formwork

Erecting Batter Boards

establish exact location and outside dimensions of the building

Squaring Corners

Pythagorean Theorem, 3:4:5 method, Diagonal Method

batter boards/ ledger boards

preserve the corner locations and provide a reference for prescribed elevation

Erection procedures

drive 2x4 stakes, 3' to 4' outside each four corners

Excavation

begins after boundaries have been determined

Purpose: removal of required amount of earth to prepare site for footing

Shoring

excavations over 4' deep

Purpose: restricts lateral movements and prevents cave-ins

Formwork

holds concrete until concrete sets; desired shape

Purpose: mold and retains the concrete into a shape outlined by the addition of a form

Formwork Materials

Earth: soil is stable

Wood: widely used

Metal: added strength is needed or construction duplicated

Types of Formwork

Footing, Ramp, Step, Column, Overhead

Footing Formwork

foundation that rests on the earth, prevents the structure from settling into the earth

"L" shaped: against another building or close to property line

Inverted "T": most common; placed all at once or separately using keyway

Slab Formwork

constructed with "2 by" set on the edge and braced by stakes driven firmly into the ground behind them

form boards are nailed to the stakes at desired elevation

Intermediate screeds used when placing large slabs

Intermediate screeds normally set 12' to 16' apart

Ramp Formwork

move heavy objects up an incline

Rule of thumb: every 12'' of rise have 6' run

consult Americans with Disabilities Act

ensure concrete is 2" thick for light traffic 4" thick for heavy

Step Forms

designed to transfer from one elevation to another

Column Formwork

subject to great pressure near the bottom

yokes placed closer together near bottom

Overhead Formwork

mold for concrete being placed in beams, girders and floor slabs above the 1st floor

Sleeper

plate resting on the slab

Mudsill

plate resting on the ground

"T" shore

Stringers: horizontal supports for joints

Posts: vertical members support stringers

Bracing: used to keep posts and stringers at 90 degrees

Scab: interlock the post to stringer

Wedge: tapered piece of wood that secures post to sleeper and provides tension

Joist: horizontal timber forming support for soffit, decking

Soffit: underside of flat surface of beam

Haunch boards (sheathing): side boards of beam

Knee brace (kicker) bracing for safety rail

Stud/Cleat: connects formwork together

Top/Bottom plates: horizontal cap the top and bottom of studs

Diagonal bracing: 1" x 6" material bracing transversely and longitudinally

Decking: 3/4" plywood sheathing concrete is poured to form the floor or ceiling

Canopy (cat walk): access walkway

Slab stop: marks the outer edge of slab

Drip cap: molding that allows water to run off

Chamfer strips: short strips of wood with beveled edges installed at top of joints

Wall Forms

Sheathing: forms water tight, smooth enclosure to shape and retain concrete till sets

Stud: vertical member that supports and adds rigidity to sheathing

Waler: horizontal member to align and brace concrete wall

Knee brace: angular member stiffens and strengthens formwork

Kicker: placed at the bottom to prevent the formwork from moving

Stake: gives nailing support for braces

Deadman: may be utilized instead of stakes

Snap ties: holds forms at the proper distance apart, prevents from spreading under pressure

Wedges: steel blocks placed over the end of snap ties for tightening

Rebar Support

High chair: supports top bars in slabs, joists and beams

Slab bolster: supports bottom slab bars

Beam bolster: supports bottom beam bars

RST

Reinforcing Steel

Plain Bars

not considered reinforcing bars

used for dowels at expansion joints

Deformed Bars

Standard reinforcing bar in US

Bar sizes

Eleven standard sizes

\#3 - \#11, \#14 and \#18

eights of an inch

Cutting Reinforcing bars

Bolt cutters: \#4 rebar or smaller

Oxy/Gas cutting torch

Iron master: Hydraulic sheers

Bending Reinforcing Bars

Bending table

Bending tool

Iron master hydraulic bender/sheer

Bending techniques

smooth, sharp bends: slip a cheater pipe over rod

heating

Placing Rebar

Splices: lap at least 30 times the bar diameter but not less than 12"

Thickness of concrete covering rebar

1. Footing: 3" of coverage on all sides

2. Exterior walls: 2" coverage for bars larger \#5 and 1 1/2" for \#5 bars smaller

3. Columns, beams, girders: 1 1/2" coverage

4. Walls, joists, slabs not exposed: 3/4" for \#11 or smaller

Importance of Proper Placement

strength of concrete member can be affected by improper positioning

damage to property, loss of life, costing money and time

WWF

Welded Wire Fabric

sheathing

form a water tight, smooth enclosure to shape and retain the concrete until it sets

stud

vertical member that supports and adds rigidity to the sheathing

waler

horizontal member used to aligns and braces concrete wall forms

knee brace

angular member that stiffens and strengthens the formwork

kicker

brace placed at the bottom to prevent the formwork from moving

stake

gives nailing support for the braces; the point of the stake should always be driven away from the form

deadman

maybe utilized instead of stakes

snap ties

holds the forms at the proper distance apart and prevents them from spreading under pressure

wedges

steel blocks placed over the end of the snap ties for tightening.

Sleeper

Plate Resting on the slab

Mudsill

Plate resting on the ground

Stringers

horizontal supports for the joists, usuall 4"x4"

Posts

vertical members that support the stringers

Bracing

used to keep the posts and stringers at 90 degrees to each other.

scab

interlock the post to the stringer.

wedge

piece of nmetal that helps keep snap ties tight