Leland:

When doing general contracting in the 70's and 80's we found that it was the
exception rather than the rule that additional layers of siding caused trapped
moisture deterioration in the original layer of siding. What was the rule was
that poor detailing at interfaces between details and elements allowed water to
enter between the layers and this caused damage. This goes back to an earlier
thread on E.I.F.S.  There are many great applications of the E.I.F.S. type of
sidings. That would indicate that the system itself is not bad it is just like
any other material, in the wrong environment and/or due to poor details, there
is the potential for problems. The real issue as I see it is that moisture
problems would be evident on the surface relatively early in the deterioration
cycle with most pre-20th century materials. These signs of problems would
provide the opportunity for a knowledgeable observant person to take action to
correct or reduce the cause of the problem. Many of the "modern" 20th century
cladding materials are more durable and less responsive to moisture conditions
and as a result mask problems until they are more of a structural nature. The
two areas that spell trouble to me are building with blown in or retrofitted
insulation and true masonry structures on a site with poor drainage.

Bryan

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Leland Torrence wrote:

> I too support John in his approach. Vinyl can be an important preservation
> step, particularly in "affordable" neighborhoods.  And if installed well,
> with sensitivity to the architectural elements and members doesn't even look
> that bad at a distance.  I have stripped back to clapboard many 1880's and
> 90's buildings covered with asbestos shingles, tar paper, roll roofing, wood
> shingles, vinyl and aluminum to name a few, but rarely seen major damage to
> the original siding as a result of the mummification.  I would venture to
> say that a layer of latex might be more dangerous than vinyl siding.  What
> say you Bryan - Moisture Meister?
> Best,
> Leland