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SUBJECT: ICF Query Response
DATE: 2/19/1999 10:08:00 AM


I have been doing some research on icfs for a house I
will be building later this year. From what I have read
I understand there are 3 types of forms available...
panel, plank, and block. Also, there are 3 concrete
shapes... flat, grid, and post and beam.

Question #1:
What manufacturers are there of a panel/post and beam
system in Canada or the US?

The only source we are aware of that provides info on
the type of systems made, by manufacturer, is a book
called "Insulating Concrete Forms for Residential
Design and Construction"(1997) by Pieter A. VanderWerf,
available from the Portland Cement Association
( Although it is a relatively
new book, some of this information is outdated since
some manufacturers are no longer in business and new
ones have started up. According to our records, Amhome
and ThermoFormed are the only panel-post and beam ICF
Amhome -- 800-393-3626,;
ThermoFormed -- 800-821-0855,

The PCA and Insulating Concrete Form Association might
have some additional info but of course they will only
have a list of members, not all manufacturers. They
are listed as contacts at the end of the ICF
technology write-up.

If specifically interested in post-n-beam systems,
there are also many block manufacturers:
American Conform --;
K-X Industries --;
K&B; Associates,Inc. -- 800-742-0862;
Ener-Grid --;
Energy Lock -- 801-288-1199;
Featherlite -- 561-575-1193;
PermaForm --;
Poly-form -- 800-537-3676;
Rastra -- 619-778-6593;
Reddi-Form --;
ThermoBlock -- 520-779-1683;
Insulform --206-242-9424.

Question #2:
The Codes section has a table of limitations for icfs
using the Prescriptive Method. What wall thickness is
this based on?

The 1999 SBC code has adopted ICF provisions based on
work the NAHB Research Center did calculating the
amount of reinforcement for basements and above-grade
walls using flat, waffle-grid, or screen-grid walls (a
screen-grid is basically a post-and-beam ICF but the
spacings of the vertical concrete columns must not
exceed 12 inches or 16 inches on center for horizontal
concrete columns). The wall thicknesses are all listed.
I'm not sure what code limitations you're reading --
I'd suggest purchasing the Prescriptive Method for
Insulating Concrete Forms in Residential Construction,
available through HUDUSER ( - can
download), PCA, or the NAHB Research

Question #3:
Is there any concern for backfill pressures when using
icfs below grade, particularly when using a panel/post
and beam system?

All systems must be designed, selected, and installed
properly in order to function properly. Manufacturers,
codes, and the Prescriptive Method should all provide
some guidance on this issue. Where unusual loads are
encountered for some reason, specific engineering may
be required.

The screen-grid (closely spaced post-and- beam) systems
are structurally capable of resisting backfill
pressures. There is some concern in certain areas of
the country that there is nothing but foam insulation
to prevent rodents from chewing through the wall.
However, Rastra, Ener-grid and K-X Industries
manufacture post-n-beam ICFs using a cement/wood chip
or cement/foam mixture that resists rodents from
entering. There have been no cases to our knowledge
where rodents have entered through the foam; however,
this is a concern with some code officials. On another
note, in order for ICFs to be used, the manufacturer
had to obtain a code evaluation report that says it's
"ok" within certain limitations. In order to get an
approval, some calculations have already been
performed. If not, many ICF manufacturers work closely
with an engineer familiar with the product. If you
decide to use a flat, waffle-grid, or screen-grid
(small post-n-beam) system, you can most likely bypass
the need for engineering costs by building to the
specifications of the Prescriptive Method mentioned



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