8.1a PRINCIPLES OF CONSTRUCTION Flashcards
A29 - What are 6 types of sound that can reach a listener? (2 types not shown below)
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Incident Sound (mirror)
- reflects off of surfaces with low a (sound absorb)
- to be effective surface area>wavelength
- returns @ angle = incident angle
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Diffracted Sound
- airborne sound waves bent by obstacle in path
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Airborne Sound
- Travels directly from source to listener
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Attenuation
- greater distance from source = lower amplitude as it spreads
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Echoes
- reflected sound waves
- loud & late enough to be considered distinct
- occurs w parallel surfaces 60’(18m) apart
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Focusing
- convergence of sound waves reflected from concave surface
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A1 - 3 BROAD ASPECTS WHICH IMPACT WINDOW PERFORMANCE
- PHYSICAL CHARACTERISTICS OF WINDOW ASSEMBLY (window as system of elements)
- PHYSICAL INTERFACE w THE ENCLOSURE (component of build. envelope)
- EFFECTS OF WINDOWS ON QUALITY OF INDOOR SPACE (part of indoor environment)
A02 - 8 MAJOR FUNCTIONS OF A WINDOW:
- • CONTROL HEAT FLOW
- • LIMIT SOUND TRANSMISSION
- • PREVENT AIR/RAIN LEAKAGE
- • TRANSMIT LIGHT wOUT GLARE
- • BRING IN FRESH AIR & BLOCK INSECTS
- • AIRTIGHT BUT EASY TO OPERATE
- • BRING IN SOLAR HEAT IN WINTER not SUMMER
- • BLOCK/REFLECT UNWANTED LIGHT & UV RAYS
A3 - FUNCTION OF CAP BEAD & HEEL BEAD. WHAT DO THESE COMPONENTS PREVENT?
CAP: KEEP RAIN OUT (flank window pane @ sash in & out)
HEEL: AIR TIGHTNESS (inside joint seal) *PREVENT AIR LEAKAGE
A4 - 3 WAYS TO MITIGATE CONDENSATION ON WINDOWS.
- ADD AIR SPACE w PLASTIC OR GLASS
- CIRCULATE WARM AIR TOWARDS GLASS
- REMOVE OBSTRUCTIONS
A5 - 4 WAYS TO MITIGATE SOUND TRANSMISSION IN A WINDOW SYSTEM.
- LARGE GLAZING GAPS
- THICKER GLASS
- SEPARATE FRAMES/SASHES (INT/EXT)
- COMPLETELY AIRTIGHT (fixed often perform better than operable)
A6 - 3 TYPES OF STRENGTHENED GLASS + PROS / CONS
1 - FULLY TEMPERED (surfaces in compression & core in tension) + 3-5x more resistant to fail due to
- bend
- impact
- heat - impact along edge will shatter sheet
2 - HEAT STRENGTHENED (lower level of surface compression compared to fully tempered, same process) + stronger than annealed glass & less susceptible to shatter due to edge impact
3 - LAMINATED (bonded together with intermediate layers of plastic) + holds together if broken + can be used for solar heat control, sound control, bullet-resistance, blast resistance - not stronger than regular annealed glass
A07 - List the 5 main forces of moisture transfer in a building envelope.
- KINETIC ENERGY OF RAIN (impact)
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SURFACE TENSION (drip edges)
- water clings to horizontal(ish) surfaces
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CAPILLARY (gaps <5mm)
- water drawn into permeable materials & small openings (cracks, joints & junctions)
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GRAVITY
- moves rain down surface and into sloped openings (holes cracks flashing)
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AIR PRESSURE DIFFERENCE
- rain driven in direction of lower pressure
A08 - Describe the 2 lines of defence in a rainscreen system.
- CLADDING
- a DRAINED CAVITY
- intercept all water that passes cladding
- dissipate water to exterior:
- evaporation
- drain via flashing
2.b or WATERPROOF MEMBRANE
A09 - A rainscreen should also be protected, what are 3 ways to do so?
- ROOF OVERHANGS
- CORNICES
- BALCONIES
A10 - What are the 4 ‘D’s of preventing rain pentration?
- deflection
- drainage
- drying
- durability
A11 - List & describe the 4 main strategies for preventing moisture infiltration.
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Integral Sills & Drip Edges on Flashings
- typ. projection of 10mm beyond cladding
- 25mm may be rqrd
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Drainage Holes in Permanent Cladding
- needs to slowly dissipate/evap water
- min. 10mm to prevent capillary bridging
- Sealants/ Gaskets reduce openings
- Joints:
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Locked Joints (open)
- manage gravity driven
- rqr 10mm overlap
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Lapped Joints (closed)
- rqr 5mm gap btwn to prevent capillary action
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Locked Joints (open)
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A12 - What STC rating does NBC rqr for dwelling units?
STC 50
A13 - What has the greatest impact on controlling sound transmission in a wall assembly? What are the 2 main ways of acheiving this with a wall assembly.
Isolate GWB
- Staggered Studs
- Double Wall
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A14 - List 4 ways to alter a wall assembly to impact sound transmission, other than isolation of GWB.
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Increase Mass
- 2xGWB will increase STC by 10points!
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Add Sound Absorbing Material
- will increase STC by 10pnts in a stag or double wall
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Increase Stud Spacing
- 400mm-600mm spacing on stag or double wall will increase StC by 1or2 pnts
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Include Resilient Channels
- good for load bearing studs
A15 - When looking to control sound transmission, what should not be done, as it has no impact on sound transmission.
- inc. gwb @ center or assembly (actually reduces cavity size)
- inc. batt insulation - not beneficial at all
A16 Define these 4 terms:
- NOISE
- PITCH
- VOLUME
- FREQUENCY
- NOISE
- Any unwanted sound
- PITCH
- Wavelength of sound
- VOLUME
- Amplitude of sound
- FREQUENCY
- # cycles/second (hertz)
A17 - Define these 5 terms:
- ATTENUATION
- ARTICULATION
- SOUND INTENSITY
- SOUND ABSORPTION
- SOUND REVERBERATION
- ATTENUATION
- reduction of sound
- ARTICULATION INDEX
- measure of speech intelligability
- >.6 = good communication
- SOUND INTENSITY
- dB
- SOUND ABSORPTION
- ratio of sound absorbed by material
- unit = sabins
- SOUND REVERBERATION
- persistance of sound after source stopped producing
A18 - Define these 3 measures of sound :
- NC
- NRC
- STC
- NC - Noise Criteria
- specifies max. background noise in a given space
- NRC - Noise Reduction Coefficient
- # rating system for ave. sound sbsoption coefficient of a material @ frequencies of 250/500/1000/2000 Hz
- STC - Sound Transmission Class
- Rating system to determine effectiveness of construction cross sections to stop sound transmission.
A19 - What is the typ. STC rating for :
- normal speech heard through a barrier
- loud speech heard through a barrier
- loud speech heard but not understood
- loud speech is faint through barrier
- loud sound other than speech heard through a barrier
- STC 25
- STC 30
- STC 35
- STC 42-45
- STC 46-50
A20 - What is the Inverse Square Law?
sound intensity = inversely proportional to square of distance to source
A21 - Decibles and hearing?
- What is the measure in dB of the threshold of human hearing
- What increment of dB is and is not noticeable?
- zero dB
- 1 dB is not noticeable
- 5 dB is noticeable
A22 - In what range of Hz does human conversation occur?
125Hz - 8000Hz
A23 What relationship does TL have to NR (noise reduction)?
NR = TL(db)
A24 - What is the function of noise criteria curves?
What is the PNC (preffered noise criteria) for each of the following spaces:
- concert hall
- bedroom
- lobbies
- kitchens
- 12-20 dB (concert hall)
- 20-30 dB (bedroom/hospital/aptmt)
- 40-45 dB (lobbies/labs)
- 45-55 dB (kitchens/light maint. shops)
A26 - What is the measure of material absorption and what values reflects absorptive/reflective materials
a = coefficient of absorption (ratio of intensity)
**NRC(noise reduction coefficient)
= ave a @ 250/500/1000/2000Hz.
<0.2 = REFLECTIVE
>0.2 = ABSORPTIVE
A27 - What is sound absorption useful for in sound control? (4)
- prevent sound reflection
- reduce sound intensity within space
- improve speech privacy
- decrease/enhance reverberation
A28 - Reverberation affects the intellgibility of speech & music. Since each space has it’s own ideal reverberation time, what is the general rule for small spaces vs. large ones.
- small space = shorter reverb time
- large space = greater reverb time
examples:
- 1.5-1.8s = auditorium
- 0.6-0.8s = elem. classroom
- 0.3-0.6s = office/small room for speech
A29 - What are 4 ways to control mechanical noise?
- spec quiet equip
- line ducts
- use inertia blocks (heavy concrete) to min. vibration
- set upon resilient blocking to isolate from structure
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A30 - Define impact noise and the associated system commonly used to measure it.
Structure borne sound generated by impact:
- footsteps
- moving furniture
Impact Insulation Class (IIC)
- single # rating prevention of transmission of impact noise in ceiling/floor construction
- higher IIC = lower sound transmission
A31 - How can Impact Noise be improved? (3)
- carpet /rsf install
- suspended ceilings
- conc. slab floated on fibreboard laid on struct. slab.
33 - What is the primary purpose of thermal insulation?
Control the flow of heat through an exterior assembly.
32 - List the 4 most common types of insulation and their r-value per inch of thickness
Batt
= 3.3 (same fiberglass or rock wool)
Rigid board
= 2.5 (cellular glass)
= 3.6 - 7.2 (the various polys - polyisocyanurate highest)
Foamed in Place
= 6.2 (polyuerethane)
Loose fill
= 2.1 -3.7 (vermiculite to cellulose)
34 - The steady state method of measuring thermal resistance of a construction assembly is useful, but these 4 factor also influence heat/loss gain:
- Surface colour / reflectivity
- Mass (time lag)
- Orientation (solar /wind)
- Latent Heat (occ. etc)
35 - As a point of reference, know the typical R value of single and double glazing (w 5mm air space).
*APPROX DOUBLE
single R = .88
double R = 1.61