It is not unusual to see older homes with two or three layers of asphalt shingles on them. Instead of removing the older roof, the homeowner or roofer simply installed a new layer over the older one. Although some communities still allow this, it is a dangerous practice and becoming less accepted. Here are reasons the old roof needs to be completely removed before a new one is installed.
Fire Codes May Demand It
Asphalt shingles are made with tar; a flammable substance. Although shingles do not catch fire easily, they will burn if subjected to enough heat. One problem presented with multiple layers of shingles is that in a fire, water may not penetrate the outer layer or layers of shingles to reach the roofing materials or the attic.
The firefighters may have to use aggressive methods to remove the layers during the fire. This is dangerous to the firefighters. The tar in the shingles burns at a greater temperature than surrounding materials and takes more time and water to extinguish. The more layers of shingles that exist on a roof, the greater the chances are of losing the structure.
Building Codes May Require It
Asphalt shingles are heavy. That is why roofers often use conveyor belts to deliver the bundles to the roofing area. Each consecutive layer adds tremendous weight to the roof, which was built to hold the weight of one layer. If the decking or rafters are week, it is possible the roof could collapse in a storm or under the weight of snow.
In some areas, a code inspector will check to see that the old roof has been removed before a new roofing installation. If the inspector finds the old roof still exists under the new one, the inspection will fail and the roofer or DIY'er can face heavy fines. The homeowner's insurance company may not pay for any damages caused by the second roof.
The Flashings And Boots Will Fit Better
If your roof has areas that feel spongy when you walk on them, your decking may be delaminating. If you have leaks inside the house, it is because water is getting past the roof, the tar paper and the decking. Removing the old roofing materials will allow the roofer to perform a proper inspection of your decking, rafters and attic. Any repairs that need to be done can be performed before the new roof is installed. This will ensure the longevity of the new roof and the safety of your home.
The Flashings And Boots Will Fit Better
When the old roofing materials are removed, the old flashings and boots should be removed as well. Flashing is a metal strip that is installed to prevent water from seeping into the attic at different junctions such as the chimney and roof, where two walls meet and in roofing valleys. Boots are the circular rubber coverings that fit over the vent pipes coming through the roof.
When a second layer of roofing material is attached, very little consideration is given to the flashing materials or boots. Instead, the shingles are cut around the boots or flashings. This creates a well for water to pool in and cause problems.
When a second layer of roofing material is attached, very little consideration is given to the flashing materials or boots. Instead, the shingles are cut around the boots or flashings. This creates a well for water to pool in and cause problems.
Fire Codes May Demand It
Asphalt shingles are made with tar; a flammable substance. Although shingles do not catch fire easily, they will burn if subjected to enough heat. One problem presented with multiple layers of shingles is that in a fire, water may not penetrate the outer layer or layers of shingles to reach the roofing materials or the attic.
The firefighters may have to use aggressive methods to remove the layers during the fire. This is dangerous to the firefighters. The tar in the shingles burns at a greater temperature than surrounding materials and takes more time and water to extinguish. The more layers of shingles that exist on a roof, the greater the chances are of losing the structure.
Building Codes May Require It
Asphalt shingles are heavy. That is why roofers often use conveyor belts to deliver the bundles to the roofing area. Each consecutive layer adds tremendous weight to the roof, which was built to hold the weight of one layer. If the decking or rafters are week, it is possible the roof could collapse in a storm or under the weight of snow.
In some areas, a code inspector will check to see that the old roof has been removed before a new roofing installation. If the inspector finds the old roof still exists under the new one, the inspection will fail and the roofer or DIY'er can face heavy fines. The homeowner's insurance company may not pay for any damages caused by the second roof.
The Flashings And Boots Will Fit Better
If your roof has areas that feel spongy when you walk on them, your decking may be delaminating. If you have leaks inside the house, it is because water is getting past the roof, the tar paper and the decking. Removing the old roofing materials will allow the roofer to perform a proper inspection of your decking, rafters and attic. Any repairs that need to be done can be performed before the new roof is installed. This will ensure the longevity of the new roof and the safety of your home.
The Flashings And Boots Will Fit Better
When the old roofing materials are removed, the old flashings and boots should be removed as well. Flashing is a metal strip that is installed to prevent water from seeping into the attic at different junctions such as the chimney and roof, where two walls meet and in roofing valleys. Boots are the circular rubber coverings that fit over the vent pipes coming through the roof.
When a second layer of roofing material is attached, very little consideration is given to the flashing materials or boots. Instead, the shingles are cut around the boots or flashings. This creates a well for water to pool in and cause problems.
When a second layer of roofing material is attached, very little consideration is given to the flashing materials or boots. Instead, the shingles are cut around the boots or flashings. This creates a well for water to pool in and cause problems.
About the Author:
Turnbull Roofing & Renovations Ltd 149 Dooley Crescent Ajax, ON L1T 4J6 Canada +1 905-686-7663 is a leader in roof repair and renovations in the Ajax area.
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