The short answer
Start with the house: when it was built gives the earliest the roof can be, unless it has been replaced. Then look at the covering and what lies beneath it, since underlay type, fixings and tile wear all hint at age. Deeds, council records and neighbours' roofs fill the gaps. A roofer can often date a roof to within a few years once the loft is open.
Begin with the age of the house
The date the house was built is the upper limit. A Victorian terrace near the Railway Village may be a hundred and forty years old and still wear its original slate, or the roof may have been stripped and renewed a time or two since. A 1980s estate house is more likely to have its first roof, and a 1960s semi may be on its second. Houses built in the same street in the same year often had their roofs replaced at different times, so use the build date as a starting point, not the answer.
Look at the neighbours. If every house in the row has a matching roof, they probably share a date. One with a different tile, a visible patch or a newer ridge has been renewed, and the owner may remember when.
What the covering tells you
Materials age at different rates. Figures in MyBuilder's slate guide, updated 21 August 2026, give well-laid slate 80 to 100 years or more, concrete tiles 30 to 50 and clay 40 to 60. A mossy concrete tile with a rough, eroded face and faded colour has probably used up most of its working life, whereas a hand-made clay tile can look weathered but remain sound for generations.
Machine-made, evenly coloured tiles with crisp edges point to the twentieth century. Slightly uneven, hand-finished ones with wavy edges point earlier. Look for delaminating slate, which flakes into layers, rusty nail stains running down the face, slipped units and a sagging ridge line. Modern replacement tiles sitting among older ones are a sign of earlier repairs. Our guide on signs a roof needs replacing describes the wear to look for.
Underlay, battens and fixings in the loft
Shine a torch from the loft hatch and you will learn more than any amount of guessing. Plenty of older roofs have no underlay at all, and daylight shows between the tiles. Others carry hessian-backed bitumen felt, which turns brittle and cracks with age. Newer roofs have a plastic breathable membrane, usually printed with a manufacturer's name and sometimes a standard reference.
The timber also speaks. Hand-sawn rafters and wide, uneven boards are old, and machine-cut softwood with regular marks is later. Battens that are dark, damp-stained and rotten near the eaves tell you the roof is leaking or condensing. Bright, clean battens with shiny nails mean recent work. Do not step between the joists; stay on the boards, and call us if you are unsure.
Look for dated clues too. Some tiles carry a maker's name or a year pressed into the back, tradesmen have been known to scratch a date into lead or a rafter, and an old newspaper or a bill left under the boards by a previous builder can put a floor under the age. None of these is proof alone, but two or three that agree make a convincing case, and we note them down at the survey.
Paperwork that dates a roof
If a previous owner had the roof replaced, there may be an invoice, guarantee or building control completion certificate in the deeds pack or the solicitor's file. Ask the seller's solicitor or look through the papers from your own purchase. Swindon Borough Council keeps building control and planning records, and you can ask the planning and building control teams whether any application was made for the property.
A survey report from the purchase may describe the covering and comment on its condition. Photographs on old estate agent listings, and satellite images with timestamps, can reveal when the roof colour changed. Dates on a solar installation certificate, a dormer or a loft conversion give the earliest the slope concerned could have been re-covered. Whatever the paperwork says, the physical evidence still has the final word.
Old roofs and asbestos
HSE's position is to assume asbestos could be present in anything built or refurbished before 2000. Around a house, that chiefly means cement sheeting on garages and extensions, and insulating board in some soffits. A corrugated sheet roof that looks several decades old must not be drilled, scrubbed or broken. If you suspect it, get a sample tested before anyone works on it.
None of this means a slate or tile roof contains asbestos. It means that when the roof or an outbuilding dates from that era, the materials are checked before a quote is drawn up, and the age you have worked out helps us do that. We cover how asbestos is handled in our page on roof replacement waste.
Why the age matters and what to do next
Age affects the repair-or-replace decision, a buyer's questions and the insurer's view of the roof. It also helps you judge whether a leak is a one-off or the first of many. For the money side, read whether a new roof adds to house value, and for the flat or metal alternatives look at metal roofing on a house. Our page on telling neighbours helps once a date is set.
We photograph the covering, the underlay and the timbers during the survey and send you the written quote with those pictures, so you see what we see. A survey can be booked on 01793 626096. It can also be useful to read about the roof replacement service before the visit.