Manhole Covers | Recessed Manhole Covers | Drain Covers and Gully Grids

Most people only buy a manhole cover once or twice. The old one has rusted through, the driveway is being relaid, or a builder has left an inspection chamber sitting proud of a new patio. This guide covers the three things that decide whether the cover you order actually fits and does its job: the size, the style, and the rating.

Start with the clear opening

The single most common mistake is measuring the old lid. Lids overhang, frames vary, and a lid that has been sitting in a frame for twenty years tells you very little. Lift it out and measure the hole in the chamber itself, the clear opening, in millimetres, in both directions. Most domestic inspection chambers in the UK are 600 x 450 mm, which is why so many covers come in that size. Some are 450 x 450 mm or 300 x 300 mm. If your numbers do not match a size on the product page, do not round up and hope. Send us the measurement and we will tell you what fits.

Recessed or standard

A standard manhole cover is a galvanised steel lid in a frame that sits on top of the surface. It is quick to fit, easy to lift, and the right choice when the surface around it is already finished and you are simply replacing a broken lid.

A recessed manhole cover is a shallow tray. You lay the same block paving, slabs or screed inside it that you have laid around it, so once the surface is down the cover all but disappears. Recessed covers come in different tray depths to suit what you are filling them with: a shallower tray for screed or thin slabs, a deeper tray for block paving. Check the depth on the product page against the material you are laying, and remember the tray needs to sit level with the finished surface, not the base.

What the load rating means

Every cover is designed to carry a certain load once it is installed to the manufacturer's instructions in a suitable frame. A cover in a lawn or on a footpath sees nothing heavier than a wheelbarrow. A cover in a driveway takes a car every day. Where a rating or standard is shown on a product page, it is the manufacturer's stated figure for that item, and it depends on correct installation. If a cover is going to carry vehicles, or sit anywhere the public walks or drives, have a competent person confirm the class you need before you buy. We sell the covers; we do not offer engineering advice, and this guide is not a substitute for it.

Galvanised steel and cast iron

Domestic covers are mostly hot-dip galvanised steel: the steel is dipped in molten zinc, which bonds to the surface and stops rust for years even when the cover sits in wet ground. Grids and gratings that take more punishment, in a driveway or a yard, are often cast iron. Lighter garden gully grids and leaf guards are usually PVC. None of them need painting, and none should be painted, because paint traps water against the metal.

Drain covers and gully grids

The small grids over gullies break, get driven over, or simply go missing. Replacements follow the common UK gully openings: 150 mm square for most modern gullies and 175 mm round for the older stadium-shaped ones. As with covers, measure the opening rather than the old grid, and choose cast iron where a car will pass over it and PVC where only feet will.

Finishing a driveway

Two other things often go in with a cover. A channel drain runs across the bottom of a sloping drive to catch surface water before it reaches the garage or the road, and comes as a kit with the channel and its grating. A gravel grid is a honeycomb of plastic cells laid under loose gravel so the stones stay put under tyres instead of migrating into ruts. Both are on the drainage accessories page.

Before you order

Measure the clear opening in millimetres. Decide recessed or standard, and if recessed, check the tray depth against your surface. Read the rating on the product page and, for anything that will carry a vehicle, get it confirmed. Then order, and if it turns up and it is not right, you have 14 days to send it back.