Stilted Arch¶
Raise an arch's curved head above its impost on two vertical continuations of the intrados, separating stilt height from curve shape so crown level and opening proportion can be controlled without mistaking taller jambs for stilting.
Core Idea¶
A Stilted Arch is an architectural arch whose curved head does not begin at the impost level. Instead, the intrados and ordinarily its archivolt or moulding continue upward as two straight vertical sections—the “stilts”—and the curve springs from their tops. The impost remains the reference level at which the supporting capital, pier, or wall receives the arch assembly; the springing of the curved portion is deliberately displaced upward. Hastings Borough Council’s technical glossary makes the essential diagnostic unusually clear: the vertical sections are not merely the jambs or imposts, but carry the same moulding or archivolt as the arch.
Scope of Application¶
Stilted Arch operates in architectural description, comparative history, measured survey, conservation recording, facade and opening design, and analysis of arch and vault geometry. The term supports repeatable field classification: a recorder can locate the impost, trace the intrados, mark the point where curvature begins, and measure h_s. That procedure works whether the arch is stone, brick, rendered masonry, or a nonstructural architectural profile, although construction and capacity must be described separately.
Clarity¶
Use a three-line field test. First draw or identify the impost line, the architectural support datum. Second mark the springing line of the curve, where the intrados ceases to be vertical and begins to bend. Third trace whether the arch treatment continues through the interval between those lines. If the springing line lies higher than the impost and the intervening sides are vertical continuations of the intrados or archivolt, the profile is stilted.
Manages Complexity¶
The concept decouples variables that casual description conflates. Overall opening height, support height, span, curve shape, stilt height, arch thickness, and decoration can all affect appearance, but only some determine type membership. By isolating h_s, an analyst can compare arches with different spans and shapes without calling every tall arch the same form.
Abstract Reasoning¶
The signature licenses constrained inferences:
- If span and upper curve are held fixed while
h_sincreases, the crown rises by the same amount. 2. If crown level and semicircular form are held fixed across unequal spans, the narrower bay requires the larger nonnegative stilt height. 3. If the curve begins at the impost, the arch is not stilted regardless of how tall its supporting pier is.
Knowledge Transfer¶
Literal reuse occurs across architecture, architectural history, building archaeology, conservation, masonry documentation, and set-out geometry. Each practice retains the same roles: impost, vertical intrados section, raised springing, selected curve, and crown. A historian uses them to compare periods; a surveyor measures them; a conservator distinguishes original profile from alteration; a designer uses them to coordinate openings.
The portable residue transfers through existing primes rather than making Stilted Arch a prime. Proportion and Scale captures the control of rise relative to span and neighboring bays.
Relationships to Other Abstractions¶
Current abstraction Stilted Arch Domain-specific
Parents (1) — more general patterns this builds on
-
Stilted Arch is a kind of Proportion and Scale Prime
stilting controls the relation among span, intrinsic curve rise, stilt height, and crown level; this is the proposed minimal live parent.
Hierarchy paths (2) — routes to 2 parentless roots
- Stilted Arch → Proportion and Scale → Ratio → Comparison → Self Checking
- Stilted Arch → Proportion and Scale → Scale
Neighborhood in Abstraction Space¶
Stilted Arch sits in a sparse region of the domain-specific corpus (95th percentile for distinctiveness): few abstractions share its structure, so a faithful description tends to retrieve it precisely.
Family — Unclustered & Miscellaneous (1565 abstractions)
Nearest neighbors
- Clock Gable — 0.83
- Interlaced Arch — 0.76
- Strainer arch — 0.76
- Categorical Lift — 0.76
- Alfiz — 0.76
Computed from structural-signature embeddings · 2026-09-08