Columbus Ohio Home Inspection Pros ®
ROOFS
Roofs play a key role in protecting building occupants and
interiors from outside weather conditions, primarily
moisture. The roof, insulation, and ventilation must all
work together to keep the building free of moisture. Roofs
also provide protection from the sun. In fact, if designed
correctly, roof overhangs can protect the buildings exterior
walls from moisture and sun. The concerns regarding
moisture, standing water, durability and appearance are
different, reflected in the choices of roofing materials.
Maintaining Your Roof
Homeowner maintenance includes cleaning the
leaves and debris from the roofs valleys and gutters. Debris
in the valleys can cause water to wick under the shingles
and cause damage to the interior of the roof. Clogged rain
gutters can cause water to flow back under the shingles on
the eaves and cause damage. Whatever the roofing material
may be including composition shingle, wood shake, tile or
metal. The best way to preserve your roof is to stay off it.
Also, seasonal changes in the weather are usually the most
destructive forces.
There are two types of roofs, flat and
pitched (sloped). Most commercial, industrial, and apartment
buildings have flat or slightly sloping roofs. Most houses
have pitched roofs. Some roofers work on both types; others
specialize. Most flat roofs are covered with several layers
of materials. Roofers first put a layer of insulation on the
roof deck. Over the insulation, they then spread a coat of
molten bitumen, a tar like substance. Next, they install
partially overlapping layers of roofing felt, a fabric
saturated in bitumen, over the surface. Roofers use a mop to
spread hot bitumen over the surface and under the next
layer. This seals the seams and makes the surface
watertight. Roofers repeat these steps to build up the
desired number of layers, called plies. The top layer either
is glazed to make a smooth finish or has gravel embedded in
the hot bitumen to create a rough surface. An increasing
number of flat roofs are covered with a single-ply membrane
of waterproof rubber or thermoplastic compounds. Roofers
roll these sheets over the roofs insulation and seal the
seams. Adhesive, mechanical fasteners, or stone ballast hold
the sheets in place. The building must be of sufficient
strength to hold the ballast.
Most residential roofs are covered with shingles. To apply
shingles, roofers first lay, cut, and tack 3-foot strips of
roofing felt lengthwise over the entire roof. Then, starting
from the bottom edge, they staple or nail overlapping rows
of shingles to the roof. Workers measure and cut the felt
and shingles to fit intersecting roof surfaces and to fit
around vent pipes and chimneys. Wherever two roof surfaces
intersect, or shingles reach a vent pipe or chimney, roofers
cement or nail flashing-strips of metal or shingle over the
joints to make them watertight. Finally, roofers cover
exposed nail heads with roofing cement or caulking to
prevent water leakage. Roofers who use tile, metal shingles,
or shakes follow a similar process. Some roofers also
waterproof and damp proof masonry and concrete walls and
floors. To prepare surfaces for waterproofing, they hammer
and chisel away rough spots, or remove them with a rubbing
brick, before applying a coat of liquid waterproofing
compound. They also may paint or spray surfaces with a
waterproofing material, or attach waterproofing membrane to
surfaces. When damp proofing, they usually spray a
bitumen-based coating on interior or exterior surfaces.
A number of roofing materials are available...
Asphalt
Asphalt is the most commonly used roofing
material. Asphalt products include shingles, roll-roofing,
built-up roofing, and modified bitumen membranes. Asphalt
shingles are typically the most common and economical choice
for residential roofing. They come in a variety of colors,
shapes, and textures. There are four different types: strip,
laminated, interlocking, and large individual shingles.
Laminated shingles consist of more than one layer of tabs to
provide extra thickness. Interlocking shingles are used to
provide greater wind resistance. And large individual
shingles generally come in rectangular and hexagonal shapes.
Roll-roofing products are generally used in residential
applications, mostly for under layments and flashing's. They
come in four different types of material: smooth-surfaced,
saturated felt, specialty-eaves flashing's, and
mineral-surfaced. Only mineral surfaced is used alone as a
primary roof covering for small buildings like sheds.
Smooth-surfaced products are used primarily as flashing to
seal the roof at intersections and protrusions, and for
providing extra deck protection at the roof's eaves and
valleys. Saturated felt is used as an underlayment between
the roof deck and the roofing material. Specialty-eaves
flashing's are typically used in climates where ice dams and
water backups are common. Built-up roofing (or BUR) is the
most popular choice of roofing used on commercial,
industrial and institutional buildings. BUR is used on flat
or low-sloped roofs and consists of multiple layers of
bitumen and ply sheets. Components of a BUR system include
the roof deck, a vapor retarder, insulation, membrane and
surfacing material. A modified bitumen membrane assembly
consists of continuous plies of saturated felts, coated
felts, fabrics or mats between which alternate layers of
bitumen are applied, either surfaced or un-surfaced. Factory
surfacing, if applied, includes mineral granules, slag,
aluminum or copper. The bitumen determines the membrane's
physical characteristics and provides primary waterproofing
protection, while the reinforcement adds strength, puncture
resistance and overall system integrity.
Metal
Most metal roofing products consist of steel or aluminum,
although some consist of copper and other metals. Steel is
invariably galvanized by the application of a zinc or
zinc/aluminum coating, which greatly reduces the rate of
corrosion. Metal roofing is available as traditional seam
and batten, tiles, shingles, and shakes. Products also come
in a variety of styles and colors. Metal roofs with solid
sheathing control noise from rain, hail, and bad weather
just as well as any other roofing material. Metal roofing
can also help eliminate ice damming at the eves. And in
wildfire-prone areas, metal roofing helps protect buildings
from fire should burning embers land on the roof. Metal
roofing costs more than asphalt, but it typically lasts 2 to
3 times longer than asphalt or wood shingles.
Wood
Wood shakes offer a natural look with a lot
of character. Because of variations like color, width,
thickness, or cut of the wood, no two shake roofs will ever
be the same. Wood offers some energy benefits, too. It helps
to insulate the attic, and it allows the house to breathe,
circulating air through the small openings under the felt
rows on which wooden shingles are laid. A wood shake roof,
however, demands proper maintenance and repair, or it will
not last as long as other products. Mold, rot, and insects
can be a problem. The life cycle cost of a shake roof may be
high, and old shakes can't be recycled. Most wood shakes are
unrated by fire safety codes. Many use wipe or spray-on fire
retardants, which offer less protection and are only
effective for a few years. Some pressure-treated shakes are
impregnated with fire retardant and meet national fire
safety standards. Installing wood shakes is more complicated
than roofing with composite shingles, and the quality of the
finished roof depends on the experience of the contractor as
well as the caliber of the shakes you use. The best shakes
come from the heartwood of large old cedar trees, which are
difficult to find. Some contractors maintain that shakes
made from the outer wood of smaller cedars, the usual source
today, are less uniform, more subject to twisting and
warping, and don't last as long.
Concrete and Tile
Concrete tiles are made of extruded concrete
that is colored. Traditional roofing tiles are made from
clay. Concrete and clay tile roofing systems are durable,
aesthetically appealing, and low in maintenance. They also
provide energy savings and are environmentally friendly.
Although material and installation costs are higher for
concrete and clay tile roofs, when evaluated on a price
versus performance basis, they may out perform other roofing
materials. Tile adorns the roofs of many historic buildings
as well as modern structures. In fact, because of its
extreme durability, longevity, and safety, roof tile is the
most prevalent roofing material in the world. Tested over
centuries, roof tile can successfully withstand the most
extreme weather conditions including hail, high wind,
earthquakes, scorching heat, and harsh freeze-thaw cycles.
Concrete and clay roof tiles also have unconditional Class A
fire ratings, which means that, when installed according to
building code, roof tile is non-combustible and maintains
that quality throughout its lifetime. In recent years,
manufacturers have developed new water-shedding techniques
and, for high-wind situations, new adhesives and mechanical
fasteners. Because the ultimate longevity of a tile roof
also depends on the quality of the sub-roof, roof tile
manufacturers are also working to improve flashing's and
other aspects of the underlayment system. Under normal
circumstances, properly installed tile roofs are virtually
maintenance free. Unlike other roofing materials, roof tiles
actually become stronger over time. Because of roof tile's
superior quality and minimal maintenance requirements, most
roof tile manufacturers offer warranties that range from 50
years to the lifetime of the structure.
Concrete and clay tile roofing systems are
also energy efficient, helping to maintain livable interior
temperatures (in both cold and warm climates) at a lower
cost than other roofing systems. Because of the thermal
capacity of roof tiles and the ventilated air space that
their placement on the roof surface creates, a tile roof can
lower air conditioning costs in hotter climates and produce
more constant temperatures in colder regions, which reduces
potential ice accumulation. Tile roofing systems are made
from naturally occurring materials and can be easily
recycled into new tiles or other useful products. They are
produced without the use of chemical preservatives, and do
not deplete limited natural resources.
Single-Ply
Single-ply membranes are flexible sheets of
compounded synthetic materials that are manufactured in a
factory. There are three types of membranes: thermosets,
thermoplastics, and modified bitumen's. These materials
provide strength, flexibility, and long-lasting durability.
The advantages of pre-fabricated sheets are the consistency
of the product quality, the versatility in their attachment
methods, and therefore, their broader applicability. They
are inherently flexible, used in a variety of attachment
systems, and compounded for long lasting durability and
watertight integrity for years of roof life. Thermoset
membranes are compounded from rubber polymers. The most
commonly used polymer is EPDM (often referred to as "rubber
roofing"). Thermoset membranes make successful roofing
materials because they can withstand the potentially
damaging effects of sunlight and most common chemicals
generally found on roofs. The easiest way to identify a
thermoset membrane is by its seams, it requires the use of
adhesive, either liquid or tape, to form a watertight seal
at the overlaps. Thermoplastic membranes are based on
plastic polymers. The most common thermoplastic is PVC
(polyvinyl chloride) which has been made flexible through
the inclusion of certain ingredients called plasticizers.
Thermoplastic membranes are identified by seams that are
formed using either heat or chemical welding. These seams
are as strong or stronger than the membrane itself. Most
thermoplastic membranes are manufactured to include a
reinforcement layer, usually polyester or fiberglass, which
provides increased strength and dimensional stability.
Modified bitumen membranes are hybrids that incorporate the
high tech formulation and prefabrication advantages of
single-ply with some of the traditional installation
techniques used in built-up roofing. These materials are
factory-fabricated layers of asphalt, "modified" using a
rubber or plastic ingredient for increased flexibility, and
combined with reinforcement for added strength and
stability. There are two primary modifiers used today: aPP (atactic
polypropylene) and SBS (styrene butadiene styrene). The type
of modifier used may determine the method of sheet
installation. Some are mopped down using hot asphalt and
some use torches to melt the asphalt so that it flows onto
the substrate. The seams are sealed by the same technique.
Are You at Risk?
If you aren't sure whether your house is at
risk from natural disasters, check with your local fire
Marshall, building official, city engineer, or planning and
zoning administrator. They can tell you whether you are in a
hazard area. Also, they usually can tell you how to protect
yourself and your house and property from damage. Protection
can involve a variety of changes to your house and property,
changes that can vary in complexity and cost. You may be
able to make some types of changes yourself. But complicated
or large-scale changes and those that affect the structure
of your house or its electrical wiring and plumbing should
be carried out only by a professional contractor licensed to
work in your state, county, or city. One example is fire
protection, by replacing flammable roofing materials with
fire-resistant materials. This is something that most
homeowners would probably hire a contractor to do.
Replacing Your Roof
The age of your roof is usually the major
factor in determining when to replace it. Most roofs last
many years if properly installed and often can be repaired
rather than replaced. An isolated leak usually can be
repaired. The average life expectancy of a typical
residential roof is 15 to 20 years. Water damage to a homes
interior or overhangs is commonly caused by leaks from a
single weathered portion of the roof, poorly installed
flashing, or from around chimneys and skylights. These
problems do not necessarily mean you need a new roof.
Fire-Resistant Materials
Some roofing materials, including asphalt shingles and
especially wood shakes, are less resistant to fire than
others. When wildfires and brush fires spread to houses, it
is often because burning branches, leaves, and other debris
buoyed by the heated air and carried by the wind fall on
roofs. If the roof of your house is covered with wood or
asphalt shingles, you should consider replacing them with
fire-resistant materials. You can replace your existing
roofing materials with slate, terra cotta or other types of
tile, or standing-seam metal roofing. Replacing roofing
materials is difficult and dangerous work. Unless you are
skilled in roofing and have all the necessary tools and
equipment, you will probably want to hire a roofing
contractor to do the work. Also a roofing contractor can
advise you on the relative advantages and disadvantages of
various fire-resistant roofing materials.
Hiring a Licensed Contractor
One of the best ways to select a roofing contractor is to
ask friends or relatives for recommendations. You may also
contact a professional roofers association for referrals.
Professional associations have stringent guidelines for
their members to follow. The roofers association in your
area will provide you with a list of available contractors.
Follow these guidelines when selecting a contractor...
- Get three references and review past work
- Get at least three bids.
- Get a written contract and don't sign anything until you completely understand the terms.
- Pay 10 percent down or $1,000 whichever is less.
- Don't let payments get ahead of the work.
- Don't pay cash.
- Don't make final payment until you're satisfied with the job.
- Don't rush into repairs or be pressured into making an immediate decision
You've Chosen the Contractor... What About the Contract?
Make sure everything is in writing. The
contract is one of the best ways to prevent problems before
you begin. The contract protects you and the contractor by
including everything you have both agreed upon. Get all
promises in writing and spell out exactly what the
contractor will and will not do.
...and Permits?
Your contract should call for all work to be
performed in accordance with all applicable building codes.
The building codes set minimum safety standards for
construction. Generally, a building permit is require
whenever structural work is involved. The contractor should
obtain all necessary building permits. If this is not
specified in the contract, you may be held legally
responsible for failure to obtain the required permit. The
building department will inspect your roof when the project
has reached a certain stage and again when the roof is
completed.
...and Insurance?
Make sure the contractor carries workers
compensation insurance and general liability insurance in
case of accidents on the job. Ask to have copies of these
policies for your job file. You should protect yourself from
mechanics lien against your home in the event the contractor
does no pay subcontractors or material suppliers. You may be
able to protect yourself by having a release of lien clause
in your contract. A release of lien clause requires the
contractor, subcontractors and suppliers to furnish a
certificate of waiver of lien. If you are financing your
project, the bank or lending institution may require that
the contractor, subcontractors and suppliers verify that
they have been paid, before releasing funds for subsequent
phases of the project. A leaky roof can damage ceilings,
walls, and furnishings. To protect buildings and their
contents from water damage, roofers repair and install roofs
made of tar or asphalt and gravel; rubber or thermoplastic;
metal; or shingles made of asphalt, slate, fiberglass, wood,
tile, or other material. Roofers also may waterproof
foundation walls and floors.
Keep these points in mind if you plan to have your
existing roofing materials replaced:
- Tile, metal, and slate are more expensive roofing materials, but if you need to replace your roofing anyway, it may be worthwhile to pay a little more for the added protection these materials provide.
- Slate and tile can be much heavier than asphalt shingles or wood shingles. If you are considering switching to one of these heavier coverings, your roofing contractor should determine whether the framing of your roof is strong enough to support them.
- If you live in an area where snow loads are a problem, consider switching to a modern standing-seam metal roof, which will usually shed snow efficiently.
Contents
PATCH
Independent Home Inspections, LLC
Serving Columbus and Central Ohio
Rick A. Harrington
13514 Falmouth Ave
Pickerington, Ohio 43147
(614) 565-4962
(614) 768-1190 fax
Home Inspections
Thermal Imaging (Infrared)
