DIY Glossary - J to L

Jamb

The vertical part of a doorframe. Also see Rails.

Jig Saw

Power tool used for making curved cuts in wooden board.

Joist

A wooden or metal beam used to support a structure such as a floor, ceiling or wall.

Junction Box

Housing for cable connections in wiring circuits.

Kerf

The correct name for the cut made by any saw.

Key

Simply scratching or roughening a surface to aid the adhesion of paint, plaster, etc.

Knot

A dark circle or oval in wood showing where a branch would have originally grown. Unless treated, these can leak resin or shrink and fall out.

Knotting

A solution that is painted onto the knots in wood to stop the resin seeping through the paint finish. Must be painted on to bare wood and allowed to dry thoroughly.

Lagging

Insulation placed around pipes to stop heat loss and to protect from freezing. Various types available.

Laminate

Can mean thin wood or wood-effect flooring and the outer surface of kitchen worktops.

Lath and Plaster

Rarely used nowadays, lath and plaster is method of constructing partition walls and ceilings. Thin strips of wood (laths) are nailed to the softwood frame and plaster is applied over the top.

Liming

A process used to lighten the colour of hardwood. Modern liming involves a specialist paste or emulsion rather than the traditional Lime.

Linoleum

Man made flooring material available in a huge variety of colours and finishes. Made from natural fibres, linseed oil and resins.

Lump Hammer

A large headed hammer used for driving chisels or demolishing brickwork.

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