Do it Yourself: [DIY] Re: Siding and Window Replacement

25 September 2015

[DIY] Re: Siding and Window Replacement

> nanmaas@sbcglobal.net wrote:

> My house was built in 1955 and had wood siding which was
> covered with aluminum siding maybe 30 years ago. I will be
> replacing a patio door and one window. All the rest have
> been replaced already. I want the siding to be replaced also.
> I would like to know what should be done first, siding or
> window. If possible I would like a smaller window. It is
> above a bathtub. And suggestions as to siding choices?
>> Our garage has vinyl which was installed about ten
> years ago when we had a new garage built. Both are
> white. Should the aluminum siding on the house be
> taken off before new is installed? Should the original
> wood siding be kept on?

> Nancy in Wisconsin

Hi Nancy;

Replacing siding and windows is an excellent opportunity
to bring your older house another significant step into the
current housing age. It can be expected that the house will,
at the least, get wrapped with an air barrier (such as Tyvek)
but replacing your siding is an excellent opportunity to also
improve the wall insulation values, and also reduce risks
from condensation, and mold/mildew/rot issues inside the
walls (and your living space). This is accomplished by
installing a layer of rigid foam insulation, under the new
siding. The recommended type is Extruded PolyStyrene
(XPS) which is usually blue or pink. PolyISOcyanurate
(ISO) can also be used, but while it has a higher rated
Rvalue, it loses much of its insulation value in colder
conditions, so it can not be expected to perform as
well as XPS in you climate.

While some people are installing 4" or more of this
foam, that much require extensive additional framing.
But, you can install up to 1-1/2" or even 2" using
fasteners that simply reach through the foam.
While standard literature for Hardie siding only
recommends about an inch of foam (it is heavy
siding) phone calls to their technicians have gotten
their word that 1-1/2" of foam is fines, too. Of
course, with special detailing, just about anything
can be done, but the objective is to optimize
between cost and performance effectiveness.
Lighter weight sidings, such as vinyl, should
be fine with 2" of foam.

House wrap can be used with the foam wrap,
but taping the foam seams (without house wrap)
is a good option, too. Since the foam covers
the whole wall, not just the cavities between the
framing, it is far more effective than its Rvalue
would first suggest. Most framing only provides
an Rvalue of around R5, so adding R5 foam to
that, cuts the heat loss/gain in half. This is a mild
level of "Deep Energy Retrofit" which prepares
a house for the next century, not only in lower
energy usage, but also as a more comfortable
and healthy place to live.

I am currently in the (gradual) process of
doing this to our home. We are upgrading the
insulation inside the walls and roofs, replacing/
/upgrading, or eliminating, windows, and also
wrapping house in a layer of foam (before
re-siding, as well as doing extensive mechanical
system upgrades, and a full interior remodeling.

Replace your windows at the time that
you install the new siding. and foam sheathing.

Use this opportunity to bring your house walls
into the 21st century, by installing a significant
layer of foam under your new siding. This is
the most cost-effective time to do it.

-Laren Corie-
Natural Solar Building Design and
Solar Heating/Natural Cooling/Energy
Efficiency Consultation Since 1975

Read my Solar house design articles in:
-Energy Self-Sufficiency Newsletter-
http://www.dongrays.com/essn/

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