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 MIL-HDBK-1001/5A
Section 10: REROOFING
10.1
Introduction. Reroofing is necessary when it is no
longer economically viable to maintain the existing roof.
Reroofing options are recovering or replacement. However, the
recover option is usually not the best option. Before deciding
on either option, determine why the existing roof failed.
10.2
Reroofing. Reroofing of steep roofing usually requires
removal of old materials - either total or individual removal of
cupped, wrinkled, or other damaged units - in tile and slate
roofs. For these materials, reroofing is governed by the same
criteria as new construction.
For asphalt and wood shingles and shakes, however,
recover roofing is an option. Asphalt shingles can be applied
over old asphalt shingles or old wood shakes or shingles and,
conversely, wood shakes and shingles can be applied over old
asphalt shingles. Roll roofing can sometimes be safely recovered
with asphalt shingles, but it is generally prudent to remove old
roll roofing before asphalt shingle replacement. For guidelines
on repairs, substrate examination, and preparation required
before recovering old steep roofing, consult the NRCA Steep
Roofing Manual and the ARMA Residential Asphalt Roofing Manual.
10.3
Premature Failure Preliminary Investigation. Analyze
the roof with the following in mind:
a)
Structural conditions contributing to the roofing
problem;
b)
Interior space psychrometrics contributing to the
roofing problem;
c)
Topside deficiencies contributing to the roofing
problem.
10.3.1
Structural Influence. The existing roof deck,
supporting structure, and, in many cases, wall sections
projecting above the roof elevation have a direct bearing on the
longevity of the roofing composite. Structural influences to be
considered include the following:
a)
Type of roof deck material;
b)
Deterioration of roof deck and/or structure;
c)
Deflection of roof deck and/or structure;
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