Flat Roof Information. A flat roof is a kind of shielding for any building. A flat roof is horizontal or close to horizontal in comparison to the more sloped variety of covering. Roofs that are nearly flat are classified as low-pitch roofs (because the angle of slope rises, therefore, the pitch is said to increase): Typically the slope of your roof is properly termed its pitch.
Each location around the globe have their own tradition or preference regarding products used for flat roofs. A few flat roofing product options include felt, asphalt or bitumen. A flat roof might possibly be covered with roofing shingle or possibly converted to a green rooftop. It may be sealed using a cold applied water-resistant coating or it can becovered with a single ply membrane layer on the whole created from a synthetic polymer that’s been intended to resist weathering, chemical oxidation and UV radiation and to preserve its physical attributes over a variety of temperatures.
Each time a leak does start on a flat roof covering then damage mostly goes unnoticed for very long time frames during which water seeps and soaks the decking and any insulation and/or structure under it. The rot which normally develops and if allowed to remain can potentially weaken the roof structure may lead to costly repairs. Although a argued point, additionally there are various sorts of health risks to those people and animals breathing in the mould spores.
Perhaps the biggest issue with flat roof repair is not generally picking out the product for your weatherproof covering, but detecting the reasons why it leaked at the outset. A great many British flat roofs are too flat and they sag in the middle because they have been constructed with weak structural products, so that allows rainwater to pond, which in turn finds its way through any pinprick imperfection. Whenever water does permeate the barrier covering (be it traditional or a modern membrane layer) it may travel a long way before creating recognizable damage or leaking straight into a property where it can be seen. As a result it is tough to determine where its leaking so that you can repair it.
The upkeep of your flat roof is usually proportional to its life-span. ten years can be the average life-cycle, although this is determined by the type of flat roof system set up.
Additional flat surfaces including balconies have got similar problems to flat roofing and tend to be handled in a similar fashion. Anti slip flooring or slip resistant flooring should also be thought about when deciding on a flooring area.
It’s worth getting suggestions from a specialized roofing contractor about flat roofing selections even if you opt to do the job by yourself. Having a flat roof is a good alternative over having peaked roofs.
Asphalt Shingles Types and Use. Two types of asphalt shingles are used: organic and fiberglass or glass fiber. Organic shingles are generally paper (waste paper) saturated with asphalt to make it waterproof, then a top coating of adhesive asphalt is applied and ceramic granules are then embedded. In the case of algae-resistant shingles, a portion of the granules contain leachable copper ceramically coated, designed to protect against discoloration from algae on the roof. This does not protect from moss growth but does slow the growth. Moss feeds on algae and any other debris on the roof. Most manufactures offer a 5- to 10-year warranty against algae growth.
Shingles are judged by warranty and ASTM test standards. Organic shingles contain around 40% more asphalt per square (100 sq ft.) than fiberglass shingles. But this extra needed asphalt makes them less environmentally friendly. The paper-based nature of “organic” shingles leaves them more prone to fire damage, and their highest FM rating for fire is class “B”. Shingle durability is ranked by warranted life, ranging from 20 years to 50 years; in some cases lifetime warranties are available.
Fiberglass shingles have a base layer of glass fiber reinforcing mat. The mat is made from wet, random-laid fiberglass bonded with urea-formaldehyde resin. The mat is then coated with asphalt which contains mineral fillers and makes the fiberglass shingle waterproof. Fiberglass shingles typically obtain a class “A” fire rating as the fiberglass mat resists fire better than organic/paper mats. Fiberglass reinforcement was devised as the replacement for asbestos paper reinforcement of roofing shingles and typically ranges from 1.8 to 2.3 pounds/square foot.
The older organic (wood and paper pulp product) versions were very durable and hard to tear, an important property when considering wind uplift of shingles in heavy storms. Fiberglass is slowly replacing felt reinforcement in Canada and has replaced mostly all in the United States. Widespread hurricane damage in Florida during the 1990s prompted the industry to adhere to a 1700-gram tear value on finished asphalt shingles.
A newer design of fiberglass asphalt shingle, called laminated or architectural, uses two distinct layers which are bonded together with asphalt sealant. Laminate shingles are heavier, more expensive, and more durable than traditional 3-tab shingle designs. Laminated shingles also give a more varied, contoured visual effect to a roof surface.
Traditionally, asphalt — also called composition — shingles were made by saturating a heavy layer of building felt (made from organic fibers) with asphalt. These asphalt-felt shingles have largely been supplanted by fiberglass-based shingles. Instead of building felt, they have a fiberglass base impregnated with the asphalt. These shingles are more durable and will last twice as long as the felt-based shingles. In addition to the asphalt coating, the shingles also have a layer of ceramic and hard mineral granules. This layer adds color to the roofing material, but its main function is to protect the asphalt base from the intense ultraviolet radiation of the sun. The asphalt-saturated base is relatively impervious to rain and snow, but without the mineral coating it would quickly break down when exposed to the sun.
People assume that most roof damage comes from the wind, rain and snow. Indeed, these elements eventually erode the granular coating from the shingles, but it is the intense heat of the sun that does the real damage. Thus the longevity of the roof covering is often determined by the amount of sunlight it is exposed to. On many houses the shingles on the northern side of the roof last longer than those on the southern side, because they receive less sunlight. For the same reason, houses in the Southern states usually need roof replacement before those in the Northern states.
Other than planting shade trees near the house, there is little you can do to shield your roof from the sun. You can, however, make sure that the attic remains cool so that heat cannot rise through the sheathing to attack the shingles. The best way to do this is by installing vents in the attic. Adding soffit and ridge vents, for example, will allow cool air to enter under the eaves, flow along the underside of the roof and exit at the peak. This circulating air can lower roof temperatures by up to 20 degrees.
The protective nature of asphalt shingles primarily comes from the long-chain hydrocarbons impregnating the paper. Over time in the hot sun, the hydrocarbons soften and when rain falls the hydrocarbons are gradually washed out of the shingles and down onto the ground. Along eaves and complex roof lines more water is channeled so in these areas the loss occurs more quickly. Eventually the loss of the heavy oils causes the fibers to shrink, exposing the nail heads under the shingle flaps. The shrinkage also breaks up the surface coating of sand adhered to the surface of the paper, and eventually causes the paper to begin to tear itself apart. Once the nail heads are exposed, water running down the roof can seep into the building around the nail shank, resulting in rotting of roof building materials and causing moisture damage to ceilings and paint inside.
Asphalt Shingle Burn Out. ACCELERATED ASPHALT SHINGLE “BURN OUT” LEADS TO LEAKAGE ON ROOF RIDGES
Have you ever wondered why hip and ridge asphalt shingles burnout faster along the ridge of the roof than shingles made from the same material on the rest of the roof? The explanation is less obvious than you might think. The asphalt shingles at the roofs’ peak, its ridge line, are being actively destroyed, even during cold winter months, from heat and moisture build-up inside an un-ventilated or poorly vented attic.
As we all know, heat rises. In this case, to the highest point of the attic, right below the ridge line. And it is here that the heat attempts to escape particularly in today’s more tightly constructed homes. The attic in earlier architectural styles was draftier and less energy-efficient than now. Unlike summer’s hot sun, winter provides a different source of destructive heat. Heat from the homes interior rises into the attic, taking with it water vapor, the unnoticeable consequence of such everyday water-related activities as bathing, washing dishes or doing the laundry.
When an inadequately ventilated attic allows this warm, moist air to accumulate, deterioration of asphalt shingles and even of wooden roof structures is the inevitable result. If winters’ less obvious destructive effects are then added to pre-existing burned-out asphalt shingles along the ridge line, your customer can expect either a long, cold winter or higher heating bills than necessary.
Here’s why. After warm, moist air rises into the attic, it cools, releasing its moisture as condensation, which settles into attic insulation. It doesn’t take much moisture to impair the efficiency of attic insulation. In fact, with only a 1% moisture content, insulation loses 36% of its R-value. During winter decreased R-value means increased heat loss from the home. Because the function of attic insulation in winter months is to help keep the homes’ interior warm and comfortable, heat that escapes through insulation is gone forever. Attracted to the cooler roof sheathing and then to the even colder outside air, heat never re-enters the homes’ interior… a chilly prediction for the owners of unventilated or inadequately vented attics.
High heat, whether from outside or inside, will bake the oils right out of petroleum-based asphalt shingles, shortening the warranty period of products intended to last many years longer than they actually do. There’s no way to prevent exposure to the natural forces of sun, wind, rain or snow but you can vastly reduce premature aging of asphalt shingles by providing good attic ventilation on your customers roof, whether new construction or retrofit.
According to university studies, ventilation is most efficient at the ridgeline where heat normally collects. Old-fashioned turbine vents, for instance, are not only less efficient because of where they’re installed but suffer from homeowner dissatisfaction as well. Owners of turbine vented roofs often regard their whirlybirds as necessary evils, but also complain of the noise, leakage and stark unattractiveness associated with using them. Many people, though, including a number of roofing contractors, still don’t realize how much damage attic heat can inflict on an asphalt shingle roof, a fact that has not been lost on regulatory agencies and corporate executives. This is why the Uniform Building Code requires adequate attic ventilation and so do the warranties of every manufacturer of asphalt shingles. In other words, if you install an asphalt shingle roof without the question of attic ventilation being asked or answered you may as well throw out the manufacturer’s warranty along with the shingle wrappers.
In the long run, a cooler, drier attic helps preserve the life of asphalt shingle roofs but what about short term benefits? Of these, the most important is customer comfort. Not only is venting through the ridge the natural way to ventilate the attic, it is also the most cost-effective. Your customer’s home stays warmer during the winter so heaters and furnaces aren’t turned on as soon in the day or left on for as long, resulting in lower utility bills. But what about curb appeal. Sales figures confirm the popularity of texture and dimensionality among homeowners who select designer premium shingle roofs, a feature no less sought-after on the hips and ridges of the roof. But since none of the dimensional hip and ridge shingles also vent the attic space, they’re especially vulnerable to early burnout.
To satisfy the attic ventilation requirements set by the UBC, your customer’s roof should be installed in accordance with a ratio of one foot net free ventilation for every 150 feet of attic space. For example, a single story 2,500 square foot house with 130 feet of ridge would need 16 square feet of net free ventilation… the equivalent of 20 turbine vents or 128 feet of through-the-ridge venting.
With the winter season almost upon us it is time to discuss the re-occurring ice dams that frustrate many home owners. So lets start with the educational segment first.
Ice Dams are created when you have fairly large snowfall and the snow melts and re-freezes before being channeled away from your roof. This is usually caused by a warmer roof surface than the exterior temperature. This simply means that the temperature of your shingles is slightly above freezing when the outside temperature is below freezing. The “warmer” your roofs temperature is translates to larger ice dams. Non-functioning eaves troughs can also cause ice dams on your roof. Improper pitch or blockage due to debris etc will cause the appearance of ice dams. If you see heating cables on eave of roof it is a pretty good indicator that there is a problem with insulation or ventilation.
Poor ventilation and insulation is the common cause of most ice dams and is the culprit for creating a “warm” roof in the winter months. Heat escapes from your heated living space and gathers in your attic. (Remember heat rises) Poor ventilation does not allow for the removal of this heat which remains trapped in your attic.
So now we have the 3 basic requirements to start building our ice dam. In review they are:
1. Snowfall
2. Heat leaking into attic area.
3. Poor ventilation allows accumulation of heat in attic.
We are going to address the heat leaking into your attic and then the poor ventilation.
Insulation
During most of my inspections in the Barrie, ON area I have come to notice one insulation deficiency that appears over and over again. People, either themselves or hired contractors, enter the attic to do work and never repair the damage they have done to the insulation. Most of my clients have never been in their attics and just assume that all is well. Pot lights are almost always an indication that someone has been in the attic and maybe it is just bad percentages but over 75% of homes I inspect have large trails in their blown in insulation and areas where instead of 10 to 11 inches of insulation, only 3. There was even a popular franchise inspection company that “bragged” that they put a “tag” in every corner of your attic. When two thirds of your R factor is missing from areas of your attic you can safely assume that you will have heat escaping into your attic. You don’t need to hire a home inspector to check your attic; most attics can be completely viewed from the access hatch with a standard spot light.
So I would suggest to anyone out there that has an ice problem, that they first check their attic for missing insulation or un-even coverage.
Ventilation
The Ontario Building Code requires 1 square foot of ventilation for every 300 square feet. Twenty-Five percent of this ventilation is required at the bottom of your roof (soffits) and Twenty-Five percent at the top(peak). The remaining fifty percent can be spaced anywhere on your roof although most designers simply just put venting at your soffits and upper roof areas.
One main area of concern in ventilation is the soffit venting. As your roof rafters or trusses come down to your walls the area becomes very restricted and the building code even allows for lesser R values in this area do to space restrictions. Soffit baffles are used to prevent the insulation from completely blocking air flow from your soffits, thus allowing for air flow from your soffits through to your roof vents allowing for any humidity and heat to be dissipated to the exterior. I have seen homes in the Barrie area that the homeowner has taken the trouble to stuff insulation along their soffits thereby completely blocking all ventilation. Another frequent insulation blunder is people who insulate their garages and add an auxiliary heat source but totally ignore the fact that a garage is built with no ice shield on eaves and usually has no roof ventilation.
Once again a simple visit to your attic will ensure that you have adequate ventilation. Most soffit baffles are either plywood sheets extending down to walls or the popular Styrofoam soffit baffles. Usually they are installed in every third or fourth joist or truss space.
French Drains or similar devices have become popular for the disposal of downspout discharges around homes. I always recommend that home owners install a Tee at the top of their drainage pipe to prevent winter freezing problems. Water in your eaves and downspouts will always freeze at some time during the winter; the problem arises when the sun comes out and melts the ice in eaves troughs and downspouts but fails the thaw the underground drainage system. This is where the added Tee relieves the system by allowing the thawed run off to spill out the Tee, thereby prevent the splitting of downspouts and the possible creation of “ice dams”.
