The Basics of Roof Replacement

Roof replacement is one of the most important home repairs since its durability affects the rest of the house. If your roof is nearing the end of its life, learn a few basics of roof replacement before soliciting bids from roofing contractors.

Signs You Need a New Roof

Here are a few signs that your home may need a roof replacement:

• Curling shingles
• Cupping shingles
• Shingle granules in the gutters
• Cracked shingles
• Damaged or missing shingles
• Roof more than 20 to 25 years old
• Light coming into the attic.

Roof Replacement Cost

How much it costs to replace a roof in your state depends on your choice of roofing materials, the roofing contractor you choose, the pitch (steepness or your roof), and the square footage of your roof.

Roofing Costs by Type

The type of materials used greatly influences the cost of the roof. A three-tab composite roof for a small home may cost as little as $6,000.

Nationally, replacing a typical roof using asphalt shingles costs between $3 and $6 per square foot, including demolition, permit fees, waste disposal, and cleanup.

Architectural shingles or slate will raise the overall cost. The national average for roof replacement ranges from $4 to $11 per square foot.

Full vs. Partial Roof Replacement

Replacing part of your roof will be less costly than replacing the whole thing. When roofers only need to remove the damaged singles in a section and replace them with new ones, it's much less invasive and requires less material resulting in a much lower quote.

A full-roof replacement when your roof is severely damaged or simply at the end of its lifespan will be much more expensive. Every old shingle and piece of roof material will need removal taking more time and effort. Labor and material costs will increase significantly.

In certain situations, the cost per square foot for a partial roof removal and replacement can be higher than that of a complete roof replacement project. This is because expenses such as debris removal and permits remain fixed, regardless of whether it's a partial or full roof replacement.

Cost to Repair a Roof

Typically, a roof repair will cost much less than a roof replacement. On average, a roof repair will cost between $382 and $1829, while a full replacement will cost between $5,848 and $12,879.

Additional Costs

In addition to labor and materials, there will be other costs to consider when budgeting for a roof repair or replacement. These include permit fees, roof inspection, a premium for expedited services in the case of an emergency, and additional damage you may have in gutters or metal flashing.

Types of Roofing Materials

Choosing roof replacement options often depends on your locality and your preference. Roof pitch (angle) also affects the roofing materials you can use. For example, wood shake shingles can be used for steeper-pitched roofs but are unsuitable for flatter, low-pitched roofs.

The most common choices for residential roofing include: 

• Asphalt composition shingles:  These are cheap and easily obtainable but less attractive than other options due to their flat appearance.
• Wood shakes:  Attractive but costly, wood shake shingles are durable but aren't a good choice in regions with fire danger. 
• Metal roofing: Metal roofs made of steel or aluminum are durable and fire-resistant.
• Slate roofing: This is a desirable, high-end roofing option, but it is expensive and heavy.
• Composition slate: These synthetic tiles resemble slate and other forms of stone tile but are much lighter and less susceptible to damage.  
• Clay or ceramic tile: Tile roofing shingles are called half-barrels because they are essentially cylinders cut in half length-wise, roughly 16 inches long.

Reroofing

Installing new shingles over existing shingles in good condition is called re-roofing. If your roof is nearing the end of its lifespan but the sheathing board and underlying elements are still in good condition, your roof could be a candidate for re-roofing.

Applying a new layer of shingles over the old shingles should be carefully considered based on its pros and cons: 

• Weight: Excessive weight can cause structural problems, especially for older houses.
• Telegraphing: Shingling over existing shingles may repeat surface irregularities such as bubbles, bumps, and waves.
• Work and waste reduction: Layering over old shingles reduces work and means fewer, if any, old shingles sent to the landfill.
• Warranties: Some manufacturers require that roofs under warranty be stripped entirely to comply with the terms of the warranty.

When to Get a Roof Replacement

The optimal roofing season is from late spring to early fall. Skilled crews can extend the work season, sometimes even roofing in the dead of winter.

There is no reason not to hire a skilled crew to roof your home during off-season. Since labor demand is low at these times, you may get lower prices.

How a Roof Is Replaced

A moderately-sized, professionally installed roofing job might take three or four days.

1. Remove shingles: Remove all existing shingles; deposit them in a roll-off dumpster: Damaged or old valley flashing and drip edging are also removed at this time. A good crew will use tarps to protect foundation plantings and shrubs during tear-off and will use magnetic tools to pick up nails and metal objects from the lawn. 
2. Repair: If the roof is in good condition, make minor repairs. If not, replace the bad wood with new plywood sheathing or 1 by 6 sheathing boards, whichever applies to your type of roof. 
3. Install ice dam barriers: Install ice dam protection in regions that require it: The ice guard membrane is a synthetic waterproof barrier material designed to prevent melting ice from backing up under the shingles and penetrating through the sheathing, where the moisture can cause severe damage.
4. Add roofing paper: Lay down asphalt roofing paper over the roof sheathing.
5. Install drip edging: Apply metal drip edging around the roof's edge, both the eave and gable sides: The metal drip edge is nailed over the roofing paper or ice guard. 
6. Install valley flashing: Apply a new valley flashing along with areas where two roof planes meet: The valley flashing is typically nailed to the roofing deck and sealed with roofing caulk.
7. Install the shingles: Apply the tab shingles, starting at the eaves and working upward toward the peak: Where roof vents are being installed, tab shingles are installed starting from the bottom, moving upwards.
8. Install flashing: Apply the flashing around all areas where leaks might come into the house—against the chimney, around skylights and stack vents Flashing installation may happen as part of the roofing installation, occurring as the rows of shingles progress upward on the roof deck. 
9. Install the ridge vent: The ridge vent is a continuous vent along the roof's peak that will help the air circulation in the attic.
10. Clean up: Complete the final cleanup and haul the debris away.
11. Inspection: Have a building inspector inspect and approve the installation.

DIY Roof Replacement vs. Hiring a Professional

Roof replacement is an extensive undertaking. Roofing is hazardous work for the homeowner, and DIYers may lack the expertise to identify hidden damage, leaks, or structural problems.

Hiring a professional roofer with the training and knowledge will ensure that you do not have problems down the road due to improper material selection or incorrect installation.