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Plastic or metal air vent cover

Updated: 16 October 2026

You already know the hole. The remaining argument is whether a plastic or metal air vent cover is the one that will still look right next winter. In this set, plastic is the material that carries the only moulded 100 mm spigot. Coated steel is the thin plate over a hole you have already measured. Neither choice closes against a draught, and neither prints a free-area certificate. The listings and prices are on the [ventilation grilles comparison](/hub/grills-and-barbecues/ventilation-grille). The Products Compared editorial team compared the amazon.co.uk extracts on 15 October 2026. We did not weather the covers outdoors. Amazon links can earn a commission if you buy, at no extra cost to you.

You already know the hole. The remaining argument is whether a plastic or metal air vent cover is the one that will still look right next winter.

Our top picks

LIRAST LIRAST 300 × 150 mm black metal grille

Best overall

LIRAST LIRAST 300 × 150 mm black metal grille
8.2/10about £15.85
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.When the plastic listings fit
  2. 2.When the steel listings fit
  3. 3.The mesh is a third material
  4. 4.What neither material does

When the plastic listings fit

Buy plastic when you need a shape that is moulded, not folded. The Kair louvre is black plastic, 155 × 155 mm, with a 100 mm male spigot, at £11.49. Across 3,590 ratings it sits at 4.5. Reviewers fit it on outside walls and soffits. They also call the screen soft. Screws are not in the box. If the job is a 100 mm bathroom fan and you can reach the mesh, this plastic spigot is the conditional top pick. Both Awenta listings are white plastic: 300 × 300 mm over a 250 × 250 mm opening at £9.40, and 150 × 150 mm over a 115 × 115 mm opening at £4.68. Their review text is one shared scrape, so the 4.6 from 3,748 line is not two tests. The Map louvre is dark brown plastic, 260 × 90 mm, with 4,400 mm² printed, at £3.99. None of these twelve extracts says UV-stabilised. You cannot borrow another brand’s UV line and stick it on the Kair or the Awenta.

When the steel listings fit

Buy coated steel when you want a thin plate over a measured rectangle, and you do not need a moulded stub. LIRAST is black sheet steel, 300 × 150 mm and 190 g, at £15.85, with 1,355 ratings at 4.6. The components line names screws, though some reviewers still had none. One reviewer failed a free-air check because the frame and louvres cut the opening. The white Repa cover is about 300 × 200 mm at £15.95, with 1,582 ratings at 4.5. Reviewers like the finish and the stiffness, and they mark it down because screws are absent. The sampled reviews do not repeat rust. The anthracite Repa plates, 260 × 105 mm at £9.95 and 300 × 100 mm at £11.95, have short UK samples. The finish is a polymer coating or a powder coat, not a stainless specification. The 260 × 190 mm Vent Systems cover says aluminium in the title and galvanised steel in the material field. Leave the clash as a clash. The Leliafleury pair is aluminium for a cupboard, not an outside duct terminal.
LIRAST LIRAST 300 × 150 mm black metal grille

Testsieger

LIRAST LIRAST 300 × 150 mm black metal grille
8.2/10about £15.85
View offer

The mesh is a third material

The plate and the screen are often different stuff. Kair reviewers call the flyscreen soft. LIRAST’s mesh is called plastic in reviews, and one buyer found it stuck only along the top and bottom. The Vent Systems 300 mm page names a nylon screen. Map’s flyscreen is fixed. Leliafleury’s bullets do not name a mesh. Do not put insect mesh, plastic or steel, over a boiler flue. None of the steel listings here is described as stainless. A plastic louvre such as the Map is the one buyers already use on decorative bricks, with the colour-shipment miss as the known snag.

What neither material does

Plastic does not become a shutter because it is light, and steel does not become one because it is stiff. Every louvre in this set that describes its blades describes them as fixed. Gravity shutters are absent here. A plastic spigot remains the right terminal when the duct is 100 mm and you can service the screen. A coated-steel plate remains the right cover when the hole is a rectangle and you will bring screws. Neither family prints an IP rating. Neither family, except the Map, prints a free area. UV stability is unclaimed on all twelve. Choose the Kair’s plastic when the hose is 100 mm and the mesh is reachable. Choose a Repa or LIRAST steel plate when the opening is already a flat rectangle. Leave flues alone.

Common questions

Will plastic survive on an outside wall?
Plastic louvres are sold for outside walls, and the Kair reviews include outside walls and soffits, at 4.5 from 3,590 ratings. The listing does not say UV-stabilised, and it does not give an IP rating, so you should not import those claims from a Blauberg or similar trade grille. Reviewers do complain that the Kair flyscreen is soft. The plate can still be the right 100 mm terminal if you can reach it to clean or replace that screen, and if you bring your own screws.
Is steel always better?
Steel is the better fit when you want a thin coated plate over a rectangle and you do not need a spigot. The white Repa at £15.95 draws comments on finish and stiffness, with missing screws as the repeated complaint, and the sample does not repeat rust. It is not better for a 100 mm hose, because it has no stub. It is not stainless, and it has no IP rating. A plastic Kair remains the listing that actually states the duct connection.
Is the 260 × 190 mm cover aluminium?
The Vent Systems listing says both. The title and the colour field say aluminium, and the material field says galvanised steel. It is 260 × 190 mm, 109 g, £13.98, with a mesh and 177 ratings at 4.6. Screws are not stated. This page will not collapse those two metals into one. If you need a known alloy, choose a listing that names one material only, such as the LIRAST sheet steel or the Leliafleury aluminium cabinet pair.
Can I paint either?
The extracts ask the question on some listings and do not answer it. A UK trade seller of air-brick covers prefers stainless if you might paint the outside, because sanding a coating can expose steel that was never stainless. Repa’s finish is a polymer or powder coat, not a stainless spec. Plastic such as the Map is already a finished colour, and one order arrived with the colours mixed. Test a hidden edge if you paint, and do not take a listing question as permission.
Which material stops a back-draught?
Neither. A back-draught stop is a gravity shutter, and no listing in this set describes closing blades. The Kair’s plastic louvres stay open. The steel plates are open covers with a mesh. Cutting the Kair spigot off makes a flat back and still does not add flaps. Choose plastic or steel for the hole and the stub. Choose a shutter, sold separately, if the wind down the duct is the problem you need to solve.

Related pages

Ventilation grille buying guide

Best ventilation grille

Ventilation grilles in 2026

100mm extractor grille: spigot, hood and free area

How to fit a ventilation grille on an existing hole

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)