structures and components. footing is located at the base of the foundation wall ◦ it is always...
TRANSCRIPT
CHAPTER 6Structures and Components
Footing is located at the base of the foundation wall◦ It is always at the
bottom◦ It is stuffed into the
ground◦ The foundation is built
on top of the footing◦ Footing is supposed to
be 6 feet below frost line If it is less than 6 feet, you
will encounter problems
Footing
Foundation is the base upon which the structure is constructed◦ It holds weight of the
structure below frost line and prevents sinking
Foundations without sufficient sideway (lateral) support will deflect inwards
Foundation
A post (pillar) is a structural component that holds up the load of a beam down to the footings vertically.◦ Pillars are support columns, often located under
stairs and decks etc.
Columns/Posts
1. Moisture2. Out of Plumb
◦ Posts made out of plumb lose strength because they are incorrectly installed – they lean sideways and are not straight
3. Footing4. Rust
◦ Steel posts rust if the basement floods
5. Undersized◦ Post is not the right size and so it cannot support load
6. Fire◦ Fire damages steel posts faster than wood posts because
even though they don’t burn, they become weak
7. Secure to Beam◦ If post is not secured property to beam, structure will move
Possible Problems With Columns/Posts
Sills are pieces of wood that are between the foundation wall and brick wall◦ They have anchor bolts that keep them in place
Studs are built on top of sills◦ They make up the exterior walls
Problems with sills◦ Termites◦ Rot◦ Point loads
Sill crushes if there is too much pressure on 1 point◦ Anchoring
If sill not properly bolted to the foundation, it may shift resulting in the entire structure moving
◦ End bearing If joists are too short, the other sills may take additional load and
become damaged
Sill
Where is the anchor bolt used?◦ The anchor bolt is used to attach the sill to the
foundation walls
RECAP
Balloon framing is typically used in single-story bungalows
One stud (vertical wall framing) goes all the way from the foundation wall to the rooftop
The inside framing is built after the wall
Balloon Wall Framing
Platform framing is used in multi-story constructions (over 95%)
1 stud goes from foundation to 1st floor, and another from 2nd floor to roof
Walls built after inside framing
Platform Framing
Balloon = bungalow; platform = multi-story
Balloon = wall then joists; platform = joists then walls
Balloon v Platform Framing
Beams are long, structural components that carry the load of the wall and floor horizontally to the foundation
It is a horizontal frame in a house◦ Studs are vertical frames
Beams can be found either in the roof or basement
Beam
Joists are a type of horizontal wood members that support ceilings, roofs or floors◦ They are typically 2 inches thick
Joists are placed on edges and they get their strength primarily from their depth
In residential structures, you can choose between hardwood, carpet, laminate etc.◦ Under this material, you have the subfloor which carries
weight of moving objects such as people◦ Under subfloor, you have floor joists which are
horizontal pieces of wood to bridge and block joists from twisting
Joist
If joists are not bridged and blocked, they will move around freely◦ Both bridging and
blocking must be done together
Bridging and Blocking
Subfloors are used to carry live loads (people)
It is typically made from plywood and is located under the top layer/final floor
It is commonly known as pre-floor
Subfloor
Rafters are a kind of beam used to support the roof of a building
They carry the load of the roof to the outer brick walls
Rafters need support or they might break◦ This support is provided by collar ties & knee
walls◦ Collar ties carry load from one rafter to another◦ Knee walls support the bottom of the rafters and
are normally found in the attic
Rafters
Collar ties typically carry the load of one rafter to another rafter
Collar Tie
Roof trusses serve the same purpose as knee walls, collar ties and ceiling joists
They hold up roof shingles and sheathing and transfer the load of the roof to the outside walls
The bottom truss also performs function of supporting ceiling finish on which insulation sits
The main problem with trusses are the cut and truss uplifts
Trusses
A knee wall prevents the collar ties and rafters from falling apart by providing necessary support
Knee Wall
Where other than the attic can one find knee walls?◦ They are also commonly found in garages◦ But not all houses have a built-in garage◦ Attached garages are also common
RECAP
Roof sheathing is now done with wafer board panels, but till 1970s, wood planks and plywood were commonly used
Sheathing serves two important functions:1. Covering rafters2. Transmitting load of material (including
sheathing shingles, snow, ice and water)
Sheathing
Roofs protect houses from climatic conditions
A roof can be damaged by a number of factors including termites, condensation, and mainly abrasion caused by tree branches scraping roof shingles and Ice Damming (build-up)
Pitch is the angle (slope) of the roof
Roof
Flashings are used to join 2 dissimilar objects◦ They are used when there is a joint in materials or
when a material changes direction◦ Roof and chimney are joined together with flashings to
prevent leakage
They are made from galvanized steel
They are most likely to be found between 2 dissimilar objects/materials
They are least likely to be found between 2 shingles, since they are the same material
Flashings
The building code sets requirements for all kinds of construction, including basements◦ There needs to be sufficient structural integrity
and capacity
Basement leaks are typically intermittent, i.e. they occur after rainfall or melting of snow
Basement Leakage
1. Poor damp proofing around the house Allows water vapor to enter through concrete
2. Cracks in walls and windows3. Down spouts and eaves troughs are
damaged/cracked This prevents water from flowing away from the
basement, aided by an outside slope
4. The yard outside is sloped towards the walls of the basement
Causes of Basement Leaks
1. Fixing exterior slope away from the house2. Ensuring downspouts and eaves troughs
are installed properly and not broken 3. Window well covers4. Interior and exterior basement drainage
systems and sump pumps5. Improving surface drainage6. Damp-proofing exterior walls by covering
the footing joint or foundation7. Apply tar from grade level to footing to
increase protection against moisture
Solutions to Basement Leaks
1. Rust on posts, baseboard nails, furnace equipment or any other metallic objects either near or fixed into the walls
2. Mildew or mould3. Discoloration or stains on drywall, floor
panels or other interior finishes4. Moisture beneath the carpets or peeling floor
tiles
Real estate agents usually depend on both home inspections and property disclosure forms to determine the existence of water damage
Potential Signs of Leaks
If water leaks through cracks in the wall, it typically mixes with salt that is used for insulation purposes
The water eventually evaporates, leaving behind white salt crystals
Efflorescence
Drainage is a system of drains that are used to remove liquids◦ They may be natural or artificial ◦ It is typically a system of pipes, ditches, conduits
or other devices that allow water to run
External drainage◦ The Building Code identifies a number of granular
materials that must be used to drain water from below the foundation, and also where drainage disposal pipes must be situated
Drainage
Internal drainage◦ Includes footings placed below basement floor
level that lead to a waste sewage system or a sump pump
◦ Internal drainage is normally less desirable than external drainage because your main goal should be to prevent water from entering your property in the first place
◦ Internal drainage is a means of dealing with water once it has already entered the property
Drainage