Short answer
Yes, on both counts. The fascia needs venting so the firebox does not bake the cabinet, and the base needs venting so any gas that leaks can escape downward, because LPG is heavier than air and collects at the bottom.
Two problems, two directions
Heat rises, so heat venting is at the top of the fascia — the slots under the grill. Gas sinks, so gas venting is at the base. A cabinet with only one of the two has solved half a problem.
People usually think of the first and forget the second. A sealed cabinet with a slow leak becomes a bomb rather than a smell, which is why every gas-rated enclosure has a low-level vent.
What heat venting prevents
A grill inside a closed box heats the box. The cabinet structure is 304 stainless over an aluminium honeycomb core, and the bond between them is the part that does not like sustained heat. Venting the fascia keeps the enclosure near ambient instead of near cooking temperature.
It also protects whatever is stored next to the grill. A drawer of utensils a module away is fine; a sealed cabinet directly under the firebox is not.
What gas venting prevents
LPG is about 1.5 to 2 times the density of air. A leak does not drift out of a gap at the top of a door; it pools at the bottom of the cabinet and stays there.
The vent must be at the lowest point, and it must not be blocked by a shelf, a drawer or the cylinder itself. This is why gas cabinets are vented in the base and the rear rather than at the top of the door.
How the vent is made
The fascia slots and the base vents are machined at the factory. They are part of the panel, not an accessory or a hole cut on site — a site cut through a finished stainless panel leaves an unprotected edge that will corrode from the inside.
The pattern is decided when the order is specified, together with the grill opening and the gas entry side.
Five signs a grill bay is not venting
The fascia is warm hours after cooking
Some warmth is normal. A fascia that is still hot to the back of the hand two hours later means the bay is holding heat, not shedding it.
The door fronts have gone dull above the grill
Heat with nowhere to go cooks the finish from the outside in. It shows first on the top rail of the door.
The gas bottle bay smells of gas after use
A sealed bay traps a small leak instead of letting it disperse. That is a ventilation fault and a safety one.
Condensation on the inside of the doors
Warm damp air in a sealed box condenses on the coolest surface, which is the door skin. Ventilation moves the air before it does.
The appliance manual asks for clearance you have not got
The manufacturer states clearance to combustible material and a minimum open area. The cabinet has to meet the figure, not approximate it.
Questions we get about this
Can I add vents later?
No, not without replacing the panel. The vents are cut and edge-finished at the factory. This is the single strongest reason to settle the grill model before ordering.
Is a louvred door enough?
For heat, partly. For gas, no — a louvre in a door sits above the floor of the cabinet and gas pools below it. A gas cabinet needs a base vent specifically.
Does venting let water in?
The fascia slots face forward and are set above the splash line in normal use; the base vents are in the floor. Driving rain can reach the base vent on an exposed site, which is why the cabinet interior is stainless on both faces.
Before you order anything
Send the grill model and the run length. You get the aperture, the module list and one itemised price back in writing — freight shown separately, valid 15 days.