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FAQ

Spotting asbestos in corrugated garage roofs
When you have worked with garage roofs as long as we have, a quick glance is often enough to tell an asbestos roof from a cement‑fibre one. It might be the shape of the sheet, the spacing between the corrugations, or simply recognising the make and age of the garage and knowing it was built after asbestos stopped being used. Some roof sheets are harder to judge, such as BIG6, which was made both with and without asbestos, and there is no guaranteed way to tell them apart just by looking. The same goes for the thin 3‑inch Eternit profile, although on Lidget or Hanson buildings it is less likely to contain asbestos. A Compton, Hanson or Lidget apex garage with a 5‑inch profile sheet and a tight‑fitting ridge tile is, in most cases, asbestos‑free. However, whatever the sheet is made from, your corrugated cement‑based roofing will still have to be treated as asbestos waste and go in the asbestos skip at the point of disposal.
Is it always necessary to replace your roof supports when you change a garage roof? In the past, factory staff dipped new steel into tanks of red oxide paint, giving it a very tough protective coating, and this continued into the mid-1990s. Later, manufacturers switched to grey and black, usually water-based coatings. To complicate things, firms like LidgetCompton also used red-coloured water-based paint on some steelwork so their Compton-branded garages could be distinguished from the Lidget range. In most garages, the internal steel is still well‑protected and more than capable of carrying a lighter modern replacement roof. If you plan to clean it with a wire brush, please take basic safety precautions, including eye protection and a suitable mask.

We see a lot of Onduline on old garages, and not always for good reasons. Often, the roof has failed early or is sweating badly, and the original roof has already been removed. Usually, the material itself is not to blame; the issue is that the installer has not followed the fitting instructions. Onduline sheets are designed to be laid over solid boarding, such as plywood or OSB, rather than directly onto the open roof bars you get on most sectional garages. Sectional garages are not built to carry the extra weight of boarding and felt, either, so boarded-and-felted conversions can also be trouble. The result is a roof that moves too much, struggles to breathe properly and often needs replacing again.

Got an old timber window or door you want to replace, or perhaps your side door and window frames are steel? Here are some simple pointers for swapping them for modern PVC. Steel-framed windows are often “notched” into the panel, so from the outside, the opening looks smaller than it really is. In that case, you will need to buy a window that fits the smaller outside dimensions, then pack out the extra space inside. The original window is usually held by flat metal plates. You will need longer plates and can also run a small timber batten into the void to close the gap. The same method works on interlocking spar garages, such as Hanson. Modern PVC frames are often thicker than the surrounding wall, and you usually do not want them sticking out beyond the wall line, so expect to bend new fixing plates in a vice to pull the frame back. Avoid PVC cills on garage windows and doors; they are not needed and can trap water under the door. Inward-opening doors can also leak, so plan carefully. When fitting an opening window, ensure the sash clears the gutter. PVC frame add-ons (extension pieces) can help fine-tune the fit and appearance.
If you are running a new power supply to your garage, and it is anything permanent, it should be armoured cable; anything else is the wrong choice for a buried or exposed external run. The thick, rigid cable is best brought up through the floor. Often, we find that someone has chipped a small channel in the base of the panel or the slab to get the cable in. Seal this afterwards with a sand‑and‑cement mix or a suitable mastic. If you need to bring the cable in higher up, look for a timber or PVC part of the building where you can drill a neat, large hole. If the electrics are already in place when the roof is replaced, ask the installer to tuck the cable under the new fascia or flashings so you do not have to pay an electrician to disconnect and reconnect it.

Many new and replacement prefab garages are now supplied with single-skin steel “box profile” plastisol sheets. These usually have a fabric anti-condensation layer bonded underneath and, from reputable suppliers, are normally around 0.7 mm thick. We have recently seen cheaper versions at just 0.5 mm thick, without an anti-drip liner, which are more prone to denting and condensation. Installers often favour standard colours such as light grey (Goosewing) or Anthracite. You may also be considering a composite panel roof, typically 50 mm thick or more, with insulation sandwiched between two steel sheets. A skilled installer can make this work on a sectional garage, but it is not really a DIY job. A more cost-effective option is often to fit a new single‑skin steel roof and then add 25 mm high-density foam boards to the underside to improve insulation at a fraction of the cost of full composite panels.

Converting a flat (pent) garage to an apex roof is a larger job than simply adding a few A-frames. First, you need custom steel trusses, and with today’s steel prices and limited local fabrication, these are not cheap. Because no two garage manufacturers use exactly the same panel heights or fixing points, the steelwork must be made to measure. You then need timber purlins running the length of the building, possibly down to the eaves to carry the new sheets, and good-quality structural timber is not inexpensive either. Finally, you have the new end fascias to build. These need timber framing cut to the exact roof pitch and height, then finished in PVC, as exposed timber has become both costly and high maintenance.

A properly supplied steel garage roof should come with an anti-drip fleece layer bonded to the underside. If this fabric becomes damp or even drips in patches, it is usually a sign that it is doing its job, soaking up condensation, and then releasing it, rather than that the roof is leaking. It can become saturated if the garage is very humid, if water is tracking in from outside, or if gutters are overflowing. If the garage or its contents were already damp, or the roof is newly fitted, everything needs time to dry. In most cases, the problem is temporary and clears up on its own. You can help things along by improving airflow – opening the main door, side door and windows, or using moisture absorbers such as silica‑gel “container dry” products. Try to avoid running a tumble dryer in the garage. Removing foam fillers at the eaves can also help with airflow. If the walls themselves are damp, you may need extra drainage, a soakaway, or new gutters, and it can take a few weeks of better weather before you see a real improvement.

A roller shutter is a type of vertical-lift garage door that does not swing outwards, which can be handy if you need to park right up to the door. In terms of security, a basic manual roller shutter is not inherently better; most lock at the bottom, similar to a normal door. Automation helps because it keeps the curtain locked, much like trying to push a car in gear. Standard single-skin roller shutters coil into a bundle at least 600 mm (about 24 inches) deep, making them difficult to fit in most apex garages with tight headroom. A pent roof may have just enough height, but you will probably lose some drive-through clearance. Compact shutters with small individual laths, usually supplied in an internal or external box and almost always electric, are possible but typically start at around £1,500 and are often fixed to the outside face of the garage, like a shop shutter. If you want a vertical lift door on a sectional garage, without losing height, and the budget allows, a sectional overhead door is often the better long-term solution.

We hear this question regularly, especially from insurers: “Can you give me a full breakdown of labour and materials?” Any tradesperson will tell you that you are paying for far more than just hours on site; you are also paying for skill, experience, and the ability to get the job right the first time. The price of a new garage roof includes insurance, training, protective equipment, and materials. Our vehicles arrive stocked not only with roof sheets but with flashings, cappings, fixings, finishing trims, timbers and specialist tools to cut and fix steel properly. In addition, we are licensed to handle hazardous waste and must dispose of it at approved sites in accordance with regulations. So, when someone says, “But my garage only cost £999,” it is worth remembering that 1995 was thirty years ago, and times – and costs – have moved on.

Cutting corners on waste disposal can become very expensive. Many skips have an inspection hatch low down so the operator can check what is inside before tipping. This helps stop people from hiding asbestos or other banned waste at the bottom. If asbestos is found, the skip can be impounded, its contents sent to a specialist site, and the customer billed for the disposal of both the asbestos sheets and everything contaminated around them, plus loss of hire on the skip while it is off the road. Buried asbestos is no better; once dug up mixed with soil, it weighs far more than it did originally, and disposal is priced by weight, not by how much space it takes up.
So how can a homeowner legally dispose of old sheets? Whether your cement-fibre roof contains chrysotile or not, it must be placed in a sealed asbestos container at an authorised site. Some council recycling centres accept small amounts – usually just a few sheets at a time – and may insist that you break them up and double‑bag them before dropping them down a chute, which can create a lot of dust if not done carefully. If you are not comfortable with that, look for a waste transfer station or skip company that will accept whole sheets and handle the paperwork and transport to a licensed facility for you.