A pantile has a shallow S in its section, so one half of the tile is a low trough and the other half a rounded roll. Laid in rows, the tiles make a ribbed roof that looks nothing like a flat plain tile roof, and you meet it on cottages, barns, farm buildings, garden outbuildings and the rear slopes of older houses. This guide is for anyone with a pantile roof who wants to understand it before work starts: how the tiles are hung, why the pitch matters more than most people expect, where leaks begin, and how repairs are carried out. It stays on the pantile itself. If you are choosing between coverings, our pages on concrete roof tiles and the wider pitched roofing service cover the alternatives and the full range of work.
What a pantile is and how it is laid
The classic pantile is a clay tile fired in a curved profile. Each tile has a pan, the low trough that carries water down the slope, and a roll, the raised curve that sits beside it. Concrete tiles are also made in a pantile shape, and they follow the same laying principle, but this guide is mainly about clay because that is what you find on older buildings.
Unlike a plain tile roof, where tiles overlap by being laid in several layers, a pantile roof is single lap. One layer of tiles covers the roof. Each tile overlaps the roll of its neighbour at the side, and its head sits under the tail of the course above. Water runs down the pans and the lap at the side is what keeps it from crossing into the roof space. That is a neat design, but it only works if the laps are tight and the slope is steep enough to carry water away before the wind pushes it sideways or upwards.
The tiles hang from timber battens, the narrow horizontal strips nailed across the rafters. A nib on the back of each tile hooks over the batten, so the tile does not depend on a nail alone. The spacing of the battens, called the gauge, follows from how long the tile is and how far its head must be covered. Underneath the battens sits the underlay, the membrane that catches any water or snow blown beneath the tiles. Some old roofs have nothing beneath the battens, only tiles on timber, which is why the building can feel draughty and why dust and daylight are sometimes visible from the loft.
The edges and the ridge
The edges need separate treatment, because a plain run of pantiles stops dead at a gable and a wall. Where the slope ends against a gable wall, the edge is called the verge. Its last tiles usually sit in mortar on an undercloak, a thin base course of slate or tile that fixes the line and keeps rain off the wall head. At a ridge, the ridge tiles are bedded in mortar along the top. BS 5534:2014 covers slating and tiling, and it will not let bedding mortar do the holding at ridge, hip or verge. Good current practice adds a clip, screw or strap. Some roofers replace the bedding with a dry system tested against BS 8612:2018.
Why pantiles leak at low pitch
Pitch is the angle of the roof slope, and pantiles are often found on roofs with a gentler slope than a plain clay tile roof would be given. That lets a pantile roof look low and settled on a barn or a lean-to. It also makes the covering sensitive. Water moves slowly on a shallow slope, and slow water has time to find its way through a gap. Wind-driven rain can be pushed upwards under the lap, and fine snow can blow under the tiles when there is no underlay to stop it.
The single lap is the weak point. On a double-lap plain tile roof, a missed gap in one layer is covered by the layer beneath. A pantile roof has no second layer. If a tile has cracked, if the side lap has opened because the roof has moved, or if the nibs have snapped and the tile has slid out of place, water has a direct route to the batten and the loft below. A low slope makes each of those failures show more quickly.
There is also the matter of what the roof was designed to do. Many old pantile roofs were laid on lath or thin battens, with no underlay, a bed of lime mortar pointing beneath the tiles to seal the laps, and a loft that was never meant to be lived in. A building like that tolerates a degree of weather coming in because the roof space was ventilated by the same gaps. Once the loft is lined, insulated or converted, the same gaps become leaks and cold spots. Often the complaint that brings someone to us is not a new fault. It is an old roof being asked to do a different job.
Moss and lichen make matters worse. Growth builds up in the pans, holds water against the tile and blocks the channel, so water spills over the roll into the lap. Clogged pans are high on our list when we inspect a low pantile roof, and they explain why the shaded slope often leaks first.
The faults we find on pantile roofs
Most faults on a pantile roof are one of a short list, and many of them can be repaired without stripping the slope. Reading the roof from the ground with binoculars, and then close up from a ladder or scaffold, we look for the following.
- Cracked tiles. Frost, a dropped branch or a footprint can crack the pan or the roll. A crack along the pan lets water onto the batten directly.
- Slipped tiles. Tiles slip when the nib has broken or the batten under them has rotted. A slipped tile leaves a gap, and the course above it may follow.
- Failed pointing and bedding. Mortar at the ridge, verge and hips cracks and falls away. Cement mortar, used in repairs over the years, is harder than the clay and can crack along the edge of the tile instead of moving with it.
- Rotted battens. If a long-running leak has wetted a batten, it softens, and the nails or nibs that hold the tiles lose their grip.
- Open or damaged side laps. On a roof that has moved, the rolls no longer fit down over each other tightly.
- Lead and flashings. A flashing is lead dressed over a joint, at a stack or a side wall for instance, to shed water away from the gap. On a pantile roof the profile of the tile makes that joint harder to seal, so flashings and the lead soakers or fillers beside them fail often.
Valleys deserve a separate word. Each valley is an inward angle between two slopes, and it collects water from both. Pantiles cannot turn that angle without cutting, so valleys are usually lined with lead and the tiles are cut to follow it. A split in that lead sends concentrated water straight into the roof, and it is one of the hidden parts that never shows from the road.
How a pantile roof is repaired
A repair starts with finding the cause, not covering the symptom. A damp stain in the loft is often several courses away from the tile that has failed, because water runs along the batten or the underlay before it drops.
Replacing individual tiles
A cracked or slipped pantile can be lifted out and a matching tile fitted in its place. The tiles on either side are lifted a little at the roll, the old tile is removed, and the new tile is slid in and hooked over its batten. Because the tiles interlock at the side, a roofer must free the neighbouring tiles carefully to avoid cracking them. On a roof that has weathered for many years, a new tile in a fresh orange stands out, which is why we look for salvaged or reclaimed tiles of the same profile and colour. Our page on reclaimed roof tiles explains how matching works.
Re-bedding the ridge and verge
Where mortar has failed, the ridge or verge tiles are lifted, the old bedding is cleared, and the tiles are re-bedded with a mortar mix suited to the roof. Given that standard, the new work should carry a mechanical fixing too. That is a different job from patching a crack with a smear of mortar, which tends to fail again within a season or two.
Re-laying a slope
If battens have rotted over a wide area or the underlay is missing, patching is no longer the right answer. The tiles are taken off and sorted, sound ones kept, the battens renewed, a breathable underlay laid, and the tiles put back with any shortfall made up with matching tiles. This keeps the look of the roof while giving it the layers it never had. It is the usual route on an outbuilding or cottage that is being brought into regular use.
Where a repair works, we repair. A roof with a handful of cracked tiles and a failed ridge does not need replacing, and we will say so after the survey and photographs of your own roof.
Matching, consent and old pantile roofs
A pantile roof is part of how an older building looks. A single re-laid slope in the wrong tile, or a mix of colours, shows from the lane. For that reason we match the profile, the size, the colour and the surface texture of the existing tiles instead of dropping in whatever is nearest in a merchant's yard.
If the building is listed, altering the roof covering is likely to need consent from B&NES Council, and carrying out work without it is an offence. The council treats consent for listed buildings and planning permission as separate applications, so ask before any tiles are ordered. Our separate guide to listed and conservation roofs sets out how matching and consent fit together. Outside Bath the same principle holds with the relevant council, whether that is Wiltshire Council or Somerset Council.
In its casework on a Grade I property in St James's Square, the Trust describes mainly Welsh slate across the roof, with some clay pantiles to the back slope. It is one example, and it shows that pantiles sit comfortably in the city's story as well as on the country buildings around it. We do not claim that pantiles are typical of any particular district. What we can say is that when the roof has them, the repair should keep them.
Replacing pantiles with a different covering is a change of weight as well as appearance. Swap to a covering heavier by 15 per cent or more and you need Building Regulations approval, with the roof structure assessed. The Planning Portal gives the thresholds, and modest like-for-like repairs generally fall under them.
Outbuildings, lean-tos and what to ask before work starts
Garden buildings, stables and lean-tos are the most common pantile roofs we are asked about, and they have their own quirks. They are often low, so the pitch is shallow. They are often unlined, so every gap is visible from the inside. And they are often used for storage, which means a small leak can spoil more than the building.
Before you instruct anyone, it helps to get answers to these points, whoever does the work.
- Which tiles will be kept, which replaced, and what will the replacements look like once fitted?
- Is an underlay going in, and is it a breathable type suitable for the building?
- Are the battens being checked or renewed, or only the tiles?
- How will the ridge and verge be fixed, given that mortar alone is not relied on?
- What happens at valleys, walls and chimneys, and is the lead being renewed or reused?
If a pantile roof sits on a lean-to against the main house, check the flashing along the wall. It is a long lead joint, usually only visible from a ladder, and a frequent source of damp patches inside the house wall. A defect of that sort is repaired in lead, dressed to the profile of the tile, rather than sealed over with mastic that will fail in a few winters.
We survey for nothing and send pictures of your roof, so you can see the cracked or slipped tiles, the battens and the flashing for yourself. A fixed price in writing follows it, listing how many tiles need replacing and whether reclaimed pantiles can be found to match the colour of the old ones. If the answer is a few tiles and a re-bedded ridge, that is what the quote will say. If you also want to understand the area around a dormer or the difference between pantiles and other coverings, the mansard planning page and the pitched roofing hub give the wider picture.