Architectural and Engineering Glossary

Lap Cement

A type of asphalt used as an adhesive between the laps of roll roofing.

Lap Dovetail

Same as lapped dovetail.

Lap Joint

1.A joint in which one board, plank,metal plate, etc.,overlaps the edge of another piece;the overlapping part of each member is cut away to half thickness,resulting in flush surfaces.2.A joint formed by placing one piece partly over another and uniting the overlapped portions.

Lap Notch

Same as half cut notch.

Lap Riveted

Said of two plates overlapped and then joined by riveting.

Lap Scarf

A flush joint formed by fitting one end of a length of wood gutter into the opposite end of another.

Lap Seam

A joint formed by overlapping the edges of metal sheets or plates and joining them by riveting,welding,soldering,or brazing.

Lap Siding

See clapboard.

Lap Splice

1.A connection of reinforcing steel made by lapping the ends of bars.2.A splice made by placing one piece on top of another and fastening together with pins,nails,screws,bolts,rivets,or similar contrivances.

Lap Weld

A weld in which the ends of the pieces are overlapped and then joined by welding.


A bedrock surface,beneath the soil,roughened as a result of action by a solution of limestone,gypsum,or other soluble rock;usually deeply trenched along joints.Such a bedrock presents hazards and results in excessive costs for footings and foundations.


Same as milliarium.

Lapis Lazuli

A rich blue semiprecious stone;either used decoratively or ground and powdered for use as an ultramarine pigment.

Lapped Dovetail, Drawer Dovetail

A dove tail at an angle in which the pegs of one member do not pass through the full thickness of the other;esp.used at the front of a drawer.

Lapped Tenons

Two tenons which enter a common mortise from opposite sides and overlap one another.


One of a series of pendants trimming the eaves of a roof.


In reinforced concrete,the overlapping of steel reinforcing bars,or other reinforcement,so there is continuity of tensile stress in the reinforcement when the concrete member is subjected to a flexural or tensile load.


Same as lacunar.


In Roman houses,a small shrine to the household gods (lares).


A fine textured,strong,hard,straight grained wood of a coniferous tree;heavier than most softwoods.


A room where food is stored.

Large Calorie

The heat required to raise 1 kilogram of water 1°C; equivalent to 1000 small calories or 1 kilocalorie.

Large Knot

A knot in wood which is greater than 11⁄2 in. (3.8 cm) in diameter.

Larmier, Lorymer

1.A corona.2.Any horizontal member or stringcourse similar in profile to a corona and projecting from a wall to throw off rain;a roll molding,drip,etc.


A mineral which is a major constituent of portland cement;beta dicalcium silicate.larry A hoe having a long handle and a blade which usually is perforated;used for mixing mortar or plaster.


In masonry construction,the laying of bricks by sliding the bricks into appropriate positions (for example,between the inner and outer walls of a cavity wall) and then filling the space between with mortar.


A device that emits a powerful beam of coherent light in an intense beam;used, for example,on building projects to provide a means of ensuring that construction is along a straight line,or to ensure that the construction is carried out to precisely the same height.


1.On drawings, abbr.for “latitude.”2.On drawings,abbr. for “lateral.”


In the architecture of the southeastern US,palmetto fronds employed as a roof covering.


A simple fastening device having a latch bolt,but not a dead bolt;contains no provisions for locking with a key;usually openable from both sides.

Latch Bolt

A spring bolt, one edge of which is beveled;when the door or window to which it is attached is closed,the bolt is forced inward;when in the fully closed position,the bolt springs back into a fixed notch or cavity.

Latch Plate

An escutcheon that protects the  area of a door around a latch.


Same as tingle.


A key used to raise and throw back  the latch of a door.


A string for raising the latch of a door from the outside;it is fastened to the latch and passed through a hole above it in the door.

Late Gothic Revival

The last phase of the Gothic Revival in the early part of the 20th century,in which an attempt was made to emulate its Gothic architecture prototype with some degree of accuracy;for example,see Collegiate Gothic.

Latent Heat

The amount of heat which is absorbed or evolved in changing the state of a substance without changing its temperature,e.g.,in freezing or vaporizing water.


A brick,formed in a mold and dried in the sun or baked in a kiln by the early Greeks and Romans;much larger and much thinner than modern bricks;each brick was stamped with the name of the maker and the year in which it was made.


Same as lateral sewer.

Lateral Buckling, Lateral Torsional Buckling

The buckling of a structural member which involves lateral deflection and twist.

Lateral Buttress

A buttress that stands at one corner of a building.

Lateral Pressure

The pressure,acting in the lateral direction,exerted by the retained soil against a structure.

Lateral Reinforcement

That part of the steel reinforcement for a reinforced concrete column in the form of transverse hoops,links,or helixes around the vertical reinforcing steel rods.

Lateral Restraint

The restraint that limits lateral movement of the compression flange of a beam.

Lateral Scroll

A fitting which curves in a horizontal plane and is used to terminate a stair handrail.

Lateral Sewer

A sewer which discharges into a branch or other sewer and has no other common sewer tributary to it.

Lateral Support

The bracing for a wall,beam,or structural member,either horizontal (by roof or floor constructions) or vertical (by pilasters,columns,or cross walls).


An emulsion of finely dispersed particles of natural or synthetic rubber or plastic materials in water.