Grilles, technical doors and hatches
Small items that are almost never ordered in advance: they come to mind once the house is already standing. What they have in common is that every one of them is made to a measured opening, not to a drawing.
Six typical products
- Window grille — fixed, welded to the opening and anchored into the reveal or the outer wall.
- Hinged grille — opens from inside, with a lock; mandatory where the window counts as an escape route.
- Technical door — to a store, a boiler room, a switch room; often with a louvred panel for ventilation.
- Floor hatch — to a cellar, with a gas strut so the lid does not drop on your hands.
- Light-well grating — holds a person but not a heel: the bars are spaced so water gets away.
- Air conditioner cage — unit on the facade, locked against removal, with clearance for servicing.
Why the survey beats the drawing
Openings in finished buildings are rarely rectangular. A difference of 10–15 mm across the diagonal is invisible in a wall but means a gap on one side of a grille and a jam on the other. So the item is welded to what is actually there: four sides and both diagonals are measured, and the frame is fitted on site.
The second thing settled at the survey is the fixing. Concrete and solid brick take anchors; hollow block takes resin with a sleeve; a timber wall takes coach screws through a plate. Substrates and fixings are set out in how ordering works.
Coating
Grilles and hatches live outdoors and almost always in places that are awkward to paint: inside a light well, in a window reveal, under the eaves. Touching them up in three years is not going to happen — there is no access. So hot dip galvanising pays here more often than in other products: it protects the inside of the section too, where a brush never reaches.
Where to go next
If grilles go round the whole perimeter along with the fence, see fences: infill and coating are chosen to match. Open grating for platforms and stairs is covered in stairs and railings.
Frequently asked questions
Can fixed grilles go on windows?
Not everywhere. Where a window serves as a second means of escape — and in habitable rooms it often does — the fire authority requires a hinged grille with a lock that opens from inside without a key. A fixed grille on such a window turns the room into a trap.
What is a window grille made of?
A frame of angle or hollow section, with an infill of 12–14 mm square bar or flat. The bar spacing is set so a head will not pass: usually not more than 15 cm. The grille is welded to the measured opening, not to the dimensions on a drawing.
Will a light-well grating hold a person?
It should: it is designed for a person carrying a load. It is not obliged to hold a heel — the bar spacing in a light well is deliberately open so that water and leaves fall through. Where people walk in heels, a fine mesh grating or solid grating is used instead.
Why cage an air conditioner?
Against theft. The outdoor unit hangs on the facade in plain view and comes off in five minutes; a locked cage makes that considerably slower. The second reason is protection from snow and ice falling off the roof.
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