Assemblages Test 3

What are low slope roofs made of?

*deck *thermal insulation *vapor retarder *membrane *ballast *drainage *flashings

ballast

loose stone aggregate or precast concrete blocks

What does the ballast do?

*holds the membrane of a low-slope roof down against wind uplift *protects the membrane from ultraviolet light and physical wear

Where should a vapor retarder be installed?

*at such a point in the roof assembly that it will always be warmer than the dew point of the interior air under every common condition of use *below the insulation (not always possible)

What are the two broad classes of plastic used to make single-ply roof membranes?

*thermoplastics *thermosetting

thermopastics

*may be softened and joined by heat or solvent welding *polyvinyl chloride (PVC) - widely used, polymer-modified bitumens, PVC alloys, etc

thermosetting

*can not be softened - must be joined by adhesives or pressure sensitive tapes *EPDM (the most widely used), Neoprene, CPE, etc

How are single-ply roof membranes fastened?

*adhesives *weight of ballast *fasteners concealed in the seams between sheets *mechanical fasteners that do not penetrate the membrane

How would you insulate and install a roof on a concrete dome?

use a fluid-applied membrane over a sprayed-on polyurethane foam insulation

What materials are part of a conventional parapet design?

*cut stone or precast concrete coping *drip groove *steel dowels to hold coping in place *continuous through-wall flashing *continuous metal counterflashing *termination bar *mechanical fastener *bonding adhesive *insulation *deck *roof membrane *base flashing *lap sealant

Why are slate shingles an excellent roofing material choice?

*extremely durable *fire resistant *low maintenance

What are the recommended minimum slopes for each type of roofing material?

minimum slopes for each material are specified by the manufacturer

What types of tile roofing units are there?

*clay tile *concrete tile

What are step flashings used for?

prevent leakage at wall intersections

What materials can sheet metal roofing be made of?

*aluminum *copper *zinc alloy *galvanized steel *stainless steel plate *Terne-Coated stainless steel *lead coated copper

Why should dissimilar metals not be used together in a roof?

galvanic corrosion is likely to result

What are the various types of roofing?

*steep roofs *low-slope roofs

What is the construction/composition of steep roofs?

*wood (shingles and shakes) *slates *asphalt *clay tiles *concrete tiles

What is the construction/composition of low-slope roofs?

*built-up roof (BUR) membrane *single-ply roof membrane *fluid applied roof membrane

What is the fire resistance of each roofing material?

*Class A: effective against severe fire exposure *slate, concrete and clay tiles, asphalt, shingles with glass felts, and most built-up and single ply *Class B: effective against moderate fire exposure *many of the built-up and single ply, metal roofs, asphalt shingles, based upon organic felts *Class C: effective against light fire exposure *fire retardant wood shingles and shakes

What is roofing underlayment?

*protects the roof sheathing from moisture and wind driven rain *has a low vapor resistance to reduce moisture accumulation

Where is flashing required?

*roof edges *roof openings: chimney, vent pipes, and skylight *prevents water from leaking into roof assembly and eventually into the interior

What are the types of operation for windows?

sliding and projecting

What are types of sliding windows?

*single-hung *double-hung *sliding

What are types of projecting windows?

*casement *awning *hopper *skylight *roof window *terrace door *french door *sliding door

Why are rubber compression gaskets used?

*they are more durable and seal more tightly than brush-type weatherstripping *seals by compression around the edges of the sash when it is closed *used in projected windows

What window types are most airtight?

projected windows

What window types are least airtight?

sliding windows

How do sliding glass doors operate?

can open to only half its area

How are double-hung windows designed?

to allow for each sash to be rotated out of its track for cleaning

Where do insect screens need to be installed in each window and door type?

*inside the sash: casement and awning windows *outside the sash: single-hung, double-hung, sliding, hopper, tilt/turn, inswinging windows *exterior sliding screen: sliding patio doors, terrace doors *hinged screen doors: french doors *no screen: fixed and pivoting windows

How has the quality of wood for window construction progressed?

*knot-free wood is becoming increasingly rare and expensive *composite wood products are increasingly used *the composite wood products are not attractive and need to be clad

How does a thermal break work?

interrupts the flow of heat through the metal with plastic or synthetic rubber components

How does aluminum conduct heat?

rapidly through the window frame, so thermal breaks are required

What material is most commonly used in frames for commercial windows?

aluminum

How are some plastic windows created?

pultrusion

What is pultrusion?

a process of continuous lengths of glass fiber pulled through a bath of plastic resin, usually polyester, and then through a shaped, heated die

What are the two broad plastics used for windows?

*thermoplastic plastics *thermosetting plastics

How are windows installed?

*rough opening *flashing (to prevent water and air infiltration) *install *plumb *fasten *anchoring in masonry

How are windows anchored in masonry?

*nailing the unit to wood strips that have been fastened inside the masonry with bolts or power-driven fasteners *attaching the unit to steel clips that have been laid into the mortar joints of the masonry

What are the two construction types of the "cores" of flush wood doors?

*solid core *hollow core

Where is tempered glass required in windows and doors?

*glass within doors *glass near doors *large lights of glass near the floor

What are the window testing and standards?

*thermal and structural performance *performance grades established covering: *design wind pressure *water resistance *structural performance *air infiltration *operating force *energy efficiency (insulating value, solar heat gain, visible light, air leakage)

thermal bridge

wall components such as metal framing members that are highly conductive of heat and therefore likely to cause localized condensation on interior surfaces

What forces can move water through a wall?

*gravity *momentum *surface tension *capillary action *wind currents (air pressure differences)

What are barrier walls?

walls that eliminate openings to keep water out

What are the components of drained/rainscreen cladding and how does it work?

*exterior cladding (rainscreen) *a drainage space behind the cladding (PEC) *a concealed air and water-resistive barrier behind the drainage space (backup wall with insulation and vapor barrier)

Why is pressure-equalized design used?

*to create an airtight boundary behind the exterior cladding *air pressure within the opening can quickly equalize the exterior *sustained airflows that could otherwise transport water through the opening are prevented *part of the drained/rainscreen cladding system

Where is the drained/rainscreen cladding principle applied?

on wall cladding and on a smaller scale at the detailing of the sill of a double-hung window

What cladding systems are designed like a drainage/rainscreen cladding system?

*the brick facing wythe is the drained/rainscreen cladding *the backup wall is the air barrier (insulation and vapor barrier) *the cavity, pressurized through the weep holes, is the pressure equalization chamber

Why is sealant important?

*prevents the passage of air and water through the exterior enclosure *allows for dimensional tolerances during assembly *allows for movement between components once the building is completed

What are soft joint sealants used for in brick veneer cladding?

*to prevent normal movements in the frame of the building from stressing the masonry veneer *to allow the veneer to expand and contract without distress *there must be a soft joint beneath each shelf angle

Why are vertical expansion joints necessary?

masonry curtain walls also must be divided vertically by movement joints to allow the frame and the masonry cladding to expand and contract independently of one another

Where should flashing terminate over a shelf angle?

should project at least 3/4" beyond the outside face of the wall

What are the components of a brick veneer cladding system?

*brick wythe *joint reinforcing/ties to backup wall and/or structure *air cavity *insulation *vapor barrier *backup wall *shelf angle to carry brick over openings

Where should brick veneer cladding be flashed?

*window heads *above shelf angles *any interruption of the cavity

How thin should stone veneer cladding panels be cut?

*no thinner than 1/4" for granite and even thicker for others, based on industry standard *extremely thin sheets of stone may be stiffened with a structural backing such as a metal honeycomb and mounted as spandrel panels in an aluminum mullion system *very thin sheets of stone may also be used as facings for precast concrete curtain wall panels

What has been the cause of a number of failures of cladding systems?

stone that has been sliced thinner than industry standards

How do you make hollow aluminum shapes?

*extruded by mounting the portion of the die that forms the interior of the shape on a steel "spider" that is attached to the inside of the die *the metal flows around the legs of the "spider" before it passes through the orifice

thermal break

materials used to control heat conduction through cladding

What are the various models of metal cladding assembly?

*stick system *unit system *unit and mullion system *panel system *column cover and spandrel system

How do aluminum mullions get water out of the wall system?

weep holes drilled horizontally through the pressure plate and vertically through the bottom edge of the external snap-on cover

How do most metal and glass cladding systems work as a drained/rainscreen cladding?

*the external gasket serves as a deterrent seal (rainscreen) *the internal gasket acts as an air barrier *the hollow spaces between the edges of the glass and the mullions act as pressure equalization chambers

How do the differential movements for glass and metal affect curtain wall design?

because aluminum and glass have such different coefficients of thermal expansion, cladding must be designed with expansion joints to allow movement to occur without damaging the cladding of the frame of the building

Who is responsible for all of the details of metal and glass curtain walls?

the manufacturer and installer of the proprietary system chosen by the architect