Depending on the condition of your roof, there are many additional factors in the installation process that can add costs to your project.
If your roof deck is still in good condition, new asphalt shingles may be able to be placed on top of your old ones. If your roof deck in poor condition, you have shake shingles or you have two or more layers, you will need to remove your current roofing before installing your new asphalt shingles. For metal roofs, you will in all likelihood need to remove your current roof first.
To avoid surprises, ask your roofing specialist to the cost of roof removal, as this can be an unexpected but costly addition to your project, anywhere from $550 to $1,500 for a ranch-style home, varying based on location and difficulty.
A roof needs strong rafters or trusses for support. If they are damaged or can’t support the weight of your new roofing materials, you will need to install new ones or risk having your brand new roof come crashing down. Depending on the level damage or if they need reinforcement, costs can widely vary anywhere from $1,000 to $13,000.
If your location experiences significant rainfall (such as Vancouver) or there is high humidity, you may want to consider algae-resistant shingles. These have a roof coating of leachable copper to resist damage and discolouration, giving your roof a longer lifespan. If you opt for algae and fungus resistance, expect to add 10 to 15% to your total cost.
Safety is always the top priority. If your home has an exceptionally steep pitch, then more precautions will need to be taken to ensure that the installers are as secure as possible. This will add more steps and time to your project, potentially increasing the cost as well. A steep pitch may also require an underlayment to earn a Class A fire rating, which will also increase the costs.
Thicker shingles will last longer and as a result cost more at the beginning, but will better withstand the elements. The added weight may also require more support from your rafters or trusses, which will also drive up costs. In the long run, however, they may save you money by prolonging your roof’s life and needing replacement or repairs less often.