Abstract: A waterproof sink insert (124, 124?, 124?, 124??, 124??) for installing an under-mount sink (108) in a built-up surround (104) having a non-waterproof support structure (116) so as to inhibit water damage to the support structure. The sink support insert is mounted within an insert opening (128) formed in the support structure. The sink support insert comprises a mounting region (144) located radially inward from the outer periphery (148) of the sink support insert. The sink is secured to the sink support structure within the mounting region. The sink support insert may optionally include one or more apertures (136) for receiving a faucet or other sink appurtenance(s).