carpentry 1- foundation supports
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list the 5 categories of residential foundations.
- 1. full basement
- 2. crawl space
- 3. surface
- 4. slab on grade
- 5. grade beam
describe how a crawl space foundation differs from a full basement.
not usable as living area
what are the requirements for the floor of a heated crawl space?
must be covered with 50mm of concrete or alternate ground cover
is the space below a surface foundation slab usable for storage?
no the foundation rests directly on compacted soil
which type of foundation is usually used for an unheated detached garage?
slab on grade
a basement slab is an example of a slab on grade. true or false?
false a basement slab is below ground and and considered slab on ground.
describe a grade beam foundation.
structural concrete beams at or near finished grade, which is supported by concrete piles, piers, or pad footings that extend below the frost line and suitable for carrying wall loads
list 5 factors that should be considered in determining the depth of an excavation for a full residential basement.
- 1. depth of frost penetration
- 2. height of first floor above grade
- 3. size of basement windows
- 4. depth of footing / sewer lines
- 5. contour of the land
which kind of settlement must you attempt to prevent in order to avoid problems with door frame alignment (racking) or cracked walls?
unequal or differential settlement because different areas settle unequally it will cause a shift leading to problems
what must be done to fill an existing trench below a footing?
if the utility trench exists prior to placing the footings the easiest remedy is to fill the area under the footing with concrete. or reinforce with rebar creating a beam over the space
under what circumstances can footings be eliminated?
if the foundation is built directly on solid rock or if solid bearing qualities are excellent and has safe load bearing capacity.
which type of soil is recommended as a base for footings?
understurbed soil (organic material free), rock, or compacted granular fill
which section to of the building code deals with footings?
nbc section 9.15
what is the minimum width for the perimeter (strip) footing for a two-storey building?
350 mm= min 250 for 1 storey + 100 mm for each storey above
what is the min. size of pad footings supporting columns 3 meters on centre for a single storey building?
√0.4 =633 mm by 633 mm
how much wider must a strip footing be to support each storey of interior walls in masonry construction?
by 100mm for each storey
what is the max. vertical rise for step footings?
is there a max. horizontal length of step footing?
no only a minimum of 600mm
what is the min. depth below finished grade for a foundation in the province of alberta?
the frost level which is 1.2 m
if an excavation under footing is made too deep, what corrective measures must be taken?
by placing more concrete and increasing the depth of the footings or have an engineer approve compacted granular fill under the footings
what is the min. thickness for a footing?
what is the max. unreinforced footing width for a 200mm wide wall with a 150 mm thick footing?
the projection of unreinforced footings beyond the supported elements shall not be greater than the thickness of the footing. therefore, 150+200+150=500mm
what is a combined footing?
a continuous footing that also supports a number of columns
using standard rules of thumb for footings, what width and thickness of footing would be required for a 200 mm wide wall?
2 times as wide as the foundation wall thickness and as deep as the foundation walls thickness so 400 mm wide and 200 mm deep
what type of footing is used to support the columns in a residential building?
isolated or pad footing
which type of footing is used to support an interior bearing wall?
"T" or curb footing
which type of report is required by most lending institutions, prior to releasing funds for construction
real property report
which 2 methods are used to transfer building lines to the excavation bottom?
- 1. transit set ups and measurements
- 2. dry lines and plumb bobs
when checking footing layout for square, what should be done if the diagonal measurement differ by 22mm?
move the longest side in by half the difference (11mm) but no adjustment is necessary because it is less than 25 mm
describe how the inside forms for a strip footing are located.
by using a gauge block cut to width of the footing and thickness of inside luber. the gauge is held against the outside form and stakes to hold the inside forms.
describe how to locate pad or isolated footings in relation to the outside perimeter.
measure along outside forms and drive a nail at the right distance to the centerline of the pad then dry lines are stretched to locate the pad
what is the function of a template as it relates to anchors?
it is used to locate and hold anchors, bolts or studs at apredetermined location
if reinforcing bars are used to increase the footing width in which direction should the primary bars be placed?
across the width of the footing with 2 or 3 the length
describe 2 methods of attaching the foundation wall to the footing.
- 1.by embedding short lengths of rebar vertically into the footing approx. 16 o.c.
- 2. key way is formed into the top of the footing by suspending a bevelled strip of lumber held by spacers (dovetail)
the top surface of the footings must be level and finished to a smooth surface with steel trowel. true or false?
false it must be left slightly rough usually by using a wood or magnesium float
under what conditions can concrete for footings be placed on frozen ground?
briefly describe a pile.
a column or post used to support structures by transfering load to a suitable bearing surface below frost line
briefly describe a pier.
similar to a pile but usually above grade and rests on a footing or pile. the centre supporting members of a bridge are called piers
what are 2 general categories used to describe piles?
- 1. friction- hole in ground
- 2. bearing- hole to bedrock
friction piles that are driven into the soul are made up of what materials?
H or I shaped steel members, treated wood posts or precast concrete
briefly describe a grade beam foundation.
consists of a series of piles or pads that support a concrete beam or girder around the perimeter of the building
what is the max. depth of excavation for a straight cut without shoring in stable soil?
do unheated buildings or carports that are attached to a heated building have to have their footings below the frost line 1.2m?
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