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Ventilation grille buying guide

Updated: 16 October 2026

You have a hole in a bathroom wall, a soffit, or a single brick, and the packet quotes one large measurement. That number is usually the face of the plate. A ventilation grille buying guide splits it into the duct size, the hole the plate must overlap, and the free area air can pass. The [ventilation grilles comparison](/hub/grills-and-barbecues/ventilation-grille) holds the twelve amazon.co.uk listings and the prices in GBP. The Products Compared editorial team read those extracts on 15 October 2026 and did not lab-test airflow. An Amazon link can earn us a commission if you buy, at no extra cost to you.

You have a hole in a bathroom wall, a soffit, or a single brick, and the packet quotes one large measurement. That number is usually the face of the plate.

Our top picks

Awenta Awenta 150 × 150 mm white plastic cover

Best overall

Awenta Awenta 150 × 150 mm white plastic cover
8.0/10about £4.68
View offer
Kair Kair black 100 mm louvre with spigot

Rank 2

Kair Kair black 100 mm louvre with spigot
8.4/10about £11.49
View offer
Map Map 9 × 3 in brown louvre with flyscreen

Preis-Tipp

Map Map 9 × 3 in brown louvre with flyscreen
8.1/10about £3.99
View offer
On this page
  1. 1.Four different covers
  2. 2.Free area is not the face size
  3. 3.Mesh and screws
  4. 4.What this is not

Four different covers

A round extractor duct wants a male spigot the hose can grip. A finished square or rectangular hole wants a flat plate that overlaps the edge. A single brick wants a 9 × 3 in louvre. A cupboard or plinth wants a small slotted pair, which is a different object from an outside terminal. Only the Kair, model DUCVKC244F/S-BK, states a 100 mm male rear spigot, on a 155 × 155 mm face. The listing names duct DUCVKC250 or a 102 mm hose, and you can cut the stub off for a flat back. The Meralo white louvre, 14 × 14 × 5 cm, claims a 100 mm fit and never uses the word spigot. Flat plates here are both Awenta covers, the Vent Systems 300 × 300 mm page, and the Repa and LIRAST steel plates. None states a spigot. Map is 260 × 90 mm for openings up to 229 × 76 mm. Leliafleury is two aluminium covers at 60 × 150 mm.

Free area is not the face size

Free area is the gap left after the frame, the blades, and the mesh. Approved Document F Volume 1, in the 2026 edition, asks for a terminal free area of at least 90 per cent of the duct. A 100 mm duct is about 7,854 mm² across, so 90 per cent is about 7,068 mm². That is a calculation from the document. It is not a lab result for any listing here. Map is the only cover in the set that prints an open area: 4,400 mm² when open. That suits a brick, a cupboard, or a shed, and it sits too low for a 100 mm fan. One reviewer failed a free-air check on the LIRAST 300 × 150 mm plate because the border, the frame, and the louvres cut the opening. The Kair, Awenta, and Repa extracts omit free area, so the amazon.co.uk text cannot show Part F compliance.
Awenta Awenta 150 × 150 mm white plastic cover

Testsieger

Awenta Awenta 150 × 150 mm white plastic cover
8.0/10about £4.68
View offer

Mesh and screws

A flyscreen stops insects and also blocks some of the air, so you need a way to clean it. The Kair listing says you flick the louvre open with a flat screwdriver. Reviewers say that clip is tight. They call the screen soft, and one buyer replaced it with stainless mesh. Map’s screen is fixed. The Leliafleury bullets describe oval slots and do not name a separate screen. LIRAST’s components line names screws with the cover, and some reviewers still had none. Awenta includes four screw caps and no screws, on both the 150 mm and the 300 mm listing. Repa and the Vent Systems 300 mm page say screws are absent. Meralo and the 260 × 190 mm Vent Systems cover do not say. The two Awenta files share one review block and the same 4.6 from 3,748 line. Read that as one scrape.

What this is not

These covers pass air through a wall, a soffit, a brick, or a cabinet. A barbecue grate has to carry food and heat, and the hub name on this site will not turn a louvre into one. They are also the wrong cap for a boiler flue. Insect mesh over a flue is a carbon-monoxide risk. A fixed louvre stays open when the wind blows back. Gravity shutters exist as their own product, including a trade grille such as the Manrose 1162W, and none of them is among the twelve listings. Cutting the Kair spigot off makes a flat back. It leaves the blades as they are.

Common questions

What size grille do I need for a 100 mm bathroom fan?
A standard UK bathroom fan uses 100 mm duct, so the cover needs a 100 mm male spigot and a face that overlaps the hole. In this set only the Kair states that spigot, on a 155 × 155 mm face. The Meralo listing claims a 100 mm fit, does not say spigot, and has no reviews in the extract. A 300 mm flat plate can hide a finished opening. The hose still needs a stub to grip.
Does the cover need a spigot?
You need a spigot when a duct has to connect to the cover. A flat plate is enough when the duct already ends in the wall and you only have to hide the opening. Kair is the stated spigot here. Awenta, Repa, LIRAST, Map, the Vent Systems flat cover, and the cabinet pair do not state one. You can cut the Kair spigot off for a flat back, and that cut removes the duct connection.
Are screws in the box?
LIRAST’s components line names screws, and some reviewers still found none. Awenta supplies four caps and no screws. Repa and the Vent Systems 300 mm page say screws are not included. Kair’s bullets omit them, and reviewers say you bring your own. Meralo and the 260 × 190 mm Vent Systems cover do not say. If the listing is silent, buy plugs that suit your wall before you start.
Can I cover an air brick?
A single-brick opening takes a louvre that matches the slot. Map is 260 × 90 mm for openings up to 229 × 76 mm, with 4,400 mm² open and a fixed flyscreen. That suits a brick, a cupboard, or a shed. It is a poor match for a 100 mm fan, because 4,400 mm² sits below the 90 per cent line for that duct. Leave a boiler flue uncovered.
Is this a barbecue grill?
A ventilation grille passes air through a wall, soffit, air brick, or cabinet. A barbecue grate supports food over heat, and none of these twelve listings is that grate. The set is louvres, flat covers, one stated spigot, and a cabinet pair. The hub name is the site’s DIY grouping. If you are shopping for cooking bars, this table will not choose them.

Related pages

100mm extractor grille

Plastic or metal air vent cover

How to fit a ventilation grille

Ventilation grilles in 2026

Best ventilation grille for the hole you already have

Sources

Listing prices, stars and review counts are from amazon.co.uk extracts dated 15 October 2026, including the shop page for B0BZPM3DZB. The public sources below cover the ventilation rules and the consumer-rights point.

  1. Approved Document F, Volume 1 (2026 PDF) (retrieved 15 October 2026)
  2. GOV.UK: Ventilation: Approved Document F (retrieved 15 October 2026)
  3. Welsh Approved Document F, Volume 1 (retrieved 15 October 2026)
  4. Manrose CF100 installation sheet (retrieved 15 October 2026)
  5. Planning Portal: extractor fan rules (retrieved 15 October 2026)
  6. Mesh Direct: insect mesh (retrieved 15 October 2026)
  7. Consumer Rights Act 2015 (retrieved 15 October 2026)
  8. amazon.co.uk: Vent Systems cover B0BZPM3DZB (retrieved 15 October 2026)