Structure Flashcards
1
Q
When inspecting under a house what safety precautions should you take for electricity
A
Touch of voltage tester to anything metal that could be energized by a ground fault and cut power especially if there is free standing water
2
Q
If there is a smell of gas in the crawlspace what do you do
A
Turn off the main valve and ventilate before entering
3
Q
Minimum crawlspace measurements
A
18 inches from the ground to bottom of floor joist
12 inches allowable to underside of a girder
Newer construction should be 16 x 24“
4
Q
Unstable Clay Hillside may need what for the foundation
A
Engineered foundation on piers extending down to bed rock
5
Q
Where the ground freezes where do foundation footings need to be
A
Below the frost line
6
Q
Why should footings be below the frost line
A
They aren’t susceptible to lifting and sinking forces of the freeze thaw action
7
Q
Why do most houses in cold climates have full basements
A
Because foundation footings need to be below frost line anyway
8
Q
Most common foundation type
A
The T or spread
9
Q
Describe slab on grade
A
A giant pad of reinforced concrete poured simultaneously with a slightly thicker perimeter footing that increases loadbearing
10
Q
This foundation type has a layer of crushed gravel beneath the slab covered by sheet of plastic
A
Slab on grade
11
Q
Why is slab on grade installed on flat lots where ground doesn’t freeze
A
Because being above frost line shallow slabs are vulnerable to Frost heaves
12
Q
Which foundation type is sometimes poured over perimeter T foundations and will show the joint along exterior ground level
A
Slab on grade
13
Q
Describe post tension slabs
A
Steel cables running through tubes inside concrete with nuts at cable ends that are tightened after concrete hardens
14
Q
These foundation types use less concrete and are the strongest
A
Post tension slabs
15
Q
Why do you never cut into a post tension slab without consulting an engineer
A
You might be cutting into the tension cables
16
Q
What are grade beams with concrete pier foundations used for and why
A
Steep slopes because they have the best lateral stability
17
Q
On grade beam foundations where are pier Holes usually drilled into
A
Strata (bedrock)
18
Q
Why are grade beam foundations less likely to migrate
A
Greater cross section than driven steel piers = greater friction against soil
19
Q
How do grade beam enhance foundations stability
A
Steel reinforced concrete grade beams placed slightly below grade connecting tops of piers
20
Q
What are driven steel pilings used for
A
Used to anchor foundations on steep or unstable soil’s
21
Q
What is a helical pier
A
Look like giant auger bits which are hollow and can be strengthened with bar and filled with epoxy or concrete
22
Q
Interior foundation elements include
A
Girders posts columns and pads
23
Q
Interior foundation elements are most often used in conjunction with what foundations
A
T
24
Q
What do girders do in interior foundation elements
A
Shorten distances Joists must span, support loadbearing walls and reduce some of the loading on foundations
25
What are common in areas with basements for supporting floors above
Adjustable floor jacks or nonadjustable Lally columns
26
What does structural settlement depend on
Type of soil, Lot slope, Amount of water, erosion in neighbouring lot, seismic activity, etc.
27
When do larger cracks happened in structural settlement
When settlement is uneven
28
Why do footings on sandy soil tend to settle evenly and quickly
Sand particles are large compared to the voids between them and water drains well and doesn’t absorb
29
How dramatically does clay soil absorb water
Up to 50% in wet seasons
30
What is clay soil also called what features does it have
Adobe soil has a distinct alligator pattern
31
Soil with organic matter will absorb moisture but if Sandy what will happen
Organic matter will decompose and the site will stabilize
32
What kind of lot types tend to Magnify problems of unstable certain types
Sloped lots
33
When has a home done most of its settling
After 30 or 40 years
34
Why does water vapour condense into a liquid
Cool air can’t hold as much water vapour as warm air, so when warm moist air comes in contact with cooler surfaces this happens
35
What time of year is condensation at its peak in a crawlspaces
Spring or summer when outside air temperature is warmest and crawl spaces are cool
36
When does the most condensation happen
The hotter the air the more moisture it can hold and the cooler the surface more condensation happens
37
How can a homeowner figure out if water is seeping through the walls
Duck tape aluminum foil to a concrete wall. If the front is dry and back is wet, water is sleeping through the wall
38
Where does moisture often migrate to and why
In the attic because warm moist air tends to rise
39
What happens with uninsulated or split ducts
They can dump moisture into the house
40
Exterior causes of dampness and seepage
Missing downspout, improper soil grade/walkway, clogged gutters, Blocked perimeter drain, cracked foundation, sprinklers leaking, undrained window well, downspouts too close to the house
41
How much seepage there is depends on
Hydrostatic pressure which is water pressure on walls
42
Signs of water leakage
Discoloured surfaces, rust stains, efflorescence, silt residue around base, deterioration of wood, for around column pads cracked, Rust in bottom Panel of water heater or furnace
43
How do you correct seepage
Fill holes with cement epoxy gel or polyurethane foam, seal entire floor, excavate soil and install waterproofing to walls, install perimeter drains, install swale drains, dig trench in basement and install proliferated drain to exterior or sump
44
If concrete is not vibrated to drive out air bubbles what happens
Finish surfaces will be more likely to crack and spall, steel bars will be more likely to corrode and water is more likely to seep
45
Short meandering cracks are usually caused by
Normal shrinkage
46
Surface cracks or welts which are slight ridges running horizontally with aggregate exposed at edges are what
Cold joints Caused by separate concrete pours which is weaker
47
Wide cracks in foundations less than 2 feet tall indicate what
Little to no steel reinforcement
48
Large vertical cracks usually mean
One end of foundation is sinking
49
Large vertical cracks that are wider at the bottom are caused by
Footings being too small
50
Horizontal cracks that leak after heavy rains with a driveway that slopes towards the house may have been caused by
Large trucks compacting soil
51
Horizontal cracks with the wall bowing in is most often caused by
Lateral pressure from water soaked soil. This is very serious as the foundation may be failing
52
In cold climates horizontal cracks and a crowning and cracking concrete floor can be caused by
Frost heaving when footings are not below frost line
53
Older concrete foundation that is rotating is caused by
Lacking reinforcing steel. The weight on the outside edge of foundation is causing it to lean
54
Substantial efflorescence indicates
Defective drainage
55
Older homes used what to reduce efflorescence temporarily
Parging which is plaster coating
56
Spalling or flaking surfaces on newer foundations indicate what
Failure to vibrate concrete or forms werent coated with a release agent
57
Rusty bars visible in concrete foundation indicates what
Concrete mix was too dry, mineral salt corroded rebar
58
Why does beach sand make for poor Quality concrete
Cement adheres better to sharp edges and beach sand is round
59
Concrete and brick foundations have decent loadbearing strength but little resistance to what
Lateral pressures
60
It is possible to improve lateral strength of concrete block by
Inserting rebar through block cores
61
What are installed on top of foundations to prevent moisture entry
Concrete caps
62
What do zigzag cracks in concrete foundations indicate
Too small or missing footings causing Foundation to settle unevenly
63
What kind of reinforcement does code require in concrete floors
Steel reinforcement (heavy wire mesh)
64
What can happen with unreinforced concrete floors
They can buckle upwards if water pressure is great
65
Concrete cracks with a vertical displacement indicate
Absence of steel reinforcing
66
Why do concrete floors crack and leak where they meet foundation walls
Because it is a cold joint (in between two pours)
67
Why is polyurethane caulking a good idea for cracked concrete floors
It can stop some water while allowing some expansion
68
Sump pits should be lined with
A permeable liner that allows water in and keeps soils out
69
What is a pedestal sump pump
Stands up straight, water cooled and has ball floats that turn pump on and off
70
What is a submersible pump
Sealed, oil cooled motors = quieter, more durable and expensive
71
Permanent sump pumps should have what for discharge
One and a half rigid PVC discharge pipe with a check valve at the bottom
72
Discharge of a sump pump should be how far away from house
20 feet
73
What is the possible reason for a floor drain emitting an odour of sewer gas
It may be connected to plumbing drains and the drain tap may have dried out
74
What will reduce evaporation in a drain trap
Pouring a small amount of mineral oil into it
75
How to check to see if floor drain is improperly connected to sewer system
Flush toilet
76
If inspecting a floor drain during dry season what do you look for, for signs of clogging
Water stains, residual silt, mold, or rotted wood
77
Where can drain clean out to be located
In a pit below the floor slab
78
A wet clean out pit could indicate
A high water table or cracked drain pipe
79
Causes of dampness in crawlspaces
Moisture from soil, poor ventilation, improper Surface drainage, split ducts, Warm moist air condensing On cool surfaces, vegetation close to house, leaky water supply pipes
80
In a crawlspace which way should the insulation batts foil or paper facing be faced
Towards living space
81
Problem with open/ventilated crawlspaces
Cold floors and heat loss in winter, warm moist air condensing on cooler surfaces in the summer which leads to mold and rot
82
How are Crawlspaces sealed
Plastic vapour barrier, polyester cord, reinforced sheeting, EPS foam panels over vent openings, mud sills are left exposed so they can be inspected periodically
83
What happens with decayed wood when it is probed
It doesn’t splinter, it crumbles
84
Floor joist spacing
16 inches on center, older houses can be 24
85
Notch limit in joists
1/6 of joist depth Max. No notches in middle third
86
Hole limits in joists
2 inches from edge max. Hole 1/3 joist depth Max
87
Notch limit in bearing studs
25% of stud width
88
Hole Limit in bearring studs
40% of stud width Max
89
Notch limit in studs that are non-bearing
40% of stud width Max
90
Hole Limit in studs that are nonbearing
60% of stud width Max
91
What keeps joists From twisting
Blocking or diagonal bracing
92
What must be installed between a joist flanges to prevent joists from buckling
Web stiffeners (plywood or OSB between flanges)
93
When a platform is framed with joists what must its rim Joists be
Engineered lumber as to not absorb too much moisture
94
Can you notch or cut into I joist flanges
No
95
All exposed I joist members in basements should be protected with
A fire rated surface
96
What sits on top of foundations
Mud sills
97
What should there be at the end of girders
Minimum of half inch clearance for circulation
98
What can rotted post bottoms cause
Floors to sag
99
What should pads be poured with
expansion joints around
100
When do Termites swarm
Spring or fall
101
How do you get rid of subterranean termites
Lowering soil levels. Fumigation does not work
102
What do carpenter ant nests look like
Like coarse sawdust. They do not eat wood for food
103
What do powder post beetles holes look like
Tiny BB gun holes. Borings look like coarse flower
104
Fungi can’t establish colonies on wood with a moisture content less than
28%. Go dormant at 20%.
105
Basement egress windows should be what measurements
20 inches wide and 24 Inches tall, Max sill height of 44 inches
106
Two forces that affect structural components
Compression and tension
107
Max joist deflection
Ceiling below= 1/360 (or 1/2”)
No ceiling below= 1/240
108
Where frost footings are required what is needed around the house perimeter for the footing and foundation system
A trench
109
Slab on grade monolithic slab description
Poured as one. Thicker around edges
110
Slab on grade supported slab description
Not poured together with foundation (basement slabs)
111
Slab on grade floating slab description
Independent of the foundation (common in garages)
112
Problems with slab on grade can go undetected for some time because
It is normally covered with sub flooring and finish flooring
113
 Strip footings (spread footings) Are run how
Continuously between foundation walls and around perimeter
114
Pad footings (spot footings) Support
Columns or piers
115
Pierre and grade beam are common with these soils
Expansive soils
116
Problems with footings
weak soils, absence of footings, underground streams, undersized footings, footing deterioration, wall failure, Lot slope, heaving, footings too shallow
117
What is the risk with adding a floor
Footings can sink
118
What needs to be done when a basement floor is lowered
Footings should be underpinned (lowered or enlarged) And a concrete curb (bench footing or Dutch wall) Around inside edge of footings
119
What do you risk when lowering basement floor
Increase risk of basement leakage
120
Damage to footings can be done by
Excavations (swimming pools)
121
What are ribbed foundations
Beams running in both directions under slab
122
What is the risk of adding an exterior basement stairwell
Grade level is lowered which lowers the level frost can penetrate increasing heaving on foundation risk
123
Added exterior stairwells should have
Deepened foundations or added insulation
124
Foundation Bowing is caused by
Lateral forces
125
Foundation deflection inward can be caused by
Backfilling, frost, walls too thin, two tall, inadequate reinforcement, inadequate house floor bracing systems
126
Foundation walls that move inward are repaired by
Tying them back with anchors and ties on the outside and buttresses (concrete block walls inside)
127
Conventional foundations can tolerate how much soil
3 to 7 1/2’
128
How can tree roots affect soil
They can dry out soil and some soil’s shrink considerably
129
Where groundwater is a problem what are used
Drainage tiles and or a sump pump
130
What problem could leaving houses unheated cause
Frost penetrating basement floors
131
What is adfreezing
Damp soil on outside of building freezes and frost heaving lifts top of wall
132
What are Pierre problems often the result of
Inadequate footings
133
Where are floor joists directly secured to
Sills which are anchor to foundations
134
What can sills be crushed by
Steel posts built into walls and joists being too short – only the end is sitting on the sill
135
Where are butt joints in wood beams
Within 6 inches of the quarter point the span
136
These give Lateral support for steel beams
Ribbons, rat tails or flanges
137
Lateral support for wood beams
Joist hangers, nailed to beams or running on top
138
What is a common problem with brick columns
Rising damp
139
If a column is out of plum by how much of its thickness then its integrity may be compromised
1/3
140
Doubling a joist increases its resistance to bends by
Eight times
141
When the room is occupied with people and furniture the centre of the floor can be how much lower than the edges
Half inch
142
Joist notches requirements
Maximum 1/3 of joist depth and not allowed in the middle of span
143
Where are joist notches allowed
Only at the top of the ends. Max Joist width in
144
Joist holes requirements
Maximum one quarter joist depth and 2 inches minimum from top and bottom
145
An offset as little as how much in bearing walls above and below can cause the joist to sag under the first floor wall above
12 inches
146
What may prevent joists from twisting
Cross bridging and solid blocking in a straight line
147
What are required at framed opening
Multiple joists and tracks
148
Where there is no ceiling how often should joists be braced
Every 12 feet
149
Steel framing should not be in contact with
Dissimilar metals or be embedded in concrete
150
Why must diagonal plank subflooring be supported at the wall
Because the ends of some planks may be several inches from a floor joist
151
What is a possibility with slab movement on slab on grade homes
Broken utility line
152
What can be used to join inner and outer wythes
Metal ties or especially sized bricks. In this case, they won’t have header courses
153
Why can outer brick wythes Bow outwards
If not properly tied to inner wythe
154
What helps prevents the spreading of roof rafters
When ceiling joists are attached to them
155
Brick corbelling (offsetting) Can only be how far beyond brick below
1 inch
156
What should bearing wood walls have at the top
A double top plate
157
What should be done under jack studs
Floor should be reinforced
158
What is a girt
Blocking between studs near midpoint
159
Stud notch and drilling requirements for bearing and nonbearing
Remaining portion must be 2/3 of stud depth- bearing
One and five eights - nonbearing
160
What is balloon framing
Well studs were continuous from foundation to roof line. Floor systems were hung from wall studs
161
What is the problem with balloon framing
Rigid structure but fire could move quickly
162
Do steel frame walls have the same insulating values of wood
No they have half
163
What are ICF walls
Insulated concrete foundations are interlocking blocks that are formwork for concrete and left in for insulation
164
What are some good points about ICF walls
They avoid thermal bridges and are airtight
165
What is chinking in the wall
Mortar used to fill air gaps between logs. (Redone every year)
166
Does wood expand and shrink more across the grain or with it
Across
167
What are points about panelized construction
Upgraded insulation treatment and less thermal bridging than in conventional construction
168
The arch in a brick wall supports a triangle section that is how much of the opening
Half the width
169
What is a jack arch
Flat top and bottom. Decorative but not functional
170
What is a keystone arch
Larger masonry units at the top/center
171
Why might a masonry wall be bulging near a window or door
arch may not have enough mass to resist the lateral thrust Of wall movement
172
Why should steel headers supporting brick veneer have no caulking between the steel in the brick above
Caulking the trap the water lead to rust
173
What is common with old gabled roofs if rafters are not adequately secured To walls at bottom edge
They spread apart. It can be seen at the eaves because soffits pull away as rafter spread
174
Attics in cold climates with good insulation but poor ventilation may be susceptible to
Condensation problems
175
What may be a problem around roof dormers
Concentrated loads
176
Top and bottom members of roof trusses are called
Cords. Interior is called Web. Fastened together with gusset plates
177
If the span of a cord is more than 10 feet or 12 feet between supports what should the bottoms be
10 feet = 2×5 and 12 feet = 2×6
178
When should trusses with Web members have braces in the midway point
When were the members are longer than 6 feet
179
What are collar ties
1×4 installed horizontally to prevent rafter movement
180
What are purlins
Rafter supports nailed on underside of an extend down on angles
181
What are knee walls
Small walls that run from attic floor to underside of rafters Midway
182
If a collar tie is more than 8 feet long what does it require
Lateral support
183
How should plywood sheathing be laid
With surface grain perpendicular to joists and rafters
184
What is the problem with the fire retardant treated plywood
It can lose roof shingles and collapse due to de lamination and weakening
185
What happens if a foundation is not large enough to carry the weight of a Masonary chimney
Localized settling
186
Why are three sided chimneys unsafe
The wall of the house is combustible
187
Where chimneys are framed in, what should be in between wood and flue
12 inches of masonry
188
What prevents fire from moving through the space between chimneys and wood framing
Fire blocking
189
What temperatures does fungus need to live
Between 40 and 115°F
190
Roof truss assemblies
Top and bottom Chords
King post in the middle
Truss web
Metal gusset plates (bearing points on bottom corners)
191
Difference between Fink truss Howe truss
Fink= no king post
How truss= straight and diagonal web members
192
Describe hammer beam roof trusses
Hammer beams are horizontal side beams on each end, hammer post above holding it in place. Rib over top. Brace underneath transmits load to corbel. Principal rafter inside, common rafter outside
193
What is a key way on foundations
Line across to lock second layer of concrete foundation
194
How wide should a bench wall be
As wide as it is deep
195
Difference between strip footing and pad footing
Strip= long and supports walls
Pad= square and supports columns
196
Is frost heaving only vertical
No
197
Is probing required by standards
Yes
198
What is honeycombing
Separation of aggregate and cement over vibration
199
Is the top of a beam in compression or tension
The top is in compression. Bottom is in tension
200
A beam is more likely to fail if notched at top or bottom
Bottom
201
Why shouldn’t a joist resting on a beam overhang too much
It can act as a lever and raise the floor
202
Plywood should be installed which way compared to joists
Long dimension should be at right angle to joist
203
2ways solid masonry wall wythes are held together
Brick ties
Header bricks
204
2 ways to prevent racking
Wood sheathing
Diagonal wood bracing
205
What do collar ties do
Prevent rafters from spreading
206
If a probe goes in more than how much, is it a problem
1 inch
207
Bearing strength of soils in order
1. Bedrock
2. Gravel
3. Coarse sand
4. Fine sand
5. Clay
6. Silt
7. Organic material
208
What is a caisson
A pile with a bell end
209
When should a dialectic union be used
When joining galvanized steel to copper
210
In a house with wood siding, does a central beam hold more or less weight than outside walls
More
211
Moisture content in wood is proportional to
Relative humidity of surrounding air
212
What is required between oil tanks and water heaters
10feet of clearance and concrete block walls
213
In ravine lots, what can indicate soil slippage
Bent tree trunks
214
For every one degree we cool the air in our house, the RELATIVE humidity goes UP
2.2%
215
Why can’t we have over 100% humidity
At 100% the air cannot hold any more water and must give up its moisture (condensation)
216
If a wall is leaning how much, is it unstable
Past it’s middle 1/3 point
217
What does a pillaster do
Strengthens foundation wall
218
How much of the air you breathe came from the crawl space
1/3 to 1/2
219
What is stack effect
The movement of air in and out of buildings. air bouyancy results from the difference in indoor and outdoor density
220
Relative humidity goes up or down with heating/cooling
Down 2.2% for every degree we heat
Up 2.2% for every degree we cool
221
For every 4% change in moisture content, how much does wood expand or shrink
1%
222
Mold needs how much relative humidity
70%
223
Can rigid insulation be touching the floor in a crawl space
No. Needs a gap
224
What is honeycombing likely caused by
Over vibration (shaking aggregate out of concrete)
225
What are flanges in regards to joists
I- joists are comprised of top and bottom flanges, which resist bending, united with webs, which provide outstanding shear resistance. The flange material is typically laminated veneer lumber (LVL) or solid sawn lumber, and the web is made with plywood or OSB.
