When you start thinking about weatherproofing your
house, look down. You may need to.. .
by Bob Johnson
Quite often homeowners are so busy insulating, caulking,
and weatherstripping obvious energy leaks that they fail to
check their homes' foundations for the kind of seepages
that can cause cold floors (and feet), higherthan-need-be
utility bills, frozen water pipes, and drafts up walls and
around heat ducts.
After years of being exposed to cold, rain, and snow, the
mortar that holds together the foundations (usually block,
rock, or brick) of older homes tends to develop holes and
cracks. It takes only a few minutes to determine whether
your underpinning needs attention, and-better still-just a
few sparetime hours to make the repairs.
WHAT CAN YOU DO?
There are two ways to stop such leakage without having to
resort to building a new foundation, and, surprisingly, the
more expensive method is not in most cases the best.
The first process-and the least effective, to my
way of thinking-is to put fiberglass batts or roll
insulation on the inside of the leaking wall. You
see, it's virtually impossible to recover the cost of this
repair in energy savings over a reasonable period of time,
and though this procedure may stop the leaks, it doesn't
stop the deterioration.
The alternative is to point or plaster (or both) the
bulwark. These jobs can be accomplished in a few hours-even
by a noviceand the raw materials are not costly.
WHAT YOU'LL NEED
The supplies necessary for pointing and plastering include
masonry-grade cement, sand, and water. (EDITOR'S NOTE:
The author recommends masonry-grade cement because it is
finely ground and thus quite adhesive, and also because it
contains additives that control the setting time and add
waterproofing.] Each project will require a different
amount of grout, but a 94-pound sack of cement (about
$4.50) and 2 cubic feet of sand (around $16.00 a cubic
yard) should carry you through a weekend of plugging the
gaps ...and even leave you with filler for the children's
If you don't have a mortar box or cement mixer on hand, an
old galvanized foot tub or a five-gallon plastic bucket-the
kind industrial supplies come in-will work fine. Just be
sure to clean all utensils as soon as you're finished for
the day. You'll also need a small pointing trowel, a
plastering trowel (if you decide to do both jobs), a wire
brush, a whisk broom, a big, sturdy screwdriver, a putty
knife, and a spray bottle (the kind window cleaner comes
Don't, however, rush off to the hardware store and pay a
big price for professionalquality trowels. Such flexible
tools, which will spring back to their original shape, are
certainly the best, but less expensive models will work
just as well for a short time, and the difference in price
is usually $10 or more. Better yet, if you plan ahead by
looking around at garage sales and flea markets, you'll
probably be able to find quality tools at secondhand
Now that you have your implements assembled and have
arranged to have the cement and sand delivered, it's time
to prepare the foundation.
Carefully clean "rotten" mortar out of all cracks that need
repair. Use the heavy-dut% screwdriver and putty knife to
pry out the decayed grout, which will be grainy and
crumbly, and then go over the cracks with the wire brush.
Finally, sweep out any remaining small particles with the
whisk broom and wipe out the dust with an old terry towel.
MIXING THE MUD
The rule of thumb for making grout is two parts sand to one
part cement. This ratio produces concrete that's rich
enough to bond well to the existing foundation material.
Before adding water to the cement and sand, though, make
sure they are thoroughly mixed. Each grain of sand
must be coated with cement if a good cohesion is to be
established. Do the dry-mixing by folding the two
components together until the whole batch is
gray-dark gray if the sand is damp-and make sure there
isn't a hint of yellow sand color anywhere, and
that there's no caking at the bottom of the container.
Next, stack the mixture to one side of the vessel and pour
water, a bit at a time, into the hole you've created. Pull
the sand/cement blend into this reservoir, mixing
constantly. Continue until the mortar has the consistency
of extra-stiff cake batter.
The proper thickness of the cement will depend somewhat
upon the skills and preferences of the person applying it.
If you'd like a stiffer grout, sprinkle a little cement on
the mixture and blend it in. If, on the other hand. the mud
is too thick to suit you, mix in a few squirts from the
When you're satisfied that the mixture is right, it's time
to apply it to the foundation. First, though, spray water
on the area to be worked so that the mortar will adhere to
it (this process is especially critical in warm weather).
Pointing involves putting grout in the cracks and-as best
you can-making it look like the original mortar. This
technique is most effective in cases where there are just a
few small cracks, or when the foundation is made of fairly
sizable pieces, such as cement blocks or large rocks.
Materials needed to repair cracks
and deteriorated joints in a brick foundation: mixing
masonry-grade cement, spray bottle, whisk broom, pointing
trowel, putty knife, screwdriver, wire
brush, and plastering trowel.
There are several steps in pointing a brick
foundation: First, remove the old, deteriorated grout
between the bricks, using the screwdriver and putty knife.
Next, give the joint a good going-over
with a wire brush. Then sweep it out with a whisk broom and
wipe it clean with a towel. Spray the
to-be-repaired area with the water bottle, apply the new
mortar to the cracks with a pointing trowel,
scrape off the excess, then smooth the grout with the broom
of the travel.
First, pick up a small amount of the mud on the edge of the
trowel and push it into the fracture. If the crack is long
and straight, you can use the trowel to form ridges in the
grout (in the container); then cut off beads with the edge
of the tool and press them into the joint. Once the mortar
is in the crevice, run the point of the trowel down the
middle of it to force it between the blocks. Repeat the
process until the fissure is filled, then scrape off the
excess and smooth it down one last time with the bottom of
the trowel. (Dampening the tool with water from the spray
bottle before the last step will give the job a
Pointed joints aren't always neat-especially when the work
is done by an amateur-because the new grout is a different
color, and it's difficult to make a filled crack look like
the original. On the other hand, the method is effective.
If you can ice a cake or spread peanut butter on a piece of
bread, you can plaster over an old foundation and usually
come out with a professional-looking job. Plastering takes
longer than pointing, and the materials cost more, but the
technique is the best one to use for badly deteriorated
foundations constructed of relatively small components,
such as bricks.
The preparations required for plastering are the same as
those for pointing, except that you need to pay a little
more attention to the consistency of the mortar, since
you'll be putting a coat of concrete over the outside of
the foundation. As noted earlier, the only additional tool
you'll need is a plastering trowel, which is a long,
narrow-handled device with square ends.
Apply the mortar in globs and then spread it over the
surface with sweeping circular strokes of the trowel, all
the while carrying the leading edge just a fraction of an
inch above the working material so the tool
doesn't gouge it. After applying a few square feet of the
cement, go back over it carefully to put on the finishing
touches. Some folks like a smooth surface-which you can get
with a little practice and patience-while others prefer a
rough, grainy look. It's really just a matter of taste.
A quarter of an inch of concrete coating on the foundation
will usually be sufficient, but up to two inches can be
used. (You can also employ a base of chicken wire or wire
mesh to give the plaster increased strength and to prevent
AND REMEMBER ...
Filling holes is only part of the job of weatherizing a
foundation. Insulation should be added to crawl space
covers, and if you have a basement with windows, those
should be given some attention, too. A good way to keep
cold air from getting in around the windows (and the
ventilation blocks) is to cut fiberglass insulation to fit
the opening, back it up with fiberboard, and then drive a
couple of stakes in the ground to hold the "sandwich" in
So, grab a trowel, mix some grout, and get down to the
basics of making your home more energy-efficient.