before it dries. Wet a clean rag with rubbing alcohol and carefully wipe the excess silicone from the wall. Be thorough with the cleaning, because silicone is not paintable. After cleaning the wall, wipe the excess silicone from around the tub spout.

Tips and warnings

  • If you don't have a pipe wrench, remove the tub spout with a screwdriver handle or pliers handle. If that doesn't work, then use a pipe wrench.
  • Do not use too much rubbing alcohol while removing excess silicone. If you wash out some of the caulk, you will have to apply more silicone.

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