The advice in "Underpinning a Foundation"
(1/07) is basically sound, except for the wall forming, as
noted by the author.
For a hand-dug footing like that, I might have used a simple
trench footing. You can form the wall later or suspend the
forms and do it at the same time.
The type of form pictured is only practical for 16- to 24-inch
walls; more than that and the force of the concrete is too
great. If you're forming a taller wall, there are a few things
to keep in mind. The 2x4 braces with one end in the ground are
holding all the concrete. That means you may have 5.25 square
inches of bearing resisting more than 1,000 pounds of lateral
force (depending on the spacing). We always drive 2x4 stakes 16
inches deep behind this type of brace to increase the strength.
The braces should be no farther apart than 2 feet. The ties at
the top of the form should also be 2 feet on-center, and
fastened with lag screws (no drywall screws here).
Even better is to split the outward force in half by using
through-ties. For a wall 3 to 4 feet tall, you can add two rows
of horizontal 2x4 whalers and bolt through the wall with
threaded rod and 3-inch washers, using wood spreaders to keep
the forms apart until the pour.
Another old-school solution is to use loops of #9 steel wire
16 inches on-center: Wrap the wire around the whalers on both
sides and use a piece of rebar to twist it tight.
The single-sided pour under an existing footing is also
tricky. I've done this using a piece of corrugated steel siding
on the inside, supported against 5/8-inch rebar stakes driven
into the ground every 8 to 12 inches. I loop the #9 wire around
the rebar, pass it through the steel, and tie it off on the
outside forms as I put them in place. This counters most of the
outward force from the wet concrete. After the concrete sets, I
strip my wood forms on the outside, and the corrugated steel on
the inside is left in place.
The item "Higher Calling" (Toolbox, 12/06) states that the
500-pound-capacity aluminum pump jacks in Werner's new line are
compatible with Alum-A-Pole scaffolding. This reference is
extremely misleading. Alum-A-Pole's lifetime warranty
specifically states it is void if any other manufacturer's
products are used with Alum-A-Pole products.
Carl E. Anderson
Donna E. Anderson
Longevity of Tankless Water
I found your story on tankless water heaters very interesting
("Heating a Home With a Tankless Water Heater," 2/07). One
thing you didn't address is the life span of the heater. I was
planning an installation — for domestic hot water only
— but three plumbing contractors in my area (upstate
New York) said they refused to install these units because they
last only a few years compared with the standard tank type,
which can last 20 years or longer.
Your readers need to know what the experts have to say about
this, because if true, it's more cost-effective to install a
conventional water heater.
East Chatham, N.Y.
Author Bob Gleason responds: I have no personal experience
with the effective life of a tankless water heater —
my unit has only been in use for three years. (However, I did
once have to replace a conventional tank-type water heater
after only three years of use.) The following information may
be of some help.
Rinnai's Web site states that its compact wall-mounted units
have "a life expectancy of 25 years" and its residential units
have "a 10-year warranty on the heat exchanger and 10-year
warranty on parts." Also, in his article "Installing On-Demand
Water Heaters" (2/06), David Grubb mentions "the security of
knowing the equipment will last 20-plus years — much
longer than conventional models." Mr. Grubb has been installing
these units for several years.
Checking other tankless manufacturers' Web sites, I found
warranties ranging from five to 12 years for domestic use. Most
state that the units have a life expectancy of 20 to 25
In researching tankless units, I too found most plumbers
reluctant to install them. I believe the reason is that these
units were originally put on the market before all the bugs
were worked out. Many plumbers found that they had to be
replaced with tank-type units, which resulted in lasting bad
Properly designed tankless units have been in the field now
for several years. Also, because of problems with faulty
installations, several manufacturers now require that their
units be installed by a factory-trained mechanic or plumber, or
the warranty is void. I have been pleased with the technical
support I have received from Rinnai's engineers — even
though I am not a trained installer — and I expect my
unit to last a long time.
In the article "Framing the First-Floor Deck" (12/06), Tim
Uhler refers several times to a flashing membrane he uses to
isolate wood from concrete. What exactly does he use?
Tim Uhler responds: We use Nervastral's concealed flashing
membrane, which is available in a variety of thicknesses
— we use 20 mil. For more information, go to
I noticed a small error on page 77 of "Block-Laying Basics"
(11/06). The line that reads "this basic 1-to-3 ratio of sand
to cementitious materials" should read " ... 1-to-3 ratio of
cementitious materials to sand."
Thanks for pointing out the mistake! — The