Questions and answers · For your plant

How do you fix an undermount sink without adhesive?

Short answer

The most secure way to fix an undermount sink is mechanically: Ø12 mm holes are drilled in the underside of the worktop, self-locking KLEIN FIX threaded inserts are pressed in, and the sink is screwed on with the brackets from the Kit Sink set. The crowns lock the insert in the hole, so the joint has full strength immediately — no adhesive and no waiting for it to cure.

KLEIN FIX is suitable for marble, granite, quartz engineered stone, sintered stone, ceramics and HPL — from 7 mm slab thickness. In laboratory tests a single insert withstands on average from approx. 80 to approx. 590 kg of pull-out force, depending on the version and material. If you don't want to drill, there are BIG BASE bonded bases.

Installation step by step

  • Drilling — Ø12 mm diamond bit, pillar drill with speed control, water cooling. In thin slabs, a bit with a depth stop.
  • Check — the GO/NO GO gauge confirms the diameter, and the depth must not be less than the “h” value for the insert.
  • Press-in — the insert is pressed in by hand or with a setting punch, flush with the surface.
  • Sink — the Kit Sink brackets are screwed to the inserts, the sink is pressed up and the wing nuts are tightened.

Why without adhesive

Glued studs have to be left to cure, and a worktop with glued-on parts takes up more space in transport. KLEIN FIX inserts are fitted in a few minutes — in the workshop or at the client's — and nothing protrudes from the underside, so worktops travel flat.

Recommended

Products for the job

StoneZone is the exclusive distributor of these brands in Poland. We can test every tool on your machine.

ITAFIX

KLEIN FIX

Self-locking stainless steel threaded insert: Ø12 mm hole, press in and full strength right away — no adhesive.

See product →
FAQ

Frequently asked questions

How many inserts does an undermount sink need?

Usually 4–6, depending on the size and weight of the sink and the type of bracket. We set the spacing for the specific sink.

Which insert for a 12 mm sintered stone worktop?

KLEIN FIX without head with 4 crowns (e.g. KF06/12/4N) — requires a slab from 12 mm and a hole 8.5 mm deep. For thinner slabs there are versions with fewer crowns or with a head.

Can the hole go right through?

No. The hole depth must match the insert, and the top of the worktop stays intact. In thin slabs a bit with a depth stop is used.

See also