INTRODUCTION
BASICS
There are arches galore in size and style and layout.
- Before The Architect is increasingly involved in
- Including and adding arches to a plan set and
- Most of those arches are
- flattened ellipse
- segmental
- Roman, with header and beam height
- Few-to- No imperatives
- The house doesn’t have to be large or of
- Any particular architectural style, usually
- Choices (a sampling)
- By structure
- intersecting arch – crossing each other as in an arcade, presenting both rounded and pointed arches in the making
- blind arch – solidly filled in below to the base of column, pier, abutment, pilaster or wall
- relieving arch – structural element
- arcade arch – columns in series, supporting arches
- colonnade arch – not really an arching at all, rather columns in series supporting, effectively, a beam called “architrave"
- by shape
- Roman or semi-circle arch
- flat or jack or splayed arch
- Gothic or pointed arch, of which acute or lancet arch may be a subset
- Tudor or depressed or flattened Gothic arch
- Syrian or segmental arch
- Moorish or horseshoe arch
- By accessory
- spandrel
- soffit
- impost – AG prefers blocked, trimmed variously albeit consistently
- hood moulding – also applied over-door and over window interior and exterior
- voissoirs
- cusp
- tympanum
- lintel
- keystone
- By support
- column
- pier
- abutment
- pilaster
- wall, usually with impost
- By physical relationship
- springing or springline
- springer
- haunch
- crown
- intrados – interior curve of arch
- extrados – exterior curve of arch
- By geometry
- major axis or span
- minor axis or rise from the springline
- arch base vertical alignment with top, interior edge of column, pier, or abutment
Selected Parts of an Arch, Section in Elevation
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Comment: The parts selected are more commonly addressed in application. Going further with identification moves us into the rigors of the Classical Orders and of more formal elaboration only occasionally engaged variously in the last few years; while distinctive, such detail is neither for everyone, nor for every style.
Comment: This is a better place than most to introduce considerations of regularity – proportion, harmony, regulating lines – in arches which necessarily include regularity of their attendant parts.
While there is intolerance with any of the Order’s rules in regard to a module’s derivatives, there are at least two offsets to help us on our proportioned way – the column pedestal variously formed which can act as a kind of vertical filler between column base and a lower, usually functional level such as patio, porch, or interior floor level; an overriding sense to the Orders overall that the Romans and, to a lesser extent, the Greeks would have found the dicta of Vitruvius, Palladio, et al. pedantic, lacking in permission for artistic latitude.
So one comes to the major axis itself and realizes that most of the proportion is already set by intercolumniation, or functional imperatives including lines of sight, or artfulness. To the extent that an arch’s major axis can be directly related by proportion to either subordinate columns or their spacing or both, all the better.
It’s the minor axis where – less constraints of both terminal height as in an eave or ceiling and structure as in a beam – proportion can play out happily.
- The Orders in so far as embellishments are concerned
Comment: For an interesting and generally practical reference on many of these matters see Traditional Construction Patterns: Design & Detail Rules of Thumb by Stephen A. Mouzon et al., McGraw Hill, 2004.
ARCHES NOT IN SERIES
Interior Arches Not in Series, Drawn Detail - Section in Elevation
This resolution of interior arches works, in AG’s opinion, not only because
- It mimics the exterior arches in segmental form and shallow minor axis, but also because
- These interior portals are not close together physically. Finally,
- In the style of design of the instant project,
- Header height had no stylistic basis for variation and, indeed,
- The regularity of interior door header height benefited desirable openness in-between larger spaces.
Comment: In this instance, AG draws to-scale the basic metrics of interior arches to a house that has substantial exterior arching. The proportions of the exterior arches – based on the dominant set at Front Of House – he takes inside.
- Of interest, these sections were not the first drawn, which first drawn were more rounded [read: marginally longer minor axis] and regarded by the clients as in need of flattening, which flattening extended to all arches both interior and exterior, considering that the exterior Front Of House arch across the wide Front Porch formed the basis for all other arch proportions.
ARCHES IN SERIES
Interior Arches in Series, Drawn Detail, Sections in Elevation
- It is the experience of Before The Architect’s designers that when arches get closer together, as in a series, as in a colonnade, it’s more salutary design to hold to the math of major:minor axes across the series.
- Before The Architect is fond of a segmental arch at major axis:minor axis::9:1, when window heads are segmental, which is almost all the time [as opposed to the semi-circular, or Roman arch, of which clients are less fond, leaving elliptical somewhere in the middle by popular demand hereabouts].
- If sequenced, as in a porch or arcade, segmental arches appear most regular when each is set at a given major-to-minor axis ratio, say 9:1, and all the springlines are held to a singular level, thereby offering marginally different crown heights when intercolumn distances vary.
- The Interior Arches In Series pic presents the stripped-down version of layouts recently done to be sure about the preferential appearance of arches in series.
- The context is
- An 8'x38' Gallery interior facing a 20'x38' Dining and Living area.
- Front entrance is on-center.
- The wider middle wall opening is set to permit full view out the far-side window wall immediately upon entrance.
- The flanking openings are equal in width and the piers and abutments are equal in width.
- Note that header height is less important in this instance as the 38' length will be taken up with beams above Gallery ceiling level, the Gallery height being 10' and the Dining-Living area being twice that.
- The tight series of openings requires more discipline in laying out the arches. While some disproportion from the Gallery view could be tolerated, the substantially wider visual perspective from the Dining-Living area would put the lie to bad judgment.
- #1 conforms both springline and minor axis based on the center arch.
- #2 conforms springlines, but holds major:minor axes proportions hard to the center arch, thereby slightly lowering the flankers heights.
- #3 conforms proportions as in #2, but levels the arches' apices, thereby lifting the flankers' springlines over the center's.
- #1 and #3 fail for the same reasons - disproportion, particularly from the Dining/Living viewpoint, and understatement of the central, arched opening.
SUMMING UP
- Arch's overall consequences can be
- Favorable: incremental formality
- Favorable: the pleasant perspective of design latitude in lieu of dogma
- Favorable: unobligated opportunity for accessories and
- Favorable: pleasing proportion and regularity (unless you’re clueless about proportion and regularity, in which case find someone who is not clueless to help you)
NAILING DOWN THE ARCH DESIGN DETAILS
Exterior and Interior Arches Design Detail Table, Alphameric
Comment: The AG goes to such extents as the Arches Table, so as to provide an orderly presentation of similar features – arches – without relying on the good spirits of construction to see through to the designer’s intent and vision. Note, for example,
- Discrete treatment of the front door arch in order to distinguish it from all other arches
- Identical treatment of similar, lesser passage at Front Of House and Back Of House
- Cross-reference to the Elevations as further guide to application
- The attention even to the arching of Courtyard wall doors
- Same springline and minor axis to the Front Porch LOH and ROH as the Front Porch FOH, even though the two sets of arches have widely dissimilar major axes, in order to provide a symmetrical frame of visual reference both from and toward the house, particularly from the house Front Porch
- Note also, please the references to the interior doors drawn in the above Figure.
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