13-60-050 Type III-A, heavy timber construction.

   Type III-A, heavy timber construction, shall have interior structural elements of heavy timber material as required in this section.

   (a)   Wood members of heavy timber construction shall be arranged so that there will be no concealed spaces within the construction.

   (b)   Columns shall have a minimum dimension of eight inches.

   (c)   Floor framing members shall have minimum nominal dimensions of six by ten inches.

   (d)   Roof framing members, except trusses, shall have a minimum nominal dimension of six inches.

   (e)   The members of roof trusses shall have minimum nominal dimensions of four inches by six inches with the following exceptions:

      (1)   Members may consist of two or more pieces of three-inch nominal thickness with intervening spaces blocked solidly or tightly closed by a continuous wood cover plate of not less than two-inch nominal thickness.

      (2)   Any member may be reduced to three- inch nominal thickness when protected by an approved automatic sprinkler system under the roof deck.

   (f)   Wood floors shall be splined or tongue and grooved planks of not less than three-inch nominal thickness or of laminated planking laid on edge of not less than four-inch nominal thickness. A top flooring of not less than one inch nominal thickness shall be added to the structural floor.

   (g)   Roof construction shall be of construction not less fire resistive than splined or tongue and grooved planks of not less than two-inch nominal thickness or laminated planking laid on edge of not less than three- inch nominal thickness.

   (h)   Construction conforming to the requirements of Type I construction may be used.

   (i)   In existing heavy timber buildings which do not conform to the floor and roof planking and joist minimum thickness as noted in (c), (d), (f) and (g) above, the floor, roof, joist, and planking systems shall be protected with a minimum of 1/2: type “X” gypsum board, or shall be fully protected by a Class 1 (0-25) flame spread rated intumescent coating. Where gypsum board is applied to the underside of joists, the joist spaces shall be fire-stopped at all beams. Existing metal columns shall be protected with one-hour fireproofing.

(Prior code § 49-4.1)

13-60-060 Type III-B and III-C, ordinary construction.

   Type III-B and Type III-C, ordinary construction, shall be that construction other than heavy timber construction in which the structural elements of the interior framing are entirely or in part of wood or other materials not more combustible than wood.

(Prior code § 49-4.2)

13-60-070 Type IV, combustible frame construction.

   Type IV-A and Type IV-B, combustible frame construction shall be that construction in which the structural elements, including enclosing walls, are entirely or in part of wood or other materials not more combustible than wood.

(Prior code § 49-5)

13-60-080 Mixed types of construction.

   When two or more types of construction occur in the same building, the provisions of this Code applying to each type of construction shall be complied with.

(Prior code § 49-6)

13-60-090 Fire-resistive values.

   The degree of fire resistance of materials, assemblies and construction shall be measured in terms of the number of hours of satisfactory performance as determined by the requirements of Sections 15-12-060 and 15-12-090.

(Prior code § 49-7; Amend Coun. J. 6-14-95, p. 2841)

13-60-100 Types of construction – Fire-resistive requirements.

   The fire-resistive values required for the various elements for each type of construction shall be as established in Table 13-60-100 as set out following this section and Section 13-60-110.

Table 13-60-100
Required Hours of Fire Resistance for Types of Construction

	Description	Type I Fire-Resistive			Type II Noncom- bustible	Type III Exterior Protected			Type IV Combustible Frame
						Heavy Timber	Ordinary
		Type I-A	Type I-B	Type I-C		Type III-A	Type III-B	Type III-C	Type IV-A	Type IV-B
1	Exterior Bearing Walls	4(d)	3(d)	2	N.C.	4(d)	3(d)	3(d)	1	1/2(e)
2	Exterior Nonbearing Wall
	Outside Exposure	2(d)	2(d)	2(d)	N.C.	2(d)	2(d)	2(d)	1
	Inside Exposure (a)	4	3	2	N.C.	2	2	2	1	1/2(e)
	Inside Exposure (b)	3	2	2	N.C.	2	2	2	1	1/2(e)
	Inside Exposure (c)	2	2	1	N.C.	1	1	1	1	1/2(e)
3	Interior Bearing Walls	4	3	2	N.C.	3	1(j)	1/2(e)	1	1/2(e)
4	Interior Nonbearing Walls & Partitions	(g)	(g)	(g)	(g)	(g)	1/2(e)	1/2(e)	(g)	1/2(e)(l)
5	Exterior Columns	4(p)(o)	3(p) (o)	2(p)(o)	N.C.	4	2	2	1	1/2(e)
6	Interior Columns
	Supporting Roofs Only	3(k)(p)	2(k)(p)	1(k)(p)	N.C.	(h)	1/2(f)	1/2(f)	1/2(f)	1/2(f)
	Other Columns	4	3	2	N.C.	(h)	1	1/2(e)	1	1/2(e)
7	Beams, Girders & Trusses
	Supporting Roofs Only	2(k)(o) (p)	2(k)(p)(o)	1(k)(o)(p)	N.C.	(h)	1	1/2(f)	1/2(f)	1/2(f)
	Other Beams, Girders & Trusses	3(o)	2(o)	1(o)	N.C.	(h)	1	1/2(e)	1	1/2(e)
8	Floor Construction	3(o)	2(o)	1(o)	N.C.	(h)	1	1/2(e)	1	1/2(e)
9	Roof Construction	2(k)(o) (p)	2(k)(p)(o)	1(k)(o)(p)	N.C.	(h)	1/2(f)	1/2(f)	1/2(f)	1/2(f)(l)
Notes Pertaining to Table 13-60-100
N.C. – Noncombustible.
(a)   Storage. industrial and hazardous occupancies.
(b)   Business and mercantile occupancies.
(c)   Residential, institutional and assembly occupancies.
(d)   When exterior walls face a street, public open space, yard or court not less than 30 feet in width, such walls may be of noncombustible materials providing fire-resistance from outside exposure as follows:
(1)   Exterior bearing walls of buildings of Types I-A and III-A construction – three hours.
(2)   Exterior bearing walls of buildings of Types I-B, III-B and III-C construction – two hours.
(3)   Exterior nonbearing walls of buildings of Types I-A, I-B, I-C, III-A, III-B and III-C construction – one hour.
(e)   Fire-resistive protection shall be required in all buildings except in one-story industrial and storage units, private garages and the various buildings and structures listed in Chapter 13-116. For single-family residential units, interior facings on wood framings of exterior walls, or ceilings under nonhabitable spaces, shall be of material providing not less than 15 minutes' protection.
(f)   Fire protection of roof construction and columns supporting such roof construction only shall not be required in one- story buildings of assembly, business, mercantile. industrial and storage occupancies except as provided in Section 13-84-130.
(g)   See Sections 15-8-120 to 15-8-250, inclusive.
(h)   See Section 13-60-050.
(j)    The use of combustible construction other than heavy timber construction for load-bearing walls or load- bearing partitions shall be limited to the support of not more than two floors and a roof unless the building is protected by an automatic sprinkler system in accordance with Chapter 15-16.
(k)   Fire protection shall not be required for construction located at a distance of 20 feet or more above any floor, mezzanine or balcony. One-hour construction only shall be required for construction located 14 feet or more above any floor, mezzanine or balcony.
(l)   In single family residential units not over one story high, having a floor area not exceeding 1,000 square feet. nonbearing partitions may be of such materials as will have a fire-resistance rating not less than a wood stud partition covered on both sides with one-half inch exterior grade plywood which will have a flame spread rating of not to exceed 30, and which will withstand an impact equivalent to 60 pounds at three and one-half feet. Ceiling material may be similar, with a fire-resistance rating equivalent to such covering on one side of said studs.
(m)   In open plan schools not exceeding three stories in height and equipped throughout with a standard sprinkler system as defined in Chapter 15-16 of this code, the required fire-resistance rating specified for various structural members under Types IA and I-B construction classes may each be decreased one hour below that required in the above table except that a minimum of one hour shall be required in each case.
(n)   [Reserved.]
(o)   Fire protection shall not be required for exterior structural members of business, residential and assembly (other than exhibition halls) occupancies when the building is equipped with a supervised standard automatic sprinkler system as defined in Chapter 15-16 of this code and does not exceed 55 feet in height. Fire protection shall not be required for exterior columns or portions of beams or girders which are outside of the building envelope, face a public way not less than 30 feet in width and do not support exterior floors or walkways intended for normal human occupancy.
(p)   Fire protection shall not be required for roof construction including columns. beams, girders, and trusses supporting the roof only of areas classified per Chapter 15-16 as “light hazard occupancy” in business, residential and assembly (other than exhibition halls) occupancies in buildings equipped with a supervised standard automatic sprinkler system as defined in Chapter 15-16 of this code.

 

(Prior code § 49-8; Amend Coun. J. 12-7-84, p. 11597; Amend Coun. J. 9-6-17, p. 55278, Art. VII, § 1; Amend Coun. J. 3-28-18, p. 74459, Art. V, § 8)

13-60-110 Exception to fire protection.

   Fire protection requirements as established in Section 13-60-100 shall be under the conditions provided in Sections 13-60-120 to 13-60-160, inclusive.

(Prior code § 49-9)