Ceramic building material
 

Introduction

A total of 541.03kg of Ceramic Building Material (CBM) was examined from the excavations; this total included 7.91kg of stone building material such as roof and floor tiles. The CBM is discussed in detail for the whole site and on a phase by phase basis elsewhere within the report. Much of the material from Walmgate was fragmentary, but some complete and almost complete examples of various forms were recovered. A broad range of forms was identified; most were medieval in date, but some Roman, post-medieval and modern forms were also present.

Methodology

The CBM was examined by a x10 hand lens and matched with the York fabric series. The fabric series is divided into Roman (R), medieval (M), floor tile (F), pan tile (P), post-medieval/modern (P0) and stone (S). The material was then recorded on a YAT pro-forma which noted the fabric number, form name, corners present, weight, length, breadth, thickness, presence of mortar, comments and whether the fragments were retained or not. A fragment was retained if it had a feature of interest (such as a paw print or a tally mark, etc.) or was a particularly good example of its form or fabric. Tracings at 1:1 were taken of all tegula flanges, flanged tile flanges, crested ridge tiles and tally marks. All other fragments were fully recorded then discarded. Photographs were also taken of some of the retained pieces. All the data was then transferred onto the Integrated Archaeological Database.

Roman forms

As no pre-10th century deposits were excavated on the site, and the site lay well outside the Roman fortress, relatively little Roman material was present or expected. The Roman material accounted for just 0.75% of the ceramic building material from the site and it was both very fragmentary and abraded. The Roman CBM clearly represents a 'background noise' of residual material.

There were three fragments of tegula present. Tegula are rectangular roof tiles with a flange down each side. The tiles were laid side by side on the roof, flanges upwards, and curved tiles called imbrices were then placed above the adjoining flanges. No imbrices were present in the Walmgate material. In addition to the tegula there was a part of a thick Roman brick, which was pierced by a circular hole, presumably done to aid firing in the kiln. Apart from these four fragments all the remaining material was so fragmentary it was impossible to tell if it was roofing material, walling material or tile from hypocausts.

Medieval forms

The overwhelming bulk of the CBM recovered from the site was medieval and consisted of a variety of forms of 11th–16th century date.

The earliest form of medieval roofing tile consisted of curved and flanged tiles, which date from the 11th to the early 13th century (K. Hunter-Mann pers. comm. and Lewis 1987, 6). The curved and flanged tile imitated earlier Roman roofing forms (tegula and imbrex) and is currently thought to be associated with high-status buildings such as churches (Garside-Neville 1995, p33). As there is no evidence for a high-status building directly on the site it seems more likely that the material originated from a nearby church. Both the churches of St Denys' and St Margaret's Walmgate were present in the 12th century and could represent the source for these fragments (Wilson and Mee 1998, 73 and 98). There is a reasonable quantity of curved and flanged tile on the site; some of the fragments are fairly well preserved and have various features of interest. Two of the curved tiles had glaze on the upper surface; curved and flanged tile in York is normally unglazed, though some glazed examples are known. One flanged tile seems to have had its flange knocked off, possibly to enable re-use. A single example of flanged tile had a possible tally mark; tally marks are thought to represent kiln batch loads.

A number of 13th–16th century roofing forms were present on the site. Roofs during this time were covered with flat tiles called plain tiles, and the ridges of the buildings were capped by ridge tiles, which could be plain or decorated with crests.

Crested ridge tile was present on site, but never in large quantities. It was not always possible to determine the shape of the crest due to damage, but ten examples were variants of fan shapes, which are the most typical shapes for York (AY 10/05, 607). One of the crested tiles had finger-smoothing parallel to the ridge, which was clearly decorative in nature (a feature that was also seen on some of the peg and plain roof tiles). One crested ridge tile was clearly a kiln-waster as it was over-fired and blown. Plain ridge tiles were far more common than crested types, accounting for 79.34% of all the ridge tiles found on site. None of the plain or crested ridge tile was glazed.

Plain tiles could be fixed to the laths of the roof structure by means of a nail or peg inserted through a hole in the tile, or by means of a projecting nib of clay. In general plain tiles in York were pegged rather than nibbed, and had a single peg hole close to the top of the tile. Peg tile can be glazed, often with splashed glaze, but is normally unglazed in York (Betts 1985, 378 and AY 11/02, 295).

The CBM from the excavations accorded with this pattern. The bulk of the plain tile was clearly peg tile with just three examples of nib tile present. The peg tile usually had a single hole, which was square, circular or diamond-shaped. A couple of examples had holes that seem to have been pecked out after the tile was fired. There were just two examples, both with circular peg holes, where the hole was so close to a corner of the tile as to imply there were originally two peg holes on the tile rather than one. It is, however, possible that the peg hole was simply off-centre as seen on examples from the Fishergate excavations in York (AY 11/02, fig.144).

Some of the plain tiles had marks relating to their manufacture. These included tally marks, usually located in the top corner of the tile, which may indicate kiln batch loads. Some of the tiles had indented borders resulting from the tiler tapping down the edges to ensure both that the edges did not stick up and that the clay filled the mould. Grip or finger marks caused when the tile had been lifted while still wet were present on some tiles. A number of marks showed that the tiles were laid on the ground to dry; these included grass or straw marks on the reverse of the tiles, and paw prints (cat and dog) created by animals walking across the upper surface of the tiles. The most unusual example had a baby's footprint in one corner of the tile. A small number of tiles had rain marks on the upper surface so had clearly been subjected to a heavy rain-storm while drying on the ground. One of the tiles was a kiln waster as it was over-fired and blown. Most of the tiles were undecorated; just two of the plain tiles had dark green glaze on the upper surface. In addition a single plain tile had curious marks on the upper surface that may have been stamp impressions. As mentioned above, a few of the tiles had deliberate finger smoothing to create a ridged effect.

A small number of other 13th to 16th century roofing forms were recovered. These included two fragments of possible valley tiles. Valley tiles occur at the junction of two roofs at 90 degrees to one another, i.e. on 'L', 'T' or 'H' shaped buildings. In addition, there were seven examples of hip tiles. A hipped roof is one where the ends of the building as well as the sides of the building have a sloping roof. Specially shaped hip tiles are needed for the junctions of the sloping roofs.

A small quantity of plain glazed floor tile was recovered. Floor tiles of this type are of 14th–16th century date and are thought to have been imported from the Low Countries, though local manufacture remains a possibility (AY 11/02, 299, 301). Plain glazed floor tiles could be square or scored along the diagonal of a square then split to give a triangular shape. The tiles were either coated in cream-coloured slip and then a clear glaze to give a yellow colour, or the glaze was applied directly to the surface of the tile to give a dark green colour after firing. Many floor tiles seem to have been placed on boards with four nails (one through each corner of the tile), presumably in order to trim the tile to a standard size. The site produced examples of both square tiles with dark green glaze and triangular tiles with cream slip and clear glaze. Nail holes were present on some of the fragments.

A large quantity of medieval brick was recovered from the site. Brick came into use from the 14th century onwards, becoming more common through time. Medieval bricks are generally long and thin (rarely exceeding 50mm thick) and were usually made in sanded moulds, though some bricks were made in moulds dipped in water (a technique called slop-moulding). In the case of this site just 18 of the medieval bricks were slop-moulded. Some of the bricks had marks relating to their manufacture; many were similar to those seen on the plain/peg tiles (grass or straw marks, rain drop impressions, paw prints, indented borders and possible tally marks). A single brick had a turning mark on the base and one brick may have had slip on the upper surface, but this was too abraded for certain identification. The most unusual of the medieval bricks on site was from context 1747. It was a specially shaped brick that was possibly for use as architectural detailing around a window. It is an unusual form and seems to have been painted, possibly to imitate stonework. It probably dates to the 15th century or later and would certainly have come from an important building (Garside-Neville in Macnab unpublished b, 137).

Much of the medieval material showed evidence for re-use in association with metalworking. Large numbers of roof tiles in particular were covered with industrial concretion, iron slag or copper slag, or were heavily sooted due to re-use in hearths/furnaces. This confirms other forms of evidence which clearly suggest that metalworking was the principal craft activity on the site.

Post-medieval forms, 16th–18th century

The post-medieval material from the site was largely brick. Most post-medieval brick in York was thicker, shorter and narrower than medieval brick, and it was generally manufactured by slop-moulding. The bricks on Walmgate largely conform to this pattern, though a few sanded bricks had with post-medieval dimensions. Three of the bricks were of interest in that they were designed for architectural detailing; two were from arches while a third had chamfers at the top and bottom of one stretcher implying it had been used as a window mullion.

The remaining post-medieval material consisted of pan tile, which is of 17th century or later date, but there was also a single fragment of a 17th century paving tile.

Modern forms

A small quantity of modern ceramic building material, including the remnants of a quarry-tile floor, machine-produced bricks, wall tiles and sewer pipes was also found. The tile floor is of interest as the tiles had maker's marks in the form of two crowns on the reverse.

Stone roof tile

A few stone roofing tiles were recovered. Stone tiles never formed a large proportion of the roofing material in York, but they do occur on many sites in small numbers.


Click to enlarge
Roman tegula from context 2115

Click to enlarge
Roman brick pierced by a firing hole from context 2638

Click to enlarge
Flanged tile from context 2936

Click to enlarge
Curved tile from contexts 2536 and 2852

Click to enlarge
Flanged tile with the flange knocked off from context 3120

Click to enlarge
Crested ridge tile from context 3118

Click to enlarge
Nib tile from context 2406

Click to enlarge
Peg tile from context 2682

Click to enlarge
Peg tile from context 2609

Click to enlarge
Plain tile with a pecked out peg hole from context 2343

Click to enlarge
Roofing tile with animal paw prints on the upper surface, from contexts 4012, 3090, 2145 and 2101

Click to enlarge
Plain tile with a baby's footpint from context 1492

Click to enlarge
Over-fired and blown tile from context 2539

Click to enlarge
Cross-sectional view of over-fired and blown tile from context 2539

Click to enlarge
Tile with finger smoothing from context 2218

Click to enlarge
Valley tile from context 2322

Click to enlarge
Hip tiles from contexts 2392 and 2852

Click to enlarge
Triangular floor tiles from context 1346

Click to enlarge
Detail of nail hole on floor tile from context 1346

Click to enlarge
Elaborately moulded medieval brick from context 1747

Click to enlarge
Tile covered with copper alloy from context 1910

Click to enlarge
Elaborately moulded post-medieval brick from context 1612

Click to enlarge
Reverse of a modern floor tile showing maker's stamp from context 1201

Click to enlarge
Detail of maker's stamp from context 1201

Click to enlarge
Stone roof tile from context 1870
© Copyright York Archaeological Trust 2003