[Greenbuilding] On Insulating Crawlspaces and Basements

[Thomas Lewis]

Hello All, 

I just purchased a home and am developing my project
list.   

I would like to pose my plan for insulating the
crawlspace and basement for your comment.

The crawlspace is ~180ft2 with a dry layed stone
foundation of unknown depth and ~2' thick.  It has
been worked on over the years.  The exterior is
pointed with a layer of stucco over that and two
sections have been replaced with 8" masonry block. 
One section is a corner and the other is a four foot
section with a vent.     
The crawlspace has ~6" - 36" clearance from grade to
floor joist, all above exterior grade.

The location is hudson valley ny, on top of a hill
with clay soil, NE exposure.  The soil in the
crawlspace appears to remain moist much of the time,
but has not been wet yet and there are no signs of
water damage on wood laying in there.  However, wood
that is partially embedded in the ground is moist but
with no signs of fungal or mold activity.

My idea is to spray foam with 1.75 lb tiger foam. (I
may just hire our local spray foam guys to do this,
being that they have air supply masks et al)  Clean up
all debris and remove a layer of soil, which is
pitched to the center of the room from all points.  I
will then dig a trench in the center, pour a small
footing for a center post, repost the center support,
then lay gravel in the trench and over cleaned floor,
then cover the floor with polyethylene with standard
lapping and sealing details.
Based on lack of evidence of water, other than ground
moisture, and the prospect of installing one into a
place that I can barely roll over in when laying
prone, I am opting to not put in a sump pump.

I will install a 6" round, the kind with a weighted
baffel, heated air supply to the space, with a return.
 The basement is loosely connected to the air supply
system, there is one 6" supply and one 8" return down
there.  If I return the crawlspace air to the
basement, will I pressurize the basement and
depressurize the living space?  Its an old loose
house, with many places where air moves between
floors.  (I imagine the stack effect is pretty
substatial here)


I am haveing a bit more trouble planning for the
basement insulation.  

Here I have 8' ceilings, the first four feet is stone,
then on top of that I have brick.  The stone is below
exterior grade and the brick generally starts 6" below
grade and goes to 3' above grade.  I was thinking of
repointing the interior where necessary, then spraying
2 lb. foam on the stone (~3") and a thin (3"?) layer
of 0.5 lb. on the brick.  
.5 lb on the brick because I am concerned with
reducing the brick's drying capability and with it
getting too cold during the winter.  My thought is
that if I insulate alot, it will be harder for the
brick to dry and the exterior will get colder during
winter and may damage the brick.


My apologies, this email seems to have gotten rather
long. Thanks for reading it and in advance for any
advice you may have.

Best, 
Tom Lewis


"Time makes more converts than reason."  Thomas Paine, Common Sense


       
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