Building in shelving, cabinets and a dog pen

A wall of built-in shelving, a run of cabinets with a countertop on top and a pen for the dog all come down to the same thing: boxes made from sheet, fixed together and to the wall. What goes wrong is rarely the joinery. It is a shelf that sags because the bay is too wide, a sheet short because the parts were never laid out, or a tall case that is not fixed to the wall.

This planner follows the order of work: measure, decide how wide each bay can be, size the cabinets, draw up the cut list and buy the sheets, then build, fix and finish. It is for sheet-built carcasses (plywood, MDF, particleboard) and gives a starting list, not a structural design.

Step 1: Measure the room and decide what goes where

Measure each wall at the top, the middle and the bottom, because rooms are rarely square. Note the height of the ceiling, any outlets, windows and radiators or vents, and mark where studs are. Sketch the plan: shelving on one wall, cabinets with a countertop along another, and a pen in the corner or an alcove where fewer sides need fencing.

Step 2: Find how wide a bay can be before the shelves sag

Shelves sag, and then stay sagging. How far a shelf can span depends on the board, its thickness and what it carries. As a guide, three-quarter-inch plywood with books on it spans about 30 inches, while particleboard needs bays about 22 inches wide. A strip of solid wood glued under the front edge, or a thicker board, stretches the span.

Step 3: Plan the bookcase or shelving wall

Divide the wall into equal bays, each no wider than the shelf span. Leave a plinth at the bottom to clear the baseboard and a gap at the top for a filler strip, since ceilings are not level. The calculator counts the bays, the shelves, the sheets for the case and the back, the shelf pins and the wall fixings.

Step 4: Size the cabinets and the countertop

A base cabinet is usually 34 1/2 inches high and 24 inches deep, with a toe kick, and takes a countertop about 1 1/2 inches thick on top. A wall cabinet is about 12 inches deep. Check the size of any sink, range or dishwasher before setting widths. The countertop calculator works out the area and the slabs; the cabinet calculator lists every part, the doors and the hinges.

Step 5: Plan the dog pen

Size the pen to the dog: a floor area that lets it lie out and turn round, a fence tall enough that it will not hop over, and bars close enough that a head cannot get through. A pen in a corner or an alcove needs less fencing. The pen calculator gives the floor area to aim for, the fence height and the panels or timber to buy.

Step 6: Draw up the cut list and buy the sheets

List every part with its size and quantity, and the calculator packs them onto sheets so you buy the right number rather than guessing. Rip the sheets into strips first, then cut to length with a track saw or a panel saw. Add a few percent for mistakes, and order the back panels and edge banding at the same time.

Step 7: Build, fix to the wall and finish

Build the cases as boxes, check them for square, then fix them to the wall through a rail into studs or masonry with the right fixings for the wall. Scribe the end panels to the wall, add the filler strip and trim, then fill, sand and paint. Fit the doors last so they are not damaged while you work.

Before you start

• Measure each wall in three places and check the ceiling and floor for level.
• Find the studs, and check for cables and pipes before drilling.
• Decide the bay width from the shelf span for your board and load.
• Check the size of appliances, a sink and a range before setting cabinet widths.
• Work out the cut list and the number of sheets before you buy.
• Plan how the case will be fixed to the wall, and fix every tall unit.

Mistakes that cost people money

• Making bays too wide, so that the shelves sag within a year or two.
• Not fixing a tall case to the wall, which makes it a tipping hazard.
• Buying sheets without a cut list, then being one short.
• Building to the wall measurement taken at one place, when the wall is not square.
• Leaving no gap for a filler strip, then having to cut the case to fit.
• A dog pen too small for the dog, or with bars wide enough for a head to get stuck.

Frequently asked questions