Common Roofing Mistakes

It is extremely important when choosing a roofing contractor you ensure the roofers that will be performing the installation are qualified and experienced. It is the job of any salesman to try and earn your business; nevertheless, things are more easily said than done. A common misconception among homeowners is that all roofs are the same. Please understand that choosing a contractor is not the same as shopping for a TV. The workmanship elements with any construction project are as, if not MORE, important than the quality materials you select. At Dayus Roofing we employ only the best and most experienced roofers in Windsor and Essex County, which guarantees you a job second to none. Below we outline some of the most common roofing mistakes and workmanship errors.

High Nailing & Low Nailing
Over or under driven roofing nails
Mixed Ventilation
Over or under ventilating
Venting a bath or kitchen exhaust fan
Misused vent types
Misused or Forgotten underlayments
Re-using or omitting flashings
Re-using or omitting drip edge
Wrong shingles for hip & ridges
Plugged Soffit Ventilation
Installing shingles over old boards


High Nailing & Low Nailing

One of the most common mistakes made with roofing installation is improper nailing patterns. Unfortunately this is also one of the most difficult problems to recognize to the untrained eye.  The accuracy in which a roofer is able to install your shingles is the most important detail in maximizing the strength of your roofing system. Many contractors sacrifice quality for speed in order to cut costs. Shingles have a nailing strip that ranges from ½ to 1 inch that is designated for nail placement. If you hit the nail strip you should catch the course of shingles below the shingle you are installing. Therefore, if you are using 4 nails per shingle, ultimately each shingle should have a minimum 8 nails holding it in place. High nails may not catch the underlying shingle and will miss the core of the shingle that provides it with the best strength for your roof’s wind protection. With laminated shingles, the nail should penetrate both the base sheet as well as the second lap of the product to maximize strength. Low nails leave nail heads exposed which will corrode over time and cause gaps after expansion and contraction occurs. To put it simply, any unnecessary holes in your roof is a bad idea. 


Over or Under Driven Roofing Nails

Similarly to nail placement on a shingle, the accuracy in which fasteners are applied is another critical element of a good roof installation. Over driven nails can cause breaks and tears in the shingle and sometimes go all the way through, completely defeating their purpose. Under driven nails can cause the next course to sit up, or create an air bubble in the roof leaving it susceptible to wind damages. Angled nails will leave gaps for water to enter. A properly driven nail will leave the head flush to the shingles and be driven straight into the decking. This workmanship element is important not only for wind protection, but the overall look of your roof.


Mixed Ventilation

Another common mistake made by contractors is mixed ventilation types. Each type of vent is designed to work and handle air flow in its own particular way. Air is intended to travel from the soffit at the base of the exhaust vents at the peak. Different vents draw air differently and combining vent types can decrease the efficiency of the ventilation and increase energy bills! Whether you choose to use ridge vents, static vents, power vents or turbines, it is imperative that you NEVER mix vent types within a separated attic space. For example, whirlibirds use the wind to draw air from your attic, whereas static vents are motionless and rely on the cooler air from the intake to force the air out through the exhaust vent. Combining the two can short circuit the system and cause unwanted moisture and even snow to be drawn into the attic. Some attic types such as cathedral ceiling can only be ventilated by a ridge vent. 


Over or Under Ventilating

More ventilation is not always a good thing. Often times roofers will miscalculate the number of vents required for propped ventilation, or will add more vents upon request of the homeowner. This can cause problems with the airflow in your attic. It is important when designing a ventilation system that you abide by all codes and manufacturers recommendations. The standard rule of thumb is 1 square foot of ventilation for every 300 square feet of attic space, although this can vary depending on your roof slope and design. Remember; always have a balanced ventilation system. In no case should the amount of exhaust ventilation exceed the amount of intake ventilation.


Venting a bath or kitchen exhaust fan

Many homes have exhaust vents in their bathrooms and kitchens to carry the excess moisture out of their home and through their roof or out their sidewalls. It is common (especially in older homes where vents have been added) that the connection between the interior exhaust vent is not properly connected to the roof vent. If this is the case, moisture is being drawn directly into your attic, which will result in condensation problems and in a worst case scenario, mold. Make sure your vents are connected properly and when adding exhaust vents you rely on the guidance of a reputable contractor. 


Misused vent types

Intake vents are designed to draw air into the attic.
Exhaust vents are designed to expel moisture from the attic.
For some reason, this confuses many contractors. Exhaust vents are often used to provide intake ventilation for a roof that does not currently have any. The problem is exhaust vents are designed to exhaust. Sounds silly, and there’s no way a “reputable contractor” will make this mistake, but it is frustratingly common to see roof vents in the wrong places. Protect yourself!  Click here to learn more about roof ventilation.


Misused or Forgotten underlayments

Many contractors will misuse underlayments or choose not to install them at all. It is very important to abide by all building code requirements and strongly recommended to follow all manufacturers’ suggestions. Code and manufacturers recommend you install ice and water shield at your eave edge, in all valleys and in any delicate areas of your roof. Then cover the remainder of the deck with No. 15 felt or equivalent. Ice and water seals the roof deck and is not breathable like some felts are. Sometimes homeowners will over use ice and water shield with the assumption that because it is more watertight it must be a better alternative to standard felts. Leak barriers prevent the migration of moisture-laden air that reaches the attic from traveling through the otherwise permeable roof system. Full-deck coverage may result in moisture related problems within an attic if certain, critical precautions are not taken. To the other extreme, sometimes no underlayments are used at all. Underlayment is a critical part of the roofing system (let alone required by code) and a dynamic component of your homes watertight protection.


Re-using or omitting flashings

Many times contractors will opt to reuse wall or chimney flashings and in some cases not install them at all. Wall and chimney transitions are two of the most problematic areas with a roof if not handled correctly. Some contractors omit this detail to save time and costs, while others may not have the knowledge on how to properly address these details. According to the building code and manufacturers recommendations all wall junctions should have proper step and counter flashings. However, many homeowners, and even some roofers, will rely on sealants and tar for the tricky areas of a roof. It is very important to make sure your roofing contractor has experience and the know-how to handle these details and that your contract specifies how the flashing is going to be addressed.


Re-using or omitting drip edge

The purpose of a drip edge is to support the shingle edge and protect the transition from your fascia to your roof line. It also helps to give a nice finishing touch to the look of your roof. When you re-use your drip edge, more often than not you will end up with a bent piece of metal ruining the finished look of your roof. Also, re-used drip edge results in old nail holes, which if left unsealed are just another area that water can enter the home. It is relatively inexpensive compared to the cost of the overall roof replacement to have your drip edge changed. This simple, often overlooked detail; can save you hundreds of dollars in repairs at a later date. If the drip edge is not installed you will see the shingles at the edges of the roof bending into the trough because there is nothing there to support them. If gutters become clogged, or you experience a bad rain, water can enter between your roof deck and fascia causing wood rot, potential interior damages and moisture build up that can lead to mold.


Using asphalt shingles in low sloped areas

Asphalt shingles are designed for 4/12 roof slopes and greater. With a special installation process they can be used on 3/12 slopes, however this often affects the warranty coverage you receive. Many times roofing contractors will ignore this detail and install shingles where they should not be installed. When asphalt shingles are installed below 4/12 slopes the water will not run off of them as quickly, which will lead to more rapid deterioration. Other problems that can arise include: wind damages, wind driven rain penetration, and Ice creep. If you choose to install shingles to a low slope area it is highly recommended to install a premium ice and watershield or leak barrier to the complete deck prior to shingling. The right solution is to install a low slope roofing material. Low slope applications can cost more than asphalt shingles, but will last longer because they are designed for that purpose.
 


Wrong shingles for hip & ridges

Some roofers, regardless of the shingle being used, will cut the shingle into 3 pieces and use it for hip and ridge cap. With a traditional 3-tab shingle this is the correct process. If done correctly, the shingle breaks into three even pieces that are flexible enough to use as a cap shingle. With the increasing popularity of laminate and designer shingles many are making the mistake of using the process you would with a 3-tab. Thicker designer shingles and laminate products are not designed for ridge caps. They do not lay flat and some may crack and break when bent over the ridges. It is highly recommended to use a Specialty shingle, which has been developed by all manufacturers, or simply using a 3 tab shingle that matches the colour of the main shingle is OK as well.


Plugged Soffit Ventilation

Even though your soffit vents appear perforated from the exterior of the home, it is very important to make sure that air is flowing through them and into the attic. Many times homeowners, and even professionals, will mistakenly cover over their soffits with insulation. This can trap moisture in your attic and lead to condensation problems. Having adequate intake ventilation is equally as important as the exhaust ventilation. In the event that soffits are blocked you can install Moore vents (Styrofoam baffles that channel the airflow to the attic) or simply pull the insulation away from the soffits to free up the airflow. Moore vents are typically found on newly constructed homes.


Installing shingles over old boards

Roofers will commonly use the existing roofing deck regardless of the type or condition that it is in. Specifically in the case of old spaced board decking, this can cause big problems. If the nails used to fasten the shingles do not have a consistent surface over driven and under driven nails will occur. What’s worse is that when expansion and contraction occurs, as seasons change in Windsor Essex, shingles will buckle. This will create gaps in the roofing system making it susceptible to water entry. If your roof deck is old or in poor condition it is always recommended that you cover the complete surface with an approved decking such as 3/8” plywood. This will provide a stronger hold for the shingles and a better roofing system.


 
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Dayus Roofing
5120 Halford Drive
Windsor, Ontario
N9A 6J3
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