Slab Foundation
Foundation built without a basement or crawl space. 

Slab Jacking 
Raising the height of a concrete slab by forcing cement grout underneath. 

Slack 
1. Loose, relaxed, not taut or firm. 
2. Free time in a schedule. Not busy. 
3. Lack of tension in a rope or cable. 
4. Free play in a mechanism. 

Slag 
The fused refuse separated from smelted metal or processed ore, which is used in concrete as an aggregate. 

Slag Concrete 
Lightweight concrete which uses, as an aggregate, furnace slag. 

Slag Inclusion 
Defect caused when a nonmetallic substance is caught in a weld. 

Slake or Slaking 
Adding water to hydrate a material, such as lime, to crumble it to use in mixtures. 

Slander 
Oral defamation of the reputation or character of a person, which could be the basis for a lawsuit. 

Slat Fence 
Fence, usually in an alternating pattern called lath and slat, which is made from 1 x 2 or 1 x 1 wood that is attached vertically to fence rails. 

Slate 
Hard, fine grain stone that splits into thin sheets which can be used as flooring, roofing or exterior facades. 

Sledgehammer
Long handled, heavy, two faced hammer which is used to drive stakes into the ground or to break rock or any other heavy pounding. 

Sleeper 
1. Treated wood timbers, installed on concrete to support flooring.
2. Treated wood timbers, used as a nailing surface for wood framing, which are embedded in poured concrete.
3. Wood braces that are used to support the bottom of a wall form. 

Sleeve
1. Tubing that slips over another. 
2. Hollow cylinder which allows another commodity to pass through. 

Sleeve Anchor
Interior threaded sleeve that is inserted into a drilled hole in a surface. When the screw is threaded into the sleeve, the tightening of the screw forces the sleeve against the inside of the hole which anchors it to the surface, floor or wall holding the shelf, cabinet, etc. firmly to that surface. 

Slenderness Ratio
The comparison of the length to the thickness of a structural piece so that the stiffness of that piece may be determined, since stiffness is relative to length and thickness. 

Slick 
Wood chisel that uses its two-inch wide blade to make wide even cuts or to smooth a wood surface. 

Slicker 
1. Plaster smoothing flat wood tool. 
2. Metal smoothing tool for mortar joints.

Slider Window 
Window composed of two windows or sashes and glides open and closed on a metal track. 

Sliding Door 
Door with sections that slide back and forth mounted on or suspended from a track. 

Sliding Gate 
Gate which slides horizontally, to open and close, on rollers on a rail, which may be manual, mechanical or electric. 

Sliding Glass Door
Door with two or more glass panels in a wood or metal frame. One frame is often stationery with the other allowed to slide back and forth on a track to open and close. Commonly used for patio doors, they provide light as well as access. 

Sliding Window 
Window where one or more panes slide open and closed. 

Sling 
Hoisting support, which fastens to both the hoist hook used to lift and the object to be lifted. 

Slip Form 
Concrete form that is raised slowly as vertical pours are made on a high structure. A jacking mechanism is used to raise the form and to place it into position for the next pour to be made, which will further extend the portion of the wall that has already set. 

Slip Form Concrete Machine 
Machine that is capable of traveling and forming and pouring a shape simultaneously. Continuous pours, such as concrete traffic barriers, utilize such a machine.

Slip Form Paver
Machine that is capable of traveling while forming and pouring a concrete roadway. 

Slip Gasket 
Elastomer gasket, usable with a bell and spigot pipe, because it has a tapered cross section. 

Slip Joint 
Joint that allows axial differential movement between the two connected objects.

Slip Ring
Electrically conductive ring, which is used around a shaft to conduct current from a rotating part to a non-rotating part as with generators or electric motors. 

Slip Sill 
Sloping sill that deflects water away from the face of a building. 

Slip Stone
Stone used to sharpen a concave cutting surface, such as a concave wood lathe. 

Slippage
Lateral movement, out of position, on a built-up roof. 

Slobber Bits
Steel guides, which are used to confine material to the front of a scraper bowl cutting edge, when attached to each side of the bowl of a road scraper blade.

Slope 
The amount of deviation from level as expressed in degrees of an angle, as a ratio of vertical rise to horizontal run, as a decimal, etc.

Slope Bar 
Attachment for a bulldozer that is used to cut slopes in rocky soil. 

Sloping 
Widening, across the top of a trench so that the sloping sides will minimize the possibility of a cave in. 

Slot 
An elongated hole. 

Slot Dozing
Moving material in an area that is only as wide as the dozer blade to limit the amount of load that is lost. 

Slow Blow Fuse 
Electrical fuse that has two element that can withstand moderate overcurrents but cannot sustain large overcurrents and will blow. 

Slow-burning Construction
Building a structure with fire-resistant material so that destruction would be reduced in the event of a fire. 

Slow Curing Cutback 
Diesel fuel thinned asphalt. The diesel fuel evaporates over a slow period, which slows the curing time. 

Slum Area 
Depressed and poorly kept locality, with vacant building, which may also be a high crime area. Poor and homeless often live in slum areas. 

Slump 
1. The stiffness of the consistency of a concrete mix. 
2. Test used to measure the consistency of concrete by determining how much a specified shape or size of a quantity of concrete will slump due to gravity when the sides are unsupported. 

Slump Block 
Concrete block that is manufactured to sag or slump prior to hardening. 

Slurry 
Liquid and solid mixture, such as concrete, in which the solid particles are suspended in the liquid. 

Slushed Joints
Head joints that are filled in with mortar after the unit is laid by throwing mortar in with the edge of a trowel.