Transcript Unit 1 Intro To Single-Ply

UNIT 1
SINGLE-PLY
ROOFING
INTRODUCTION
INTRODUCTION TO
SINGLE-PLY ROOFING
When you complete this unit, you will be able
to:
1. Explain what single-ply roofing is.
2. Describe the advantages and disadvantages
of single-ply roofing.
3. Look up the features of a single-ply material.
4. Discuss the three factors that ensure your
safety.
SINGLE-PLY ROOFING
Single-ply roofing is any roofing system that uses
only one layer of roofing material instead of builtup layers. You may have worked on a single-ply
roofing job or have seen the material.
All single-ply systems must provide three basic
qualities:
• Waterproofing
• Strength
• Surface protection
SINGLE-PLY ROOFING
Waterproofing is provided by the roof
membrane.
SINGLE-PLY ROOFING
Strength is usually provided by a reinforcement
scrim (a mat of fiberglass, polyester, etc.)
embedded in the membrane. It makes the
membrane stronger, resists punctures, keeps it
from cracking, and helps the membrane expand
and contract.
SINGLE-PLY ROOFING
Surface protection is provided by some material
applied to the membrane. A surfacing can be a
coating applied in the factory, or it can be a
coating or a ballast (such as rock or pavers)
applied in the field.
SINGLE-PLY ROOFING
Surfacing's have several purposes:
• Protect the roof from the weather and ultraviolet rays
of the sun.
• Protect the roof from foot traffic.
• Extend the life of the membrane.
• Improve appearance of the roof.
• Hold down the membrane and insulation.
• May be fire resistant.
• May reflect heat.
Membrane
The membrane is a sheet of single-ply roofing.
(Membrane means a pliable sheet.) Different
materials are used for the membrane.
Membrane
Membranes should have these features:
• Good appearance
• High tensile strength (resistance to pulling
apart)
• Flexibility
• Long life
• Easy maintenance
Membrane
Membranes must be able to:
• Adjust to building movement.
• Expand and contract with temperature
changes.
• Hold up under aging and temperature
extremes.
• Resist weathering.
Membrane
Membranes must be able to:
• Resist the effects of ozone and ultraviolet rays.
(Ozone is a form of oxygen that can be damaging.
Ultraviolet (UV) rays from the sun shorten the life
of the membrane.)
• Resist becoming brittle at very low outdoor
temperatures.
• Resist tearing.
Size and Thickness
The membrane may range from about 40 mils to 120 mils
thick. The most common sizes are 45, 60, and 90 mils. A
mil is 0.001” (one thousandth of an inch). Because
membranes are relatively thin, mils are easier to use than
fractions of an inch. The comparison below will give you
an idea of mil thicknesses:
• 45 mils- Slightly over 1/32” (about as thick as a dime)
• 60 mils- 1/16” (about as thick as a nickel)
• 120 mils- Almost 1/8”
Size and Thickness
Membranes are usually applied in sizes as large
as is practical to handle. This reduces the
number of seams (which cuts clown labor costs)
and reduces the chance of leaks.
Common sizes are 6 to 50 feet wide and 100 feet
long. Some membranes are up to 250 feet long.
ADVANTAGES
Single-ply roofing has many advantages:
• May be lighter than built-up roofing. May sometimes be
laid over the existing roof, avoiding the cost of removing
the old roof.
• Easier to work with: Less material to haul up to the roof. No
hot bitumen and kettle to handle. Fewer seams to seal.
• Expands and contracts more easily. Flexible with
temperature changes and movements of the building.
• Attractive: Comes in different colors.
• Adapts to any shape of roof.
DISADVANTAGES
Single-ply roofing has these disadvantages:
• Products and installation methods change often
because manufacturers are constantly improving
the products and methods.
• Some products are not yet time-tested.
• Some membranes are damaged by grease, oil,
asphalt, tar, etc. The designer and the roofer
must know what materials will damage a
product.
DISADVANTAGES
• Damage to a new roof by other crafts is a
constant problem. Any puncture will cause a leak.
• Some systems have to be installed at a certain
temperature range.
• Shrinkage can cause damage at base flashings .
• Some membranes and materials have a short
shelf life.
DISADVANTAGES
• Many solvents and adhesives are a fire hazard
or health hazard.
• Leaks are difficult to find, especially on
ballasted systems.
• The system is unforgiving. The seams are the
only barrier against moisture, so they have to
be done right the first time.
Wind and Air Pressure Danger
Other wind conditions have to be considered.
The taller the building, the more the speed and
direction of the wind on the roof can vary. The
building location (for example, among tall
buildings or surrounded by hills) affects wind
patterns.
Wind and Air Pressure Danger
The building structure is also a factor. For
example, the corners of a roof have a high wind
uplift because a partial vacuum is created at the
edge, especially if there is a parapet wall. The
higher the parapet wall, the stronger the
negative pressure.
Wind and Air Pressure Danger
Air pressure from below can also be a problem.
For example, if a building has large overhead
doors, when the doors are opened, air pressure
may rush into the building and put pressure on
the underside of the roof membrane.
It could be enough to raise the membrane and
damage it, causing leaks.
MATERIALS
The materials used for single-ply roofing
membranes are complex chemicals with
confusing names. You will use a trade term, such
as TPO or EPDM. After you use these products a
few times, their names will be as familiar as any
other material you use regularly.
MATERIALS
There are three categories of single-ply roofing
materials:
• Elastomers
• Thermoplastics
• Modified bitumens
Elastomers
Elastomers have elastic, rubber-like qualities.
There are two types-cured and uncured:
• Cured elastomers cannot be formed. They are
generally used for the field membrane.
• Uncured elastomers can be formed. They are
generally used for detailing.
Thermoplastics
A thermoplastic becomes soft when heated and
can be hot-air welded. It can be reshaped as
needed for detailing. Hot-air welding fuses
membranes together.
Modified Bitumens
Modified bitumens are asphalt sheets modified
with plastics or rubber. Chemically, they are
quite different from elastomers or
thermoplastics.
However they are generally classed with singleply membranes. Modified bitumens are
generally applied by torch or with hot asphalt.
Some are self-adhered.
MANUFACTURED PRODUCTS
The products used in single-ply roofing are
known by a trade name, such as Sure-Seal or
Ultra-Ply, or by the initials of the chemical name,
such as PVC (polyvinyl chloride) or TPO
(thermoplastic polyolefins).
MANUFACTURED PRODUCTS
Products based on the same chemical may be
similar, but they are not exactly alike. Every
manufacturer uses slightly different processes
and chemicals for membranes. Each product has
different features and different installation
methods.
MANUFACTURED PRODUCTS
For example, the EPDM mernbrane from one
company has a workable temperature range
"above 40°F." The EPDM from another company
has a workable temperature range "from 20°F to
120°F.“
Whenever you install a new material, consult
the instructions and specifications.
MANUFACTURED PRODUCTS
Since single-ply is constantly developing, the list
of membranes being used will continue to
change.
A reinforcement scrim is sometimes laminated
to the membrane or embedded in it. Common
reinforcement materials are polyester fibers or
fiberglass.
MANUFACTURED PRODUCTS
Surfacing may be applied in the factory or in the
field. Factory-applied surfacings may be such
things as:
• Liquid coating
• Embedded granulated minerals
• Laminated metal foil
MANUFACTURED PRODUCTS
Field-applied surfacings may be such things as:
• Ballast (rock or pavers)
• Mineral granules
• Liquid coating
Learning About Products
Internet
Manufacturers have web sites that describe
their products.
SAFETY AND HEALTH
The most important subject in your training is
safe working practices. If an accident leaves you
handicapped or dead, all your skill as a roofer
means nothing. And it can happen to YOU in one
second.
SAFETY AND HEALTH
Roofing is one of the most dangerous trades. It
is always among the ten industries with the
highest accident rates. The odds are against you
unless you work to change them for yourself.
Look at four other roofers on the job.
Statistics say that you or one of these four will
be injured on the job this year. That is 1 in 5very bad odds-and only you can change them.
SAFETY AND HEALTH
Because safety is so important, it is repeated
throughout your apprentice training.
Safety will be taught whenever it applies to a
particular process.
SAFETY FACTORS
Safety is not a set of rules you learn in class. A
book can only give you information about
accidents. This does not make you safe. SAFETY
IS YOU.
Unless you make safety a way of life, neither you
nor those working near you w ill be free from
the danger of sudden death or injury.
SAFETY FACTORS
To work safely, you must practice three things:
• An ATTITUDE of safety.
• A KNOWLEDGE of safety.
• A DECISION to work safely.
An Attitude of Safety
You can read the safety rules in this unit and say,
"Uh-huh, that's great“ and then forget about them.
Or you can change those 1 in 5 odds for yourself:
• Think about safety rules when they are taught so
that you know a hazard when you see it.
• Think ahead of the job for potential safety
hazards.
An Attitude of Safety
• Refuse to take a risk to save a few minutes. Take time
to get safety goggles. Wear a respirator or fall
protection when needed. Don't take a shortcut if it is
risky.
• Remember that routine jobs and boredom are
accidents ready to happen. Don't let your mind
wander.
Your body is the only one you've got. Taking even a slight
risk to save a few minutes is just plain stupid. You may
have to pay for it the rest of your life.
A Knowledge of Safety
You have to know the hazards on the job so that
you can protect yourself. For example, if you
know that a high wind can balloon a loose
membrane and throw you off a roof, you can
protect yourself against it happening to you.
Learn the hazards of every operation you do.
A Decision to Work Safely
A decision to work safely means that you make
up your mind to work safely and demand safe
working conditions.
It means that you are not going to be "one of
the guys" and go along with dangerous work
practices just because some others on the job
are doing it.
A Decision to Work Safely
It is easier now to work safely. In the old clays
safety was not enforced. Anyone who wore a
respirator or safety goggles was considered soft.
Today almost everyone recognizes that it is plain
good sense to work safely.
A Decision to Work Safely
But some of the old mind set is still around.
Suppose you are working with a crew on a day
when the wind begins to be dangerous. Most
workers will hesitate to be the first one to
question whether it is safe to work.
This is when you need determination.
A Decision to Work Safely
Sometimes it takes guts to stand up to your
employer. Most employers want you to work
safely because they care about their employees
and because accidents are costly.
A Decision to Work Safely
Every accident costs them money in lost time
and in higher insurance rates. But there are still
some employers who would rather save a few
dollars on safety and let their employees take
the risks.
This is less common on union jobs because the
union enforces safety rules where needed.
A Decision to Work Safely
If there is a safety problem on the job, go to
your supervisor first. Employers do not always
know all the job conditions.
Sometimes even the employer who means well
will let unsafe conditions develop. In such cases,
you must decide to have unsafe conditions
corrected before you continue work.
A Decision to Work Safely
You can count on your union to back you to
correct a legitimate safety hazard. In some
areas, labor-management health and safety
committees address these issues.
A Decision to Work Safely
You are responsible to work safely. If you are
injured because the employer is at fault, the
employer is legally responsible. However, you
are also morally responsible.
You must be determined to work safely. Nobody
will take care of you better than you can.
Acts of God
Some accidents are classified as "Acts of God."
These are accidents that no one could have
prevented, like an earthquake. But most accidents
are caused by people. Being struck by lightning
could be called an act of God.
However, if you were foolish enough to be working
on a wet roof during a lightning storm, you can't
put the blame on God.
COMMON HAZARDS
Some safety hazards are common to all roofing
work. They are covered in the Roofers Safety
and Health Manual and in other parts of your
apprentice training. You always have to be
aware of these dangers.
Single-ply, especially thermoplastic, can be
slippery when wet or icy, so it is a special hazard
for falls.
Falls through Roof Openings
Before roofing is started, you and your foreman
must see to it that all roof openings are
adequately guarded or covered. Falls through
openings are the second leading type of falls,
next to falls from roof edges.
Falls through Roof Openings
If a roof opening does not have a guardrail around
it, it must be covered.
Don't be tempted to use a makeshift cover if the
proper material is difficult to get.
Covering an opening with a makeshift cover is as
bad as leaving it uncovered. A worker will step on
the makeshift covering, expecting it to carry weight,
and fall through.
Falls through Roof Openings
Laying a membrane over an uncovered opening
is setting someone up for a fall. If a membrane
must be laid over an uncovered opening, cut it
immediately and guard the opening.
Falls Through Skylights
Glass or plastic skylights will not hold a person's
weight. Roofers have leaned or sat on skylights
and have fallen through.
Skylights must be guarded.
Never walk backward near a skylight.
Falls from the Edge of a Roof
Falling off the edge of the roof is one of the
most common accidents for roofers. On low
slope roofs (where single-ply is usually installed),
it is very easy to trip and fall from the building.
Falls from the Edge of a Roof
Follow these personal safety practices:
• Never walk backwards within 10 feet of the
roof edge.
• Never operate mechanical equipment outside
the warning lines.
• Keep the area free of tripping hazards.
Falls from the Edge of a Roof
Warning lines must be
installed at roof
perimeters where there
are no guardrails or
where the parapet wall
is not the required
height.
Falls Caused by Wind
Wind is a special hazard with single-ply
membrane. The membrane will act as a sail if
the wind gets under a large area of it.
For example, it is not uncommon to have a piece
20' x 1 00‘ or larger spread out on the roof. If a
high wind gets under it, it can easily carry
workers and material off the roof.
Falls Caused by Wind
The only safe practice is not to work with loose
membranes under very windy conditions. Be
aware of the dangers of wind as you work with
membrane that is not yet attached or weighted
down.
Falls Caused by Wind
On a day with even a slight wind, weight down
the edges of a loose membrane to prevent the
wind from getting under it. If wind speed rises
when you are working on a roof use enough
ballast to hold the membrane down.
Falls Caused by Wind
If you are carrying insulation boards near the
roof edge, a strong wind can blow you off the
roof. A piece of insulation blown across the roof
by the wind can knock you off the roof.
Handling Membrane Rolls
A roll of membrane is long and heavy-it can
weigh as much as 2800 pounds. Save your body
from injury by following safe working practices.
Never try to move a roll by yourself. It requires
several workers even to roll it. Plan your moves.
Handling Membrane Rolls
Use equipment to do most of the moving:
• Have the membrane hoisted and placed on the roof so that
moving it by hand is kept to a minimum.
• Make sure the material is placed over secure supports.
• Use equipment to move the roll as close to the final
position as possible in order to avoid moving the roll by
hand.
• Use a roll mover to move the roll on the roof.
• To move a roll a small amount, use several workers to
either roll it, or pivot it on a block.
Handling Membrane Rolls
After a membrane is unrolled and approximately
positioned, it can be moved slightly if a number of
roofers hold the edge and flap it slightly. This puts
air under the membrane and it can be easily moved
to the final position.
CAUTION: If this is done on a windy clay, the
membrane can become a sail and get out of
control.
HAZARDOUS MATERIALS
There are two important things to understand
about hazardous materials:
• The hazards vary considerably with different
products.
• Hazards can be short term (acute) or long term
(chronic). You may not notice any effects when
you are working with a material, but you could be
disabled from it 5, 10, or 20 years later.
HAZARDOUS MATERIALS
Each single-ply product has different hazards.
New products are being developed constantly.
Each new product has a different set of safety
practices.
However, the general trend with new products is
toward materials that are safer-for both the
person and the environment.
HAZARDOUS MATERIALS
The labels on adhesives, solvents, and other
materials contain safety information. They
inform you of the hazards of the material and
how it should be handled to avoid the hazards.
Check each product for specific safety practices.
For example, for many adhesives and solvents,
gloves must be worn, but the type of glove
required will vary with the product being used.
HAZARDOUS MATERIALS
You can get more information from a material
safety data sheet (MSDS). This is an information
sheet about hazards and safe handling practices.
OSHA requires your employer to have an MSDS
for every hazardous product on the job. If you
have questions about the safety of a product,
you have a right to see the MSDS.
Solvents
Solvents are chemicals that dissolve other
materials. The common danger with solvents is
that they evaporate very quickly, so they release
a large amount of vapor into the air. Most of
these vapors are toxic and highly flammable.
Solvents
Consider all liquids and adhesives used in singleply work dangerous because almost all contain
solvents, including:
• Cleaners
• Primers
• Splice adhesives
• Bonding adhesives
Solvents
Short term (acute) effects-such as dizziness,
lightheadedness, a feeling of being high,
headache, nausea, vomiting, coughing, and lack
of concentration-are the result of breathing so
lvent vapors.
Solvents
Long term (chronic) effects can result from repeated exposures.
They can include damage to kidneys, liver, and blood. Some
solvents can cause such conditions as:
•
•
•
•
•
Cancer
Liver damage
Reproductive problems
Impaired use of legs and arms
Lack of coordination and
alertness
• Loss of memory and mental
abilities
• Depression
• Loss of sleep
• Skin problems
Solvents
Assume that solvent vapors are heavier than airmost of them are. This means that they will
settle in areas without sufficient ventilation.
Vapors are especially hazardous along a parapet
wall, in an excavation, or in other spaces that
are not easily ventilated.
Solvents
But vapors are also a hazard on an open roof on
a still day or when you work very close to them,
as when you install flashings. A build-up of
vapors means danger from inhaling vapors and
danger from the vapors catching fire.
Solvents
Follow these safety measures:
• Work upwind of vapors.
• Use a medically-approved respirator in a confined
area.
• Eliminate all sources of spark or fire. There have
been cases where solvent vapors ignited and the
fire carried along the seams and under the
membrane to ignite the entire roof.
Solvents
• Wear gloves- most single-ply solvents are
harmful and can be absorbed through the
skin. Check the label or the MSDS for the
proper type of glove to use. Each solvent is
different and requires a particular type of
glove material.
• Keep solvents in approved, covered
containers, and store them in a safe area.
Solvents
• In the work area, have only small amounts of
solvent in dispenser cans. This reduces the
amount of vapors and limits the amount of fuel in
case of a fire.
• Store solvent-soaked rags in a tightly covered
container. If solvent- soaked rags are exposed to
the oxygen in the air, they can ignite
spontaneously.
Personal Protective Equipment (PPE)
Too much sun can cause skin cancer. That's why
you should wear a long-sleeved shirt and a hat.
Long sleeves also protect your skin from the
various solvents and adhesives you will be using.
Sun screen or sun block can protect your skin
from the sun.
Personal Protective Equipment (PPE)
Because light colored membranes reflect so
much light, wear good tinted safety glasses that
are UV rated to protect your eyes.
Personal Protective Equipment (PPE)
You should use gloves and a respirator when
working with single-ply adhesives and primers.
When needed, respirators and special gloves are
supplied by the contractor.
The contractor must supply the proper type of
respirator or gloves required for the hazard.
Personal Protective Equipment (PPE)
OSHA has strict rules on the use of respirators.
Respirators must be certified by NIOSH (National
Institute for Occupational Safety and Health)
and must be chosen and used according to the
limitations printed on the NIOSH-certification
label.
Personal Protective Equipment (PPE)
At a minimum, the employer is required to:
• Make sure the employee is medically approved
for using a respirator.
• Have each employee fitted properly and trained
to use the respirator.
• Supply the proper type of respirator for the
hazard.
• Have a written policy on choosing and
maintaining respirators.
Fire Hazards
Modified bitumens sometimes require the use of an
LP (liquid petroleum) gas torch. The heat of LP
flames is over 2,000°F, so fire is a serious hazard.
Too much flame can cause the modified bitumen to
burn.
Fires often start around roof vents or in hidden
spots in the roof, such as behind wall flashings.
Natural gas lines on the roof can be a fire hazard.
Fire Hazards
Kitchen exhaust vents often have cooking grease
coating the duct and the roof around the vent. A
flame in this area can cause a flash fire that will
travel clown the duct and through the building.
Fire Hazards
Vents for clothes dryers often have lint coating
the inside of the exhaust duct and the roof
around the vent. This is especially true in dry
cleaning and laundry buildings. Here too a torch
can cause a fire that will travel into the building.
Fire Hazards
Fire can start in hidden places such as in the
insulation boards or under a cant strip. It can
smolder for hours and suddenly burst into flame
after everyone has left the job.
Therefore torching is not allowed over tectum or
wood deck or other combustible materials. A
thermal barrier must be installed before
torching.
Fire Hazards
No flame is allowed around single-ply adhesives
and solvents. Adhesives give off flammable
vapors that can catch fire and ignite the entire
roof.
When membranes must be heated, they must
always be heated with an electric hot-air gun.
Fire Hazards
A gas torch can be a real fire hazard. Anyone using this
equipment must know how to handle it properly. The
proper care and use of the LP gas torch and tank is
covered elsewhere in the training program.
A certification program for the safe and proper
application of modified bitumens may be required by
some insurance companies. Don't handle torching
equipment until you are trained to do it properly.
Fire Hazards
Fire extinguishers should always be available on
the roof while any torching is going on. The fire
department may be called even if a fire has
been put out with a fire extinguisher.
The fire department can make sure that no
hidden fire is still smoldering.
Fire Hazards
A fire watch should be on duty for at least two
hours after the last torch is turned off, to
examine the area for hot spots and make sure
no fire will break out.
INTRODUCTION TO
SINGLE-PLY ROOFING
QUIZ