Many homeowners are surprised when the cost for a new roof is much more than the cost of just replacing the shingles. The reason this occurs is simple — your roof is much more than just shingles. There are several other components that must be assessed and sometimes repaired during a general roof replacement. Knowing what these are can help you get a more accurate quote for your new roof.

1. Decking Damage

Decking makes up the main structure of your roof plane. It is the plywood base that is attached to the roof trusses, and to which the shingles attach. In homes with an unfinished attic, the decking is also the ceiling surface for the attic. The decking shelters your home, and the shingles shelter the decking against the weather.

If you replace the shingles before aging and damage lead to leaks, then your decking will likely be in good condition and won't need to be replaced. Decking can survive undamaged for decades, often outlasting several roofs. If water incursion does occur, though, then the water-damaged decking boards will need to be replaced. Unfortunately, it can be hard to tell if decking is damaged, particularly if the attic is finished with a drywalled-in ceiling.

2. Eave Replacement

The eaves run the perimeter of the roof. They consist of two main parts. The fascia is the outward-facing board on the edge of your roof. The soffit is the underside board that connects the roof edge to your home's wall. There are also vents in the soffits, which allow for airflow through the attic and roof.

Homes with wood eaves are most likely going to require some repair or replacement when you put on the new roof. Wood rot and cracks are relatively common. You can opt to upgrade to aluminum or vinyl eaves, as these are less likely to suffer damage in the future.

3. Poor Ventilation

Every roof has vents in the soffits and a ridge vent. There may be additional vents between these on the roof surface, depending on your home and roof design. Air flows through the soffit vents and out of the ridge vents constantly, which prevents moisture and heat from collecting in the attic.

Poor or damaged roof vents impede airflow. Moisture in the attic can lead to mold, while poor heat dissipation increases the chances for ice dams in winter. Replace damaged vents and add additional vents as needed when you have your roof replaced. 

Contact a roofer in your area if you need a new roof. They can do a full inspection of all parts of the roof, not just the shingles, which means you get an accurate quote.