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Alberta Prestige Roofing believes in education and wants you to have all the information you need to make wise decisions. We’ve provided answers to the top 10 most frequently asked questions we hear from customers. We also provided 10 most common problems. Do you have a question? Let us know.


10 Frequently Asked Questions

What is drip edge?Can I apply new shingles on old?What is eave protection?What's underlay, and do I need it?Can I expect Rotten Wood?

6. What is ice damming?

7. Can step and wall flashing be reused?

8. What should I know about air venting?

9. What should I expect after the job?

10. What kind of valleys should I use?

1. What is a drip edge?

The drip edge protects your deck from rot by diverting water into your eaves-trough. It is a band of metal fastened to the deck at the eaves. Our image shows what happens to the edges of a roof that does not have a drip edge. The wood will need to be replaced.

2. Can I apply new shingles on old?

No. The only way to ensure a good surface for fasteners is to strip the old shingles off down to the deck. If you don’t remove the old shingles, you might be covering up wood rot.

3. What is eave protection?

Eave protection consists of 2 plies of tar paper or 1 layer of SBS modified fiberglass base sheet or 1 layer of self-sealing ice and snow membrane on the bottom of the roof. This would extend from the bottom of the roof a minimum of 12 inches past the exterior wall. On most houses, this would be approximately 3 ft or 36 inches. This is the part of your house where most of the heat escapes from the house’s outer wall, causing ice-damming. So that is why this area gets extra protection. We prefer to use either the SBS modified fiberglass base sheet or the self-sealing ice and snow membrane depending on the customer’s decision.

4. What's underlay, and do I need it?

Underlay is a layer of #15 lb tar paper (felt) or a layer of synthetic plastic underlay that covers the entire roof, from the point where the eave protection ends to the termination point at the ridgeline or wall. Yes, you need to have underlay for proper installation. Shingles are tested by the CSA with underlay in place. Additionally, it is recommended by manufacturers and you may void part of your warranty if you don’t use it. Shingle underlay is a second line of defense in the event of shingle blow up, windblown rain under the lap of a shingle and weather protection during the shingle installation.

5. Can I expect Rotten Wood?

The age of your house and whether it was shingled properly are important factors in determining if you should be concerned about wood rot. In most cases, rotting occurs in the bottom 12” of your roof. It’s difficult to assess the damage without removing shingles. A good contractor like Alberta Prestige Roofing will let you know prior to inspection if he expects to find rot and how much it will cost to replace it. We’ve included an image of wood rot that all happened at the bottom edge of the roof. It might have been avoided if a drip edge were in place.

6. What is ice damming?

The melting and freezing of snow on your roof can result in the formation of an ice dam. This situation occurs as snow melts and travels down the roof and then freezes up again, causing a ridge or dam of ice. After the ice dam is established, it holds back water each time a melt occurs, which can lead to a back-up under your shingles and potentially a leak. This is another reason why an underlay is important.

7. Can step and wall flashing be reused?

On a re-roof, we generally try to save the old wall and step flashing as they are pinned in behind your siding or stucco. Each piece of flashing is inspected and replaced carefully if it is deemed that the flashing cannot be used. Shingle underlay is run up in behind the wall, and step flashing and all old nail holes have sealant applied to them.

8. What should I know about air venting?

Air venting is critical to your home and the proper installation of your roof. Your manufacturer’s warranty may become void without proper venting. You may also experience condensation leaks and a shortened lifespan of your roof. You should turn to installers like Alberta Prestige Roofing in Calgary who fully understand airflow and the manufacturer’s specifications.

9. What should I expect after the job?

You should expect a full clean-up and final inspection upon completion to ensure that all workmanship was completed according to standards. Alberta Prestige Roofing recommends that you get all written guarantees for labor and materials before work begins.

10. What kind of valleys should I use?

Manufacturers and installers have their own preferences on the proper way to shingle a valley. There are many methods used. In almost all situations, Alberta Prestige Roofing uses the open valley method: 1 layer of 36” eave protection run up the center of the valley and a layer of 24” pre-painted sheet metal installed over the top. The shingles are then lapped over the top of the valley metal but cut back from the center to allow for water flow. Water drains from the valley area quickly with this method and ensures that water does not get trapped between plies of shingles, creating an air pocket as it tries to evaporate. This causes the shingles in the valley to blister and age prematurely. Galvanized metal is shown in our photo to make it easy to see, however, we generally use pre-painted metal to match the shingles for a more uniform look.


10 Common Roof Problems

Poor or Faulty InstallationLeaks and MoistureImproperly Installed FlashingCrittersPuddling Water

6. Punctures and Penetrations

7. Trees

8. Ventilation

9. Shrinkage and Blistering

10. Improper or Lack of Maintenance

1. Faulty Installation

A faulty installation of your roofing material can dramatically increase the likelihood of problems and reduces a roof system’s life expectancy. You need to hire a professional to tell you if your roof has been installed correctly.

2. Leaks and Moisture

Wind, rain, hail, snow, ice, and debris ... all of these and more can lead to moisture getting under the layers of roof and causing everything from leaks to mold and rot.

3. Improperly Installed Flashing

Flashing is the process of sealing the roof areas to keep water out. When they are improperly installed, this can cause open seams and laps, cause tiles to blow-off, and reduce the puncture resistance of your roof.

4. Punctures and Penetration

Wind and hail damage can cause punctures in the roofing material. The sealant and flashing around penetrations (such as vents for household appliances and HVAC) added after the roofing was completed need to be looked at regularly.

5. Water Puddles

Having stagnant water on your roof is a sure sign of a problem. The common causes range from debris buildup to improper drainage of HVAC units and gutters.

6. Critters

Even animals can cause damage to your roof. It’s best to evict small animals, birds, and insects before they get a foothold.

7. Trees

Overhanging tree limbs can rub on a roof, abrading the surface of the shingles and wearing away the protective top layer. It is best to removing 2-3 feet to prevent damage.


Roof and attic ventilation are integral parts of making a roof last. Vents are commonly placed at the base of the roof and near the top of the roof so warm air can leave through the top and cool air can be drawn through the bottom. Adequate ventilation regulates temperature and moisture levels in the attic. Left unchecked, heat and moisture can build up causing damage to rafters, sheathing, shingles, insulation, and rising energy costs and may lead to some ugly mold and mildew problems.

9. Shrinkage and Blistering

Roof shrinkage often occurs when membranes that cover roofing materials shrink down in size. If left unhampered, blistering, ridging, splitting, and surface erosion of the shingles could lead to bigger roof problems.

10. Improper or Lack of Maintenance

Lack of roof maintenance is probably a roof’s worst enemy. Many problems start out as minor, such as the need to remove overhanging tree limbs or cleaning backed-up gutters. But when not corrected these problems can create serious damage. Routine inspection and maintenance can extend the life of your roof and that can save you a lot of money.

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