How to Properly Waterproof a Roof? A Comprehensive Guide

Roof waterproofing is a key element in ensuring the durability and functionality of any building. Properly installed, it protects against leaks, moisture, and structural damage. In this guide, we'll demonstrate how to properly waterproof a roof, discuss available materials, and highlight important aspects of the process.

What is roof waterproofing?

Roof waterproofing is the process of protecting the roof surface from water and moisture penetration. It involves the use of special materials and techniques that create a water-impermeable barrier and protect the building structure from the harmful effects of atmospheric factors.

Why is it necessary to waterproof the roof?

Lack of proper waterproofing can lead to many problems, such as:

• water leaks into the building,
• development of molds and fungi,
• damage to the roof structure,
• reduction in energy efficiency,
• shortening the life of the roof.

That is why it is so important to ensure proper waterproofing already at the construction stage or during roof renovation.

Types of roofs and their waterproofing needs

Different roof types require different approaches to waterproofing. Below, we present the most popular roof types and their specific needs.

Flat roof waterproofing

Flat roofs are particularly susceptible to waterlogging, requiring careful waterproofing. Roofing felt is often used here, and while it initially performs well, it loses its properties over time and requires specialized equipment during renovation, such as a blowtorch. It's worth considering applying a modern polyurea coating , such as Neoproof® Polyurea R, which is highly flexible and weather-resistant. Applying this material to a flat roof provides complete resistance to standing water and reduces the roof temperature (if white is used) by nearly half!

Waterproofing a pitched roof

Pitched roofs, due to their slope, are less susceptible to waterlogging. However, proper waterproofing is crucial. For roofs covered with tiles, metal, or shingles, it's worth using liquid waterproofing membranes such as Neoproof® PU W-40 , Neoproof® PU Fast-30 , or Neoroof® . Their single-component construction based on water-soluble resins translates into easy application and low odor. Furthermore, these products can be safely applied to any of the above-mentioned substrates. The only remaining step is choosing the right primer: Revinex® Neotex® Metal Primer for metal substrates .

If the pitched roof is covered with bituminous shingles, it's recommended to seal each shingle with a flexible polyurethane filler – Neotex® PU Joint . This will enhance the waterproofing properties and extend the life of the entire waterproofing layer.

Roof waterproofing with roofing felt

Roofs covered with felt require regular maintenance and possible waterproofing repairs. For renovations, consider using a polyurea coating , such as Neoproof® Polyurea R , which can be applied directly to the felt without primer. This reduces the work time by 24 hours! This highly durable and flexible product can therefore achieve a coating lifespan of up to 25 years. Alternatively, liquid polyurethane membranes , such as Neoproof® PU W-40 or Neoproof® PU FAST-30 , are excellent options, but they do require priming. They create a durable and flexible protective layer.

Waterproofing a sheet metal roof

Metal roofing is susceptible to corrosion and leaks at joints. To ensure proper waterproofing, it's worth using flexible protective coatings such as Neoroof® or Neoproof® Polyurea C1 Neoproof® Polyurea C1 to sheet metal in a single layer, saving not only time but also material.

How to choose the right materials for roof waterproofing?

The choice of appropriate waterproofing materials depends on the roof type, its structure, and operating conditions. Below, we present the most popular materials used in roof waterproofing.

Acrylic coatings

These are budget-friendly solutions that provide excellent waterproofing properties and are easy to apply. Liquid acrylic coatings are UV-resistant, which is everything a liquid waterproofing membrane should be. An example of such a membrane is Neoroof® , a hybrid product based on acrylic resins that cures under UV light. It is suitable for use on many substrates, but is particularly effective on metal, concrete, and bitumen shingles. On the first two substrates, it has reduced consumption, allowing for the creation of a proper waterproofing coating while simultaneously saving material.

Polyurethane coatings

Modern solutions, such as Neoproof® PU W-40 and Neoproof® PU FAST-30 , offer high flexibility, UV resistance, and durability. Polyurethane coatings can be applied to various types of roofs, including existing felt or sheet metal roofing. These single-component, water-based products are easy to apply using a roller, brush, or spray. This construction also reduces the unpleasant odor typical of solvent-based products.

Cold-applied polyurea coatings

These are state-of-the-art solutions derived from so-called "hot polyureas." They retain the characteristics of polyurea, including high flexibility and full UV resistance, but do not require any specialized equipment for application. This significantly simplifies the use of this type of material while offering the highest possible quality in waterproofing coatings. Examples of liquid polyurea membranes include Neoproof® Polyurea R and Neoproof® Polyurea C1 . In addition to their high flexibility, these materials are resistant to early rainfall and are based on organic solvents. This allows them to be applied outdoors from early spring to late autumn without worrying about the success of the entire application process. Waterproofing layers made using polyurea membranes can last up to 25 years.

How to prepare the roof surface before waterproofing?

Before applying waterproofing materials, the roof surface must be properly prepared. Here are the most important steps:

1. Cleaning the surface 

Removing all dirt, dust, leaves, moss, and lichen is crucial to the effectiveness of waterproofing. It's worth using a pressure washer or a brush to thoroughly clean the roof. To degrease the surface, we recommend using Sulfanol A , which will remove greasy residue from exhaust fumes. For mold removal and preventing its future growth, we recommend Grzybostop .

2. Repairing damage

Before applying a waterproofing layer, check the roof for cracks, gaps, or leaks. Any damage should be repaired, for example, by filling in the felt or sealing sheet metal joints. Filling gaps can be done using Neotex® PU Joint Jointex acrylic sealant . It depends on whether a two-component, solvent-based system or a single-component, water-based product is being applied.

3. Drying the surface 

The roof surface must be dry before applying waterproofing. Failure to do so may result in the coating peeling or air pockets forming.

4. Land use

To improve the adhesion of waterproofing materials, it is recommended to use a suitable primer, e.g., for concrete, felt, or metal. For example Revinex is designed for felt and concrete under waterproof polyurethane membranes such as Neoproof® PU W -40 , Neoproof® PU Fast -30 , or Neoroof® .

Step by step – how to waterproof a roof?

The roof waterproofing process consists of several key steps that must be performed carefully to ensure long-lasting protection. 

1. Choosing the right material

Based on the type of roof and its technical condition, select the appropriate waterproofing material, e.g. Neoproof® Polyurea R for flat roofs, Neoproof® PU FAST -30 for quick application or Neoroof® for sheet metal.

2. Applying the first layer and securing the joints

Once the primer has dried, it's necessary to protect joints, such as those between felt sheets, as well as all surface joints, such as vertical and horizontal joints, fireproof walls, etc. Neotextile® , which is bonded to the waterproofing compound using the "wet-on-wet" method. Then, the first layer of waterproofing is applied. A roller, brush, or airless sprayer are most commonly used.

3. Applying subsequent layers

For full protection, apply at least two coats of waterproofing, allowing the recommended drying time between applications.

Drying and curing of waterproofing materials

Drying time depends on the type of material used and weather conditions. For example, polyurethane products such as Neoproof® PU W-40 take from several to several dozen hours to cure, while Neoproof® PU Fast-30 achieves initial cure in just one hour. Full waterproofing properties are achieved in up to 7 days.

How to care for roof waterproofing?

To ensure that roof waterproofing remains effective for many years, it is worth following a few rules:

• Regular roof inspections, especially after heavy rainfall or winter,
• Removing leaves and debris,
• Inspection of critical areas and filling in any gaps,
• Use of dedicated preservatives for the selected waterproofing.

Roof waterproofing – frequently asked questions

What are the costs of roof waterproofing?

The cost of waterproofing depends on the roof type, material chosen, and application method. Average prices range from several dozen to over one hundred złoty per square meter. 

How long does roof waterproofing take?

The duration of the work depends on the roof surface and the type of material used. In the case of polyurethane coatings, application may take 1-2 days. It all depends on the complexity of the roof, the weather, and the initial conditions, such as the amount of dirt on the roof.

Can I waterproof my roof myself?

Yes, if you have the appropriate knowledge and skills. However, for larger surfaces or complex structures, it's better to use the services of professionals. 

What are the most common mistakes when installing waterproofing? 

The most common errors are:

• Inadequate cleaning of the surface,
• Use of inappropriate material, 
• No or improperly primed substrate,
• Failure to maintain appropriate layers and drying times,
• Lack of sealing in critical areas.

Summary

Roof waterproofing is an investment that provides long-term protection for your building against moisture and leaks. Choosing the right materials, such as Neoproof® Polyurea R , Neoroof® , or Neoproof® PU W-40 and PU FAST -30 , and carefully crafted, guarantees effective and durable protection. Regular maintenance and roof inspections will ensure your roof remains watertight for many years to come.