PPD & PDD - Overall Set Flashcards
What is a skin load dominated building?
Buildings that have a lot of surface volume relative to their volume, thermal response is heavily influenced by the conditions outside
What is an internal load dominated building?
Buildings with minimal surface area relative to volume (hospitals, skyscrapers, office buildings) or buildings that generate a lot of heat regardless of their volume (theater while in use, factory) aka have a lot of loads. Only need heating on worst winter nights, and around the perimeter. It’s more about shedding heat year round
What is solar heat gain coefficient? What is the range & what is high vs low?
The fraction of net solar radiation through a window, both directly transmitted and absorbed and subsequently released inward
ranges from 0 - 1, higher means more of radiant heat goes through
Typ high is 0.7 - 0.9, low is 0.2 - 0.4
What is insolation?
radiant energy per sf of the sun
What is a British Thermal Unit (BTU)?
the heat needed to move 1 lb of water up 1 degree F
What is psychrometry?
The relation between air temperature and humidity
When things evaporate, they make everything around them colder
Warm air can hold more moisture than cool air
Does evaporation make the environment cooler or warmer?
cooler
Which hold more moisture: warm or cool air?
warm
What are degree days?
a unit used to determine the heating requirements of buildings, representing a fall of one degree below a specified average outdoor temperature (65°F) for one day
The higher the CDD, the longer or hotter the summer
The higher the HDD number the most severe the winter
What does a high number of cool degree days mean?
the longer or hotter the summer
What does a high number of cool degree days mean?
What is conductivity (k)?
the rate at which heat passes
higher conductivity the faster heat moves across
What is resistivity (r)?
the rate at which a material resists the transfer of heat
inverse of conductivity, 1/r
we generally want materials with high r
can be higher than 1
What is conductance (C)?
homogeneous materials of any given thickness or for heterogeneous materials with known thermal properties
What is resistance (R)?
homogeneous materials of any given thickness or for heterogeneous materials with known thermal properties
Inverse of conductance
R = r x d
What is U value?
measure of the overall ability of a series of conductive and convective barriers to transfer heat
value between 1 & 0
the lower the value, the better the insulator
U = 1 / R1 + R2 + R3 + …
What is conduction (including equation)?
heat exchange between two surfaces that are in contact
heat will move as a function of the temperature difference between the two surfaces (delta T), the area of the surfaces that are touching (A), and the U Value of the materials touching
Q=U x A x deltaT
What is Outdoor Design Temperature?
worst case scenarios seasonal low, similar to 100 year flood
Allows to calculate what equipment you need to heat on the coldest day
What is air change?
rate per hour at which an entire volume of air leaves and is replaced by outside air
0.9 air change means 90% in one hour
Need to convert air change per hour to cubic ft or air per minute
2 is good amount, anything below 0.3 you have to intentionally bring in outside air
What is radiation?
thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles
ex. surfaces around you have higher temps than the air - higher radiant heat
What type of surfaces absorb, what type reflect?
dark and matte surfaces absorb more heat
light or reflective material reflect heat
What is emittance?
a material’s ability to release heat through radiation
What is low E glass?
microscopic layer of reflective coating inside glass
reflects heat back inside during winter, reflects heat out in the summer
What is thermal mass?
the ability of a material to absorb, store and release heat
-Thermal lag - peaks are later and less sharp
-Moderating effect takes severity out of temp swings
What are 3 types of passive solar gain?
Direct gain space - you are occupying the space that’s being heated up
Indirect gain space - solar energy heating up a gap between window and concrete wall (Trombe wall), thermal mass has a good view of the sun
Sun space - also indirect, sun heats up one space, which is not conditioned, conditioned space is inboard of that
What is an evaporator loop?
Coolant that is evaporating or boiling is cold
Low pressure induces boiling
The side that is typ inside the house
What is a condenser loop?
Coolant that is condensing is warm (heat is produced when changing from gas to liquid)
High pressure induces condensation
The side that is typ outside the house
What is an economizer cycle / free cooling?
Cooling large buildings on cold nights with cool air using cold air outside the building (need to cool b/c heat generated inside the building offsets some of the heat losses from the envelope)
Can be air or water
What is a heat pump?
Reverse flow of coolant so cold side is outside and hot side is inside
can be geothermal
What is a grille?
air goes in
What is a register?
air goes out
What is a diffuser?
air is spread out
What is a heat exchanger?
allows heat from the exhaust air to be shared with the intake air, without coming into direct contact
What is a single zone HVAC?
use one outdoor condenser and one indoor head for a single area of the home
ideal for small homes
What is a Terminal Reheat (with VAV)?
If a room needs to be heated, a valve opens to allow heating water to flow through the reheat coil which reheats the air that passes through the coil. The controls that monitor air flow and heating coil are normally linked to the room’s thermostat.
advantages are lots of control & space and equipment efficiencies, disadvantages are wasted energy
What is a dual duct system?
not really used anymore, have one hot duct and one cold, mix together in a mixing box per room to achieve desired temp
What is a split system?
compressor and condenser are outside, evaporator is inside, mostly for residential, must keep evaporator within 100’ of eachother
What is a fan coil unit?
Fan in the space rather than remotely, generally minimal ductwork, but noisier, efficiency and maintenance, increase control, need less space (pipes rather than ducts), common for multifam
What is an evaporative condenser?
water sprayed over top of the condenser, helps cool it quicker aka more efficient
What are the issues with putting equipment on the roof?
Structural demands, noisier, ugly, inefficient because heat/cool loss as you run things across the roof
What is a minisplit unit?
Fan coil unit in each zone, and each can be either a condenser or evaporator when needed
What is a rooftop water to water system?
Chiller using water to cool the condenser (cooling tower) bring cool to building through chilled pipes
Can have the chiller be remote (up to ½ mi away) and feed multiple bldgs
Can have chiller in the basement and cooling tower on roof
Could be geothermal water to water - condenser heat goes through pipes in ground to cool/heat depending on season
What is a Rooftop Water to Air System?
Condenser side has water cooled by water tower, evaporator has fan blowing air over coils
What are the different materials of pipes?
Copper - more expensive, more friction
Plastic - less expensive, less friction (ABS, PE, PVC, PVDC - can be used with hot water)
rated by thickness (k thicker, l medium, m thinner)
DWV - used for drains and vents
What are the different types of valves?
Gate - used for maintenance, can open it completely or close it
Globe - used for faucets, repeated use
Check - used for backflow prevention, near where water enters the bldg
What is the equation for pressure? In the context of water in pipes.
Pressure (P, psi) = 0.433 (constant) x Height (h, ft)
What are the temperature requirements for hot water?
140 deg for kitchen and laundry
110 deg for shower
105 for handwashing
What are the different types of vents (plumbing)?
Traps require vents, some can share, some need their own
Soil stack - black water
Stack vent - vent above the soil stack, lavatory, etc
Waste stack - grey water
Vent stack - not directly above stack, off to the side
Describe a septic system.
Solids are anaerobic decomposed, liquids to a leach field
Different types of soil absorb at different rates. Need percolation (perc) test
What is an artesian well?
comes from an aquifer under positive pressure (earth on top of the water is so much that if you stick a pipe down into it, the water will come up)
What is a shallow well?
single straw down to water (up to 25’) sucks water from underground
What is a deep well?
deeper than 25’, uses deep well pump, sends some low pressure water down into the well, uses venturi effect to suck water up
What are 1, 2, 4 pipe systems?
1 pipe system - water is not as hot near end of loop, but has a control valve so you can turn on / off different zones in a basic not that effective way
2 pipe system - for each fan coil unit has a return
4 pipe system - each coil has a hot and cold and a separate supply and return
What is the Power equation?
W (power in watts) = I (current in amps) x V (voltage in volts, standard is 120V) x PF (power factor)
What is non metallic sheathed cable?
two or more insulated conductors in a plastic sleeve (residential), easy to work with, not protected well
What is flexible armored cable?
two or more insulated conductors in spiral wound steel tape
metal clad (MC) - has a separate ground wire
What is Delta vs. Wye connected power?
Delta - has a single voltage available (phase to phase) so only 208V or 480V, 3 hot wires connected in a triangle, does not include a neutral wire*
*you will not be able to run most equipment directly off this arrangement
Wye - has two voltages available (phase to phase and phase to neutral) so 120/208V or 277/480V, has a neutral wire, connected in a Y shape
What is a rectifier?
electrical device that converts alternating current (AC) which periodically reverses direction, to direct current (DC) which flows in only one direction
What is an inverter?
electrical device that converts direct current (DC) which flows in only one direction to alternating current (AC) which periodically reverses direction
What are disconnects / safety switches / switch gear?
first thing where power comes in bldg, a switch that can turn off other switches behind it, for emergency situations so you don’t have to touch high voltage high amp
leaves emergency power on
What is a GFI (ground fault interrupter outlet)?
receptacles that will interrupt circuits if they sense a 4 to 6 milliamp difference in current between the hot and neutral wires at the outlet
used wherever there will be water
What is a transformer?
step down public power to a voltage usable by buildings
watts stay constant, but volts and amps change
occasionally can be used to step power up
What are the pros and cons of an exterior transformer?
pro: no bldg space, no noise in bldg, low initial cost, easy maintenance & replacement, no interior heat generated, can use oil without having to fire rate
con: requires land & shade
What are the pros and cons of a below grade transformer?
common in urban settings
pro: useful when little land is available, o bldg space, no noise in bldg, low initial cost, easy maintenance & replacement, no interior heat generated, can use oil without having to fire rate
con: earthwork costs
What are the pros and cons of an interior transformer?
oil filled transformer must be located in a fire rated vault with the switchboard in an adjacent row
dry type transformers may be combined with switchboard in a main elec room or suubstation
con: requires proper ventilation for safety & heat loss, noise, heat generation
What is Ohm’s Law
current is directly proportional to voltage & indirectly proportional to resistance. if current increases, voltage increases
V = I x R, I = V / R, R = V / I
What is the electrical set up for a shed?
120V, single phase, 2 wire
What is the electrical set up for a single family residence?
120V/240V, single phase, 3-wire
The 240V for the high voltage equipment (AC system, electric range, electric dryer)
What is the electrical set up for a larger bldg?
120V/208V, 3 phase, 4 wire
3 phases - because voltage cycles to 0 twice per second (sine wave) and you want to ensure the 0s don’t line up because that wears down your motor, req more maintenance, and more power
What is the electrical set up for a really big building?
277V/480V, 3 phase, 4 wire
480V for motors, pumps, elevators, etc
What do decibels measure? What is the threshold of hearing and threshold of pain? If you double the distance how many decibels drop?
(dB)
unit of sound pressure / intensity
0 dB = threshold of hearing
130 dB = threshold of pain
every time you double a distance there is a 6db drop
What are A weighted decibels?
an expression of the relative loudness of sounds as perceived by the human ear
What are octave bands
groupings of decibels (dB) and frequency (HZ)
What is the speed of sound?
typically moves 1,128 feet per sec, about 1 ft per millisecond
What is (acoustic) transmission?
the propagation of a sound wave through an object or medium
What is (acoustic) reflection?
the bouncing back of the sound wave on striking a surface such as a wall, metal sheet, plywood, etc.
What is (acoustic) absorption?
the process by which a material, structure, or object takes in sound energy when sound waves are encountered
What is absorption coefficient?
represented by alpha symbol
0-1, 0 means all the sound energy is absorbed, 1 means none of the sound energy is absorbed
What is noise reduction coefficient (NRC)?
the avg of sound absorption at four frequency bands
0-1
higher means quieter, good is above .75
What is reverberation time? And what are some typ reverberation times per room type?
time it takes for the sound to drop by 60 dB
Decay takes longer in a larger room or less absorptive room
2 sec - concert hall (least amt of speech)
1.5 sec - opera house
1 sec - theater
.75 sec - classroom
.5 sec - small office
.25 sec - living room
What is transmission loss?
the accumulated decrease in intensity of a waveform energy as a wave propagates outwards from a source, higher means quieter
What are flanking paths?
“leaks” where sound can get in
ex:
through ducts
through ceiling into plenum
leaks between adjacent construction
transmission and impact loss thru partition
loss thru outlets and other openings
leaks at floor / wall intersection
impact sounds thru floor
What are strategies for sound reduction in wall construction?
massive - single layer gwb < multilayer GWB with staggered panel joints
airtight: ex. standard block wall < grout filled block wall
structurally discontinuous: ex. standard stud wall < staggered stud wall or double stud wall or resilient clip
What is Noise Criteria level (NC)? What is the range of quiet to loud?
relative loudness of “background” noise in a space, higher means more noise
Lower than NC 30 is quiet, louder than NC 55 is loud
What is STC (Sound Transmission Class)?
an integer rating of how well a building partition attenuates airborne sound, higher means quieter
50 STC req between multi fam
What is Impact Isolation Class (IIC)?
measures impact sound transmissions through floor assemblies
higher means quieter
req atleast 50 between multi fam,
fix with resilient mat in the floor detail
How can you reduce mechanical noise?
Overall - the more space you can allow to mech space the better
Buy quiet equipment
Have silencer inside duct
Increase duct length
Internally lined duct - but there are air quality concerns with this
Have slower duct velocities
Smooth duct transitions rather than abrupt
How do you space skylights?
1.5 x ceiling height = spacing O.C.
What is color rendering index (CRI)?
a quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with a natural or standard light source, 0 - 100 with 100 being perfect
For us to see a color there has to be that color in the source light
What is correlated color temperature?
color that the lamp appears (warmer - cooler)
higher temperature lights are cooler, lower temperature lights are warmer
What is an incandescent lamp? What are the pros and cons?
tungsten filament placed in a sealed bulb with inert gas
Pro: high color rendition index (CRI=100), inexpensive, compact, dimmable, warm light
Con: low efficiency (lot of watts going in and less lumens going out), short life, high heat
What is a fluorescent lamp? What are the pros and cons?
a mixture of inert gas and low pressure mercury vapor. Requires a ballast which produces noise. Class A lights are quietest, Class F are loudest
Pro: high efficiency, low cost, long life, variable colors, dimmable
Con: CRI of 65-85
What are the features of metal halide lamps? Pros & cons?
High color temp (cooler looking), CRI of 85
Long lamp life
Used in stadiums, warehouses, car washes, etc
What are the features of high pressure sodium lamps? Pros & cons?
CRI of 20
Often in street lighting
Long lamp life, very efficient
What are the features of high light emitting diodes? Pros & cons?
Pro - high CRI (85), produce minimal heat, low energy cost, long life span, very efficient
Con - have a hard time shedding heat, fade as they die
What are some strategies to utilize daylight in an office?
Occupancy sensor
Zoning of lights - lights closest to window on one sensor, mostly off, next row in 50% on, etc
Demand response - shed lighting laid during peak energy usage times
What is Lamp Lumen Depreciation (LLD)?
over time lamps produce less light, so you overlight at beginning, knowing that the lamps will degrade, number from 0-1, if you lose 10% of LLD you have an LLD of .9
What are footcandles?
the unit of illlumination, equal to the number of lumens falling on each SF of a surface
= lumens / area in sf
normal interior levels are 10-100
What are wet pipe sprinklers?
most common, the sprinkler piping is constantly filled with water. When the temperature at the ceiling gets hot enough the glass bulb or fusible link in a sprinkler will break. Since the system is already filled with water, water is free to flow out of that sprinkler head
What is a dry pipe sprinkler?
filled with pressurized air or nitrogen instead of water to prevent frozen and burst sprinkler pipes in areas with colder temperatures, best for unconditioned space in a cold climate
What is a pre-action sprinkler?
a dry sprinkler system, water is not contained in the pipes but is held back by a pre-action valve. A voice command will then say sprinkler are about to go off in 30 second, giving the opportunity to cancel the sprinklers
What is a deluge sprinkler?
for high hazard area, when triggered, all the sprinkler heads in a zone will spray
What is fire extinguisher type A?
water based, used for paper or wood
What is fire extinguisher type B?
foam based, used for chemical fires
What is a fire extinguisher type C?
foam based, used for electrical
What is a fire extinguisher type D?
foam based, used for combustible metals
What is a hydraulic elevator? Pros & cons?
powered by hydraulic jack, which are fluid-driven pistons that travel inside of a cylinder
pro: low initial cost, low maintenance cost
con: high energy demand, hydraulic fluid is an environmental hazard, slow, limited travel distance
What is a traction elevator? Pros & cons?
utilize steel ropes or belts on a pulley system
pro: more efficient, last longer, require less maintenance, faster, smoother ride, longer travel distance
con: high initial cost, medium maintenance cost
What is a geared elevator?
traction, max rise of 150’, 5-15 stops, 500 fpm
has more torque, so often used in freight elevators
What is a gearless elevator?
traction, max rise of 2000’, 15-60 stops, 2400 fpm
What is a machine roomless elevator? Pros & cons?
either traction or hydraulic
mac height 250’ max
500 fpm (traction), 150 fpm (hydraulic)
pro: requires less space, energy efficient, similar cost to general traction
con: difficult to implement, restricted by code, no destination dispatch system, not suitable for freight
What is the shaft requirement for hoistway?
required to have a vent that is 3.5% of hoistway or 3 sf, whichever is bigger
What are the capacities of an escalator?
Slope: 30-35
Speed: 100 to 125 fpm
Clearance: 7ft req.
Capacity: 1.25 people per tread
Max rise: 20-40 ft, 60ft if supported in the middle
How does pipe “schedule” naming work?
Pipe sizes are named by wall thickness, have same diameter (ex. Schedule 40 pipe has thinner walls than schedule 80)
What is a low slope roof? What are the possible issues?
less than 2” per foot or 17% (but above 1/4” per ft)
Relatively slow drainage, small errors resulting in ponding. Membranes must be flawlessly watertight. Water vapor from the building inside or wind from outside can cause blistering, flapping, displaced or cracked membranes
But can cover buildings of any horizontal scale, simpler geometry, can be planted & occupied
What is a steep roof? What are the possible issues?
greater than 2” per foot or 17%
Use gravity to shed water, overlap small units (shakes, shingles, thatching, etc). These smaller units can be easily repaired and replaced, and bend and flex with the roofs expansion and contraction.
However they are visible
What are 3 ways to slope the roof?
- slope the structure
- taper the structure
- tapering the insulation
What are topside roof vents?
Allows moisture vapor to escape from beneath the membrane but closes to prevent water or air from entering
What are 3 types of low slope roof membranes?
- bituminous (made from asphalt, overlapping layers)
- single-ply (rolled up plastic that we unroll)
- fluid applied (take a chemical sealant and mop or spray it on)
What is emissivity?
ability for the roof to shed heat, high emissivity roof means it can shed the heat quickly so its cooler
What is albedo?WHat % albedo do we want minimum?
solar reflectance, high albedo is light color & reflective (we want atleast 65% albedo)
What is the difference in strength b/w springwood & summer wood?
Summerwood - grows slower, more strength
Springwood - grows faster, less strength
What is the modulus of elasticity?
measure of overall strength / stiffness, higher number means stronger
What is plain sawn wood?
cheaper, more likely to warp, produces less waste
What is quarter sawn wood?
finer grain (better aesthetics), more dimensionally stable, more expensive
What is moisture content (MC)?
how much moisture is in the wood, the less moisture the greater structural quality
MC = ((Weight when wet - weight when dry)/Weight when dry) * 100
Ex. MC15 = 15% moisture, MC19 = 19% moisture, MC15 is stronger
What are 3 grades of wood?
Stud grades - for studs, including load bearing
#1 structural framing - for headers and long spans
Utility grade - for blocking, etc
What is glue laminated wood?
layers of dimensional lumber bonded together with durable, moisture-resistant structural adhesives so that all of the grain runs parallel to the longitudinal axis
What is cross-laminated timber?
several layers of kiln-dried lumber boards stacked in alternating directions, bonded with structural adhesives, and pressed to form a solid, straight, rectangular panel
Lightweight yet very strong, with superior acoustic, fire, seismic and thermal performance, CLT is also fast and easy to install, generating almost no waste onsite.
What is laminated strand lumber?
dried and graded wood veneers, strands or flakes that are layered upon one another and bonded together with a moisture-resistant adhesive into large blocks known as billets
(longer strands) not super strong, inexpensive
What is oriented strand lumber?
OSL is made from flaked wood strands that have a length-to-thickness ratio of approximately 75. The wood strands used in OSL are shorter than those in LSL. Unlike OSB, the strands in OSL are arranged parallel to the longitudinal axis of the member
What is parallel strand lumber?
Dried and graded wood strands are layered upon one another and bonded together with a moisture-resistant adhesive into large blocks known as billets
In the case of PSL, long strands (longer than those used in LSL) are laid lengthwise in parallel.
strong, heavy, relatively expensive
What are wood i-joists?
dimensional lumber with an OSL board in between, used in floors, roofs, etc
What is laminated veneer lumber?
an engineered wood product that uses multiple layers of thin wood assembled with adhesives
like plywood but thicker
What are wood plastic composites?
weather resistant, less likely to shrink and warp more flexible
How do you calculate board feet?
Board feet = (nominal width (in) x nominal ht (in) x length (ft)) / 12
What are the differences between nominal and actual dimensions?
1 - 5/4 = -1/4”
2 - 7 = -1/2”
8 - 12 = -3/4”
What is oriented strand board? What is it used for?
strongest & stiffest of nonveneered panels
most common in subfloors and exterior sheathing
What is fiberboard?
made from the smallest grain of wood (compared to OSB and particleboard)
best for interior uses
smoothest surface
What is sheathing rating # / # ?
roof spacing OC / floor spacing OC
ex. 32/16 means spacing of 32” OC for roof and 16” OC for floor
What are the plywood bond classifications?
Exterior - for exterior use
Exposure 1 - can handle some water, etc, but not meant to be exposed to weather long term (95% of plywood)
When do you have to treat wood?
-Wood joists are less than 18” above grade
-Wood beams or girders are less than 12” above grade
-Plates, sills, or sleepers are in direct contact with masonry or concrete which is in direct contact with the earth
-Wood framing members or sheathing are less than 8” from the soil
What woods are VERY decay resistant?
black locust, red mulberry, osage orange, pacific yew
What woods are SLIGHTLY decay resistant?
cypress, catalpa, cedar, chestnut, white oak, redwood, black walnut
What is balloon vs platform framing?
Balloon - requires fire stopping,
Platform - Newer and more common now, shorter lumber, less prone to fire spread, can frame wall horizontally
What are strategies for drainage @ the foundation?
dampproofing / waterproofing
Overhangs
Drip edges
Sloping ground away
Gravel fill
What is a rim board or band joist
Sits on top of the header or floor below or foundation
Seals the open ends o the joists
provides surface for attachment of exterior insulation, cladding, and finish elements
Transfers some of the loads to the floor below
After the attic, this is the most likely place for insulation gaps & air infiltration
What is an ice guard?
a mat under the shingles at the outermost edge of the roof to prevent ice or water from infiltrating the roof construction
What is the attic vent ratio?
IBC requires min vent area 1/150th of attic footprint or, if theres a vapor barrier, 1/300th
Which is stronger, cold rolled or hot rolled steel?
Cold rolled steel is stronger than mild steel
How does carbon content affect metal strength / brittleness?
the more a metal has, the stronger but more brittle
-cast iron is stronger than wrought iron b/c carbon content
depth to span ratio: beam
Beam depth is generally 1/20 the span, width is ⅓ the depth
depth to span ratio: girder
Girder depth is 1/15 the span, width is ⅓ the depth
depth to span ratio: open web
Open web is 1/20 the span
Roofs, lightly loaded floors, or closely spaced can be 1/24 the span
depth to span ratio: steel decking
Steel decking depth is 1/40 the span
depth to span ratio: triangular steel truss
Triangular steel truss depth is ¼ the span
depth to span ratio: rectangular steel truss
Rectangular truss depth is ⅛ the span
What is Type 1 cement?
normal
What is Type 1A cement?
Normal, air entrained. Tiny bubbles introduced to the concrete and those help with durability (freeze/thaw) and make the concrete more workable, Used for exposed concrete in cold climates
What is Type 2 cement?
moderate resistance to sulfates. for coming into contact with groundwater or below grade in sulfate heavy soil.
What is Type 2A cement?
moderate sulfate resistance, air entraining
What is Type 3 cement?
high early strength concrete. useful for precast concrete, concrete block manufacturing, tilt up concrete, and anywhere we would want to strip the formwork soon after pouring
What is Type 3A cement?
high early strength, air entraining
What is Type 4 cement?
low heat of hydration. for massive structures like dams where there is so much heat of hydration
What is Type 5 cement?
High resistance to sulfate attack
What is the aggregate sizing rule of thumb?
have the aggregate be less than ¾ the distance between rebar and less than ⅓ the depth of a slab
What is the rebar naming convention?
Rebar # refers to the 1/8ths of an inch in diameter
Ex. #8 rebar is 8/8” or 1” diameter
What are the rebar grades?
Grade 60 = 60k PSI, most common
Also comes in 40 & 75, use 75 for columns