Basement Flashcards
(21 cards)
What is the purpose of ‘Footings’?
To receive loads through posts or foundations walls to transmit them to the soil.
What is important to consider for footing sizing?
- A soil test must be done beforehand.
- Sizing is done by a structural engineer.
- Must be below the frostline.
A footing is made up of what material?
Poured concrete or wood.
Here are some things to consider for ‘Footings’
-Undisturbed soil, rock, compacted granular fill ( When soil is taken out, properties of soils are now different )
- Drainage
- Insulation
- Key or re-bar to resist lateral pressure, bonds footing to foundation wall
Define ICF
Insulated Concrete Formwork
True or False. Foundations supports building loads including snow and occupant loads.
True.
Name a few materials used for formwork.
- Steel
- Plywood
- Plastic sheets
What are anchor bolts used for?
To hold sill plates in place. ( 1/2” dia. max 8’ apart; embedded minimum 4” in concrete; bent to provide maximum bond )
What do we used to reinforce concrete foundations?
10mm bars @ 600mm made of steel, glass or plastic fibres.
What are some components of ICF?
- Replaces conventional systems
- Made of polystyrene
- Proprietary systems, plastic clips hold rebar in place
- Ultra efficient
- Expensive but payback period is short
- Must add a membrane on the exterior
Describe Basement Slabs.
- Generally 4” thick
- Sloped towards drain
- Reinforcing mesh
- Typically to prepare for the basement slab, 4” ( 100mm ) minimum of 3/4” ( 19mm ) crushed stone is compacted over the subsoil as a drainage layer to keep water away from the underside of the slab.
- Put coarse gravel and a polyethylene vapour diffusion retarder under a concrete slab to keep water vapour and water in the ground from getting into the slab from underneath.
- Pyrite
Describe ‘Foundation Wall Drainage’
- Foundation drainage normally consists of a drain tile installed around the perimeter of the basement and a wall drainage layer ( also known as a drainage mat )
- The perforated drain tile is usually 4” in diameter and is laid at the level of the bottom of the footing. The tile is wrapped with a geotextile fabric to keep out of the fine soil particles.
- The tile is then covered with min. 6” (150mm) clean gravel or crushed stone.
- This tile is then connected to basement sump pump.
Describe Radon and Soil Gases
- Radon is caused by the decomposition of soils that contain uranium
- Radon is radioactive, colourless and tasteless, and can cause lung cancer
- Keeping soil gas ( radon, water vapour, herbicides, termiticides, methane, etc. )
- Soil gas moves due to pressure differences
- Since we cannot eliminate the holes, the best thing we can do is control the pressure.
- The granular fill located below the concrete slab can be integrated into a sub-slab ventilation system to control soil gas migration by creating a zone of negative pressure under the slab.
- A vent pipe connects the gravel layer to the exterior through the roof.
Define WWF
Wielded Wired Mesh
Name the 4 sources of moisture.
- Rainwater draining from a roof
- Rainwater entering the ground
- Natural springs in the ground
- Ground water table
Describe what is ‘Water Vapour’
- Water vapour flows from warm to cold
- Water vapour dries through a process called evaporation
Definition: Particles of liquid moving from an area of higher concentration to one of lower concentration.
Describe basements, water managed foundations.
- Keep rainwater away from the foundation wall perimeter.
- Drain groundwater with sub-grade perimeter footing drains before it gets to the foundation wall.
What is Iron Ochre?
Iron ochre is a bacteria present in soils that are generally sandy and rich in oxygen. The bacterium appears as a slimy paste that clogs drains and prevents them from functioning properly. ( due to geotextile membrane )
Waterproofing vs Dampproofing
- Waterproofing relies on creating a watertight barrier without holes
- Waterproofing seeks to prevent the passage of water through the basement wall by the application of a waterproof membrane.
- Damproofing protects foundation materials from absorbing ground moisture by capillarity.
- Dampproofing is not intended to resist groundwater forces ( hydrostatic pressure )
- If water management is used, waterproofing is not necessary
- However, control of capillary water is still required ( dampproofing )
- Dampproofing is typically provided by coating the exterior of a concrete foundation wall with a bituminous paint or coating
- This coating is usually spray-applied or applied with a brush.
- A waterproof membrane could be applied to foundations in situations where drainage and dampproofing cannot provide sufficient protection such as in areas with high water tables.
- The most commonly used are liquid-applied membranes or peel-and-stick sheet membranes.
Describe a Drainage Mat.
A drainage mat is a manufactured product made of a loose mat of stiff, inert fibres, a plastic egg-crate structure or some other very open porous material. It is faced on the outside with a filter fabric that prevents fine soil particles from entering and clogging the drainage passages in the mat.
- Any subsoil water that approaches the wall falls through the porous material of the mat to the drain pipe at the footing.
Describe ‘Foundation Insulation’
- Minimum 600mm below grade, inside or outside
- Insulation on the outside reduces the temperature swing that the foundation wall experiences which often reduces thermal stresses and cracking that results.
