Roof Drainage System Waterproofing Cost

Waterproofing is a vital aspect of maintaining a roof’s integrity and longevity. One crucial area that needs attention is the roof drainage system. Ensuring that water is effectively drained away from the roof is essential to prevent leaks, water damage, and costly repairs. But what are the estimated costs involved in waterproofing a roof drainage system? In this article, we will delve into the various factors that influence the cost of this process and provide you with a comprehensive estimate.

Factors Affecting the Cost of Waterproofing a Roof Drainage System

Several factors come into play when determining the cost of waterproofing a roof drainage system. These factors can vary depending on the type of roof, the complexity of the drainage system, and the materials used. Let’s take a closer look at these influential factors:

  1. Roof Size and Pitch: The larger the roof surface area and the steeper the pitch, the more materials and labor will be required, ultimately impacting the cost.

  2. Drainage System Complexity: The complexity of the drainage system involves considering the number of gutters, downspouts, and other components. A more intricate system will require more materials and labor, leading to higher costs.

  3. Roof Access: Difficult-to-reach roofs or those requiring special equipment to access can result in additional expenses due to the extra time and resources needed.

  4. Materials Used: The choice of materials for waterproofing will significantly affect the overall cost. Different options, such as EPDM rubber, TPO, PVC, or modified bitumen, come at varying price points.

  5. Labor Costs: Experienced contractors with a track record of quality work may charge higher rates. The complexity of the project and the time required for completion will also impact labor costs.

  6. Additional Repairs: In some cases, repairs may be necessary before waterproofing the drainage system. These repairs can include fixing damaged gutters, replacing corroded downspouts, or patching up cracks, which will add to the overall cost.

Estimated Costs for Waterproofing a Roof Drainage System

To provide a more precise estimate, let’s break down the cost factors and consider each one individually:

  • Roof Size: On average, waterproofing a small to medium-sized residential roof could cost between $1,500 and $4,000. Larger roofs or commercial buildings may range from $5,000 to $10,000 or more.

  • Drainage System Complexity: An average-sized residential home with a standard drainage system will typically cost around $2,000 to $4,000. However, for more complex or customized systems, costs can increase to $5,000 or more.

  • Roof Access: If your roof is challenging to access or requires special equipment like scaffolding or lifts, additional costs can range from $500 to $1,000 or more.

  • Materials Used: The choice of materials is crucial when waterproofing a roof drainage system. For example, EPDM rubber is a cost-effective option, with materials costing around $1.50 to $3.00 per square foot. On the other hand, TPO or PVC membranes can cost between $3.50 and $7.00 per square foot. Alternatively, a modified bitumen system may fall within the $2.50 to $5.00 per square foot range. These prices are approximate and can vary depending on the region and supplier.

  • Labor Costs: Professional labor charges can range from $50 to $100 or more per hour. The time required for the project will depend on its complexity and size. On average, labor costs for waterproofing a roof drainage system can range from $1,500 to $3,000.

  • Additional Repairs: If your drainage system requires repairs before waterproofing, costs can increase accordingly. The extent of the repairs needed will determine the final expense. It is essential to have a contractor assess the condition of your drainage system before providing an accurate estimate.

Frequently Asked Questions (FAQs)

Q1: Can I waterproof my roof drainage system myself?

A1: While it is possible to attempt waterproofing as a DIY project, it is best left to professionals who have the necessary expertise and experience. Improper installation or use of substandard materials can result in future leaks and costly repairs.

Q2: How long does the waterproofing process last?

A2: The longevity of the waterproofing treatment depends on various factors, including the materials used, weather conditions, and maintenance. On average, a well-installed and properly maintained roof drainage system can last 15 to 20 years or more.

Q3: Can I reduce the cost by using low-quality materials?

A3: It is not recommended to compromise on material quality. While cheaper materials may lower the upfront cost, they often result in shorter lifespans and more frequent repairs. Investing in high-quality materials from reputable suppliers will provide long-term cost savings.

Q4: How can I find a reliable contractor for waterproofing my roof drainage system?

A4: It is essential to research and choose a licensed, insured, and experienced contractor. Ask for references, read reviews, and compare quotes from multiple contractors before making a decision.


Waterproofing a roof drainage system is an integral part of protecting your home or building from water damage and costly repairs. The estimated cost involved can vary depending on several factors, including roof size, drainage system complexity, materials used, labor costs, roof access, and any additional repairs required. By understanding these factors and seeking professional guidance, you can ensure an accurate estimate and maintain the integrity of your roof for years to come.

Holmes Waterproofing

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