Interior Finishes: Part One

Sequencing

Interior finishing begins when the “shell” of the building is sufficiently weatherproof to protect the interior.Mechanical, Electrical and Plumbing, (this may

also include fire suppression systems)Vertical runs through a building are typically

accommodated by the use of shaftsHorizontal runs through a building are

typically placed in raceways or chases

Sequencing, (continued)

Full height partitions and smoke partitions Partitions “tight to deck” Fire stopping Joint covers – building separation joints Fire safing – perimeter of floor slab

Strategic Locations

Strategic Locations

Strategic Locations

Interior Finish Systems

Interior finish systems are selected based upon a number of criteria:

AppearanceDurabilityAcoustic CriteriaFire Criteria

Acoustic Criteria

Interior finish materials have an effect upon interior sound quality: noise levels, listening conditions and sound transfer from space to space. The sound transmission is qualified by two measurements:

STC – Sound Transmission Class

and

ITC – Impact Transmission Class

Acoustic Criteria

STC – Sound Transmission ClassMeasure of sound wave vibrations transferred through

the membrane of a wall. STC rating may be reduced by partition details such as dampening clips and resilient mountings that reduce the transfer of vibration from the collection panel through the wall, (typical), assembly or by the addition of sound absorbing insulation, (typically mineral batts), in the wall cavity.

ITC – Impact Transmission ClassMeasure of transmission of impact generated noises

through a floor/ceiling assembly.

Acoustic Isolation

Construction methodsSolid construction

Acoustic Isolation

Sound attenuation batt insulation

High CAC panels

Isolation clips: resilient channels

Fire Criteria

The code develops requirements for interior finishes with respect to both combustibility and flame-spread.

Combustibility is the surface burning characteristics of a material, and is described using two criteria: the flame-spread rating and the fuel-contributed rating.

Combustibility

The Steiner Tunnel test measures both the flame spread and the amount of fuel contributed by the material as well as the amount of smoke developed.Flame-spread rating is a measurement of how

fast fire moves across the surface of a materialFuel-contributed rating indicates the amount of

combustible substances in the materialSmoke developed rating classifies the material

by the amount of smoke given off when it burns

Fire-Resistance Requirements

Interior wall and ceiling finish requirements are governed by occupancy classification in the IBC, table 803.4, (page 797 in the text)

Sprinklered vs. UnsprinkleredVertical exits and passagewaysExit access corridorsRooms and enclosed spaces

Fire-Resistance Requirements

Class A materials: flame-spread ratings lie between 0 and 25

Class B materials: flame-spread ratings between 26 and 75

Class C materials: flame-spread ratings between 76 and 200.

Smoke-developed ratings may not exceed 450 for any of the three classes.

Fire-Resistance Requirements

The scale of the flame-spread ratings is somewhat arbitrary: cement-asbestos board has a value of 0 while red oak has a value of 100.

Trim materials are removed from application if their total area does not exceed 10% of the total wall and ceiling area of a room.

Fire Resistance Ratings

Fire barriers: a building assembly that meets the required fire resistance rating for separation of occupancies.

Fire walls separate buildings: where the maximum allowable area for a given occupancy is exceeded, multiple buildings may be used.

Fire Resistance Ratings, (continued)

In order to achieve a given fire resistance rating, an assembly is tested in a furnace and subjected to the structural load for which it is designed according to:1770° at one hour and 2000° after four hours

In order to achieve the fire resistance rating in hours, the assembly must:Safely carry the design load, (structural failure)Must not develop any openings that would permit

smoke or gases to penetrate the assemblyMust insulate sufficiently against heat to maintain

surface temperatures on the side away from the fire within specified levels.

Fire Resistance Ratings, (continued)

Walls and partitionsMust also pass the “hose test”: a duplicate

assembly is subjected to half the fire rated exposure of the original tested part and then subjected to the calibrated stream of a fire hose

This simulates the behavior of an assembly subjected to a fire hose during an actual fire.

Fire Resistance Ratings, (continued)

PenetrationsOpenings in rated ceiling, floor and wall

construction are restricted in size and must be protected against the passage of fire Fire rated doors and frames Fire dampers Fire stops

Separation of Occupancies

Underwriters Laboratory

1-hour rating UL U305 Drywall System

2-hour rating UL U301 Drywall System

http://www.usg.com/resources/handbooks/ViewSection.do?bookId=1&chapterNum=10&sectionNum=3

Penetrations

Partition tight to deck and wall penetrations

Penetrations

2-hour rated wall assembly

Penetrations

Partition wall assembly

Penetrations

Structurally reinforced penetration through wall assembly

Cost

First Cost:Installed cost of the finishOf paramount importance when the budget is tight or

the expected ownership of the lifespan of a building is short

Life-cycle costCost that includes the first cost, but also includes the

expected lifetime of the finish, maintenance, fuel costs, monetary inflation and the replacement cost of the finish.

Of paramount importance when the building owner expects to maintain ownership over an extended period of time.

Interior Walls and Partitions

Interior WallsFire WallsShaft WallsFire BarriersSmoke Partitions

Some additional rated assembliesExit access: corridors and egress stairsDwelling unit separations

Interior Walls and Partitions

Partition WallsNon-bearing partition walls

Plaster

Term typically applies to “gypsum” plaster, but may also be applied to other systems, including stucco.

Gypsum is quarried, crushed, dried and then ground into a fine powder; then heated to 350° F. in a process called “calcining”

Product is rehydrated and is able to re-crystallize quickly.

Calcination

When a gypsum building component is subjected to fire, a thin surface layer is calcined and disintegratesIn the process, this layer absorbs heat and gives off steam, both of which have a cooling effect on the fire.Slow process: thin layer by layer

Plaster and Plaster Systems

Plaster Plaster Gypsum plaster Gauging plaster Keenes cement Molding plaster

Lime and Portland Cement Plasters Finish lime Portland cement lime - stucco

Plaster Systems

2-coat: requires a rigid lath substrateBrown coatFinish coat

3-coat: preferredScratch coatBrown coatFinish coat

Veneer Plaster

Veneer plaster board, (“blue board”)Plaster is applied to a specially prepared

gypsum board in two successive layers The first thin “veneer” coat is followed immediately

by a “skim” coat that is then troweled to the desired finish texture

Plaster Systems

2-coat

3-coat

veneer

Gypsum Board

TypesGypsum board Water-resistant gypsum boardType-X: reinforced with glass fibers, when

exposed to a severe fire, the fibers hold the calcined gypsum in place to continue to act as a barrier to fire.

Foil-backed: includes an integral vapor retarder in exterior wall assemblies

Gypsum Board, (continued)

Types, (continued)Type-C: a proprietary version of Type-X,

typically a thinner application of Type-C may be used instead of Type-X to achieve the same protection.

Coreboard: 1” thick panel used in shaft applications, (24” panels rather than 48”)

High Impact: 5/8” Type-X panel with polycarbonate film bonded to the back.

Gypsum Board, (continued)

Typical thicknesses:¼”: used for backing applications and in multiple

layers to achieve tight radius curves5/16”: modular construction to reduce shipping weight½”: the most common, used where joist or stud spacing

is 24” or less on center5/8”: also limited to joist or stud spacing is 24” or less

on center, often used for additional stiffness or fire rating

¾”: Type-X can achieve a 2-hour rating with ¾” on one side of the partition, only.

Gypsum Board Partition Systems

1-hour partition

1-hour partition with an STC of 60-64

2-hour partition

4-hour partition

(page 832)

Specifying Gypsum Board

Gypsum board wall finishes have standardized levels of finish that are included in the drawing specifications:Level 0: attached boards only, no tapeLevel 1: joints covered in tape set in joint compoundLevel 2: a finish coat of compound over the tape and

accessories, (garages, warehouses)Level 3: a second coat of compound, (prior to textured

coating)Level 4: a third coat, (flat paints, light wallcoverings)Level 5: skim coat

Finish Ceilings

“Tightly Attached” Ceilings

Suspended Ceilings