How do I find a stud behind bathroom tile?

A magnetic stud finder works through tile: it finds the screws holding the backer board to the stud, which is exactly the line you want. Electronic finders often misread tile. Studs typically sit every 16 inches; confirm with two screw hits on the same vertical line.

Can a grab bar go into drywall without a stud?

Not as fall protection. Ordinary drywall anchors are not rated to catch a falling adult, and the wallboard itself crumbles under shock load. Anchor into a stud, use a masonry wall, or use a floor-to-ceiling tension pole instead.

How do I know if my shower wall is fiberglass?

Knock on it. Fiberglass and acrylic surrounds sound hollow and flex slightly under palm pressure; tile over cement board sounds dead and does not move. A surround is a thin shell with air behind it — nothing screwed into the shell alone is fall protection.

What does a renter do about all this?

Skip the wall entirely. A tension pole braces floor to ceiling, grip strips and mats work underfoot, and a clamp-on rail rides the tub rim. All of it comes down without a trace when the lease ends.

What wall do you have? A 60-second test

Every grab-bar disappointment we've read starts the same way: somebody bought the hardware first and met the wall second. Do it in the other order. One knock, one magnet, and one look at the surface tell you which of four walls you own — and the wall, not the product page, decides what can hold a falling adult.

The four walls, in section

Cross-sections of four bathroom walls: drywall on a wood stud, tile over cement board on a stud, a hollow fiberglass surround, and solid masonry — with the stud and masonry marked as holding a rated anchor and the hollow shell marked as failing — Two of these walls take a 500 lb anchor. One takes it with an extra drill bit. One never will.

The test itself

Do this	If you get	You have	It means
Knock across the wall	dead thud everywhere	Tile on cement board or masonry	HOLDS with the right anchor
Knock across the wall	hollow ring, slight flex	Fiberglass / acrylic surround	WILL FAIL — shell only, use a pole
Run a magnetic stud finder	screw hits every 16 in	Stud line located	HOLDS 500 lb at that line only
Look at the tile surface	matte, textured, stone-look	Suction-hostile finish	WILL FAIL for any suction device

What each wall allows

Drywall on studs — most bedrooms and hallways

The board itself holds nothing worth trusting; the stud behind it holds everything. Anchored into a stud, a steel bar like the Moen Home Care series carries its published 500 lb rating. Between studs, no anchor sold in a blister pack changes the physics.

Tile over cement board — most tiled showers

Same stud, one extra step: a carbide bit through the tile at slow speed, no hammer mode, painter's tape to stop the bit wandering. If drilling tile is out of the question — rental, deposit, nerves — the tension pole stands beside the tub instead.

Fiberglass surround — the hard case

Three millimetres of shell with air behind it. Nothing screwed into the shell alone is fall protection, and suction cups only grip its smooth zones for balance. This wall is the single strongest argument for the pole: floor and ceiling are structure; the surround never was.

Concrete or masonry — older buildings, some condos

The best wall in the house: a sleeve anchor holds anywhere, not just every 16 inches. It costs you a hammer drill for an afternoon — rentable — and repays you with placement exactly where the reaching hand wants it.

Questions people actually ask

How do I find a stud behind tile?: A magnetic finder locates the screws holding the backer board to the stud — that screw line is your anchor line. Electronic finders often misread tile. Confirm with two hits on the same vertical.
Can a grab bar go into drywall without a stud?: Not as fall protection. Drywall anchors aren't rated for shock load and the board crumbles. Stud, masonry, or a tension pole — those are the three honest options.
How do I know if the shower wall is fiberglass?: Knock. Hollow ring and slight flex under a palm means surround; a dead thud means tile on backer. The surround is a shell — treat it as untouchable and work floor-to-ceiling instead.
What does a renter do about all this?: Skip the wall. Pole, strips, mat, clamp-on rail — the full renter's setup touches nothing permanent and leaves with you.