Chapter 6: FOUNDATIONS
1. Introduction
HFHSL has used traditional foundations throughout most of its history. The foundation wall forms were set up and the concrete was poured by subcontractors. In the most recent builds, a new system has been used that is largely done by volunteers. The foundation walls are built of insulating concrete forms (ICF) called iForms that are stacked by volunteers prior to having the concrete poured in them. They have two foam skins that are connected by embedded plastic ties that give shape and strength. Examination of the outside of the iForm shows ridges that indicate the location of the embedded ties. Screws can be anchored into these ties to hang drywall on the inside and siding, if called for, on the outside. These walls are built on the concrete footings that were poured by volunteers prior to the day when the foundation walls are built, therefore at least two different days will be needed for this project.
HFHSL is also using a new system for the footings, upon which the foundation walls are placed. A product called form-a-drain that is made of PVC is used for the footing walls and will remain after the footings are poured. It performs the function of a foundation drainage system. This system eliminates the need to strip the forms and place drain tile.
2. Safety Issues
- Be aware of the risk of cuts from rebar and cutting tools
- Be aware of falls when working on walk boards or ladders
- Be aware of the risk of leg injury as volunteers will be walking on uneven surfaces
- Use safety glasses when using power tools
3. Prior tasks to have been completed before starting
- The site should be excavated and prepared for the footings and foundation
- Location of the foundation wall should be marked by HFHSL construction staff with stakes and string lines
4. Recommended Staff/Crew Assignments
- 5 – 6 to prepare forms for footings
- 10 – 12 people to install iForms
- 3 – 4 people to pour concrete
5. Order/Tasks to be completed
____1. Locate the inside and outside of the footings and mark with string lines
____2. Use form-a-drain pieces for the forms, ensuring that forms are level and straight.
____3. Pour concrete and level to the top of the forms.
____4. Allow concrete to cure for one day.
____5. Drill and insert vertical pieces of rebar in the center of the footings.
____6. Strike a chalk line on the the footings for the inside and outside of each wall.
____7. Place lightweight metal guides to hold the first course of iForms.
____8. Place first row of iForms, always starting at the corners and meeting at a convenient place in the span of the wall.
____9. Ensure that the first row is level and straight. Mistakes now are hard to fix later.
____10. Continue subsequent rows making sure that the iForms are placed so that each row is staggered from the proceeding.
____11. Ensure that horizontal rebar is placed in each row and that vertical rebar is inserted and secured every 3 feet.
____12. When the wall is five courses high, the bracing system should be attached every 5 - 6 feet and used to ensure the walls are straight and secure.
____13. Walk boards can be placed on the bracing system to allow for placement of higher iForms.
____14. Construct all door and window bucks making sure they are braced straight and plumb.
____15. Reinforce all intersections of the iForms that are not secure (typically one per wall).
____16. If the plan calls for a ledger board, insert the hardware at the appropriate location.
____17. Place concrete in multiple lifts of approximately 4 feet in height, tapping or vibrating the walls to ensure proper consolidation of concrete.
____18. Level concrete with the top of the forms and the window bucks.
____19. Place anchor bolts for the sill plates every 4 feet.
6. Tools/Equipment list
- Chalk-line
- 2 Levels (2' and 4', 7' if available)
- 1 Framing Square
- 100' Measuring Tape
- Rebar Bender/Cutter
- Foam Gun
- Cordless Screw Gun (Heavy-Duty, 18 Volt)
- Reciprocating Saw (Preferably Cordless 18 Volt)
- Circular Saw
- ICF Hot Knife
- Transit or String/Laser Level
- Anchor Tunnels w/Bolts
- 3 in. Wide Fiber Strapping Tape
- Anchor Bolts for Rim Joist (if applicable)
- (3) 25' Tape Measure
- Hand Saw
- (2) 100' Extension Cords
- (1) 6' and (1) 8' Ladder
- 8# Sledge Hammer
- 3 Claw Hammers
7. Material List
- Form-a-drain linear sections, couplings, corners, and drainage outlets
- Brick Ledge Material (if needed)
- Foam for Foam Gun (1 can per 1000 sq ft of wall)
- 5# 3-1/2'' Coarse Thread Deck Screws
- 5# 1-1/4'' Drywall Screws, Coarse Threads
- String (enough to go around building twice)
- Bracing and Scaffolding
- Stakes
- Rebar Wire or Plastic Ties
- Treated Lumber for Rough Openings
- iForm blocks, straight and 90 degree corners
- Light gauge metal guides
- 2 x 4’s for bracing
8. Quality Checkpoints
____1. Footings are level and straight.
____2. iForms are stacked level and straight.
____3. Rebar is placed and secured vertically and horizontally per specification.
____4. Window and door bucks are straight and plumb.
____5. Walls are plumb and properly braced.
____6. All common seams are adequately braced with OSB or plywood.
____7. All corners adequately braced with OSB or plywood.
____8. Concrete poured and leveled.
____9. Anchor bolts for sill plates inserted.
9. Construction Drawings and Text
NOTE: The purpose of the drawings and diagrams on the next few pages is for them to be used on the job site when a question arises as to methods and procedures associated with the task. The notes on the drawings have been geared toward use as a quick reference. If a more in-depth explanation is needed, please read the text description of Construction Details. Also consult your Habitat Site Supervisor and Construction Manager for advice as needed.
The location of the inside and outside of the footings should have been located and marked with string lines by HFHSL construction staff. The footings should be sized according to the plans. The forms are constructed out of form-a-drain linear sections and appropriate accessory pieces. To begin constructing the forms, a laser level or other leveling device is used to determine proper height at each corner. String lines are used between the corners as guides for the top of the forms. A 3 foot level is laid between the inside and outside forms at various locations to ensure that they are level. Rebar stakes are driven through vertical holes in couplings and corners to help keep the system aligned. Grade stakes hold the system at the proper elevation. If necessary, use a shovel to remove or add dirt for proper sizing of the footings.
The HFHSL construction staff will check to make sure that the forms are properly built and secured. Concrete is then poured. It is leveled using a 2 x 4. The concrete must then cure for at least one day.
Two chalk lines are snapped on each portion of the footings, one for the inside and one for the outside of the foundation walls. The wall layout should be roughly in the center of the footings, conform to the plans, and ensure that the corners are square. Drill and insert vertical rebar pieces.
Place lightweight metal guides on each chalk line to hold the first course of iForms. These are anchored to the footings using screws every 12 inches. Place first row of iForms, always starting at the corners and meeting at a convenient place in the span of the wall. The forms can be cut with a handsaw or reciprocating saw for proper sizing where they meet. The location of a door or window can be used to minimize the joints that will have to be secured later. The laser level and the use of string lines can be used to ensure that the entire first row is level. The forms are secured to the lightweight metal guides using screws. If necessary, forms can be shimmed up to the string lines. A level should also be used to ensure that the insides and the outsides of the forms are level.
Horizontal rebar is inserted into the plastic rebar guides in the iForms. Each iForm has several guides for rebar. Only one piece is needed on each course, and will be placed either toward the inside or the outside. It will be toward the opposite side on the next course and continue to be alternated with each row. Rebar will have to be bent to go into the corner iForms. Vertical rebar is inserted after several rows have been placed and should be placed in the center between the horizontal rebar pieces. It is secured with zip ties to the horizontal pieces.
The second row is again started in the corners with the corner pieces inverted from the previous row. This ensures proper staggering of the forms. Each subsequent course will be done in the same manner, continuing this staggering pattern.
When the wall is five courses high, the bracing system should be attached every 5 - 6 feet and used to ensure the walls are straight and secure. This is usually done on the inside of the foundation. Walk boards can be placed on the bracing to allow continuing stacking subsequent rows.
Construct all door and window bucks making sure they are braced straight and plumb. They are built from 2 x 4 lumber cut to the proper size of rough opening. Each corner should be braced with a diagonal to prevent the corner angle from changing. An opening will need to be cut in the iForms with the handsaw. The buck is inserted. 4 inch strips of ¾ inch plywood or comparable lumber are nailed onto the front and back to keep it in the forms. 2 x 4’s are attached and run to stakes in the ground.
Reinforce all intersections of the iForms that are not secure (typically one per wall). This should be done on the inside and outside of the wall. Use ¾ inch plywood strips or comparable lumbar secured with screws.
Foam can be used as needed to seal any small holes or cracks in the iForm wall.
Beam pockets should be created using 2 x 4’s. If any ledger boards are called for by the plans, install the hardware.
After final inspection by the HFHSL construction staff, concrete is poured into the wall. The person handling the boom from the concrete truck will typically work on the walk boards on the bracing. Place concrete in multiple lifts of approximately 4 feet in height. Another worker should be tapping or vibrating the walls to ensure proper consolidation of concrete. Level concrete with the top of the forms and the window bucks. Use a trough to smooth the concrete. Place anchor bolts for the sill plates every 4 feet.
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Page last updated Saturday, May 3, 2008 at 6:39:49 PM
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