A hob produces real heat and an open flame, and the things around a cooker — wall units, shelves, a cooker hood, curtains — are often combustible. Clearances exist so that heat and flame can't set fire to nearby materials or damage them over time. This guide explains the principles and where the numbers come from. It's study material; only a Gas Safe registered engineer may carry out the work.

Figures come from the MIs. Clearances are specified by BS 6172 and, crucially, the manufacturer's installation instructions for the specific cooker (and for any cooker hood). They vary by model, so the exact millimetres must be read off the instructions — treat any general figure here as a starting point to verify.

Clearance above the hotplate

The biggest concern is what sits above the hob. There must be adequate vertical space to any overhead surface, and particular care where that surface is combustible (a wooden wall unit) or is a cooker hood. Cooker hoods state a minimum mounting height above a gas hob — commonly around 650 mm or more — and that figure comes from the hood manufacturer. A combustible surface directly above may need a greater clearance or protection, per the cooker's instructions.

Clearance to the sides

Side clearances matter too: a tall combustible panel, a fridge or a curtain hard against the edge of a hotplate can be scorched by a side burner. The instructions give minimum side distances to combustible surfaces; where they can't be met, a non-combustible spacer or shield may be required.

Behind and below

Consider the wall behind (especially if it's a combustible finish), and what's below an eye-level grill or oven. The aim throughout is that no combustible material sits within the heat-affected zone the manufacturer defines.

Everyday hazards to point out. Loose items are part of the picture: tea towels draped over a rail in front of burners, curtains beside the hob, plastic utensils or packaging left on the hotplate. Commissioning is a good moment to advise the customer to keep combustibles clear — it's a common cause of kitchen fires.

How it ties together at commissioning

When you commission a cooker you check the clearances above and beside the hotplate against the instructions, confirm any cooker hood is mounted at the right height, and make sure no combustible material encroaches. It sits alongside the other CKR1 checks — stability, FSDs, ventilation, gas rate and combustion — as part of leaving a safe installation.

  1. Why: hob heat and flame can ignite or damage nearby combustibles.
  2. Figures: from BS 6172 and the cooker (and hood) manufacturer's instructions — verify per model.
  3. Above: adequate vertical space; cooker hoods often need ≈650 mm+ over a gas hob.
  4. Combustible overhead may need greater clearance or protection.
  5. Sides: keep combustible panels, fridges and curtains clear; shield if needed.
  6. Behind/below: mind combustible wall finishes and what's under a grill/oven.
  7. Advise the customer to keep tea towels, curtains and packaging away from burners.

10-Question Mock Test

Click an option to see whether you got it right. Explanations appear instantly — no submitting at the end.

Your score: 0 / 10
Question 1 of 10
Why are clearances to combustibles required around a cooker?
Question 2 of 10
Where do the exact clearance figures come from?
Question 3 of 10
The main clearance concern is usually:
Question 4 of 10
A cooker hood over a gas hob commonly needs a minimum mounting height of about:
Question 5 of 10
A combustible surface directly above the hob:
Question 6 of 10
A tall combustible panel hard against the side of a hotplate could:
Question 7 of 10
Which else should be considered?
Question 8 of 10
Which is a common everyday fire hazard to advise the customer about?
Question 9 of 10
A generic clearance figure you've memorised should be treated as:
Question 10 of 10
Clearance checks at commissioning sit alongside:

Clearances are a manufacturer's-instructions habit. Build it.

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