Learn more about roofing
The roofing experts at Murray Shaw Roofing, London, Ontario answer FAQs about:
If you still have a question, please contact us
and one of our representatives will be happy to answer it.
General Questions What causes ice dams? Ice dams
are formed when heat from the inside of a home escapes into the attic and warms the roof decking during the winter. This heat, combined with heat from the sun, can melt snow on the roof. Melting snow on the upper roof and in the valleys then runs down toward the eaves as water. When it reaches the cold eaves and gutters it refreezes. The continual thaw and re-freeze process creates ice dams. The result is water backing up under the roof shingles or behind fascia board where it can soak through the roof decking or wall sheathing, causing damage to attics, ceilings and walls. How do you prevent ice dams?
Because ice dams
can be caused by the warmth of the sun melting snow on the roof, it is not always possible to prevent them from forming. Ice dams are not necessarily a sign of a poorly installed roof. There are three ways to defend against ice dams: insulation, ventilation and waterproofing shingle underlayment.
- Keep the attic space cold by insulating it from the warm house interior.
- Ensure ventilation at the eaves.
- Ensure that the outer edges of gutters and eavestroughs are lower than the slope line to allow snow and ice to slide clear.
Skylights and cathedral ceilings present special challenges that can be addressed by using insulation with higher R-values (a measure of thermal resistance) and installing a moisture retarder to prevent condensation and waterproofing underlayment in affected areas. How do I know when my roof needs to be replaced?
There are several signs that your roof may need to be replaced. If you see any of these signs or if you are in doubt, please contact us
What is the benefit of hand-nailing shingles?
- Watch for leaks in your attic after an ice build-up or a wind-driven rain.
- If your shingles appear cracked, curled or dirty, you may need a new roof.
- Inadequate shingle underlayment can cause problems with mold and mildew on interior ceilings and walls.
There is no benefit to hand-nailing shingles. None of the leading shingle manufacturers recommend hand-nailing. Some roofing companies promote this technique, but the technique itself is not what is important to a quality installation. What counts are the skills and training of the installer. Our factory-certified installers
use pneumatic nailers which are often more efficient and consistent than hand nailing. Top
About asphalt roofing Should I be concerned about small cracks on my shingles?
Small cracks, often not visible until up close, are generally not cause for concern. However, if the reinforcement (structural base of the shingle) is damaged or split by a crack, then the shingle may be unable to prevent water leakage. These cracks require immediate attention. Why is the actual life expectancy of asphalt roofs so much less than the product warranty and what does that mean for the warranty?
The reality is that all shingles, whether organic or fiberglass, are likely to last only 60 to 70 percent of the warranty period. Because all the warranties are pro-rated in favour of the earlier years, the length of the warranty becomes largely insignificant. Both wood
roofing have longer life expectancies and more closely match the warranty
period. What would cause black and brown streaks on my roof?
These discoloration streaks are commonly caused by algae growth. Though streaks can be somewhat unsightly, they do not impair the water resistance of asphalt shingles. Should I have a new shingle roof installed over my existing one, or remove the old one first?
We highly recommend the removal of the old roofing material before installing new asphalt shingles. The removal allows a professional to inspect the condition of the existing wood deck and all related roofing components to find any defects so that they can be fixed. Once all repairs are done, new shingles can be installed evenly and effectively. If the old shingles are not the same size and shape and are not laying flat without buckles or curls, the new roof will likely look much like the old roof and experience premature leaks due to further cracking or buckling. Are there standard ventilation requirements?
Yes. Because proper ventilation is one of the key factors in the life expectancy of a roof, the Asphalt Roofing Manufacturer’s Association (ARMA) and the Canadian Asphalt Shingle Manufacturers’ Association (CASMA) have established a recommended standard. Ventilation requirements can range from 1 sq. ft. (0.3 m2
) of ventilation for every 300 sq. ft. (91.4 m2
) up to 1 sq. ft of ventilation for every 150 sq. ft. (45.7 m2
), depending on the slope of the roof and the type of the roof. Researchers have found that increasing the number of soffit vents can improve air flow. The standard ratio of soffits to roof vents used to be 1:1. Now it’s shifting towards 2:1. Should I be worried about granules collecting in my gutter?
Over the lifetime of the roof, the excess granules that are not fully embedded into the shingles during the manufacturing process, will wash away. Normally this is not cause for concern unless large areas of exposed asphalt start to appear, in which case immediate attention is required. Top
About wood roofing What is the difference between a shingle and a shake?
A wood shingle roof has a finer look and is used most often in homes with a modern architectural design. Shakes are more rustic looking because they are thicker and bigger and are used often for homes with a Victorian or Tudor style. Top
About metal roofing How much do metal roofs cost compared to asphalt?
A metal roof
will outlast several asphalt roofs and will always have a higher upfront cost. However, metal roofs will always cost less in the long run, since you will save the hassle and costs of replacing several asphalt roofs. How long will a metal roof last?
A properly installed metal roof will last a lifetime. Quality, high-tech finishes provide long-term protection and have the option of re-coating and restoring the finish in 40 or 50 years’ time. These finishes do not curl, blister or peel. When it rains, is a metal roof noisy inside my home?
No. Inside the building there is no difference between asphalt shingles, wood roofs and metal roofs. This is because most metal roofs float over the roofing deck, providing an air space that deadens sound waves. Also, modern building codes make buildings more resistant to noise than in the past. On the outside of the home, some metal roofs are slightly noisier. Top
About flat roofing What is the difference between APP (Atactic Polypropolyne) and SBS (Styrene-Butadiene-Styrene) and how would I choose one over the other?
APP (Atactic Polypropolyne) is easier to install and maintain with its painted aluminum finish while SBS (Styrene-Butadiene-Styrene) has a “shingle” look to it and is recommended if the roof has any slope to it since it requires less heat to install and is more pliable. Our installers are also certified to install TPO. [link to TPO page] Why is proper insulation and venting particularly critical for flat roofs?
We find that flat roofs
are particularly vulnerable to moulds that grow in condensation and will rot the supporting wood deck eventually leading to leaks. This is why it’s especially important to follow the manufacturer’s recommendations for installing flat roof systems. Top
About skylights Why do skylights sometimes leak?
Skylight leaks are generally a result of improper installation or a poor quality self-flashing skylight. Self-flashing skylights are designed to be sealed to the roofing system without the use of sealant. This type of skylight will leak if the self-flashing is not properly installed. We recommend VELUX® skylights
that come with a custom designed flashing kit for each size of skylight and material. Should I get a skylight that opens?
An opening skylight provides the most advantage to a converted attic living space which needs maximum ventilation. The risk is the skylight being left open and rain warping the wooden frame, thus preventing a proper seal when the skylight is closed. Small animals can also enter the skylight. We recommend a special type of VELUX® ventilating skylight that can be left open at any time without the risk of interior damage. Top
About decks and balconies What are maintenance-free railings?
Railings made out of aluminum are virtually maintenance free, compared to wood, steel or iron railings. Aluminum requires occasional washing to reduce dirt and grime buildup but incurs no rusting, rotting and repainting. Top
About replacement windows Do vinyl replacement windows have to be white?
offers a wide range of external and internal colours to choose from. We’ll be glad to help you find exactly the right shade to match the decor of your home. Top
About maintenance-free exteriors What is the difference between fascia and soffit? The soffit
is the underside of overhanging eaves that surround your roof, while the fascia is the trim board that finishes and secures the rafter ends of the roof. Both are commonly finished with maintenance-free vinyl or aluminum panels. Ventilation holes in soffit panels play an important part in controlling air flow and moisture in the attic.