Apr 20, 2011, 12:09 AM
chililadyHere are some instructions I received on making a roof over a flat one.
N INEXPENSIVE METAL ROOF
Install It New Yourself
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What? Me install a metal roof myself? You gotta be kidding! Nope, we’re not kidding. If you
can run a drill and a saw, you can install a new metal roof that will last you 20+ years with very
little maintenance.
If you’ve got an older manufactured home that has a
metal roof, it’s probably been sealed and resealed and
then sealed a few more times (like the picture to the
left). And now it’s time to seal it again, where will it
ever stop!! Guess what, it won’t stop. Once that
bottom layer of sealant starts to work loose, the top
layers don’t do much good. The only way to remedy
that situation is to scrape the roof clean, and that’s a
lot of work!
figure 1 - before
Using the following the steps outlined in this booklet,
but a roof that’s sturdier, reflects the sun and provides
some extra insulating value.
The picture to the left shows a new finished roof.
With a helper or two, you should be able to finish this
roof in two days. Experienced crews can do it in a
day. In most cases, material cost will be less than
$1800.
figure 2 - after
Materials and Tools
All materials for this project can be purchased at any local lumberyard. This chapter will show
you how to install the basic simple metal roof. You can also go as far as to add eaves, soffits and
gutters. This chapter doesn’t cover those items in detail, but at the end there is a photographic
view of one such method.
Before gathering the materials, first measure the length and width of your roof. The metal you
will be purchasing is a corrugated metal. This is the same metal used on roofs and exterior walls
of many commercial buildings and pole barns. The corrugated metal is available in many colors,
but for roofs white is best. The metal comes in various lengths and can be special ordered to the
nearest inch if so desired. Most lumberyards stock the metal in lengths of 12, 14, 16 and 18 feet.
Each sheets covers an area 3’ wide. If your roof is 14’ x 67’, then you’ll need to purchase 23
sheets of 16’ metal. Even though your roof is only 14’ wide, you’ll have enough extra for a 3-4”
overhang on each side. The 29 gauge metal will slightly bow to the contour of a domed roof as
pictured on page 1.
Materials:
. White corrugated sheet metal 29 gauge.
. 1 box of 3” white sheet metal screws with neoprene washers.
. 1 box of 3½” deck screws.
. Enough ½” fan-fold insulation to cover the entire roof. 4x8 sheets of ½” or thicker
insulating board will also work.
. 1x4 boards in 12’ or longer lengths for furring strips (54 boards for a 16x80, 44 for a
14x70).
. Foam closure strips, two per sheet of metal.
. 32 feet of metal corner (gable) trim.
. 2-4 tubes of neoprene rubber roof cement.
Tools:
. drill (cordless 12 volt or bigger works best)
. circular saw
. tin snips
. tape measure
. marking pencil
. metal-cutting blade for circular saw (or put in an old blade backwards)
. ¼ nut driver for drill
. bit for drill for deck screws
. chalk line
STEP 1 – INSULATION
Starting at one end of the home, lay down 3 or 4 rows
of insulation. Fan-fold insulation is nice because it
simply unfolds across the home. Cut to fit and duct-
tape the seams. Working in small sections at a time is
safer in case wind or inclement weather comes up.
figure 3 – unfolding the fanfold
insulation
STEP 2 – 1x4 FURRING STRIPS
Lay down the 1x4 furring strips. The 1x4 furring
strips run lengthwise (end to end) across the rafters.
The first and last rows are placed along the edge of the
roof. Then space the rows every 2 feet or so apart. If
you have a peaked roof, a row of 1x4’s also needs to
run at the top on each side of the peaked roof.
figure 4 – lay down rows of furring
strips every 2 feet.
The furring strips are then screwed into the rafters. Most rafters are 2 feet apart. The best way to
locate the rafters is to feel with your feet. Once the rafters are located along each edge, snap a
chalk line across the roof to mark the boards for screwing. Screw the boards into the rafters using
3½” deck screws.
figure 5 – feel for the rafters, snap chalk line along rafters, screw 1x4 to rafters
STEP 3 – CORRUGATED METAL
First decide how much you want the metal to
overhang the roof. If you already have gutters on the
home, it should hang to the middle of the gutters.
Otherwise, a 3-4” overhang should suffice. Again,
measure the width of your roof and add for the
overhang (6-8” when including both sides). Cut with
a circular saw using a metal-cutting blade or an old
blade installed backwards.
figure 6 – cut the metal
roofing to length
Position the first piece of metal roofing into place.
Adjust the roofing so you have an even amount of
overhang on both sides. The first piece should be
flush with the end of the home. Add an inside closure
strip to each end of the metal.
figures 7 & 8 – position metal,
add inside closure strips
Important: To prevent leaks, the metal can only overlap one way.
On one edge of the metal you will find writing. The edge with the
writing must lap underneath the edge with no writing.
figure 9 – proper overlap
of corrugated metal.
Once you’re sure the first sheet is positioned straight
and square, screw it into each furring strips. 4 screws
across each row should be sufficient (or whatever the
manufacturer recommends) which works out to about
every other ridge (figure 10). Use screws that have
neoprene washers and screw on top of the ridges. At
each end of the metal, drive a screw into every ridge.
Don’t over tighten.
figure 10 – drive a screw into the top of
every ridge along the ends and every
other ridge in the middle
TIP: An easy way to start a screw into metal is to first give the screw a quick ‘push’ with your
drill before engaging the trigger. If your drill has a high and low speed, use the high speed. The
faster you can spin the screw, the easier it will drive in (figure 11).
figure 11 – correct method of driving screws into the ridges of the metal
Lay down the second sheet, making sure that the edge
without writing is overlapping the edge with
writing on the first sheet. Insert the closure strips into
the ends and then screw it down like you did the first
sheet (figure 12). After you've done the first couple
sheets, you won't believe how easy this is.
figure 12 – continue laying &
screwing sheets of metal.
STEP 4 – VENTS
You’ll just get rolling and before you know it you’ll
run into a vent. No problem. For straight vents such
as sewer vents, simply take careful measurements, cut
a hole and set a sheet of metal down over it. Then seal
around the vent with long-lasting neoprene. If the
vent has a rubber boot around it, then try to remove it
and replace with a new one.
figure 13 – cut opening for vent
and seal with neoprene
Besides removing the old rubber boot, some vents will need to
be extended (figure 13). As a general rule, vents should be
extended above the roof line to function properly. To do this,
glue a coupler onto the vent and add another piece of pipe.
Once the roof is completed, adding
a new rubber boot over the pipe is
also a good idea. The boot pictured
to the left has flexible flanges, which
will conform to the corrugated metal.
Also the top opening can be cut to
accommodate any size of pipe.
Figure 13 -- extending a roof vent.
Furnace and other wide-topped vents can pose a little more of a challenge. First, take careful
measurements and cut an opening in the metal just big enough to slip down over the top. Then
cut two pieces of flashing from the metal scraps.
Shape each piece to fit snugly around the bottom of
the vent. The two pieces should overlap in the middle.
Be sure the top piece overlaps the bottom. Seal the
entire underside of the flashings with neoprene and set
in place. Then seal around the vent with neoprene
(figure 14).
figure 14 – cut pieces of flashing
to fit snuggly around wide-top
vents.
Note: For some vents or roof jacks, such as furnace and water heater vents, it’s probably wisest
to remove the vent and re-install it after the corrugated roof is in place. This would simplify
future repairs that would involve removing or replacing the vent. Most vents are simply removed
by unscrewing and lifting up. When re-installing, apply a generous bead of neoprene under the
base and around the edges.
STEP 5 – HEIGHT CHANGES
Some older manufactured homes have a section of the roof that’s higher than the rest. Although
common sense will need to be used, the metal will easily bend over even the sharpest changes in
ceiling height. Some trim may need to be used along the edges.
STEP 6 – GABLE TRIM
Install gable trim on each end using screws every foot or so on the
top and bottom. This gives the peak a finished look and prevents
the wind from ever getting underneath.
figures 15 – gable trim on the ends make
a nice finishing touch
PITCHED ROOFS
If your roof is not nearly flat or slightly domed, then
you have a peaked roof. The only difference is that
you’ll span your roof with two pieces of metal
instead of one. Where the pieces meet at the peak,
you’ll need to add outside closure strips and a ridge
cap as illustrated in figures 16. Screw the cap in
place by driving screws along both edges of the cap
into each rib of the metal.
figures 16 – a ridge cap covers the peak of a pitched roof.
JOB COMPLETED!
As mentioned in the beginning, doing the roof in 12’
sections is the safest. Once you’re done with the first
12’ section, start over on the next and keep going
until you’re done! About the only maintenance your
new roof should need is to check the neoprene
around the vents. Neoprene is long lasting, so it
should be many years before having to worry about
it.
figure 17 – nice job!
Adding an Overhang and Soffits to Your Mobile Home
The overhang is pre-built and screwed-up in place.
This picture shows the construction of the overhang on
the front without the soffit board yet in place.
This picture shows the back with the soffit board in
place and lined-up with the sides.
This picture shows how the roof edging, fascia and soffit are installed. The roof edging will need
to be installed before the metal is put on the roof. The
fascia and soffit are metal or vinyl, a good choice as
they will never need painting.
All done!
