Edmonds Roofing Contractor

Glossary

D

Deck or Decking

The structural “skin” of a roof over which roofing in felt paper or base sheet is applied. Most new homes have decking made of plywood. There are four main types of decking commonly used on residential roofing projects:

  • Plywood: Plywood is strong, durable, and light. It comes in many grades with ratings from A to D. Use only exterior grade plywood for decking. The thickness of plywood depends on the spacing of the rafters.
  • OSB: Oriented strand board (OSB) is cheaper than plywood, but not as strong as plywood, and does not hold nails as well as plywood. One side has a slip resistant coating and should be placed facing up.
  • Tongue and groove 2×6: If a roof will be seen from the inside (no ceiling installed), tongue and groove is used. It is a wood decking that provides great insulation with the use of rigid roof insulation in moderate climates. Also, the boards can be painted or stained on the inside to match the interior.
  • Skip/Split Sheathing: Skip sheathing is used alone or in combinations with solid sheathing for installation of shakes. Skip sheathing allows air circulations under the shakes by using 1×4 or 1×6 boards that are evenly spaced so that air can move under the shake roof.

Dormer

A framed small roof that projects through the sloping plane of a roof.

Double coverage

Application of asphalt roofing such that the lapped portion is at least two inches wider than the exposed portion, resulting in two layers of roofing material over the deck.

Downspout

A pipe for draining water from roof gutters.

Drip edge

A non-corrosive, non-staining material used along the gable, rakes or edges to allow water run-off to drip clear of underlying construction.

Dutch lap method

Application of giant individual shingles with the long dimension parallel to the eaves. Shingles are applied to overlap adjacent shingles in each course as well as the course below.