a cathedral ceiling is a grand way to open up your space, but

Lofty
ambitions
A cathedral ceiling is a grand way to open up
your space, but structural and insulation
details need to be done right. Here’s a cottage
owner’s primer on raising the roof
By Josey Vogels
74 cottagelife.com
October 2012
true
2 types of
cathedral
ceilings
vaulted
76 cottagelife.com
October 2012
Chad Martin sat in his 70-year-old
lakefront cabin, wondering what to do.
Tear it down and start over? It would be
a shame, he thought, to lose the architectural detail and the history of the 1940s
cabin that was once part of the Cedar
Brae resort on Paudash Lake, Ont. But
the low ceiling made the small space feel
dark and cramped, and the front windows were so tiny he could hardly enjoy
the gorgeous western lake view.
“I thought, Why not open it up with a
cathedral ceiling and bigger windows?”
says Martin, who bought the old resort’s
main building and the one remaining
625 sq. ft. guest cottage in 2007. “I had
no idea if it was possible.”
It is possible, but converting a cottage’s
flat ceiling into a cathedral ceiling is
not exactly a Saturday afternoon DIY project. Still, the appeal of a cathedral ceiling at the cottage is obvious—more light,
potentially better views of the lake, and
an open, airy feeling that helps blur the
line between outside and in (between the
heavens and the earth, if you want to
get churchy about it).
In theory, the steps are basic: Remove
the existing ceiling surface and the attic
insulation, brace the walls before taking out the joists, insulate between the
rafters, add a vapour barrier, slap on
your interior finish and, voilà, kick back
and enjoy the celestial view.
But the devil is in the details, and they
can be “pure hell to get right,” says Don
Fugler, a building science researcher in
Ottawa. Before you talk to a contractor,
do your homework: Take photos, measure
the span of the ceiling joists, and investigate how the walls and the roof are
attached. Ultimately, says Fugler, each
cottage has its own obstacles—the information you gather can help your contractor find solutions.
Even in a cottage that’s structurally
sound, you can’t just remove a flat ceiling without consequence. “These old
cottage roofs rely on a triangle structure,” explains Ken Davis, a structural
engineer whose Toronto-based company,
K.H. Davis Engineering Consultants,
is seeing an increased demand for this
kind of renovation. “Press the fingertips of your two hands together to form
a steeple. Now picture the ceiling joists
running between your elbows. Remove
them and your elbows—the walls—push
outward, causing your fingers—the roof—
to come down, possibly collapsing the
whole structure.
“Because you’re changing the structure,” adds Davis, “you need a building permit. And you need to work with
someone who understands how a handframed roof differs from a trussed engineered roof.”
Many modern roofs are built with
engineered trusses—triangular wood
structures designed with the help of
engineering software. A new truss roof
this page, photo: derek shapton. illustration: ritzco. opposite: jim norton. previous pages: left, paul orenstein; right, jim norton
A system of steel rods
(opposite and p. 75), like
the more commonly seen
airplane cable, performs
one of the key functions
of ceiling joists: holding
the walls together. Structural challenges may push
you to consider a vaulted
ceiling (left); it doesn’t
reach the full height of a
true cathedral ceiling, but
is much simpler to build.
a skylight, doesn’t it? maybe not
paul orenstein
that angled plane just begs for
can incorporate a cathedral or vaulted
ceiling without adding a lot of cost, says
Ron Kapitain, a custom carpenter in Bancroft and an Albion Lake cottager. But
it’s difficult to modify existing trusses
without weakening them.
Trusses aren’t the only cathedral
ceiling framing option that’s possible in
new construction: Another method uses
a heavy load-bearing beam for the roof
ridge. The beam, supported on each end
by a structural post, shares the roof’s
load with the walls. That’s fine in new
construction, but retrofitting this system
into an old cottage is a major structural
change that may be impractical.
Chad Martin’s cabin had sat empty
for 30 years, and in that time the weight
of the roof and snow load had caused
the walls to bow outward. The contractors he hired for the job—brothers Mark
and Jeff Graham—were concerned that
removing the ceiling joists, with the
walls already compromised, would cause
the tiny cottage to collapse. Their solution was to strip the walls down to the
studs and permanently rig airplane
cables diagonally from corner to corner
inside the framing to tie the walls
together. Over a few weeks, they slowly
cranked the cables tighter, pulling the
walls inward 51/2 inches, until they were
straight and secure enough to remove
the ceiling joists. A creative and viable
solution, says Davis, as long as builders
get “proper advice on how many cables
to use, how best to install them, etc.”
Even with airplane cables, Martin’s
contractors advised him to go with a
vaulted ceiling. Unlike a true cathedral
ceiling, which follows the entire pitch of
the roof, a vaulted ceiling (see “2 Types
of Cathedral Ceilings,” p. 76) stops short
of the peak, with a central portion that
remains flat. To do this, the Grahams
installed 2x8 collar ties between opposing rafters about a foot and a half higher
than the old ceiling.
This approach allows for a higher
ceiling while still tying in the roof and
walls, says Davis, but “you have to make
sure the new collar ties are well fastened
to the rafters with the ­adequate—and
legal—number of nails. If you only go
up a foot and a half, 2x8 collar ties may
be fine,” he explains. “But the higher
you go, the greater the tie force on the
structure and the more nails you’ll need.
If you have to put nine or 10 nails into
the end of a 2x8, it’s going to start splitting, and you’re once again in danger of
compromising the structure. You may
need to go with 2x12 collar ties, but you
have to ensure the roof can handle the
extra weight.”
Then there’s the weight of the interior
finish to think about, says Ron Kapitain.
“The original rafters may not be able to
support drywall or tongue-and-groove.”
Reinforcing the rafters may be possible,
but often that means the whole project
will become so complicated—“the domino effect takes over,” he says—that a
cathedral ceiling is not a good idea.
The great insulation debate
By choosing a vaulted ceiling, Martin
not only avoided weakening the structure,
he also created airspace that simplified
venting and insulation—two of the most
important, and hotly debated, concerns
with cathedral ceilings.
My husband and I winterized the
cathedral ceiling in our own 784 sq. ft.
1970s Viceroy, also on Paudash Lake.
Our rafters, like those in many older,
stick-framed buildings, were too shallow
for conventional winterizing: batt insulation, vapour ­barrier on the warm side,
with a venting airspace between the
batts and the underside of the roof deck
(see “Insulating a Cathedral Ceiling,”
p. 83). One solution would have been to
add depth to the rafters, but we didn’t
want to lose ceiling height. Instead, we
opted for spray foam insulation. Because
it could be sprayed onto the underside of
On lonesome Georgian
Bay, the bones of this
seasonal cottage
(opposite) are as exposed
as the rocks outside.
Where walls are unusually
short, a cathedral ceiling
makes the difference
between cramped and
comfortable. A cottage
like this can be winterized,
without covering the
open studs and rafters,
by adding a second roof
overtop the original.
the roof deck and rafters without venting,
and could add plenty of R-value without
changing the roof structure, spray foam
seemed ideal—until the following spring,
when rivulets of water started dripping
down from parts of the ceiling. We have
yet to determine what exactly is going on.
According to Fugler, the problem with
spraying foam in an old cottage ceiling is
that if it’s not applied correctly, you can
get gaps and cracks. In winter, warm air
can find its way into the ceiling cavity.
When it hits the cold roof deck, moisture
condenses. And, if your roof deck is getting wet every spring and drying out over
summer, says Jim Sangster, a cottagecountry building inspector and bylaw
officer, it may eventually rot. “Because
the foam is sprayed directly onto the
roof deck, you may have to pull the whole
roof and ceiling structure apart to fix it.”
Ken Davis, however, has seen spray
foam work well in converted cathedral
ceilings, including his own, but not all
municipal building departments share
his opinion. “Check whether yours will
accept spray foam insulation sprayed
October 2012
cottagelife.com 79
In some cases,
collar ties at every
rafter pair...
sECURING A
CATHEDRAL
CEILING
...can be replaced
with doubled ties at
every third pair.
80 cottagelife.com
October 2012
directly into the roof joist cavity with
no vented space above the insulation
and below the sheathing.”
Davis also says it’s unclear whether
this product voids the warranty on roof
membranes or shingles that have already
been installed, or whether you still need
a vapour barrier on the warm side of the
roof after the foam is sprayed on. (Some
manufacturers suggest that the spray
foam is, in itself, a vapour barrier.)
For these reasons, most contractors I
spoke to—including Ron Kapitain—prefer to stick to the tried-and-true method
of placing rafter vents (also called “moor
vents”) along the underside of the roof
deck from soffit to peak, a vent along the
peak, and insulation batts between the
rafters, followed by adding a vapour barrier, and finishing with drywall or tongueand-groove panelling (see “Insulating
a Cathedral Ceiling,” p. 83). Where the
roof rafters are too shallow to fit enough
insulation to meet the R-values required
by the Ontario Building Code, you can
attach strips of wood to the underside
of the rafters to deepen the cavity.
Of course, nothing’s that simple. “Even
if there is a continuous flow from soffit
to peak,” says Fugler, “and you create
enough ventilation, you may still draw
in unwanted air and moisture. And what
if you have, as you often do in these old
Viceroy cottages, multiple beams that
run along the roof deck from front to
back? You simply can’t create an uninterrupted airflow from soffit to peak.”
One way to avoid strapping rafters or
venting around beams is to insulate over
the existing roof deck. After removing the
shingles (or other roofing material), insulate above the roof deck and then lay new,
vented roof sheathing and shingles on
top (see “Insulating a Cathedral Ceiling,”
p. 83). This is also the easiest way to
maintain the exposed-rafter look that’s
typical of old, unwinterized cottages.
That’s the approach Rita Cordeiro
took after buying a 1920s Muskoka cottage with a very un-1920s insulated
drop ceiling—“it looked like a ’70s suburban basement family room.” When
she removed a ceiling tile, she discovered
the fireplace’s stone chimney soared to
the peak of a gorgeous, spruce-plank
cathedral ceiling. Desperate to maintain
the original ceiling but equally desperate
to enjoy all four seasons at the cottage,
Cordeiro enlisted the help of a clever
contractor who suggested simply building a new roof over the old. The drop
ceiling was not integral to the roof structure, so removing it created no structural
problems, although the cottage’s old
foundation piers had to be replaced to
support the weight of a second roof.
How to light the space
As with the great cathedrals of Europe,
lighting this cavernous space can be difficult, day and night. That angled plane
this page, photo: daniel ehrenworth. illustration: ritzco. opposite: laura arsiÈ
A new second storey
(right) topping an old log
cabin lets the sun stream
in. At night, though, the
space is hard to illuminate;
pendant fixtures bring
light to the cottagers’ level.
A hallmark of traditional
cottages, partial walls
(left) aid airflow and are
simpler to build than
working around collar ties.
The effect is casual and fun
(until the snoring starts).
When the ceiling will be
clad in tongue-and-groove
wood panelling (opposite)
or drywall, builders usually
insulate between rafters
with batts or spray foam.
this page: ritzco. opposite: daniel ehrenworth
of the new ceiling just begs for a skylight, doesn’t it? Maybe not. “If you want
to cause problems in roofing,” says Don
Fugler, “skylights are almost as problematic as cathedral ceilings.” In a vented
roof, a skylight creates a barrier in the
soffit-to-ridge venting. While the technology of skylights is improving, you are
essentially adding a large, heated hole
in your roof, says Fugler. If heat escapes,
it will melt any snow or ice around the
skylight and could cause ice damming.
At night, recessed pot lights can create wonderful, warm ambiance in a room
with a cathedral ceiling, but the space
limitations in the roof cavity can make
installing and wiring them tricky. More
importantly, pot lights create a break in
the insulation, setting you up for moisture problems. Opt instead for pendant
lighting that hangs low to help light specific areas of the room. Combine these
with floor and table lamps to layer the
lighting and keep a large, open room
feeling soft and warm.
The cost of overhead
In each cottage, the challenges of creating a cathedral ceiling will be different.
And so will the final bill. “If you find out
the cottage is structurally inadequate, it
may not be worth it,” Fugler says. “Of
course, anything can be fixed, if you have
the money.” Chad Martin spent about
$14,000 to vault the ceiling in his cabin.
Rita Cordeiro estimates the cost of the
second roof and accompanying structural reinforcements at about $17,000
back in the mid-’90s, still much cheaper
than removing the roof and rebuilding it
entirely, as some contractors suggested.
Since the reno, Cordeiro and her family
have enjoyed what was once strictly a
seasonal cottage year round. “You can’t
Conventional insulating
vents a cathedral ceiling
below the roof deck with
baffles that allow airflow
from soffit to ridge (1).
Builders extend the rafter
depth (2) with strapping
(3), attached with metal
plates or plywood gussets
(4), then pack in batt insulation sealed with a vapour
barrier. Use mineral wool
instead of fibreglass, suggests Donald Peckover,
an architectural technologist at sustainable.TO.
“It’s less likely to support
mould,” he says. “And
mice dislike chewing it.”
Insulate
between the
rafters...
4
2
1
Vented
A newer method avoids
venting by spraying foam
onto the underside of the
roof deck (5). It’s more
expensive, but spray foam’s
higher R-value per inch
means rafter extensions
may not be needed.
If you want exposed rafters,
or if the roof structure
will be hard to seal, you
can insulate overtop
the existing roof with layers of rigid polyisocyanurate foam or mineral wool
sheets (6). This ceiling
design is easy to vent (7)
with strapping on top of
the sheets—but it can
also be left unvented (8).
even tell the place has a second roof,”
she says, adding that when guests walk
in, their eyes immediately go up, and
everyone’s in awe of the majestic stone
chimney and plank ceiling.
Martin is thrilled he was able to keep
the charm and history of his wee cabin,
now lovingly known as “Little Red,”
while bringing it out of the Dark Ages.
My own insulation saga is still waiting for its happy ending. We’re working
with our contractor to stop air leakage,
which is likely causing our condensation problems. Still, whenever I get frustrated or discouraged, I just look up at
that big, open space and, I swear to God,
I love my cathedral ceiling.a
Writer Josey Vogels lives on Paudash Lake
near Bancroft, Ont. A former city girl,
she never thought that dew points, ridge
vents, and strapping would become topics
of her everyday conversation.
5
unvented
...or above
the old roof.
6
7
Vented
8
unvented
insulating
A CATHEDRAL
CEILING
October 2012
cottagelife.com 83
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