Installing A Terne-Coated Stainless Steel Sheetmetal Roof

Procedure code:
761013S
Source:
Hspg Prepared For Nps - Sero
Division:
Thermal and Moisture Protection
Section:
Sheet Metal Roofing
Last Modified:
12/31/2014


INSTALLING A TERNE-COATED STAINLESS STEEL SHEETMETAL ROOF


PART 1---GENERAL

1.01 SUMMARY

A. This procedure includes guidance in the application of
four different types of seams for a terne-coated
stainless steel sheetmetal roof. For terne, see
procedure 07610-07-R.

B. In this procedure, it is assumed that the roof deck is
wood, and that any insulation that may be required is
installed within an attic space and allows for proper
ventilation of the underside of the roof. If conditions
other than this exist, consult roofing material
manufacturer.

C. For terne-coated stainless steelroofs, there are
typically four types of seams used, depending on the
appearance of the existing roof:

1. Flat seam (also called flat locked seam): A seam
between adjacent metal sheets, formed by turning up
both edges, folding them over, and then flattening.
In a flat seam roof, and at valleys, all seams are
soldered.

2. Standing seam: A seam between adjacent metal
sheets, formed by turning up the edges of two
adjacent sheets, and then folding them over.

3. Batten seam: A seam that is formed around a wood,
fiberglass or plastic core. Typically, nearly
square in cross-section.

4. Cross seam: Cross seams are perpendicular to the
above seams and are intended to provide the correct
length for sheet metal pans. They should be
staggered from bay to bay to ensure strength and
stability of the sheet metal.

D. Historic and regional roofing craftsmanship and details
which are characteristic of the structure are to be
treated with sensitivity. Such details are to be
preserved and copied.

E. Replacement roofing work shall be equal to original
workmanship. The appearance of the new roof shall match
the existing roof in exposure, bay size, pattern and
material.

F. Safety Precautions:

1. Wear rubber-soled shoes that have non-slip or grid
type tread (preferably sneakers with a high top for
good ankle support). Avoid wearing loose clothing.

2. There should be no unnecessary walking over roof.
The roof shall not be used as a storage area for
other materials.

3. Wear a safety belt or harness and secure it to a
substantial chimney or to a window on the opposite
side of the house. Leave only enough slack so you
can work comfortably in one area, and adjust the
slack as you work on other sections of the roof.

4. Keep the deck clear of waste material as the work
proceeds. Sweep the deck clean after all old
roofing has been removed.

5. Steep roofs: On roof slopes greater than 4 inches
rise per foot, special consideration must be given
to both footing and materials handling.

a. Secure chicken ladders or cleats at the top
for adequate footing.

b. Hang and secure approved safety lines with
ropes of sufficient strength.

c. Carry a limited number of materials so that
balance and footing are not impaired.

d. Use scaffolding, ladders, and working
platforms as required to execute the work.
Scaffolding legs shall be planked to
distribute load to not exceed the specified pounds per square
foot on roofs as directed by applicable regulations and codes (see OSHA 3150 2002 (revised)). Ladders shall not be supported
on hanging gutters. They may be distorted
which can affect the slope to drain.

F. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:

1. Safety Precautions

2. Historic Structures Precautions

3. Submittals

4. Quality Assurance

5. Delivery, Storage and Handling

6. Project/Site Conditions

7. Sequencing and Scheduling

8. General Protection (Surface and Surrounding)

These guidelines should be reviewed prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).

1.02 DEFINITIONS

A. Bay - a unit of sheet covering as laid between seams.

B. Capping - a strip, covering the top of a batten roll,
welted to the edges of the sheets which are dressed up
the side of the roll.

C. Cleats or Clips - strips, cut to specified length
according to the type of seam being used, placed at
intervals directed by roofing manufacturer. Cleats are
securely nailed to the roof deck and the ends are welted
in with the edges of the sheets to hold the roofing
sheets in position.

D. Drip edge - formed metal sheets at roof edges which
prevent water from dripping down vertical surfaces. One
edge is welted to roof sheeting to form weather-tight
seam.

E. Expansion cleats - additional cleats which accommodate
the thermal movement of the metal covering when a single
length of metal exceeds 30'.

F. Lock joint - a single or double welted joint.

G. Saddle End - the completion of a batten roll covering or
a standing seam against an abutment.

H. Solder - metal or metallic alloy of tin and lead used to
join metallic surfaces.

I. Standing Seam - a double welted joint formed between the
sides of adjacent bays and left standing.

J. Welting - joining metal sheets at their edges by folding
together. Welting may by single or double folds, such
joints being termed single or double welts respectively.

1.03 SUBMITTALS

A. Shop Drawings: Before replacing roofing, prepare
working drawings showing bay width and length between
seams. Prepare typical and unusual seam details, valley
details, and fastening patterns for reroofing guidance.

1.04 PROJECT/SITE CONDITIONS

A. Wet weather: Do not apply new metal roof in misty or
rainy weather. Do not apply metal roofing to wet roof
sheathing.


PART 2---PRODUCTS

2.01 MANUFACTURERS

A. Revere Copper
www.revere.com

B. Zappone
www.zappone.com


C. Metal Sales Mfg. Corp.
www.metalsales.us.com

D. Vulcan Supply Corporation
www.paradigmshingles.com

E. Fine Metal Roof Tech
www.finemetalrooftech.com

2.02 MATERIALS

A. Fasteners:

1. Nails - 7/8" minimum length, flat head, stainless
steel roofing nails

2. Screws - For batten seam roofs, use stainless steel
screws, long enough to securely fasten batten to
roof deck.

B. Terne-coated stainless steel cleats - 2" wide, length as
required by type of seam being used. Consult roofing
manufacturer. Pre-formed cleats are often available.

C. Terne-coated stainless steel sheetmetal - to match gauge
of existing roof, .015 (28 ga.) or .018 (26 ga.) as
directed by roofing manufacturer based on type of
application; see 3.02 below.

D. Solder - 50% tin, 50% lead

E. Rosin soldering flux

F. 15-lb. felt underlayment

G. Rosin Paper

H. Paint (optional) - red iron oxide, linseed oil;
especially formulated to be used on terne metal

I. Wood, fiberglass or metal battens - size dictated by
existing roof.

2.03 EQUIPMENT

A. Chicken ladder, safety belt or harness

B. Protective gloves and gear

C. Straight snips for cutting straight or slightly curved
lines in sheet metal

D. Soldering copper, soldering iron

E. Tongs for bending the edges of the solder

F. Metal seamer

G. The application of sheet-metal roofing requires a full
range of metal-working tools and shop equipment, plus
special handling, hoisting equipment, and machinery for
long lengths.


PART 3---EXECUTION

3.01 PREPARATION

A. Surface Preparation:

1. Prior to installation, remove all oil, dirt, and
other debris from the roof deck. All surfaces
shall be dry and free from frost.

2. Carefully examine, measure, and record existing
sheetmetal patterns at edges, hips, ridges, and
other special conditions.

3. Be careful not to damage old metal wall and vent
flashings that may be used as a pattern for cutting
templates. If metal cap flashings at the chimney
and other vertical masonry wall intersections have
not deteriorated, bend them up out of the way so
that they may be used again. Be especially careful
roofing in these areas to avoid damaging reusable
base flashing.

4. At this point, inspect the deck to determine
whether it is sound.

a. Remove loose or protruding nails or hammer
them down.

b. Replace rotted, damaged, or warped sheathing
or delaminated plywood. Spacing between
boards shall be no more than 2". Plywood
shall have a minimum thickness of 1/2".

5. Make whatever repairs are necessary to the existing
roof framing to strengthen it and to level and true
the deck.

6. Lay down one layer of 15-lb felt underlayment.
Secure as required. Cover underlayment with rosin
paper. DO NOT secure to deck. This paper serves
as a slip sheet between the sheetmetal and the
underlayment.

3.02 ERECTION, INSTALLATION, APPLICATION

A. Flat Seam Applications:

1. Terne-coated stainless steel shall be .015 (28
ga.). Terne-coated stainless steel is available in
14" x 20" and 20" x 28" sheets. Maximum sheet size
is 20" x 28".

2. Form sheets on a brake as indicated by roofing
manufacturer.

a. Mark folds 3/4" from edge on all four edges.
Clip corners at 450 angle at intersections of
markings.

b. Fold two adjacent edges up and over and the
opposite adjacent edges down and under the
sheet.

3. Before beginning the first course, be governed by
proper application at ridge, drip edge, end or side
wall, gutters, valleys, etc. Consult roofing
manufacturer. All roof perimeters shall have
appropriate terne-coated stainless steel metal drip
edge.

4. Place first sheet into position at the lowest point
of roof slope. Top edge must be one of the edges
which is folded up and over. Hook one end of cleat
into edge formed on sheet and nail free end of
cleat to deck. Place nail close to the fold but DO
NOT NAIL THROUGH ROOFING SHEET. Bend end of cleat
up and over nail head. Attach each sheet with two
cleats per side.

5. Continue laying roofing sheets in this manner.
Align horizontal joints, stagger all vertical
joints. Lay individual sheets so that the fold of
the sheet higher on the roof hooks onto and is over
the fold of the lower adjoining pan.

6. At valleys, edges of individual roofing sheets will
require custom fitting to provide proper flat lock
seam. Sheet metal used for valleys should be as
long as possible to reduce the number of cross
seams.

7. All seams must be soldered. Use solder that is 50%
tin and 50% lead only. Use rosin only as a flux.
Remove excess rosin before painting.

NOTE: FLUX CONTAINING ANY ACID SHALL NOT BE USED.

8. If required to match color of original roof, paint
surface as directed below in D.

B. Standing Seam Application, 3" per foot minimum pitch (for
lower slopes consult roofing manufacturer):

1. Terne-coated stainless steel shall be .015 (28 ga.)
or .018 (26 ga.).

2. Determine width and length of each pan. Maximum
recommended width between seams is 21", with
maximum length of 20'. If pan length is between
20' and 30', pan width between seams should be
reduced to 17". Final pan width should match
original roof. Individual pans may be either
preformed by the manufacturer or formed on site.

a. Taper pans longitudinally (narrower at the
bottom) a minimum 1/16" to fit at the cross
seams.

b. To form on site, fold one long side up 1-
15/32", forming a 90 degree angle. Fold top 15/32"
over 900 to create a "C" in section. The
folded piece is called an upstand.

c. Fold opposite long side up 1-7/8", forming a
90 degree angle. Fold top 7/8" over 90 degrees away from
the pan. Fold 3/8" of top edge down so that
it is parallel with the 1" upstand.

d. To form fold for cross seam at both the top
and bottom of the pan make a 3/4" long cut
parallel to the upstand and 1" away from the
upstand. At the top end of the pan, make a
fold up and over. At the bottom of the pan,
make the fold up and back behind.

3. Lay down first pan into position. Hook one end of
cleat into side of pan whose upstand has only two
folds. Nail free end of cleat to deck using two
nails. Place nails close to the upstand but DO NOT
NAIL THROUGH PAN. Bend end of cleat up and over
nail heads. Cleats should be spaced approximately
12" on center, the entire length of the pan.

4. Where cross seams are required:

a. on roofs with pitch greater than 6" per foot,
slide two cleats onto fold at top of pan.
Place each one about 1" away from the upstand.
Nail as described under A.5. above. Hook next
higher pan over fold and cleat of lower pan
and carefully mallet seam together.

b. on roofs with pitch less than 6" per foot,
cleats secure lower pan as described above.
Approximately 4" below the fold of pan solder
a strip of terne-coated stainless steel,
approximately 1-1/2" wide by the full width of
the pan. Use solder that is 50% tin and 50%
lead only. Use rosin only as a flux. Remove
excess rosin. Solder only the upper edge of
the strip in place. The bottom fold of the
next upper pan hooks onto this strip rather
than the fold of the pan which has been folded
in with the cleat. The upper pan will then
cover both the fold and cleat of the lower
pan, and the strip.

5. With first row of pans secure, lay second row next
to the first row, leaving a 1/16" gap between the
upstands. Fold upstands of two pans together and
down creating a 1" tall standing seam. Continue in
this manner until roof is covered. Stagger cross
seams in a uniform pattern.

6. At valleys, drip edges and other special
conditions, sides of pans will require custom
fitting to provide proper seams. Consult
manufacturer for difficult situations. Sheet metal
used for valleys should be as long as possible to
reduce the number of cross seams.

7. To form the ridge, the top of last pan on one slope
should extend beyond the ridge the desired height
of the ridge seam, plus 1/2". The last pan on the
other slope should extend the desired height of the
ridge seam plus 3/4". Make a 180 degree fold in each pan
so that the folds on both slopes butt against each
other. Approximately 3" before the ridge, fold all
standing seams flat, facing in the same direction.
Fold the top 1/4" of the higher of the ridge
upstands over the shorter ridge upstand. Fold both
ridge upstands over a minimum of 1/2" and press
together.

8. Standing seams and cross seams need NOT be
soldered. Seams at valleys, however, MUST be
soldered. Use solder that is 50% tin and 50% lead
only. Use rosin only as a flux. Remove excess
rosin.

NOTE: FLUX CONTAINING ANY ACID SHALL NOT BE USED.

9. If required to match color of original roof, paint
surface as directed below in D.

C. Batten Seam Application for application of 3" per foot
minimum pitch (Consult roofing manufacturer is roof
pitch is less than 3" per foot):

1. Terne-coated stainless steel shall be .015 (28 ga.)
or .018 (26 ga.).

2. Determine width and length of each pan. Maximum
recommended width between seams is 21". Final pan
width should match original roof. Maximum length
of each pan in 10'. Individual pans to be formed
on site.

a. Taper pans longitudinally (narrower at the
bottom) a minimum 1/16" to fit at the cross
seams.

b. Folds required for this type of seam are
complicated. Form sheets on a brake as
indicated by roofing manufacturer.

3. Lay down battens which have been sized to match
original roof. Screw battens to roof deck,
matching center lines of original battens.

4. Nail cleats to vertical sides of battens, two nails
per cleat. Space cleats 12" on center the length
of each batten, placing cleats opposite on another.
Cleats shall extend 1" above the top of each
batten.

5. At valleys, drip edges and other special
conditions, sides of pans will require custom
fitting to provide proper seams. Consult
manufacturer for difficult situations. Sheet metal
used for valleys should be as long as possible to
reduce the number of cross seams.

6. Lay individual pans as directed by manufacturer.
Allow 1/16" space between vertical side of pan and
the batten. Fold seams as directed.

7. Form cross seams as directed above in 3.02.B.4.

8. If required to match color of original roof, paint
surface as directed below in D.

D. Painting terne-coated stainless steel roof after
completion of installation.

1. All surfaces must be clean and dry. DO NOT PAINT
OVER CONDENSATION.

2. Painting shall be done on a warm, dry day, when
both the roof surface and air temperature is
approximately 50 degrees F.

3. Apply one coat of primer made especially for terne.
Paint shall be brushed on to allow oil to
adequately penetrate and adhere to metal. Allow to
dry before applying finish coat.

4. Apply one top coat, using finish paint which has
been made to be used with selected primer. Top
coat shall be brush applied.

E. Roof Maintenance:

1. Whenever possible, make inspection from ground or
from above if possible.

2. Inspect ridge details and eaves for metal
punctures, and broken joints or seams. Inspect for
rust, excessive weathering or exposure, erosion, or
staining indicating overall deterioration.

3. Inspect the underside of the roof deck from the
attic to detect leaks. Flashings are the most
vulnerable points. Therefore, inspect the
underside carefully at all flashing points for
evidence of leakage such as water stains.

4. In addition to scheduled inspections, inspect after
each exposure to unusually severe weather
conditions such as strong winds, hail, or long
continuous rains.

5. Rinse dirt with water annually.

6. Keep the roof clear of debris, and trim all
overhanging branches that might cause mechanical
damage.

7. Inspect for and eliminate ant hills and/or bird
droppings which can corrode sheet metals.

8. Inspect the secureness of cleats and fasteners and
the condition of the sheet metal after particularly
heavy storms.


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