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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