Most roof repairs fall into a short list of faults. A tile or slate has slipped, a flashing has lifted from a chimney, a ridge has loosened, a valley or gutter has split, or the felt under the covering has given up. The surface symptom is nearly always a stain, a drip or a missing piece on the lawn, and the cause is often somewhere else on the roof. This guide describes each common repair in turn: how the fault shows itself, why it happens and what a sound repair involves. It is written for someone who has noticed a problem and wants to understand it before calling anyone. Where a fault needs a closer look, that is stated directly. Where repair is the right answer, that is stated too, because a roof that is mostly sound should be mended, not replaced. Everything here applies to Bath stone and clay roofs as much as to slate, with differences noted as they come up.
Slipped, cracked and missing tiles and slates
This is the repair people picture first, and it is also the most common. A tile hangs from its battens (the thin timber laths running across the roof) by a nib, and nailed or clipped courses hold it down. Over the years the nails corrode, the nibs crack, frost lifts the clay and wind works at the edges. One tile drops a few centimetres, then another, and a gap opens that water can run through.
From the ground you may see a dark line where a tile has sunk, a ragged edge on a course, or fragments in the garden or gutter. From inside, the first sign is usually a brown ring in a bedroom ceiling that shows up following rain driven from one side. The fault is nearly always above the stain, up the slope, so a patch on the ceiling tells you the neighbourhood of the problem rather than its address.
The repair depends on the covering. A single plain clay tile is lifted with a slate ripper or by easing the course above, then a matching tile is slid in and held with a clip or nail. A natural slate that has slipped is replaced by sliding in a new one and fixing it with a tingle, which is a little copper or lead tab that takes the place of the missing nail head. Interlocking concrete tiles are lifted and relaid. Stone tiles are heavier and need more care, because the old pegs and the weight of the course above make them awkward to disturb.
Matching is the part that separates a neat repair from a visible one. A new red tile on a weathered roof stands out for years, so where the colour matters we use reclaimed or weathered stock. On older roofs we keep the covering the house was built with, so natural slate stays slate and clay stays clay.
Lifted and failed flashings and lead at chimneys and walls
A flashing is lead (sometimes zinc) shaped over the junction between a roof slope and anything that rises through it: a chimney stack, a party wall, a dormer cheek or a vent pipe. It is one of the most frequent places for water to enter, because the joint is where two materials move at different rates. A soaker is a small lead square worked in beneath each course at that junction, and together the soakers and the flashing carry water back onto the roof.
Lead fails in recognisable ways. It can lift at the top edge where the mortar pointing has crumbled, split along a fold after years of expansion and contraction, or slip downward because it was never well supported. Sealant smeared along the join is a sign someone has tried a quick fix, and it rarely lasts, because it hides the gap without closing it.
Inside the house, a leak at a chimney breast shows as a brown mark on the chimney wall or ceiling beside it, often after wind-driven rain. Outside, you may see a lead strip standing proud of the brickwork, a gap at the top of the flashing, or staining on the stack itself.
A proper repair opens the joint, rakes out failed pointing, and re-fixes the lead into a cut groove in the masonry, a detail called a chase. The lead is then wedged and repointed. On a Bath stone stack the pointing is lime mortar, since a hard cement pointing can hold water against softer stone. The Bath Preservation Trust argues the same in its comments on listed chimney stacks. If the lead is badly split, new flashing and soakers are cut and fitted, rather than patched. Typical UK figures reported by MyBuilder's chimney repair guide (2026) put a flashing repair at £250 to £1,200, and a simple chimney patch at about £250 without scaffold or £550 to £650 with it. The final figure on your own roof depends on access and the extent of the lead, and your fixed price follows the survey.
Ridge, hip and verge faults
The ridge runs along the apex. A hip is the angled arris where two slopes turn an outside corner. A verge is the sloped edge that finishes a gable. These lines take the worst of the wind, and they are finished with special pieces: ridge tiles, hip tiles, and a verge treatment of mortar, cloaks or a dry system.
The classic failure is a ridge that has loosened because the mortar bedding has cracked and fallen away. You may see tiles that rock when the wind blows, dark gaps between the ridge and the slope, or mortar crumbs in the gutter. At the verge, a cracked mortar fillet lets rain run in under the last tiles and rots the timber behind it. Neither fault produces a dramatic leak at first. The damage is slow, and the loft timbers or the gable wall take it.
Under BS 5534:2014, a bedding of mortar is not trusted to hold ridge, hip or verge fittings unaided, so a clip, screw or strap is added. For a repair, that means rebedding the ridge in fresh mortar with clips or screws, or converting to a dry-fix system, in which the ridge sits on a batten and is held with fixings and sealed with a vented strip, with no mortar to crack. The test specification for dry systems is BS 8612:2018. Dry-fix is quicker to install and needs less upkeep, though it suits some tile profiles better than others.
MyBuilder's dry ridge guide (2026) reports dry ridge at £40 to £60 a linear metre, while a standard installation lands at £500 to £1,000. The same guide does not give a figure for mortar rebedding, so we do not quote one. Ridge work needs a scaffold or a tower to be done safely, which is a large part of the price on a two-storey house.
Valleys, parapet gutters and rainwater goods
A valley is the V where two slopes fall towards one another. It is lined with lead, or on newer houses a GRP or plastic trough, and it takes the run-off from both sides down to the gutter. A box gutter is a lined trough tucked between two roofs or behind an edge, out of sight from the street. A parapet gutter is the same trough behind a parapet wall, and some Georgian and Victorian terraces in Bath drain this way, through lead-lined channels along the back of a stone upstand.
These hidden channels take a lot of water and fail slowly. The lead splits at a drip (the step that lets water fall from one level to the next), cracks where it has been walked on, or has been patched with bitumen until the patches overlap. Outlets block with leaves and moss, the water backs up, and it finds its way over the lap and into the wall below. Indoors, expect damp patches on a top-floor ceiling, or on the wall below a parapet, that bloom during prolonged rain rather than a short shower.
The repair depends on how far the lead has gone. A split at a single seam can sometimes be lead-welded or replaced as a patch. Where a long run has gone hard and cracked, the better answer is relining the whole gutter, with lead of a thickness suited to the job and falls corrected so water drains. We do not quote code thicknesses on this page because they are a matter for the survey.
Ordinary gutters on the eaves are a simpler repair: a leaking joint, a sagging run where the brackets have loosened, or a downpipe choked at the shoe. Typical UK figures reported by MyBuilder's gutter guide (2026) are £30 to £70 per metre for guttering, and scaffold adds a further £20 to £40 per square metre of wall. A gutter left overflowing soaks the wall behind it, so a simple blockage is worth clearing before the stain starts.
Flat roof repairs: felt, EPDM and GRP
Flat roofs fail differently from pitched ones, because they have no slope to shed water quickly and every join in the membrane is a place where ponding water can sit. The covering is usually one of three. Bitumen felt is layered sheets, torched or stuck on. EPDM is one sheet of synthetic rubber, adhered to the deck. GRP is a laminate of glass matting and resin, brushed over the deck and left to cure rigid like a boat hull.
The faults to look for are blistering and splits in felt, a lifted or punctured sheet of EPDM at an edge or a pipe, and cracking in GRP, often at the perimeter trim at the junction with an upstand, where the building moves a little. Ponding after rain suggests the deck has dipped or the falls were never right. Water that comes through a ceiling under a flat roof may have travelled along the deck before dropping, so the entry point can sit some distance from the stain.
Repairs follow the material. Felt can be patched, though one patched many times over has little life left. An EPDM puncture is cleaned and repaired with a glued patch and primer, and a failed edge is re-glued under fresh flashing. GRP cracks are ground back and relaminated with new resin and matting. Where the deck beneath is soft or the insulation is soaked, covering over it hides the trouble, so the damaged board is cut out and replaced first.
MyBuilder's flat roof cost guide (2026) puts typical replacement at £70 to £150 per m² across the three, with felt cheapest and GRP dearest. Those are replacement rates rather than repair prices, and they are useful mainly to show when repeated repairs begin to cost more than a new membrane. If you are weighing that choice, a survey will show what is wrong with the deck.
Underlay, timbers and the faults you cannot see
Some repairs begin under the covering. Underlay is the thin membrane that sits between the rafters and the battens, and it works as a back-up barrier to blown rain and condensation. Some older roofs were laid with none, or with a bitumen felt that has since turned brittle and torn. Where it has failed, water from a small defect in the tiles runs down the underside and soaks the timbers rather than the plasterboard, so there is no early warning.
Signs of this kind of failure are subtle. You might find a patch of daylight in the loft, felt that crumbles when touched, damp on the underside of the sarking (the boards laid over the rafters on some older roofs), or a musty smell at the eaves. Rafter feet, the lowest ends at the point they land on the wall plate, are the usual casualties, because the water ends up there. Soft or dark timber that gives under a screwdriver has gone past surface staining.
The repair is proportionate to the damage. Light surface damp can be dried and monitored once the entry point is closed. Rot is cut out and the beam is either spliced, with a new section bolted alongside, or replaced. Where the underlay has failed over a limited area, the covering is lifted, the underlay renewed and the tiles re-fixed. If the felt is perished over a whole slope, that is a conversation about re-covering the slope, not about repair.
Ventilation matters here too. A loft that cannot breathe gathers condensation beneath the cold roof covering, which can look like a leak and rot timber just as well. Our page on telling a leak from condensation explains the difference. It is worth settling that before paying for a repair that will not cure the problem.
When repair is enough and what it can cost
Repair makes sense when the damage is confined to one area and the remaining roof is in good order. A handful of slipped tiles, a failed flashing, a split in a valley or a loose ridge is a defined job. The test we use is whether fixing it brings the roof back to something that will last, or only delays a larger problem. If fixings are going on every course, or the underlay has perished wherever you look, a series of small repairs becomes more expensive than the roof they are supporting.
Typical UK costs reported by MyBuilder's roof repair guide (2026) average between £150 and £1,500. Light jobs, such as chasing a small drip or replacing a few tiles, typically cost £100 to £300. A moderate repair reaches £500 to £1,000, and major work begins around £2,500. Storm damage repairs are typically £500 to £1,500. These are national figures, and what you pay depends on how far the roof is from the ground, whether materials have to match, and how much of the hidden structure is affected. Our guide to roof repair costs goes through the numbers in more detail.
Building Regulations rarely apply to repair. Repairs and re-covering are not normally notifiable, according to the Planning Portal, unless they reach the thresholds it sets for the envelope and the roof. If the replacement covering weighs at least 15 per cent more than what it replaces, approval and a structural check follow. On a listed Bath house, B&NES Council grants listed building consent, and it is sensible to ask them before any repair that changes the covering or the lead.
Some people consider doing the work themselves. Our page on DIY roof repair covers what is realistic from the ground. If water is coming in now, read the guide to an emergency roof leak first. We survey free of charge, take photos of your roof and put a fixed price on paper afterwards. Before you call, note where the water shows indoors and how heavy the rain was, as that narrows down the cause quickly. The full roof repairs service is described on its own page, and you can reach us on 01225 285181 or through WhatsApp.