Slab maker requirements for the cabinets underneath
A countertop ends up only as flat as the boxes below it. Quartz and stone manufacturers publish the conditions their slabs need, and those conditions treat old cabinets and new ones alike.
- Sound, straight, level, and square. Cambria's installation FAQ asks homeowners to confirm that walls and cabinets are structurally sound, straight, level, and square before installation.
- Fixed in place and in one plane before templating. The same Cambria FAQ says all cabinets must be permanently installed and in the same plane for an accurate template.
- Flat tops with regular support. MSI's quartz installation guidelines call for cabinet tops flat and true to within 1/16 inch in 18 inches, perimeter support, and front-to-back support every 24 inches.
Requirements change with the material and the slab, so the fabricator's checklist is the final word. What these documents make clear is that the test is the cabinets' condition, not the year they went in.
One-hour cabinet inspection before the countertop showroom
Run this check before visiting a single countertop showroom. It costs an hour and can prevent an expensive surprise on install day.
- Inspect the sink base. Look for swollen, soft, or stained panels, and press on the cabinet floor. Water damage from a slow drip is the most common reason a box cannot take a new top.
- Level the tops. With the old counter off, or across it if it is still on, check along the run and from front to back.
- Check fastening at corners and walls. Make sure the boxes are screwed to the wall and to each other, and that face frames are tight.
- Read the door gaps. Uneven gaps can mean loose hinges, or a box that has moved out of square.
- Identify the door material. Thermofoil fronts that peel, bubble, or yellow near the stove and dishwasher do not take paint reliably, and they are usually refaced.
In a home built before 1960, test any old painted cabinet finish before sanding. Health Canada says homes of that age probably contain lead-based paint.