Hip Roofs on London Victorian Terraces: Structure, Tiling, and Repair

HIP ROOF STRUCTURE: A HIP ROOF ON A LONDON VICTORIAN TERRACE IS FORMED BY: - RIDGE BOARD: THE CENTRAL HORIZONTAL TIMBER AT THE APEX — SHORTER THAN IN A GABLE ROOF (BECAUSE THE HIP SLOPES TAKE OVER AT EACH END). - COMMON RAFTERS: RUN FROM THE RIDGE TO THE WALL PLATES AT THE EAVES ON THE MAIN SLOPES. - HIP RAFTER: THE DIAGONAL RAFTER THAT RUNS FROM THE END OF THE RIDGE DOWN TO THE CORNER OF THE BUILDING AT THE EAVES. THE HIP RAFTER CARRIES THE JACK RAFTERS ON EITHER SIDE. HIP RAFTER SIZE: TYPICALLY 150MM × 50MM OR 175MM × 50MM C24 KD — LARGER THAN THE COMMON RAFTERS BECAUSE IT SUPPORTS THE ADDITIONAL JACK RAFTER LOADS. IN A VICTORIAN TERRACE, THE HIP RAFTER IS OFTEN 100MM × 75MM OR 125MM × 75MM — THICKER THAN MODERN PRACTICE BECAUSE VICTORIANS COMMONLY USED HEAVIER TIMBER SECTIONS. - JACK RAFTERS: SHORTER RAFTERS THAT RUN FROM THE HIP RAFTER DOWN TO THE EAVES ON THE CORNER SLOPES — THEY DECREASE IN LENGTH AS THEY APPROACH THE CORNER OF THE HIP. - VALLEY/HIP BOARD: ON A HIP BAY WINDOW ROOF, A VALLEY BOARD (SIMILAR TO A HIP RAFTER BUT FORMING THE INTERNAL ANGLE BETWEEN THE BAY ROOF AND THE MAIN WALL) CARRIES THE ROOF STRUCTURE.

HIP TILE TYPES ON LONDON VICTORIAN TERRACES: - BONNET HIP TILE (MOST COMMON ON PLAIN CLAY TILE ROOFS): THE TRADITIONAL HIP TILE FOR A PLAIN CLAY TILE ROOF — A SHAPED CLAY TILE WITH A ROUNDED UNDERSIDE THAT STRADDLES THE HIP LINE, COVERING THE EXPOSED TILE EDGES ON EACH SIDE. BONNET HIP TILES ARE THE SAME WIDTH AS THE MAIN TILES (165MM) BUT HAVE A CURVED UNDERSIDE RATHER THAN FLAT. THEY INTERLOCK WITH THE PLAIN TILES ON EACH SIDE AND ARE MORTAR-BEDDED AND (NOW) MECHANICALLY FIXED. - ANGLE HIP TILE: FOR ROOFS WITH A RIDGE ANGLE INCOMPATIBLE WITH A BONNET HIP — A FLAT-PROFILED ANGLED CLAY TILE WITH A SHAPED SECTION TO COVER THE HIP. LESS COMMON ON LONDON VICTORIAN TERRACES. - LEAD SOAKER HIP (FOR SLATE ROOFS): ON A WELSH SLATE ROOF, THE HIP IS TYPICALLY FORMED WITH LEAD SOAKERS LACED BETWEEN EACH COURSE OF SLATES AT THE HIP LINE — SIMILAR IN PRINCIPLE TO SIDE ABUTMENT SOAKERS. NO HIP TILE IS USED — THE SOAKERS PROTECT THE EXPOSED SLATE EDGES AND THE SLATES MEETING AT THE HIP ARE MITRED TO A CLEAN JOINT. ALTERNATIVELY: A LEAD HIP ROLL (A ROLLED LEAD BEAD NAILED TO THE HIP RAFTER AND DRESSED DOWN OVER THE SLATE EDGES ON EACH SIDE) IS USED ON SOME VICTORIAN WELSH SLATE ROOFS.

BONNET HIP TILE BEDDING: BONNET HIP TILES ARE FIXED WITH THE SAME SYSTEM AS RIDGE TILES — MORTAR BED (TRADITIONALLY 1:3 OPC:SAND OR LIME-BASED FOR CONSERVATION AREA PROPERTIES) APPLIED TO THE LAST PLAIN TILE EDGE ON EACH SIDE; THE BONNET HIP TILE IS SET INTO THE MORTAR BED AND THE TAIL (LOWER EDGE) OVERLAPS THE PLAIN TILE BELOW. MECHANICALLY FIXED WITH A STAINLESS STEEL SCREW THROUGH A DRILLED HOLE IN THE CROWN OF THE BONNET TILE INTO THE HIP RAFTER BOARD (OR A PROPRIETARY BONNET HIP CLIP).

COMMON DEFECTS AT HIP LINES: 1. SLIPPED OR DISPLACED BONNET HIP TILES: MORTAR FAILURE — THE SAME PROBLEM AS RIDGE TILES. A DISPLACED BONNET HIP TILE LEAVES A GAP THAT ALLOWS WIND-DRIVEN RAIN AND BIRDS TO ENTER UNDER THE TILE COURSES AT THE HIP. 2. MISSING LEAD SOAKERS (SLATE ROOFS): WHERE SOAKERS HAVE BEEN OMITTED OR CORRODED, THE HIP JOINT ON A SLATE ROOF IS UNPROTECTED — WATER ENTERS ALONG THE MITRED SLATE EDGES. 3. FAILED HIP RAFTER: THE HIP RAFTER IS IN A CORNER POSITION — IT CAN RECEIVE WATER FROM BOTH ROOF SLOPES AND IS A CONCENTRATION POINT FOR MOISTURE. INSPECT THE HIP RAFTER THROUGH THE LOFT HATCH — LOOK FOR STAINING, SOFT SPOTS, OR VISIBLE ROT AT THE FOOT OF THE RAFTER (WHERE IT BEARS ON THE CORNER OF THE WALL PLATE).

HIP TILE REPAIR AND RE-BED: - HIP TILE REPOINTING (HACK OFF AND RE-BED WITH FLEXIBLE COMPOUND): THE SAME PROCESS AS RIDGE TILE REPOINTING. USE GEOCEL MORTAR MATE OR GEOCEL TRADEMATE FOR THE BEDDING MORTAR AND SIDE POINTING — FLEXIBLE COMPOUND IS MORE DURABLE THAN OPC:SAND MORTAR AT THE HIP. - MECHANICAL FIXING: STAINLESS STEEL SCREW THROUGH DRILLED CROWN OF EACH BONNET HIP TILE INTO HIP RAFTER. WHERE THE HIP RAFTER CANNOT BE DIRECTLY REACHED (A DEEP HIP BOARD IN PLACE): USE A PROPRIETARY BONNET HIP CLIP (AVONSTAR BONNET HIP CLIP, ROOFIT BONNET HIP CLIP — NAILED TO THE TILE BATTEN BELOW). - SOURCING REPLACEMENT BONNET HIP TILES: MARLEY CLAY BONNET HIP TILE (HEATHLAND — DARK RED, BUFF), DREADNOUGHT CLAY BONNET HIP TILE, KEYMER CLAY BONNET HIP TILE. RECLAIMED BONNET HIP TILES FROM ROOFING SALVAGE YARDS (LASSCO, THORNHILL, BUILDSTOCK) IF A MATCH TO ORIGINAL IS REQUIRED IN A CONSERVATION AREA.

LEAD SOAKER INSTALLATION AT SLATE HIP: REPLACING OR FITTING LEAD SOAKERS AT A SLATE HIP LINE: 1. REMOVE THE LAST COURSE OF SLATES ON EACH SIDE OF THE HIP LINE (BACK 2-3 COURSES) TO GAIN ACCESS. 2. FORM AND FIT CODE 3 LEAD SOAKERS AT EACH COURSE — UPSTAND TOWARD THE HIP RAFTER (25MM), LAP (SAME AS SLATE HEADLAP — 65-75MM), WIDTH (GAUGE + LAP + 25MM). SLIP THE SOAKER UNDER THE TAIL OF THE SLATE ABOVE AND ONTO THE BATTEN BELOW. 3. REFIT THE SLATES. 4. A LEAD HIP ROLL (CODE 4 — DRESSED DOWN OVER THE SLATE EDGES ON BOTH SIDES, FIXED WITH COPPER TACKS AT 300MM CENTRES THROUGH THE EDGE OF THE ROLL TO THE HIP RAFTER): COVER THE SOAKER UPSTANDS AND SEAL THE HIP LINE.

COSTS (SUPPLY AND FIT, LONDON 2025-2026): HIP TILE RE-BED WITH FLEXIBLE COMPOUND (PER M RUN): £40-100/M HIP TILE RE-BED WITH MECHANICAL FIX (PER M RUN): £60-130/M BONNET HIP TILE REPLACEMENT (NEW — PER TILE, SUPPLY AND FIT): £30-80 PER TILE LEAD SOAKER INSTALLATION AT SLATE HIP (PER M RUN): £120-250/M FULL HIP RE-TILE (STRIPPING AND REPLACEMENT OF ALL PLAIN TILES AND BONNET HIP TILES — PER M OF HIP LENGTH, SUPPLY AND FIT): £150-350/M