Basin on a vanity: which edges need silicone?

Read the mounting drawing

A rocking basin needs stable support. The tap and waste may have their own gaskets. A surface bead can hide a leak from underneath without repairing it.

Where the detail calls for sanitary silicone on two compatible surfaces, consider OTTOSEAL S100. Porous stone needs a stone-compatible product.

If one edge is marble or natural stone, trial OTTOSEAL S70 on an offcut and check the tooling agent before touching the visible surface.

Inspect the rear edge

Where the manufacturer requires a splash seal, identify the vanity material and check the cartridge against both surfaces. S100 can suit compatible sanitary surfaces. Use a light behind the bowl and retain access to the trap and fittings.

Try the Presch silicone gun behind the tap before final assembly. Check the clearance for your hand and the trigger as you turn the corner.

Practise behind the tap

Offer up the empty gun and check whether the tool can turn the last corner. If the tap is not fitted yet, agree the order with the installer. A swollen panel needs the water source and board condition investigated before sealing.

Try the FUGENFUX profile behind the basin. If you cannot finish the pass, agree on a sequence that leaves the tap out until you are done.

Should I seal the side of the unit to the wall?

Only if the installation detail calls for it. Keep doors, drawers and removable panels free. Photograph hidden seals before fitting the basin.