While this issue is not at the center of the
unity debate, we in Ontario should realize that Canadians in the rest of
this country think we’re a little nuts because of our fixation with
brick houses. Our theory is that people in Ontario were raised on
stories like the “Three Little Pigs”. We want a house that nobody can
huff and puff and blow down.
What most people in Ontario don’t realize is
that there are two very different types of brick houses: brick veneer
and solid masonry.
Solid Masonry
Solid masonry construction is also called
‘Solid Brick’, ‘Double Brick’, and sometimes ‘Brick and Block’. In its
most common form, a solid masonry wall consists of an outer layer of
brick and an inner layer of brick (a layer of brick is called a ‘wythe’
in masonry circles).
The reason why solid masonry is a more
accurate description than solid brick or double brick is because the
inner wythe may not be brick. Because the inner wythe will never be
seen, concrete or cinder block is sometimes substituted for brick.
As a brick wall increases in height, there is
more and more danger that the inner wythe will separate from the outer
wythe. To hold the two wythe’s together, header bricks are installed,
usually every six rows. From the outside, header bricks look like
regular bricks except they are shorter. In reality, they are the same
size as a normal brick, however they are installed sideways so that the
end of the brick is visible from the exterior of the building. The
header bricks act as a bridge between the outer wythe and the inner
wythe and prevent the two from separating.
Therefore, most solid masonry walls display
header bricks in every 6th row or course. Sometimes, every brick in the
course is a header brick, however there are a number of common patterns.
It is not unusual to see two long bricks followed by two short ones
then two long ones then two short ones. (The long bricks, by the way,
are called stretchers.)
Sometimes bricks are installed over windows
with their long face parallel to the wall but the brick standing on its
end. These are called soldiers.
It is possible to build a solid masonry wall
using metal ties to hold the two wythes of masonry together. When this
is done, no header bricks will be visible and the wall can easily be
mistaken for a brick veneer wall.
So What’s so Good About a Solid Masonry Wall?
There is no question that the big bad wolf
will find this wall the hardest to blow down. Structurally, solid
masonry walls are very strong and can, if properly maintained, provide
hundreds of years of service.
If solid masonry is so good, why is it that most brick houses built in the last 30 years are brick veneer construction?
Firstly, we have to understand the difference
between brick veneer and solid masonry. The biggest difference is that
with solid masonry, the brick is holding up the house. With brick
veneer, the house is holding up the brick!
When we say brick veneer, we don’t mean those
little thin slices that you glue on your kitchen wall. We mean an
honest to goodness brick. However, the wall is only one wythe thick.
Behind the brick veneer is a wood frame wall which is actually holding
up the house. The brick veneer is, in effect, siding!
Insulation
Brick veneer became the norm when building
codes began to require insulation in the exterior walls. One of the best
insulators is air. Most good insulation does nothing but trap air;
that’s why most insulations are light and fluffy. Brick is not exactly
light and fluffy. Therefore it’s not really a very good insulator. A
brick veneer house then, is really a wood frame house where the cavity
between the studs in the wall can be insulated.
The walls are built, covered with sheathing
and often insulated before the brick is even installed. As the brick is
being installed, metal ties are nailed onto the wood frame wall. It is
important that they be nailed into the studs and not just into the
sheathing. The metal ties are then bent so that they are horizontal
where they become imbedded in the mortar joints as the brick veneer wall
is constructed. The brick veneer is built on the outer edge of the
foundation wall so that a one inch air space remains between the brick
veneer and the sheathing.
How Waterproof Is Brick?
The short answer is “not very”. With a wind
driven rain, moisture will pass right through a brick wall. The one inch
air space behind the brick allows this water to run down the back
surface of the brick. At the bottom of the wall cavity, a plastic or
metal flashing collects the water and allows it to drain out through
weep holes. You’ll find weep holes spaced at approximately 32″ (every
fourth brick) along the top of foundation walls and above doors and
windows.
Not only do the weep holes let the water
drain out of the wall, but they also allow the wind to get behind the
brick and pressurize the one inch airspace between the back of the brick
and the sheathing. Believe it or not, this extra air pressure reduces
the amount of rain that gets forced through the wall.
So Which is Better?
Well that depends on your criteria. Solid
masonry walls are certainly stronger, however brick veneer walls are
plenty strong and are certainly better insulated. In the big scheme of
things, the differences between the two types of construction should not
be important enough to affect a purchase decision. In the interests of
national unity, you shouldn’t even care whether the house has any brick.
Line drawings are from Carson Dunlop’s Home Inspection Training Program
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