New Countertops – Preformed

Installing a countertop can be simple and straightforward (if the countertop just runs straight) or very time consuming and frustrating particularly if the countertop needs to fit between two walls or go around a corner. 

For laminate countertops, the two common types of countertops are pre-formed and self-rimmed. Pre-formed tops come assembled from the manufacturer while self-rimmed tops are built at the jobsite using raw materials (laminates and plywood or particle board). Preformed countertops are available only in standard sizes so you will need to cut it to length as those generally purchased are a little longer than you need. 

The top sections of preformed countertops offer a great variety of treatments including molded-in backsplash and a front lipped edge, called “cove.” Or the front edge can have other treatments including: square, rounded or bullnosed, with a 45-degree angle edge, or even wood edging applied. The front edge can be of the same design or a contrasting pattern for more variety. 

If an L- or U-shaped top is desired, sections are joined together with a 45-degree miter joint.

Tools and Materials

  •  Glue
  •  Screwdriver or Power drill and screwdriver bits.
  •  Drywall screws
  •  Square
  • Large clamps
  • Hammer
  • Level
  •  Scriber compass
  • Screwdriver
  • Caulking gun and caulk
  •  Sandpaper
  • Belt sander
  •  Large clamps
  •  Safety glasses


Installing Pre-formed Laminates

1. Add the counter overhang (usually between 3/4 and 1 inch in front and on open ends) and add it to the dimensions of your cabinet when you measure the length you need.

2. Subtract 3/4 inch from the length of the counter top on that side if an end splash is to be included. Measure and mark the appropriate size on your preformed countertop. Place masking tape along the lines you want to cut and mark your cut line on the tape. (The masking tape will prevent any chipping of the laminate surface).

3. The end splash is screwed directly onto the edge of the counter top or into wood batons previously attached to the edge. Apply silicone sealant to all surfaces to be joined and hold the end splash in place with C-clamps while driving in the screws.

4. An end cap is a pre-shaped strip of matching laminate which will be glued to the end of the counter top.

5. U- and L-shaped counter tops will need to be ordered mitered or cut to order as it is difficult to accurately miter these sections at home. These pre-mitered sections should have small slots for draw bolts cut into the bottom edges. 

Install a preformed countertop in an L- of U- shape by putting together two/three pieces cut on 45-degree angles. These pieces would have been cut readily and include cut outs on the underside to help hold them together using specially designed fasteners. Lay the pieces upside down on a solid, level surface. Spread carpenter\’s glue on the joining edges of the pieces. Install and tighten the joining hardware/fasteners enough to hold the pieces close together. Align the corners carefully and ensure the seam is smooth. (This is a slow, iterative process – tighten a little, realign, tighten a little more and realign). It\’s important that the corners line up and the joint is smooth. Allow the glue to dry once the pieces are properly aligned. Turn the countertop over (carefully), and install it as if it were a single section. 

6. Fasten the adjoining backsplashes together with wood screws.

7. Counter tops rarely fit perfectly against the back or side walls. Often, they come with a scribing strip that can be trimmed to the exact contours of your irregular walls. Scribing simply involves running a strip of masking tape along the edge to be scribed then positioning the counter top. Place the countertop on the base cabinets and align it as close as possible to the wall. Quite likely the straight cut countertop won\’t fit closely along the wall. Clamp the countertop in place and using a compass mark the outline of the wall onto the countertop. (Open the compass about 1/2″, run one leg along the wall and run the pencil leg along the countertop – making and exact profile of the wall). Use your belt sander to carefully remove the excess marked by the scriber. Test fit and do more sanding if required to fit the countertop to the wall. Install the countertop onto the base cabinets as above, using glue and drywall screws. Apply caulking along the seam between the countertop and the wall. 

8. Once your contours are correct, position the counter top on the cabinet base. Check that all is level and shim where needed. Check also that drawers and doors may be opened freely.

9. Fasten down the counter top by running screws up from below through the top frame and corners. If there are no corner brackets, install them on the base units. This will allow you to install the counter to easily. Again, self-drilling bugle head screws are great for this job. Round head screws work best here because they will not be seen so do not have to be counter sunk and they bear more weight in this position. Use screws that will be long enough to reach 1/2 inch into the counter core.