OC – On center, the measurement between rafters or studs from the center of one to the center of the next

Open Ground – If found on three prong electrical outlets, it means that the outlet does not have a working ground wire (the round hole), or it has a bad connection or disconnected ground wire. Dangerous condition, needs repair.

Open Junction Box – Electrical junction box without a cover, all junction boxes must have a cover.

Open Valley – Method of valley construction in which shingles on both sides of the valley are trained along a chalk line snapped on each side of the valley. Shingles do not extend across the valley. Valley flashing is exposed.

OSB – Oriented Strand Board, a compressed wood fiberboard. Used for decking, sheathing, and sub flooring. Comes in 4?x 8? sheets. Does not warp like plywood.

Outrigger – The extension of a rafter passed the wall line, commonly a smaller size piece of wood nailed to the larger rafter to form a cornice or roof overhang.

Over Fused Circuit – A circuit for the fuse or breaker where the amperage is too high for the wiring. Dangerous!

Parapet Wall – A party or firewall extending above the roofline. Any wall around a balcony.

Parging – A coat of plaster or cement applied to masonry or concrete walls.

Partition Wall – Dividing wall that has no load bearing function. Could be removed without affecting the structural integrity of the building.

Performing Intended Function – It works!

Pier – A column used to support other structural members.

Pitch – The slope of the roof or the degree of roof inclined expressed as the ratio of the rise, in feet, to the span, in feet.

Pitched Roof – The roof that has one or more sloping surfaces.

Plumb – Perpendicular, been perfectly vertical.

Plywood – A wood made of three or more layers glued together to make one board.

PPM – Parts per million Primer – A basecoat or first coat of paint.

Putty – Typically refers to the glazing compound used on windows to hold the glass in the frame.