Replace a chimney cooker hood like-for-like on a dot-and-dab plasterboard wall

Swap a chimney cooker hood for a new one on the same wall, matching brackets, ducting and electrics safely.

CH-01Isolate power and protect the kitchenTurn the cooker hood off at its wall switch or isolator, then switch off the circuit at the consumer unit if it is wired in directly rather than plugged in. Unplug it if it uses a plug and socket. Lay dust sheets over the hob and worktop and clear anything flammable nearby.

1 each · Dust sheet

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CH-02Record the current setup before you touch anythingTake photos of the hood, its bracket, the ducting run and the cable or fused spur connection. Note the height above the hob and the duct route to the outside vent. This makes reconnecting the new hood far quicker.

CH-03Disconnect and remove the old hoodDetach the ducting from the hood outlet by loosening the jubilee clip or peeling back the foil tape. Disconnect the wiring at the fused spur, or unplug it, then undo the mounting screws. Cooker hoods are awkward and heavier than they look, so get a second person to help lift it clear.

1 each · Screwdriver set

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CH-04Mark up the new hood's fixing pointsHold the manufacturer's template or the new bracket against the wall at the same height as the old hood, or the manufacturer's minimum clearance above the hob (usually around 650-750mm, check the instructions). Use a spirit level to keep it square, then mark the fixing holes with a pencil.

1 each · Pencil

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CH-05Check for cables and pipes, and find your stopcockRun a detector over the marked area, but treat it as a guide only — detectors miss cables that are deep, in metal conduit, or behind metal-backed plasterboard, and dot-and-dab hides its dabs unpredictably. Drill a small pilot hole first and stop the moment you feel any resistance change or see anything other than dust. Before you drill, find your stopcock (usually under the kitchen sink) and check it turns, and if there's any doubt about what's behind the wall, isolate the circuit at the consumer unit first.

1 each · Cable/pipe detector

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CH-06Drill and fit the wall fixingsOn dot-and-dab, drill through the plasterboard and the air gap behind it into the solid masonry, using a bit long enough to reach at least 40mm into the brick or block — 75-100mm total drilling depth is typical. Fit a matching wall plug and screw so the fixing grips the masonry, not just the plasterboard skin. On solid brick or block with no dot-and-dab, drill straight in and use a standard wall plug and screw sized for the hood's weight. If the wall behind the hob is a stud partition rather than the original chimney breast, do not rely on plasterboard alone — fix into a timber noggin, or through to the masonry behind, because cooker hoods are too heavy for a plasterboard-only fixing.

1 each · Masonry drill bit 8mm x 100mm

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4 each · Red wall plugs (heavy duty)

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4 each · Screws 6mm x 80mm

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CH-07Fit the bracket and check it's levelScrew the new bracket or mounting plate to the wall using the fixings from the previous step. Check it is level and square before fully tightening, as a tilted bracket will make the whole hood sit crooked.

1 each · Spirit level

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CH-08Hang the new hood on the bracketLift the hood onto the bracket with help from a second person and locate it onto the fixing points. Add any safety screws underneath as specified by the manufacturer, so it can't be knocked off the bracket.

1 each · Chimney cooker hood (new, like-for-like)

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CH-09Reconnect the ductingFit new ducting if the old ducting is perished, crushed or too short, matching the diameter of the hood outlet. Push it fully onto the outlet spigot, secure with a jubilee clip, and seal the joint with foil tape. Check the external wall vent flap opens freely when the fan runs.

1 metre · Ducting pipe (150mm dia)

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2 each · Jubilee clip

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1 roll · Foil duct tape

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CH-10Reconnect the electrics and testReconnect the wiring at the fused spur, matching the original connections, or plug the hood back in. Restore power at the consumer unit and test all fan speeds and the light. Like-for-like reconnection to an existing fused spur or plug is not notifiable work, but adding new fixed wiring or a new circuit in a kitchen is notifiable under Part P of the Building Regulations, and should be done or checked by a competent electrician.

RULES

KNOW THE RULES

New fixed electrical wiring in a kitchen is notifiable under Part P — reconnecting existing wiring like-for-like isn't, but adding a new circuit is.

CH-11Seal gaps, fit the filter and tidy upRun a bead of silicone sealant around any gap where the ducting passes through the wall or cabinet to stop grease and draughts. Fit the grease filters, wipe down the hood, and remove dust sheets. Take the old hood to a household waste site or electrical retailer for WEEE recycling rather than the bin.

1 tube · Silicone sealant

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