Appendix BO Existing Buildings and Structures
Section BO101 Purpose and Intent
BO101.1 General.
The purpose of these provisions is to encourage the continued use or reuse of legally existing buildings and structures. Structural elements and systems shall comply with Section R102.6.1 and the provisions of this appendix. Repairs, alterations, additions and relocation of existing buildings and structures shall comply with the provisions of this code for new construction, except as modified by this appendix.
Section BO102 Compliance
BO102.1 General.
The work shall not cause the building or structure to become unsafe or adversely affect the performance of the building; shall not cause an existing mechanical or plumbing system to become unsafe, hazardous, insanitary or overloaded; and unless expressly permitted by these provisions, shall not make the building any less compliant with this code or to any previously approved alternative arrangements than it was before the work was undertaken.
BO102.2 Identification of work.
The work shall be clearly identified on the permits issued under these provisions.
BO102.3 Structural.
Structural elements and systems that are altered, repaired or replaced shall comply with Section R102.6.1 and the structural provisions of this appendix. The work performed shall not cause the structure to become less compliant with this code than it was before the work was undertaken.
BO102.3.1 Design loads.
The minimum design loads for the structure shall be the loads applicable at the time the building was constructed. The minimum design loads for new structural components shall comply with this code. Structural elements that are uncovered during the course of the alteration and that are found to be unsafe shall be repaired in accordance with Section R102.6.1.
BO102.6 Replacement windows.
Where an existing window, including the sash and glazed portion, or safety glazing is replaced, the replacement window or safety glazing shall comply with the requirements of Sections BO102.6.1 through BO102.6.3, as applicable.
BO102.8 Equivalent alternatives.
Work performed in accordance with the International Existing Building Code shall be deemed to comply with the provisions of this appendix. These provisions are not intended to prevent the use of any alternative material, alternative design or alternative method of construction not specifically prescribed herein, provided that any alternative has been deemed to be equivalent and its use authorized by the building official.
BO102.9 More restrictive requirements.
Buildings or systems in compliance with the requirements of this code for new construction shall not be required to comply with any more restrictive requirement of these provisions.
Section BO103 Definitions
BO103.1 General.
The terms used in this appendix, and not provided in Chapter 2, are defined as follows:
DANGEROUS.
Any building, structure or portion thereof that meets any of the conditions described below shall be deemed dangerous:
- 1.
The building or structure has collapsed, has partially collapsed, has moved off its foundation or lacks the necessary support of the ground.
- 2.
There exists a significant risk of collapse, detachment or dislodgement of any portion, member, appurtenance or ornamentation of the building or structure under permanent, routine or frequent loads; under actual loads already in effect; or under snow, wind, rain, flood, earthquake aftershock or other environmental loads when such loads are imminent.
Section BO104 Repairs
BO104.1 General.
Repairs shall comply with the applicable provisions of this code for new construction or as permitted by this appendix.
BO104.2 Materials.
Materials used during repairs shall comply with this section.
BO104.2.1 New and replacement materials.
Except as otherwise required or permitted by this code, materials permitted by this code for new construction shall be used. Like materials shall be permitted for repairs and alterations, provided that unsafe conditions are not created. Hazardous materials shall not be used where this code would not permit their use in buildings of similar occupancy, purpose and location.
BO104.2.2 Existing materials.
Materials already in use in a building in compliance with requirements or approvals in effect at the time of their erection or installation shall be permitted to remain in use unless determined by the building official to be unsafe.
BO104.2.3 Plumbing materials and supplies.
The following plumbing materials and supplies shall not be used:
- 1.
All-purpose solvent cement, unless listed for the specific application.
- 2.
Flexible traps and tailpieces, unless listed for the specific application.
- 3.
Solder having more than 0.2 percent lead in the repair of potable water systems.
Section BO105 Alterations
BO105.1 General.
Alterations to existing buildings shall comply with the provisions of this code for new construction, except as permitted by Sections BO105.2 through BO105.8. Engineered design in accordance with Section R301.1.3 shall be permitted to meet the requirements of this section. Alterations shall not cause the existing building to become less compliant with the provisions of this code for new construction than the existing building was prior to the work.
BO105.2 Newly constructed elements.
Newly constructed elements, components and systems shall comply with the requirements of this code.
BO105.3 Nonconformities.
The work shall not increase the extent of noncompliance or create nonconformity to those requirements that did not previously exist.
BO105.4 Structural.
Altered structural elements and systems shall comply with Section R102.6.1 and the structural provisions of this appendix.
BO105.4.2 Increased design loads.
Where an alteration causes an increase in loads as described in this section, the existing structural components that support the increased load, including the foundation, shall be shown to comply or shall be altered to comply with the applicable provisions of Chapters 3, 4, 5, 6 and 8. Existing structural components that do not provide support for the increased loads shall not be required to comply with this section.
BO105.4.2.1 Dead load increase.
Dead load shall be considered to be increased for purposes of this section when the weight of materials used for the alteration exceeds the weight of the materials replaced, or when new materials or elements are added.
Exceptions:
- 1.
Buildings in which the increase in dead load is due entirely to the addition of a second layer of roof covering weighing 3 pounds per square foot (psf) (0.1437 kN/m2) or less over an existing single layer of roof covering.
- 2.
Installation of rooftop-mounted photovoltaic (PV) panel systems weighing 4 psf (0.1915 kN/m2) or less over an existing single layer of roof covering.
These exceptions shall not be applied simultaneously.
BO105.4.2.3 Snow load increase.
Snow load shall be considered to be increased for purposes of this section when alteration of the roof configuration creates new areas that accumulate drifted snow.
BO105.4.2.4 Wind load increase.
Wind load shall be considered to be increased for purposes of this section when the exposed surface area of any exterior elevation subject to wind pressure is increased by more than 5 percent.
BO105.4.2.5 Seismic load increase.
Seismic load shall be considered to be increased for purposes of this section in existing buildings assigned to Seismic Design Category C, D0, D1 or D2 where new materials replace lighter-weight materials in one of the following conditions:
- 1.
Concrete tile or tile roof covering of similar weight is installed on more than 50 percent of the total roof area.
- 2.
Brick veneer or cladding of similar weight is installed on walls above the second story.
BO105.4.3 Unreinforced masonry parapets.
Unreinforced masonry parapets located in Seismic Design Category D2 shall have wall anchors installed at the roofline and additional bracing installed above the roofline whenever a reroofing permit is issued and work involves removal of roofing materials from more than 25 percent of the roof area. Such masonry bracing and wall anchors shall be of an approved design, unless an evaluation demonstrates compliance of the existing bracing and anchorage.
Exception: Bracing above the roofline shall not be required where the maximum height of unbraced unreinforced masonry does not exceed a height-to-width ratio of 2.5. Height shall be measured from the top of the parapet down to the highest existing brace or anchor point attached to the structure.
BO105.5 Electrical equipment and wiring.
Electrical equipment and wiring shall comply with this section.
BO105.5.2 Electrical service.
Service to the dwelling unit shall be not less than 100 ampere, three-wire capacity, and service equipment shall be dead front having no live parts exposed that could allow accidental contact. Type “S” fuses shall be installed where fused equipment is used.
Exception: Existing service of 60 ampere, three-wire capacity, and feeders of 30 ampere or larger two- or three-wire capacity shall be accepted if adequate for the electrical load being served.
BO105.5.3 Additional electrical requirements.
Where the work area includes any of the following areas within a dwelling unit, the requirements of Sections BO105.5.3.1 through BO105.5.3.5 shall apply.
BO105.5.3.1 Enclosed areas.
Enclosed areas other than closets, kitchens, basements, garages, hallways, laundry areas and bathrooms shall have not fewer than two duplex receptacle outlets, or one duplex receptacle outlet and one ceiling- or walltype lighting outlet.
BO105.5.3.2 Kitchen and laundry areas.
Kitchen areas shall have not fewer than two duplex receptacle outlets. Laundry areas shall have not fewer than one duplex receptacle outlet located near the laundry equipment and installed on an independent branch circuit.
BO105.5.3.4 Lighting outlets.
Not less than one lighting outlet controlled by a listed wall-mounted device shall be provided in every bathroom, hallway, stairway, attached garage and detached garage with electric power to illuminate outdoor entrances and exits, and in utility rooms and basements where these spaces are used for storage or contain equipment requiring service. The wall-mounted control device shall be located near an entrance to the room.
BO105.7 Ceiling height.
Where a habitable attic or habitable space is created in an existing building, ceiling heights shall be not less than 6 feet 8 inches (2032 mm). Bathrooms, toilet rooms and laundry rooms shall have a ceiling height of not less than 6 feet 4 inches (1930 mm).
Exceptions:
- 1.
For rooms with sloped ceilings, the required floor area of the room shall have a ceiling height of not less than 5 feet (1524 mm), and not less than 50 percent of the required floor area shall have a ceiling height of not less than 6 feet 8 inches (2134 mm).
- 2.
At beams, girders, ducts or other obstructions, the ceiling height shall be not less than 6 feet 4 inches (1930 mm) from the finished floor.
BO105.8 Stairs, handrails and guards.
Stairs, handrails and guards shall comply with this section.
BO105.8.1 Stair width.
Existing basement stairs and handrails not otherwise being altered or modified shall be permitted to maintain their current clear width at, above and below existing handrails.
BO105.8.2 Stair headroom.
Headroom height on existing basement stairs being altered or modified shall not be reduced below the existing stairway finished headroom. Existing basement stairs not otherwise being altered shall be permitted to maintain the current finished headroom.
BO105.8.3 Stair landing.
Landings serving existing basement stairs being altered or modified shall not be reduced below the existing stairway landing depth and width. Existing basement stairs not otherwise being altered shall be permitted to maintain the current landing depth and width.
BO105.8.4 Stair treads and risers.
An existing stairway shall not be required to comply with Section R318.7.5 where the existing space and construction does not allow a reduction in pitch or slope. Where risers are added to an existing stair, the tread and riser dimension of the added risers shall match the existing stair.
Section BO106 Addition
BO106.1 General.
Where existing buildings with the addition are within the scope of this code, additions shall comply with this section and other applicable provisions of this code for new construction or as permitted by this appendix. Engineered design in accordance with Section R301.1.3 shall be permitted to meet the requirements of this section.
BO106.2 Structure for horizontal additions.
Where an addition involves new construction attached to an existing building, the new construction shall meet all of the structural requirements of this code for new construction. Alterations to the existing building shall comply with the requirements governing alterations within this code. In wood light-frame additions, connection of the structural components shall be permitted to be provided using wall top plates and addition studs that abut the existing building. Wall top plates shall be lapped and spliced in accordance with Section R602.3.2. Abutting studs shall be fastened in accordance with Table R602.3(1).
Exception: The addition structure shall be permitted to be connected to the existing building in accordance with accepted engineering practice.
BO106.3 Structure for vertical additions.
Where an addition involves new construction that adds a story to any part of the existing building or vertically increases the height of any part of the existing building, the new construction and the existing building together shall be shown to comply with, or altered to comply with, all of the structural requirements of this code for new construction.
Exception: Where the new structure and the existing structure together are evaluated in accordance with accepted engineering practice and are shown to be sufficient to support the combined loads from the new structure and existing structure, no structural alterations are required.
Section BO107 Relocated Buildings
BO107.1 General.
Residential buildings or structures moved into or within the jurisdiction are not required to comply with the requirements for new construction under this code, provided they comply with all of the following conditions:
- 1.
- 2.
Any repair, alteration or change of use undertaken within the relocated structure shall comply with the requirements of this code applicable to the work being performed.
- 3.
Any field fabricated elements shall comply with the applicable requirements of this code.