A common worry with flat pack cabinets is that something will go wrong and you will end up with a kitchen that does not fit together.
In practice, the errors that cause problems are usually the same few mistakes, and they are all avoidable.
This guide walks through the full assembly process, the tools you actually need, the mistakes that matter, and how to adjust doors and drawers after installation.
Tools you need (and a few that help)
Essential tools:
- Cordless drill/driver with quality Phillips bits
- Tape measure
- Carpenter's square
- Pencil
- Rubber mallet
- Spirit level (at least 600mm)
- Good lighting
Do not underestimate lighting. Misaligned panels are much harder to spot in a dim garage.
Useful additions:
- Cabinet clamps to hold panels while driving screws
- Magnetic bit holder for tight spaces
- Knee pads
- Right-angle drill attachment for corners
Before you start: inspect your delivery
Open and check every package against your delivery note before your return window closes.
Confirm:
- No panel damage
- Hardware bags are complete
- Door quantities and finishes match your order
Report missing or damaged parts immediately. It is far easier to resolve before assembly than after.
Step 1: Read the instructions fully before touching anything
Spend 10 minutes reading the full instruction set for one cabinet first. Understand component names, the sequence, and warnings.
Quality flat pack instructions are written to prevent rework. Skipping them creates avoidable errors.
Step 2: Sort components for one cabinet at a time
Do not unpack every cabinet at once.
For each cabinet:
- Lay out all panels
- Identify each part
- Check all hardware is present
- Keep small items (cam bolts, dowels, screws) separated in bags or containers
Mixing hardware across multiple cabinets is one of the fastest ways to lose time mid-assembly.
Step 3: Assemble in the correct sequence
Standard sequence:
- Join base and sides
- Attach back panel
- Add top panel
- Install internals (shelves and drawer boxes)
- Attach doors last
Do not attach doors until the carcass is fully assembled, squared, and installed.
Hardware tips
Cam locks:
- Insert cam bolt first
- Engage cam lock and turn until firm
- Stop at solid resistance, do not force
Dowels:
- Add a small amount of PVA glue
- Wipe excess immediately
Screws:
- Drive straight
- Stop when flush
- Avoid over-driving and stripping
Step 4: Check square before tightening fully
This is the step most people skip, and it causes most alignment issues later.
Measure diagonally corner-to-corner in both directions. Measurements should match. If they do not, gently rack the cabinet until they do, then tighten all fasteners.
An out-of-square carcass causes door gaps and alignment problems. It takes seconds to check now and much longer to fix after installation.
The 5 mistakes that cause most problems
- Rushing: budget 45-60 minutes per cabinet
- Not checking square: do it every time
- Over-tightening: firm is enough
- Wrong orientation: verify panel faces before each step
- Loose back panel: ensure full seating in grooves and fix as directed
Adjusting doors and drawers after installation
Even well-built cabinets need adjustment once installed.
Quality soft-close hinges offer three-way adjustment:
- Height (up/down): loosen mounting plate screws, move door, retighten
- Depth (in/out): adjust the rear screw on hinge arm
- Side (left/right): adjust the front screw on hinge arm
Adjust one axis at a time, then recheck.
Drawer runners typically allow height and tilt adjustment via clips or screws. If a drawer catches, confirm the runner is fully seated at the rear before adjusting.
When to call a professional installer
DIY is not always the right call. Consider professional flat pack installation for:
- Complex layouts with multiple angles
- Projects where level and plumb installation is uncertain
- Any job involving stone benchtops (always professional)
Many Perth trades specialise in flat pack installation at reasonable rates, a practical middle ground between full DIY and cabinet-maker pricing.
Arc Interiors provides detailed assembly instructions, phone support, and parts replacement for all cabinets we supply.