Masonry
outdoor fireplace construction
is a major undertaking compared
to installing a
prefabricated metal firebox.
It requires more than just
framing the metal firebox and
installing cultured stones over
the walls.
In my line
of work generally I encounter
with there types of outdoor
fireplaces: Masonry, the
traditional fireplace where the
unit is built from brick and
mortar and the firebox is lined
with
fire resistant bricks
and
prefatory mortar.
The prefab or pre-fabricated,
consisting of a metal firebox
and metal (many times stainless
steel) chimney, and last the
combination of the two.
In this
article I will outline the steps
we took to build an outdoor
fireplace using masonry
materials and an outdoor
stainless steel firebox.
Most
masonry outdoor fireplace
presents a significant amount of
weight. The finished fireplace
can weigh up to 6 tons so the
first step is to excavate a
proper footing that can hold the
fireplace. As a general rule the
footing should be about a foot
deep and a foot wider than each
side of the fireplace walls. So
if for example you are building
an outdoor fireplace that
measure 6’x 4’ the footing
should be 8’x 6’. The concrete
you pour should be at least
3000PSI in strength and
reinforced with 4 #5 rebars each
way.
Note: If
you are building an outdoor
fireplace that holds a
prefabricated metal firebox,
modular component masonry
fireplace or a
ventless firebox
that needs no chimney the
footing can be a 5” concrete
slab. These types of fireplaces
do not have significant weight
so the size of the footing can
be significantly smaller.
As with
indoor fireplaces their outdoor
counterpart can be fueled with a
multitude of ways. However,
traditional wood burning and the
more modern-day gas burning
options are the most popular
choice for today’s outdoor
fireplaces.
If you are
installing a gas burning outdoor
fireplace you might want to have
the gas lined up and the
connection placed ready before
you pour your concrete.
Building
an outdoor fireplace:
Although
our out door fireplace was wood
burning we incorporated an
outdoor BBQ grill on the back of
the fireplace that was fueled
with propane gas from a nearby
tank.
So we
needed to place a 2” PVC pipe
for easy connection of the
copper gas line for our out door
barbeque.
After
pouring our concrete we needed
to establish our layout both for
the BBQ grill and the fireplace.
Since the structure was built
with CMU concrete blocks the
measurements was set by the
blocks’ size and the size of our
42” outdoor firebox. After
setting the firebox in place we
needed to put a concrete lintel
above it that rested 8” on both
sides of our wall. This lintel
was reinforced with a piece of
rebar and filled up with
concrete for extra support. This
allowed us to continue erecting
our walls and the chimney for
the fireplace. As with most
prefab outdoor fireboxes we also
received the entire chimney flue
and other accessories. The
chimney flue snaps up easily and
comes with one 30% elbow to make
the turns necessary avoiding the
possible beams on the roof. We
needed to cut some part of the
roof in order to be able to
erecting our chimney.
Note:
As a general rule your chimney
pipes should be at least an inch
from contact with any
combustible materials. It is
required to put a 4”x4” angled
flashing materials at the place
where the chimney meets the
roof.
After
erecting our chimney and
installing the caps we needed to
stucco the fireplace.
Since this
outdoor fireplace had all the
bells and whistles, we added to
the comfort of the fireplace
with a built in barbeque grill.
The grill was made of CMU blocks
and a Profire grill was built
in.
The next
step was the design element of
the front of the fireplace.
Since most
fireplaces have a shelf we
formed, reinforced with rebars
and poured it with concrete.
The owners
of the home wanted to create a
façade of the fireplace that
protruded out so we decided to
frame the walls for the veneers.
We made these with
pressure-treated wood and cement
backer boards. The veneer of our
choice was quartzite
natural stone panels.
If you wish
to read a detailed guide on how
to install natural stone panels
on any surface see our page
about
natural stone panel
installations.
The design
of the hearth of our outdoor
fireplace included the timeless
beauty of handcrafted stone from
Cultured Stone®. We picked a
darker brown color to complement
the natural stone veneer on the
fireplace creating a
high-quality, custom look.
We saw cut
each piece to custom fit to our
fireplace and grouted each
joints with matching color. The
top of the Barbeque Island got
the same cap as the hearth of
the fireplace for perfect
continuity.
The top of
our veneer vas covered with a
sill from the same type of
materials to tie-up our
fireplace with the BBQ Island in
the back.
To finish up our outdoor wood
burning fireplace we applied the
paint in matching color to the
home.
