Dating a building from the pavement

A building is a document. It was written by people who had particular materials to hand, particular laws to obey and a particular idea of what looked respectable, and almost none of them were trying to disguise the date. Most British buildings will tell you theirs to within about twenty-five years, and you never have to go inside.

What follows is a routine in the order a surveyor uses it: the slow structural evidence first, because it is hardest to fake, and the fashionable ornament last, because it is the first thing a Victorian would have bolted on.

Start with the wall

Brick bond — the pattern in which bricks are laid — is the single most useful thing on a British façade, because it follows structure rather than taste.

English bond alternates a whole course of headers (bricks laid end-out) with a whole course of stretchers (laid long-side out). It is strong, it is the dominant bond in Britain until roughly 1700, and it survives afterwards for bridges, viaducts and retaining walls where strength matters more than fashion. Flemish bond alternates header and stretcher within every course, giving that chequered rhythm of small squares. It arrives in the later seventeenth century, becomes the polite Georgian norm, and is what most people picture when they picture a brick terrace. English garden wall bond, three or five stretcher courses to each header course, is the cheap compromise used on the sides and backs of buildings whose fronts are Flemish — which is itself a clue about where the money went.

Then the killer. If the wall is stretcher bond and nothing else, with no headers anywhere, there is no solid thickness to tie together: it is a cavity wall, and that means the 1920s at the earliest and usually later. One glance at the bond puts a floor under the date.

Brick size refines it. Tudor bricks are thin, roughly 50 mm, irregular in colour and laid with thick joints; Georgian bricks run around 60 mm; Victorian bricks are harder and far more uniform at about 68 mm; modern metric bricks are 65 mm and machine-perfect. The practical measure is the gauge — how many courses fill a metre of wall. More courses means thinner bricks means, broadly, earlier. The brick tax of 1784 to 1850 was levied per thousand bricks, which pushed some makers to enormous ones: a tax can be a dating tool.

Mortar and pointing come next. Pre-twentieth-century walls are laid in lime mortar, soft and pale and usually more weathered than the brick; hard grey cement smeared into a raised ribbon over the brick edges is a twentieth-century repair and dates only the repair. The prize find is tuck pointing, where mortar tinted to match the brick is finished with a fine raised white ribbon down the middle of each joint, faking the ultra-fine joints of expensive rubbed brickwork. It is a Georgian and Regency conceit, roughly 1750 to 1850, and its survival proves the front has never been repointed.

Then the windows

Windows carry the finest-grained evidence on any British building, which is exactly why replacement windows cause so much misdating.

Before the sash, England glazed with casements: small leaded quarries in an iron or timber frame, hinged at the side. The sash window, counterbalanced on cords and weights in a hollow box frame, arrives from the Low Countries in the 1670s and conquers polite building within a generation. From then on the story is one of steadily thinning glazing bars. Around 1700 a bar is a chunky 35 mm or so with a heavy flat face; by 1750 it has slimmed and acquired an ovolo or astragal moulding; by 1800 it can be 15 mm or less, and Regency joinery pushes it finer still, sometimes with margin lights — a narrow border of small panes, often coloured, around a larger centre.

The London Building Acts add hard dates: the Act of 1709 required frames to be set back four inches from the wall face as a fire precaution, and the Act of 1774 hid the box behind the brick reveal altogether, so a flush sash box in London means pre-1709 work.

The best single tell is the horn: the small projecting lug at the bottom corners of the upper sash, running past the meeting rail. It strengthens the joint against the weight of large sheets of glass, and appears once cheap sheet glass does — from the 1840s, universal by the 1860s. A Georgian house with horned sashes has had its windows replaced. Pane size grows alongside: six-over-six through the Georgian period, two-over-two mid-Victorian, then one-over-one plate glass, then the Queen Anne Revival deliberately putting small panes back in the upper sash only, from the 1870s.

Arch, roof, eaves, chimney

Arch shape is a period language in itself. Round-headed arches with thick walls are Norman; pointed arches Gothic; the flattened four-centred arch with its almost drooping profile is Tudor; round again for the classical seventeenth and eighteenth centuries. Within Georgian brickwork, the cheap head is a segmental arch of ordinary bricks on edge, used on backs and vernacular fronts; the polite head is a gauged flat arch of soft rubbing bricks cut to wedge shapes and set in joints so fine you must look twice to see them.

Roof pitch is really a question about covering, and covering a question about geology and transport. Thatch, stone slate and plain clay tile shed water only at 45 degrees and up; pantiles manage 35 or so; thin Welsh slate is watertight at 25. Welsh slate travelled by canal from the 1790s and by rail from the 1840s, at which point it swept the country and roofs flattened. A low-pitched slate roof is therefore, almost anywhere in England, post-1800.

The wall-to-roof junction comes next. A deep projecting timber eaves cornice, boldly moulded, is late-seventeenth or early-eighteenth century — and was banned in London by the Act of 1707 in favour of a brick parapet hiding the roof, which is why Georgian London has such flat, straight skylines. Parapets read urban and polite; exposed eaves read rural or later.

Chimneys give you the plan. A massive stack through the middle of the ridge means a vernacular lobby-entry house of the sixteenth or seventeenth century, with fireplaces back to back either side of the front door. Gable-end stacks are the polite Georgian arrangement. Tall, thin, diagonally set shafts in moulded brick are Tudor, or a Victorian quoting Tudor.

Doors and giveaways

The Georgian front door is six-panelled, the two upper panels tall; above it a rectangular overlight early on, then from around 1770 the fanlight — a semicircle of fine lead ribbon radiating in fans, spiders’ webs and teardrops, lighting a hall that has no window. Doorcases run from the carved shell hood of about 1700, through mid-century Doric or Ionic columns and pediment, to the restrained reveal-and-fanlight of the 1790s. Victorian doors go to four panels, the upper pair often glazed with coloured or etched glass, and the case becomes a pair of stucco pilasters.

After that, ornament: the Venetian window (round-arched centre, flat-headed flankers) for Palladian, roughly 1720–70; baseless Greek Doric for the Greek Revival, 1800–40; deep bracketed eaves and paired round-arched windows for the Italianate, 1840s–70s; banded red-and-black structural polychromy for High Victorian Gothic, 1850s–70s; red brick with white-painted woodwork and Dutch gables for Queen Anne Revival, 1870s–90s; roughcast and long horizontal casements for the 1920s and 30s.

Reading the alterations

Most buildings are palimpsests, and the interesting question is usually not “what date is it?” but “what date is each part?”.

A refronting — an older house given a fashionable new face — betrays itself at the edges. Look at the corner for a straight vertical joint where new brick abuts old walling; check whether the flank is a different bond, a different brick gauge or timber-framed; check whether floor levels inside line up with the windows outside, which they will not if the façade was designed independently. A related trick is mathematical tiles, hung brick-shaped tiles giving a timber-framed house a brick face, spotted at the corners where the bond cannot quite turn convincingly.

A raised roof shows as a change of brickwork in the top metre or two, a ghost of an older steeper roofline on the side of a chimney stack, or top-floor windows that fail to diminish in height as they should. And a Victorian shopfront punched into a medieval hall house is so common in English market towns that the rule is simply to ignore the ground floor and look up.

Where the rules break

Three things defeat over-confident dating. Regional lag: fashion radiated from London, so a detail that is 1720 in Bloomsbury may be 1770 in Cumberland. Vernacular indifference: a building put up by local masons in local stone to local custom may have no fashionable content at all, which is why Clifton-Taylor’s The Pattern of English Building is really a dating manual in disguise — the material tells you where you are, not when. Revivals and reclamation: a Gothic Revival church is not Gothic, a Tudorbethan pub is not Tudor, and second-hand bricks, reused slates and salvaged doorcases will all lie to you. The defence is the same in every case: never date a building from one feature. Date it from the agreement of five.

The official apparatus

Two systems govern what can be done to what you are looking at. Listing protects individual buildings of special architectural or historic interest across the whole structure, interior included, plus fixtures and pre-1948 structures in the curtilage. Grade I is exceptional (about 2.5 per cent of listings), Grade II* is particularly important (about 5.8), and Grade II covers the remaining 92 per cent. Age governs the odds: essentially everything pre-1700 surviving substantially intact is listed, most of 1700–1850, with selection tightening after 1850 and again after 1945, and nothing under thirty years old unless outstanding and threatened.

Conservation areas work the other way round. Under section 69 of the Planning (Listed Buildings and Conservation Areas) Act 1990, a local planning authority designates an area whose character or appearance it is desirable to preserve or enhance. The protection is of the ensemble — roofline, materials, trees, the rhythm of the street — and an Article 4 direction can withdraw the permitted development rights that would otherwise let owners swap timber sashes for uPVC without asking.

Finally, the reference book. Nikolaus Pevsner’s The Buildings of England ran to forty-six county volumes between 1951 and 1974, published by Penguin and now revised under Yale, with companion series for Scotland, Wales and Ireland. Entries run alphabetically by place and usually open with the parish church. The trick is not to look up your building first: read the county introduction, which explains the local geology, walling stone, roofing material and regional habits. After that the entries make sense, and so does everything you see out of the car window.

How to spot it in ten seconds

1. Bond. Stretcher-only means cavity wall, so post-1920s. Flemish means Georgian or later polite. English means pre-1700 or engineering work.
2. Brick gauge and colour. Thin, soft, irregular bricks with wide joints are early; thick, hard, uniform bricks are Victorian or later.
3. Window type. Leaded casement, or sash? If sash: how thick is the glazing bar, and does the upper sash have horns? Horns mean 1840s at the earliest.
4. Pane pattern. Six-over-six is Georgian, two-over-two mid-Victorian, one-over-one late Victorian, small panes in the top sash only is Queen Anne Revival.
5. Arch head. Four-centred is Tudor, gauged flat arch is polite Georgian, segmental brick-on-edge is vernacular, stone or contrasting-brick voussoirs are Victorian.
6. Roof pitch and covering. Steep with thatch, stone slate or plain tile is early and local; shallow with Welsh slate is post-1800.
7. Eaves or parapet. Deep timber cornice is c. 1680–1710; parapet hiding the roof is Georgian urban; bracketed overhang is Italianate.
8. Chimney position. Central ridge stack is vernacular sixteenth or seventeenth century; gable-end stacks are Georgian; tall moulded shafts are Tudor or Tudor Revival.
9. Door and fanlight. Six panels with a radial fanlight is 1770–1810; four panels with coloured glass is Victorian.
10. Then check the flank, the rear and the corners for a refronting, a raised roof or a rebuilt skin — and only now commit to a date, and only if at least five of the above agree.