Town of Babylon, NY Additional Standards and Specifications.

The area fixed in this section may be increased 100% when the building is sprinklered.

Buildings of greater areas than herein specified for the respective conditions may, considering their location and purpose, be constructed by special permission of the Board of Appeals, provided that they do not exceed two stories in height.

§ 89-35 Fire limits.

The fire limits of the town, as established and amended from time to time by the Town Board upon the recommendation of the Boards of Fire Commissioners for their respective districts, shall bound the more congested business and industrial area within a fire district where a fire hazard is deemed to exist.

Such fire limits shall be designated as Class I or Class 2, according to the extent of the existing fire hazard and shall be indicated on maps which are incorporated herein by reference as fully as if printed herein and which are deemed part of this chapter.

§ 89-36 Determining buildings within fire limits.

A building or structure shall be deemed to be within the fire limits if more than 1/2 the area of the building or structure is located therein.

§ 89-37 Construction within fire limits.

Class 1 fire limit. No building or structure of frame or unprotected metal construction shall hereafter be erected in a Class 1 fire limit.

Class 2 fire limit. No building or structure of unprotected metal construction or wood frame construction exceeding one story in height shall hereafter be erected in a Class 2 fire limit.

§ 89-38 Wooden shingle roofing within fire limits.

Within all fire limits wooden shingle roofing is prohibited.

§ 89-39 Public garages within fire limits.

All public garages hereafter erected within a fire limit, which exceed one story in height, shall be of semifireproof construction.

§ 89-40 Additions to buildings within fire limits.

Within the fire limits, no building or structure shall hereafter be extended on any side or increased in height unless the construction of such extension conforms to the requirements of this chapter for new construction.

§ 89-41 Frame or unprotected metal structures permitted in fire limits.

Nothing in §§ 89-35 through 89-40 shall prohibit, within the fire limits and subject to the specified limitations, the erection, extension or enlargement of the following buildings of frame or unprotected metal construction:

Private garage; stable. A building of wood frame or unprotected metal construction occupied exclusively as a private garage or stable, not more than one story in height nor more than 750 square feet in area, located on the same lot with a dwelling or business dwelling.

Outhouses. Outhouses not more than eight feet in height nor more than 100 square feet in area, provided that the roofs are covered with incombustible or fire-retardant material.

Greenhouses. Greenhouses not more than 15 feet in height, erected on the same lot with and accessory to a dwelling or a store.

Sheds. Sheds open on the long side, not more than 15 feet in height nor more than 500 square feet in area, with roofs covered with incombustible materials.

Builders' shanties. Builder's shanties not more than one story in height, for use only in connection with a duly authorized building operation.

Coal tipples, bins, tanks, etc. Coal tipples, icehouses, materials, bins, trestles and water tanks, when built of planking and timbers of the dimensions specified by the Building Inspector.

Signs. Display signs.

§ 89-42 Ventilation of habitable rooms.

Every habitable room shall have one or more windows opening directly on a street, yard or court. Such rooms shall be not less than six feet wide in any part and shall contain not less than 60 square feet of clear floor area. It shall be unlawful to divide a habitable room or enclose a portion thereof by fixed or movable partitions unless each part of the room so divided or enclosed shall separately conform to the requirements of this section.

§ 89-43 Ventilation of rooms in business buildings.

Every room in every building hereafter erected and occupied for business purposes shall be provided with one or more windows or ventilating skylights opening directly on a street or on a court, or such rooms shall be provided with an approved means of mechanical ventilation. When the unoccupied space exceeds 500 cubic feet for each occupant, such room may be ventilated by transoms or other similar devices opening into rooms having windows or skylights opening directly to the outer air as herein prescribed.

§ 89-44 Ventilation of rooms in public buildings.

In public buildings every room used as an auditorium or for public assembly and every other room that is not provided with windows opening on a street, yard or court shall be provided with an approved system of mechanical ventilation.

§ 89-45 Ventilation of bathrooms and water closet rooms.

Every bathroom in a building used as a dwelling shall be ventilated by one or more windows on a street, yard or court. Every other bathroom and every room containing one or more water closets or urinals, shall be ventilated by one or more windows opening on a street, yard or court or on a vent shaft which extends to and through the roof or into a court or by a separate duct of incombustible and noncorrodible material, extending independently of any other duct to the roof, or by an approved means of mechanical ventilation.

§ 89-46 Rooms without windows in residence buildings.

Nothing in this Article shall prohibit, in residence buildings occupied by not more than two families, rooms without windows, provided that every such room opens without obstruction directly into another room which has one or more windows having an aggregate area between stop beads of not less than 20 square feet and that the opening between such rooms is not less than 40 square feet in area.

§ 89-47 Window glass area.

The total area of window glass required by this Article shall be not less than 1/10 of the floor area served by them, provided that in habitable rooms such area shall not be less than 10 square feet. Such window glass shall be so arranged when fully opened that the total space open shall be not less than 50% of the total required window space.

§ 89-48 Width of courts.

In every building hereafter erected every court provided under the provisions of this Article for the lighting or ventilation of any room shall have a width at every point of not less than one inch for every foot that such point is distant from the highest point of the court, but in no case less than four feet. Every such court shall be open and unobstructed for the required widths from its lowest point to the sky, except for the ordinary projections of window sills, belt courses and similar ornamental projections, to the extent of not more than four inches.

When a court is located along a side of a lot, the lot line shall be deemed an enclosure of such court, except that when a court opens on a street or any public space, such street or open space may be considered as part of the court.

§ 89-49 Overcrowding in residence buildings.

If a room in a residence building is overcrowded, the Health Officer may order the number of persons sleeping or living in said room to be so reduced that there shall be not less than 480 cubic feet of air to each adult and 300 cubic feet of air to each child under 12 years of age occupying such room.

§ 89-50 Egress from business and public buildings.

All business and public buildings shall be in conformity with the provisions of this Article, provided that they comply with state laws governing such buildings as to means of egress.

§ 89-51 Exits from multiple-family dwellings.

In every multiple-family dwelling hereafter erected, there shall be at least one exit from every apartment or suite of rooms.

The exit shall be to a public hall connected with a stair not more than 50 feet distant from such exit, except that in buildings not exceeding two stories in height, every multiple dwelling hereafter erected shall have at least two stairways extending from the ground floor to the roof. Such stairways shall be at least 15 feet distant from each other, unless they are on opposite sides of a public hall.

One of these stairways shall be constructed of incombustible material enclosed on all sides by fireproof partitions with automatic fire doors at all floors and at the roof and shall be ventilated by windows in the exterior wall or by skylights glazed with wire glass in metal frames with fixed or movable louvers or may be a fire escape construction of open iron or stone balconies and stairs. All stairs shall be at least three feet wide in the clear and shall have treads not less than 9 1/2 inches wide, exclusive of the nosing, and the rise shall not be more than 7 1/4 inches.

§ 89-52 Hallway width in multiple-family houses.

The minimum clear width of every hallway or passage leading to a required exit in multifamily houses shall be 36 inches.

§ 89-53 Standards for materials.

Lumber; timber. The grades and quality of lumber and timber used structurally shall conform to the accepted standards and specifications as prescribed by the Building Inspector.

Other materials. All other building materials shall be of good quality and shall conform to specifications which the Building Inspector prescribes. The accepted standard specifications for quality of materials shall be those of the American Society for Testing and Materials.

§ 89-54 Weights of materials.

The weights of the various building materials in pounds per cubic foot shall be assumed to be as specified in the 1967 Edition of the Building Code of the American Insurance Association, successors to the National Board of Fire Underwriters.

§ 89-55 Working stresses and loads.

Computations. The dimensions of the several materials and the form of each construction to be used in building shall be computed as required in this chapter.

Factors of safety. The relation of the allowable unit stress to the ultimate strength of any material shall be as 1:4 for metal, as 1:6 for timber and as 1:10 for natural or artificial stones and brick or stonemasonry.

Temporary supports. Every temporary support placed under any building or structure or any part thereof during the erection, finishing, alteration or repairing of such buildings or any part thereof shall be of sufficient strength to safely carry the load to be placed thereon.

Working stresses. The safe carrying capacity of the various materials of construction shall be determined by the working stresses in pounds per square inch, as specified in the 1967 Edition of the Building Code of the American Insurance Association, successors to the National Board of Fire Underwriters.

Loads. Every building and structure shall be designed and erected of sufficient strength in all its parts to sustain safely all live loads depending thereon, whether permanent or temporary, in addition to the dead loads. The live loads per square foot, uniformly distributed, shall be assumed to be as specified in the 1967 Edition of the Building Code of the American Insurance Association, successors to the National Board of Fire Underwriters.

Bearing value of soils. The safe bearing capacity of soils shall be determined in tons per square foot as follows: loan, one ton; quicksand, 1/2 ton; soft clay, one ton; wet sand, two tons; coarse sand, four tons; firm clay, two tons; sand and clay, two tons; fine dry sand, three tons; and gravel, six tons.

§ 89-56 Workmanship standards.

Workmanship in the fabrication, preparation and installation of materials shall conform to generally accepted good practice. Specific provisions of this Article shall not be deemed to suspend any requirements of good practice, but shall be regarded as supplementary or emphasizing them and shall be controlling.

§ 89-57 Excavations.

Whenever an excavation is carried below an adjoining wall, the person causing such excavation to be made, if afforded permission by an adjacent owner, shall, at his own expense, preserve every nearby wall, building or structure from injury and support the same by proper foundation or retaining walls so that they shall be safe, and for this purpose foundation or retaining walls may be built upon adjacent premises.

If necessary consent is not accorded to the person making the excavation, then it shall be the duty of the person refusing such license to preserve and protect such building or structure from injury and, when necessary, to underpin and support the same by proper foundations, and for that purpose such person shall, when necessary, be permitted to enter upon the premises where the excavation is being made.

All such excavations for buildings shall be properly guarded and protected in order to prevent the same from becoming dangerous to life or limb and shall be sheathpiled when necessary to prevent the adjoining earth from caving in.

§ 89-58 Foundations.

Depth. Except when erected upon piers or posts on the bay or oceanfront, foundation walls shall be carried not less than four feet below ground level, shall rest on solid ground and shall have the space between the first floor and the grade enclosed, except for necessary ventilation, provided that when one-story buildings of frame construction do not exceed 750 square feet, they may be erected on foundation walls which shall be carried not less than two feet below ground level, provided that they rest on solid ground. The foundation walls of dwellings or two-and-one-half-story frame buildings may be stopped at a depth of three feet below ground level.

Materials. foundation walls shall be built of approved masonry, reinforced concrete or steel protected by masonry. All masonry foundation walls shall be laid in cement mortar.

Thickness. If built of brick, concrete or hollow building blocks, a foundation wall shall be at least four inches thicker than the masonry walls next above them, but in no case less than 12 inches. For buildings of frame construction not more than 2 1/2 stories in height, the foundation walls shall not be less than eight inches in thickness.

§ 89-59 Foundation footings.

Materials. The footings of foundation walls shall consist of masonry, concrete or reinforced concrete. Wood footings may be used, if they are entirely below the permanent water level.

Thickness. Footings shall be not less than 12 inches thick, except that for frame buildings, the thickness shall be not less than eight inches.

Design. Footings shall be so designed that the pressure they produce on the soil per unit of area shall be uniform so far as possible under all parts of the foundation walls, and such pressures shall not exceed the bearing capacity of the soil as specified in § 89-55 of this chapter.

Cellar floors. In all buildings hereafter erected, the cellar floor or any floor resting directly on the ground shall consist of stone, gravel or cinder concrete.

§ 89-60 Masonry construction.

Materials. All masonry shall be constructed of approved materials and shall comply with the provisions of this section.

Protection. All masonry shall be adequately protected against freezing for at least 48 hours after being set.

Erection.

Except when carried independently by girders at each floor, no wall shall be built up more than 25 feet in height in advance of other walls of the building.

No masonry shall be supported on wooden girders or other form of wood construction.

Isolated piers shall not exceed in height 10 times their least dimension.

Masonry walls that meet or intersect shall be adequately bonded or anchored. Piers having less than four square feet of cross section when located at an intersection with a wall shall be bonded into and built as part of that wall.

Door and window openings in walls shall be spanned by well-buttressed arches or linters having bearings at each end of not less than four inches.

Every pier supporting a girder, arch, column or lintel carrying a wall over an opening of more than 10 feet shall be built of approved masonry.

Brick masonry.

Except when laid in Flemish bond or faced with running bond, at least every sixth course in brick walls shall be a full header course.

Brick shall be wet immediately before being laid except in freezing weather.

All horizontal and vertical joints in brick masonry shall be filled with mortar.

Hollow building block masonry.

In hollow walls of brick and in walls and piers of hollow building blocks, suitable provisions shall be made at each line of floor beams and wherever load concentrations occur to ensure good bearing and a uniform distribution of load.

Where two or more hollow units are used to make up the thickness of a wall, the inner and outer courses shall be bonded at vertical intervals not exceeding three courses by lapping at least one cell completely over a cell of the unit below.

Brick facing or lining, when used with hollow building blocks, shall be bonded to the backing with at least one header course in every six courses of brick or there shall be at least one full length header in every 72 square inches of wall surface.

Hollow walls of brick or walls of hollow building blocks shall not be used as bearing walls in buildings or structures exceeding 40 feet in height.

Except in buildings one story in height or of frame construction and not in a fire limit, hollow walls of brick or hollow walls of building blocks shall not be used as party walls.

Mortar.

Mortar for masonry construction shall be either cement mortar, cement lime mortar or lime mortar as hereinafter specified.

Cement mortar shall be made of one part of Portland cement, three parts of an approved clean sand and not more than 15% of lime, all ingredients measured by volume. The maximum allowable compressive stress in cement mortar of the above proportions shall be 325 pounds per square inch of gross cross-section area.

Cement lime mortar shall be composed of one part Portland cement, one part of lime or lime putty and a maximum of six parts of sand, all ingredients measured by volume. The maximum allowable compressive stress in cement mortar of the above proportions shall be 250 pounds per square inch of gross cross-section area.

Lime mortar shall be composed of one part of lime putty or hydrated lime and a maximum of three parts of sand; all ingredients measured by volume. The maximum allowable compressive stress in lime mortar of the above proportions shall be 100 pounds per square inch of gross cross-section area.

Veneer construction.

Masonry veneer shall consist of bricks, stone, concrete, terra cotta, hollow building blocks or other approved material.

Such veneer shall rest directly upon a foundation wall or upon other approved masonry.

It shall be securely attached at intervals of not more than 16 inches vertically and 24 inches horizontally to the wall or, in the case of frame construction, to approved sheathing combined with a weatherproof lining.

Flashing to prevent moisture from penetrating behind the veneer shall be provided at wall openings.

§ 89-61 Thickness of masonry walls.

General. The thickness of masonry walls hereafter erected shall conform to the provisions of this section and, irrespective of other requirements of this chapter, shall be sufficient to keep the stresses in the masonry within the working stresses prescribed by this chapter.

Dwellings. In dwellings, walls may be eight inches thick, when not more than 30 feet in height nor more than 50 feet in length between cross walls or adequate buttresses, provided that in a gable wall of a dwelling the portion of such wall within five feet of the peak need not be considered in fixing the height.

Business buildings, public buildings and storage buildings. In business buildings, public buildings and storage buildings, the thickness of masonry bearing walls shall be not less than 12 inches for the uppermost 35 feet of their height and shall increase four inches for each successive 35 feet or fraction thereof measured downward from the top of the wall, provided that solid masonry walls eight inches thick may be used for buildings not exceeding 30 feet nor two stories in height and hollow walls of brick or walls of hollow blocks eight inches thick may be used for buildings not exceeding one story in height. The thickness of reinforced concrete bearing walls shall be not less than 3/4 of the thickness required for masonry bearing walls, but in no case less than nine inches.

Supported walls. Walls supported by girders at each story may be eight inches thick.

Nonbearing walls. The thickness of nonbearing walls may be four inches less than required for bearing walls.

Party walls. Party walls shall be constructed of solid brick masonry laid in cement mortar or cement lime mortar or of reinforced concrete, not less in thickness than required for exterior bearing walls, provided that in business buildings and storage buildings exceeding 20 feet in height, no part of the wall shall be less than 16 inches thick.

§ 89-62 Height of party walls.

Party walls shall extend at least three feet above the roof.

§ 89-63 Reinforced concrete standards.

General standard. Except as may be otherwise provided by law or ordinance, the Building Regulations for Reinforced Concrete, as adopted by the American Concrete Institute, shall be deemed to be the generally accepted good practice in reinforced concrete construction.

Concrete; materials and mixtures. All materials used in connection with concrete construction shall be subject to the approval and acceptance of the Inspector of Buildings.

All sand used in connection with building construction shall be clean, sharp, coarse and free from any inorganic matter.

Quicklime and hydrated lime shall conform to the specifications of the American Society for Testing and Materials.

Portland cement shall comply with the standard specifications of the American Society for Testing and Materials.

The coarse aggregate in concrete shall be crushed granite, trap rock, gravel or other durable material that may be approved by the Building Inspector. When gravel is used, it shall be thoroughly washed and screened. Where mass concrete is used, the coarse aggregate shall be of such size as will pass through a two-inch ring. All aggregates shall be free from dust or other deleterious materials.

All concrete, except in connection with reinforced concrete structures or parts of structures, shall be made of one part of Portland cement, not more than 2 1/2 parts of sand and five parts of coarse aggregate.

Concrete for reinforced concrete shall be mixed of one part of Portland cement and not more than six parts of aggregate, fine and coarse, either in the proportion of one part of cement, two parts of fine aggregate and four parts of coarse aggregate or any such proportions that the resistance of the concrete to crushing shall not be less than 2,000 pounds per square inch at the age of 28 days.

(7)

Ingredients shall be accurately measured, thoroughly and uniformly mixed and sufficient water added to make a plastic mixture. Concrete shall be placed immediately after mixing.

§ 89-64 Steel and iron standards.

Except as may be otherwise provided by law or ordinance, the Specification for the Design, Fabrication and Erection of Structural Steel for Buildings of the American Institute of Steel Construction shall be deemed to be the generally accepted good practice in steel construction.

§ 89-65 Firesafe construction standards.

Walls. The walls of a building of firesafe construction shall be of approved masonry or reinforced concrete.

Stair walls.

In all firesafe buildings, the enclosure of stairways shall be of approved masonry or reinforced concrete.

When stair walls are built of brick or concrete they shall be at least eight inches thick. If built of reinforced concrete and properly supported, they shall be at least four inches thick. When built of terra cota blocks, supported by suitable steel framing, such walls may be six inches thick, if properly supported.

Floors within stair walls. Floors within stair walls shall be of fireproof construction and shall be of terra cotta, stone, concrete, cinder concrete or other approved material.

Doors in stair walls. All doors, excepting only an outside entrance door, shall be approved fire doors, with approved self-closing devices and incombustible sills, jambs and trim.

Stairs. Every firesafe building more than one story in height shall have at least one stairway and such others as may be required by state law.

Beams.

Wood beams, except header and tail beams, shall have bearings of at least four inches.

The ends of beams resting on masonry walls shall be cut to a bevel of three inches in their depth.

Trimmers, headers and tail beams over four feet in length, unless supported on walls or girders, shall be hung in approved stirrups.

Floor and roof beams, except in the case of pitched roofs, shall be rigidly bridged at intervals not exceeding eight feet.

Each tier of beams resting on masonry walls shall be anchored at intervals of not more than four feet. Where floor or roof beams run parallel to masonry walls, similar anchors fastened to two or more beams shall be secured to the walls.

The ends of wood beams resting on girders shall be butted end to end and anchored to the same beams as the wall anchor or they shall lap each other at least 12 inches and be well spiked or bolted together where lapped.

(7)

Wall plates and roof construction shall be anchored to the walls at least every six feet.

(8)

No beam shall be cut or pierced in any manner that will cause the beam to be insufficient for the load.

(9)

No floor or roof beams of structures within a Class 1 fire limit may be less than three inches in thickness.

Girders. Wood girders shall be anchored to the walls and fastened to each other with suitable steel straps.

Separations in walls. Wooden joists, beams and girders resting on opposite sides of a masonry wall shall be separated from one another by at least six inches of solid masonry.

Stud partitions. Stud partitions which rest directly over each other and are not parallel to the wood floor beams shall run down between the floor beams and rest on the top plate of the partitions below and shall have the studding filled in solid between the uprights to the depth of the floor beams with suitable incombustible materials.

Fire stops. Where walls are studded off, the space between the inside face of the wall and the studding directly over such space shall be fire-stopped with incombustible material for a depth of not less than four inches, securely supported.

Wood posts.

Wood posts shall have iron or steel caps and bases with pintle connections, or steel or iron caps with projecting shelves to support girders.

Wood posts shall not be used in cellars.

Roofing. All roofs shall be of asbestos or prepared composition shingles, asphalt-asbestos felt, asphalt impregnated ragfelt and gravel, concrete, brick, slate, tin, copper or other approved incombustible material.

§ 89-66 Wood frame construction standards.

Walls.

All interior studding shall be but one story in height, set on caps or shoes, except where partitions are over girders and fire-stopped as approved by the Building Inspector.

Walls and partitions shall be constructed to develop a strength and rigidity equivalent to wooden studding, not less than two inches by four inches, spaced not to exceed 16 inches on centers.

Where exterior walls or parts thereof are sheathed, the boards shall be not less than 3/4 of an inch in thickness, shall be laid tight and properly nailed to each stud and shall be covered with a waterproof sheathing paper. An approved insulation board not less than 1/2 inch in thickness may be used as sheathing, provided that it is properly nailed and covered with a waterproof sheathing paper. Where sheathing is omitted, all corners shall be diagonally braced and such other measures shall be taken to secure rigidity as may be necessary.

Wooden sheathing may be omitted when other approved types of construction of adequate strength and stability are used.

Ledger or ribbon boards used to support joists shall not be less than one inch by four inches, shall be cut into the studs and shall be securely nailed to each stud.

No part of the wood frame shall be placed below ground level.

Beams.

All floor beams, roof beams and roof rafters shall be at least two inches thick. Floor beams and roof beams shall be spaced not more than 16 inches on centers. Roof rafters shall be not more than 24 inches on centers and not less than six inches in depth, except that rafters less than eight feet in length may be four inches in depth.

One-half the length of the span of beams in feet shall determine the minimum depth of the beams in inches, but in no case shall the allowable stresses of the beams be exceeded.

No beam shall be cut or pierced in any manner that will cause the beam to be insufficient for the load.

Exterior finish. Either brick, stucco, shingles, siding or other approved material shall be placed over the waterproof sheating paper as an exterior finish.

Separating walls. Walls or partitions separating two or more dwellings of frame construction shall consist of wooden studs covered on both sides with gypsum mortar or cement mortar, not less than 3/4 of an inch in thickness, on expanded metal lath, or of some other construction having an equal or better fire resistance.

Roofing. All roofing shall be of wood or composition shingles or other approved waterproof material.

§ 89-67 Wood beams near flues and chimneys.

All wood beams shall be trimmed away from flues and chimneys. The header and trimmer beams shall be not less than two inches from the outside face of the chimney. Any header beam supporting a trimmer arch in front of a fireplace shall be not less than 18 inches from the face of the chimney breast.

§ 89-68 Fire partitions and walls.

Fire partitions. Fire partitions shall be constructed of approved masonry or reinforced concrete or of a form of construction of incombustible materials having an equal or better fire resistance, in accordance with the state Industrial Code. Fire partitions may be used as bearing walls, provided that in addition to meeting the requirements for fire partitions, they conform to the requirements of this chapter for bearing walls.

Fire walls. Fire walls shall be constructed of solid brick masonry laid in cement mortar or cement lime mortar or of reinforced concrete, stone or terra cotta blocks, in accordance with the provisions of the state Industrial Code.

§ 89-69 Fire precautions relating to garages.

Private garages.

A private garage located or attached to a building occupied for any different purpose shall be separated from the balance of the building by wood-joisted ceilings and wood stud walls covered with gypsum mortar or cement mortar not less than 3/4 of an inch in thickness, on expanded metal lath, or of some other construction having fire resistance of not less than one hour.

Proper precautions shall be taken to prevent the seepage of fumes from such a garage to adjoining parts of the building.

Public garages.

No public garage shall hereafter be located within or attached to a building occupied for any other purpose, unless it is separated from such other occupancy and the walls, floors, and ceilings enclosing it are of fireproof construction or semifireproof construction.

Walls, floors and ceilings which effect such separation shall be continuous and unpierced by openings of any kind; provided, however, that door openings equipped with self-closing fire doors leading to salesrooms or offices that are operated in connection with such garages shall not be prohibited; and provided, further, that the use of elevators and stairways to other stories accessible only by vestibules or balconies constructed and arranged as required for fire towers shall not be prohibited.

Proper precaution shall be taken to prevent the seepage of fumes from such a garage to adjoining parts of the building.

No public garage shall hereafter be built of unprotected metal or wood frame construction.