740 likes | 2k Views
Building Foundations. Foundation Walls. A base Monolithic construction Independent construction. Footings. Spread footings Undisturbed soil. Foundation-Wall Footings. Prevent settling or cracks Minimum of 12” below grade. Below frost line Thickness = thickness of foundation wall
E N D
Building Foundations Foundation Walls
A base Monolithic construction Independent construction Footings
Spread footings Undisturbed soil Foundation-Wall Footings
Prevent settling or cracks Minimum of 12” below grade. Below frost line Thickness = thickness of foundation wall Width = 2x thickness of foundation wall Footing Design
Rebar embedded 2 lengths of ½” diameter (#4) rebar Positioned minimum of 3” above bottom Footing Reinforcement
Form steel, lumber, or combination of lumber & plywood. Keyway Footing Forms
Pier and post Stepped Footings Other Types of Footings
4” diameter pipes at base of footing Carries water away from house. Sloped at least 1/8” per foot Landscaping Fabric Footing Drains
Durable & water resistant Most building sites Support any type of house 8 –10” thick Min. compressive strength 2500 psi Most 8’ high Poured-Concrete Foundation Walls
Formwork Reusable forms Wales Full Height Walls
Wood or metal Built on site Prefabricated forms Snap-ties 3 –7 days Standard Wall Forms
ICFs (Insulating Concrete Forms) Permanent Basic components planks, sheets, or hollow blocks Standard wall Grid wall Insulating Wall Forms
Poured continuously without interruption Cold joint Water content Remove Air pockets Concrete vibrator (stinger) Placement
Advantage – reduced cost Soil cover Ventilated Insulated Piers support Crawl-space Walls
Rebar centered in wall Lintel Reinforcing Concrete Walls
Anchor bolts Metal strap anchors Sill sealer Sill Plate Anchors
Special features: Brick-veneer siding Utility Sleeves Foundation Wall Details
Metal vents Rust-resistant steel frame windows Wood framing (pressure treated) Foundation Vents And Windows
Girder flush with top of sill plate Beam Pockets
Wood wedges (no metal pry bars) Stiff bristle (not wire) brush Form-release agent – Bio-slick Stripping and Maintaining Forms
Bituminous (tar) coating Top of footings to finished grade level Moisture Protection
Filling in excavation area Too soon, push in foundation walls First floor framing Temporary bracing Backfilling
Popular for foundation walls No formwork Blocks inexpensive Work stopped and started Concrete Block Walls
Concrete Masonry Unit (CMU) Head Joint Bed Joint Common bond Pilasters Protect from freezing & moisture Concrete Block Basics
Brick hammer and chisel Portable masonry saw Cutting Block
Mortar bond strength depends on: Type & quantity Workability, or plasticity Surface texture bedding areas Rate at which masonry units absorb moisture from mortar Water retention Skill of person laying block Mortar
Portland cement, hydrated lime, sand, & water. Prepackaged mortar mix Type N Type M Type S Type O Mortar Mixtures
Evaporation Hydration 2 ½ hour when air temp is 80ºF or higher 3 ½ hours when air temp is below 80ºF. Mixing and Placing Mortar
Skilled masons Corners built first Story pole (course pole) Laying Block Foundation Walls
Control joint Intersections
Weather tight joints & neat block walls “Thumbprint hard” Tooling compacts Head joints, then bed joints Tooling the Joints
Hollow block walls capped Strengthened with rebar Completing the Walls
Damp proofed or waterproofed Parging Moisture Protection
Colorless & odorless radioactive gas Extremely toxic Lung cancer Soluble in water 9X heavier than air Radon
Gas-permeable layer Soil-gas retarder Sealants Vent pipe Cap course Radon-Resistant Construction
Review • What is the minimum depth required for an exterior-wall footing? • Describe the type and position of reinforcement that is commonly added to strengthen a footing. • What is a keyway and how is it formed? • For nearly all poured-concrete foundation walls, formwork must be constructed for each wall face. What holds the formwork together? • What creates a cold joint? • Why are the joints in a concrete block wall tooled? • When using mortar, why is it helpful to know the differences between hydration and evaporation?