Fitting flat-pack kitchen units is one of the most rewarding — and most unforgiving — DIY projects in the home. The cabinets themselves are straightforward, but accuracy compounds: a base unit 3 mm out of level will leave every worktop joint, door gap and cornice line looking wrong. Done carefully, you can save £1,500–£3,000 on a medium kitchen by doing the installation yourself.
Most flat-pack ranges — IKEA SEKTION, Howdens Clerkenwell, B&Q Santini and similar — work on the same principle: a carcase screwed or clipped to a wall, soft-close hinges and adjustable legs that let you dial out any floor undulations. The process is the same regardless of brand.
Tools and Materials You Will Need
- Spirit level (at least 1.2 m long) and laser level
- Cordless drill/driver plus SDS hammer drill for masonry
- Jigsaw and circular saw
- Stud finder / live-wire detector
- Silicone sealant gun
- Pozi screwdrivers (sizes 1 and 2)
- Wall plugs rated for masonry or cavity walls (use Fischer or Rawlplug rated ≥ 4.5 kN per fixing for wall units)
- Cabinet screws (4.5 × 40 mm for carcase-to-carcase; 5 × 80 mm for wall)
- Adjustable legs (most flat-packs include these; extras cost ~£1 each)
- Plinth clips and kick-board sections
- Filler, primer and paint for patching
Understanding the Layout
Start with a measured drawing — or use the supplier’s free planning tool. Mark the following on your walls with a pencil:
- Floor high point — find the highest point of the floor using a long level or laser. All base units will be set to this height (typically 870 mm to bottom of worktop, though this varies by worktop thickness).
- Wall unit height — standard is 500–600 mm above worktop, giving a finished top height of ~2,100 mm. Mark a horizontal datum line.
- Stud positions — mark every stud (typically at 400 mm or 600 mm centres). Wall units MUST hit at least two studs per cabinet, or use hollow-wall anchors rated ≥ 6 kN pull-out for plasterboard-only fixings.
- Services — use a pipe and cable detector before drilling. Gas, water and electric often run vertically from sockets and horizontally between floors.
Step-by-Step: Base Units
1. Set the leg height. Adjust all legs to the same approximate height. Use your laser or spirit level to project a horizontal line at 870 mm from the floor’s high point across the full run.
2. Assemble the carcases on the floor following the manufacturer’s instructions. Most use cam-lock fittings and wooden dowels. Do not over-tighten cam locks — you risk splitting the chipboard.
3. Position the first unit, typically starting from a corner or appliance space. Use a shim under any leg that won’t adjust finely enough.
4. Level front-to-back and side-to-side, adjusting the four legs individually. Once level, screw adjacent units together through the face-frame or side panels (4.5 × 40 mm screws, two per junction, front and back).
5. Fix to the wall. Drive at least two 5 × 80 mm screws through the hanging rail into studs, or use appropriate cavity fixings for dot-and-dab plasterboard. This prevents the units tipping forward once loaded.
6. Fit the plinth. Snap plinth clips onto the legs, cut kick-board to length and push into the clips. Scribe and cut end pieces as needed.
Step-by-Step: Wall Units
1. Mark the bottom line of the wall units using your datum. Double-check it’s level across the full run — a 2 mm error over 3 m is barely visible; a 10 mm error is obvious.
2. Fix a temporary ledger — a straight 75 × 25 mm batten screwed to the wall along your datum line. Units rest on this while you fix them, freeing up your hands.
3. Hang each unit by fixing through the rear hanging plate. Most flat-pack wall units take two screws per cabinet into studs or cavity anchors. Adjust the height-setting cam inside the hanger plate until each unit sits on the datum.
4. Link adjacent units through the sides with 4.5 × 40 mm screws, two per joint.
5. Remove the ledger and fill the screw holes. Touch up with paint.
Fitting Doors, Handles and Soft-Close Dampers
Hinges are typically Blum or equivalent 35 mm clip-on. Clip to the mounting plate already screwed inside the carcase. Adjust height, depth and side position until door gaps are even — target 2 mm all round. Screw handles through the door face using the template provided.
Typical Costs
| Item | DIY Supply Cost | Tradesperson Supply & Fit |
|---|---|---|
| Base unit (600 mm) | £90–£250 | £250–£500 |
| Wall unit (600 mm) | £80–£200 | £200–£400 |
| Worktop (laminate, per m) | £50–£120 | +£80–£150 labour/m |
| Kitchen fitter day rate | n/a | £200–£350/day |
| Average medium kitchen fit (no worktops) | £0 labour | £1,200–£2,500 labour |
Costs are 2026 estimates including London weighting.
Common Mistakes to Avoid
- Not finding the floor high point first. If you set your first unit to the floor at the lowest point, every subsequent unit will be too low and your worktop will be uneven.
- Skipping the ledger for wall units. Holding a heavy wall unit single-handed while trying to drive a screw into a stud is how cabinets get dropped and walls get damaged.
- Using the wrong fixings. In houses built after 2002, many internal walls are lightweight metal-stud plasterboard. Standard wall plugs pull straight out. Use Molly bolts or Snap Toggles rated ≥ 6 kN.
- Forgetting services. Always scan before drilling. Clipping a buried cable is dangerous and expensive to repair — up to £600 per cable-chase repair.
- Rushing the scribing. Where units meet a wall or tall housing, scribe the filler panel carefully with a compass and jigsaw. A visible gap between a panel and an uneven wall is the most common tell that a kitchen was fitted by a first-timer.
When to Call a Professional
If your kitchen involves moving gas supplies, relocating a consumer unit, or altering soil stacks, you will need Gas Safe and Part P registered tradespeople. Electrics near sinks (within 3 m of an open water source) fall under Zone 2 of BS 7671 and should be tested by a registered electrician. Worktop joins and upstand silicone are often best left to a fitter if you want a finish you’d be happy showing off — a single poorly cut join can look worse than the rest of the kitchen combined.
A solo DIYer fitting a standard 12-unit kitchen with no structural changes can realistically complete the job in two days, saving approximately £1,800–£2,500 on labour.
