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Dictionary of Roofing Terms

If you would like to add a term to the list please feel free to e-mail us by clicking on the link above and we will add it for you.

Jack: See Roof Jack.

Joint Tape: Tape used to seal joints between insulation boards.

Joist: Any of the parallel horizontal beams set from wall to wall to support the boards of a floor, ceiling or roof of a building.

Kelvin: Thermometer scale on which a unit of measurement equals the Celsius degree but with zero being equal to minus 273 degrees Celsius

Knee Cap: Sheet metal trim that fits over a panel rib after it has been cut and bent.

Kynar Coating: Architectural coating that is UV stable and suitable for exterior use on aluminium and other metal surfaces.

Laitance: An accumulation of fine, powdery aggregate particles on fresh cement caused by the upward movement of water; indicates that too much water was used in the mix resulting in poor surface adhesion for a waterproofing layer.

Lap: The part of the roofing material that overlaps a section of adjacent material.

Lap Seam: Where two materials that overlap are sealed together.

Lead: A malleable metal once extensively used for flashing.

Leader Head: A component used to direct water from a through-wall scupper to a downpipe.

Leader Pipe: A conduit for carrying water from a gutter, scupper, drop outlet or other drainage unit from roof to ground level. Also known as Downpipe or Downspout. (See Fig 1)

Lift: The rise in Sprayed Polyurethane Foam resulting from a pass.

Liquid Applied Membrane: Generally applied in one or more coats to provide a fully-adhered waterproof membrane which conforms to all contours.

Live Loads: Temporary items on a roof such as equipment, people, snow, etc. which the roof must be designed to support.

Loose-Laid Roof Membranes: Roofing material attached only at the perimeter and at penetrations and held in place by ballast, pavers, or other materials.

Although these pages are checked regularly and every care is taken with the information within. Delston can not accept any responsibility or liability for information or results displayed within due to third party interference.

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