Dimensional shingles have a shadow near the top of the expsosure to give
them added depth and definition.
Most dimensional shingles are metric in size as indicated above. The
values have been changed to inches for clarity. If they aren't metric, then their
measurements are like those of standard 3-tab strip shingles which is 36" by 12"
with a 5" exposure.
Most dimensional shingles are two pieces of material laminated together.
An example is shown above. Nailing on the nail line is a must because it is very important
that the nails penetrate both pieces of material. With most dimensional
shingles such as these, there is only about a 3/4" wide
strip where both materials are laminated together.