Chapter 23Interior Walls & Partitions

Interior Partitions

Performance CriteriaStrengthFire ResistanceDurabilityAcoustical Isolation

MaterialsMetal or wood studs faced with plaster or gypsum boardConcrete block (CMU) or structural clay tiles

Types of Interior Partitions

Fire Walls

Shaft Walls

Fire-Rated Walls

Smoke Barriers

“Other” Non-bearing and/or non-rated

Elements common toFire Walls, Shaft Walls, Rated Walls & Smoke Walls Wall Assembly is tested (often by UL)Materials (type, size, composition, etc.)Installation (method, application, anchorage, etc)Actual construction must comply

Extend from rated assembly to rated assemblyWall Penetrations are RestrictedOpening size, material used, installation, operationOpening assembly also ratedEX: fire dampers, pipe selves, door closures, etc.

Fire Walls

Restricts the Spread of Fire (area to area)

Extends from Foundation through RoofMust abut a non-combustible roof , orExtend above the roof (generally 32”)

Divide the Building into “smaller units”Each unit considered a separate blg for codeEX: Wood framed apartment complex

Fire wall

Shaft Walls

Enclose multi-story openings Elevators, stairways, mechanical chases

Composition - masonry, plaster or drywall

Typically: Higher fire rating (2hr+)

Restricting floor-to-floor fire migration Primary means of egress (exit for blg.)

Gypsum Shaft wall AdvantagesLighter, installed dryCan be erected from floor outside the shaft

1” Gypsum shaftwall panel

C-H Stud

Typically 1/2” or 5/8”

ShaftwallConstruction

In anElevator Shaft

Gypsum Shaftwall Constructionin a stairwell

Stairway

Fire-Rated Walls

Restrict the spread of fire in an area (typ. 1-2 hr)May not extend from foundation to roof, but mustBe floor to floor (or floor to fire-rated assembly)Fire-rated Walls Separate:Mixed occupancies/use or tenant spaces Dwelling unitsGuest rooms in hotels, dormitories, hospitals, etc.Enclose stairways & exit corridors

Composition; typically metal framing with multiple layers of drywall

Fire Rated Assemblies

•Often tested by UL

•Construction must “match” UL assembly

(excerpt from UL book)

(excerpt from

UL book)

Smoke Barriers

Protect occupants from smoke (the #1 killer)Continuous, air -tight assemblyOpenings - self-closing doors (rated)

Typically - Fire Walls also qualify as smoke barriers

“Smoke” caulking @ MPE penetrations

Partition Framing

Wood or Metal framing

WoodUse limited by the building codesFire treated wood - expensive

Metal FramingTypically cold-formed metal studsMost UL assemblies use metal studsCommercial work - almost exclusively

Plaster

Generic term - Cementitious substances (w/ or w/o gypsum)

Plaster SystemsOver Expanded Metal Lath (3-coat)

Scratch coat - cover lath Brown coat - add thickness, smooth base Finish Coat

Applied to CMU (lath or bonding agent)

Veneer Plaster - thin coat over a gypsum board base

Stucco - similar, but accessories must resist the elements

Plaster

Wet System

Relatively expensive system

Typical usesSpaces with High Moisture Surfaces where Impact Resistance is req’d

Gypsum Board

Gypsum:Major component of many building interiorsAdvantages

In comparison w/ alternatives -durable and light Resists passage of sound Inexpensive Highly fire resistant

Disadvantage - soluble in water

Gypsum BoardForm of most gypsum used

Gypsum Board

Names: Gypsum wallboard, plasterboard, drywallSizes: 4’ x 8’ to 14’1/4” to 1” thick

TypesRegularWater ResistantType X (rated assemblies)Foil-backed (acts as VB)Coreboard (1’ thick)Others

Gypsum Board

Edges:Tapered Edges

(most common)

Allows joints to be “finished”

(concealed)

Gypsum Board Installation

Install partition framing

MPE partition rough-in

Hang gypsum drywall (screws, ring-shank nails)

Finish gypsum drywall joints, edges, & cornerscorner beads, metal trim, and accessoriesTape (& bed)- 1st coat & tape 2nd coatFinish - 3rd/final coat (may require sanding 1st)Sand

Corner Beads

“Crimped”

Screwed

Nailed

Crimped

Nailed

Tape & Bed Coat

Second Coat

Application

Sanding

Joint Compound

‘Stilts’ Joint ‘Tape’

Gypsum Products & Sustainability

Gypsum: not renewable, but plentiful

Gypsum mined – habitat & overburden issues

Synthetic gypsum – from recycled materials

Embodied energy is low

Gypsum paper face mostly recycled material

Approx. 10% is waste – large % to a landfill

Gypsum dust; nuisance & discomfort

Gypsum products have extremely low emissions