Waterproofing film for the roof: how to choose and carry out installation correctly

To ensure the longevity of your roof and shield your house from water damage, pick the appropriate waterproofing film. In order to stop leaks that could result in expensive repairs and structural problems, a waterproofing film serves as a barrier against rain, snow, and moisture.

Think about things like material durability, weather resistance, and installation ease when choosing a waterproofing film. Depending on your climate and price range, popular choices include thermoplastic membranes, rubberized asphalt membranes, and synthetic rubber membranes, each of which has special benefits.

The secret to optimizing the performance of your waterproofing film is proper installation. Before applying, make sure the roof surface is clear of debris, dry, and clean. To create a seamless barrier against water infiltration, carefully follow the manufacturer’s instructions, paying particular attention to overlaps, seals, and adhesive application.

You should do routine maintenance to make your waterproofing film last longer. To stop water from seeping through and causing interior damage, periodically check your roof for signs of wear and tear, such as cracks, tears, or loose seams. If you find any of these problems, take quick action to fix them.

Films and membranes: what is the difference?

Let’s start by pointing out the distinctions between the two roof materials: waterproofing film and waterproofing membrane. Many people think that factors like price, multi-layering, and vapor permeability are where they differ.

Manufacturers also attempt to persuade people that membranes are a totally new material and film is a thing of the past for marketing reasons, but they do not clearly delineate the differences between the two materials.

While the World Encyclopedia of Knowledge states that the membrane is a "thin flexible film, usually fixed along the perimeter," this is only partially accurate. Consequently, it would be more accurate to think of the membrane as a brand-new, contemporary kind of film.

The protective sub-seal space against moisture and leaks is the nearly identical mechanism of action used in both films and membranes:

Furthermore, the way that traditional and contemporary films are installed is still the same today:

Selecting the appropriate waterproofing film for your roof and making sure it is installed correctly are essential steps in protecting your house from water damage. This article examines important factors to take into account when choosing a waterproofing film, including compatibility with your type of roof and material durability. It also offers helpful installation advice, stressing the need of using the right methods to guarantee longevity and efficacy. Knowing these factors will help you protect your investment in the safety and longevity of your home, whether you’re taking on a new roof project or renovating an old one.

How to choose a film for waterproofing roof?

Now let’s examine more closely at what the current market has to offer and the materials that roofers prefer. Furthermore, depending on what you specifically want to see in the ending, there are many different kinds of contemporary subcutaneous films.

Resistance to ultraviolet

Have you ever noticed that after just one summer spent outside, the film can become brittle and turn into rags? particularly if you bought the cheapest available and just covered it with bricks, for instance.

Furthermore, despite having withstand the same amount of sunny days, the coating for greenhouses can appear significantly fresher at first glance. The key factor is not film thickness, but rather a characteristic of the film like its UV resistance.

At first glance, the roof film’s resistance to UV light appears to be a negligible factor because it will be concealed by facing material! Indeed, it is true that many people overlook situations involving force majeure. For instance, you intend to spread and cover the low-UV resistance waterproofing film you purchased in a day or two.

The fire department arrives promptly, the film "zanders" along the crate, and the roof installation is the only thing left to do. And now, out of the blue, there’s rain, a thunderstorm, a shortage of supplies, missing fasteners, cutting the power, and much more. A few days of this kind of inactivity on a hot day can reduce a film’s strength by fifty percent! Now figure out how much its ultimate durability will drop.

So, is taking a chance worth it? It’s not fun, I assure you, to completely remove all waterproofing, replace it with a new one, and perform all installation work—especially when it comes to removing old, unexpectedly outdated films from beneath metal brackets.

You might be shocked to learn that waterproofing films from upscale brands can have extremely low UV resistance. Regretfully, not every seller will inform you that they are only intended for internal installation work and not for use on the roof.

Life time

Durability is the second crucial need for a waterproofing film. After all, do you really want to resettle waterproofing every five years without having to completely disassemble the roof?

As a result, the majority of manufacturers enhance the strength and wear resistance of such films by adding unique components. Modern reinforced films for waterproofing roofs are one example of this:

Water strength for water

Another quality that makes a waterproofing film stand out is its resistance to water column pressure. This is the characteristic that enables you to hold it under water pressure for an extended period of time without allowing it to enter.

Do you have heavy or prolonged rains where you live? Next, take note of this parameter. Or is the layout of your roofing material such that snow melts beneath it like a metal tile?

Films that are installed without any connections are handled effectively when used in their entirety: as a complete roll:

For instance, a three-layer under-trotted film with a supporting reinforced grate and lamination from both sides is the best waterproofing solution for these types of roofs. This hydraulic cane with hydro-battery power is superb.

Clutch with the base

There are two types of waterproofing film: mechanically laid and felled.

There are multiple layers in the melted polymer film. At higher temperatures, the thin film that makes up the lower layer melts readily. Such waterproofing is particularly useful for complexly designed roofs, but every joint needs to be tightened with care.

In the second instance, brackets or nails are used—the standard mechanical method—to attach the film. This can be fastened to any type of base, such as wood, concrete, or profile; the only requirement is that it be as level as possible.


The roof can also benefit from the so-called anti-condensate films, which must be installed with two ventilated gaps. In the event that the roofing material is a metal from which something is constantly leaking, this waterproofing is practically required.

The unique moisture-holding material included in the composition of anticandenate films sets them apart from other types of films. Such a film is rougher and thicker with more density.

It is long-lasting, resistant to UV light, and does not burn, but its vapor permeability is low. If you were fond of this choice, consider ventilation.

Additionally, the way that such a film is installed is the same as usual:

Price and quality

Handle the least expensive movie available with caution. The truth is that since they are nearly invariably made of polypropylene wound on coils, the roof is left without either wind protection or waterproofing.

More costly and contemporary films have the benefit of providing under-wrapping space protection from moisture intrusion as well as aiding in its evaporation. Now, more information about this.

And even more. There is a widespread belief that a subcutaneous film is easily torn during the roofing sheet installation process and that it needs to be replaced virtually annually thereafter. That is obviously very concerning.

The film’s fragility (leave for the winter; by spring, only rags will remain) actually makes it impossible for it to function as a separate coating, but as a crucial component of the entire roof pie, it performs its duties admirably.

Furthermore, even tiny tears in the film caused by bracket fastening are not dangerous because the moisture will quickly evaporate in the morning sun. Never forget that it is always noticeably hotter on the roof than it is below.

Vapor permeability

And finally, one of the most crucial waterproofing film parameters. Finding out whether your roof is "warm" or "cold" should be your first priority. i.e., insulated or not, which is directly related to whether or not you leave a basic attic open or put a living space under the roof.

Additionally, take your time choosing the least resistance and abandoning this non-residential area. In a large house, rooms eventually "end," so I want to outfit at least a closet beneath the billiard room, personal account, or workshop. So, as soon as possible, take full advantage of everything, provided that your budget permits.

Furthermore, if your home’s attic is likely to be insulated, you will not be able to use a basic steam-gydro-insulating film for such a roof because, in the first place, it is not appropriate for these uses and will not last long, and, in the second place, the heater itself will become problematic.

The truth is that double-circuit ventilation is present in standard waterproofing films: one between the insulation and waterproofing, and the other between the roofing and waterproofing. This substance is used to arrange the so-called "cold" roof.

However, for the "warm" device, it’s crucial that the insulation’s steam escape at this precise moment, and the waterproofing film doesn’t obstruct it:

Of course, contemporary movies already have this quality even more:

What does the modern market offer?

Additionally, the options offer a lot. As a result, we will first study how to decipher the marking and take a closer look at the top few brands.


Thus, a film that functions as a breathing membrane is referenced in the AM label.

The main purpose of Films A and AM is to allow steam to flow well.

However, the real blossoms in films A and B are notebooks, whose primary function is to absorb moisture and then swiftly evaporate. And if only a ventilation gap is planned and equipped, they truly manage their work.


Thus, Utafol. These are premium vapor barrier and waterproofing films, along with installation and warranty components. These films are composed of robust polymers:

Sealing Tyvek membranes that are permeable to steam. This material can be referred to as "smart" because it removes extra couples, keeps moisture from becoming a problem, and lasts a long time.

Membranes containing tycetan have been manufactured for many years. The ability to lay directly on insulation without an air gap is their primary benefit. which allows you to forgo the crate and save a significant amount of money on this.

The Delta membrane is used to waterproof the lower roof and is particularly useful for protecting the roof structure from metal folding and piece materials. Roofs that have an angle of inclination of only 10 ° less than what is advised can safely use it.

Additionally, the isopan films are particularly well-liked domestically:

How to properly lay a waterproofing film?

Let’s begin with the crate’s construction. Make sure there is no more than 1.2 meters between the rafters when they are installed. 40–60 mm is the ideal gap between the roof insulation and the waterproofing film.

Recall that applying a waterproofing film to the roof can only be done during dry weather, following the completion of the rafter system installation and, if planned, the laying of insulation.

We spread the film

There is specific technology involved in applying waterproof film, including overlap, only so, and from the cornice to the ridge. Installing the film is easy: we force rainwater to always overflow the roof. The only thing that matters is keeping water out of the roofing area. Additionally, the film’s lower edge makes sure that falling drops are removed from a drainage groove.

The typical waterproofing film, in contrast to dense membranes, is laid out along the roofing cornice so that it sags by 1-2 cm between the rafters. Additionally, this sagging is required to prevent condensate from building up on the rafter system:

However, the absorption surface’s rafters are covered in the anti-condensate film. Use a wide-hatted galvanized nail or a construction stapler to secure it. Ensure that the insulation does not come into contact with any part of its lower surface.

We make the right overlap

Depending on the roof’s slope, the waterproofing film overlap is different:

  1. With a slope of less than 30 °, the overlap should be within 15-20 cm.
  2. With a slope of 12-30 °, the overlap is already required 25 cm.
  3. If you make waterproofing of four -sided steep roofs, increase the overlap on the ridges by another 5 cm.

We fix the rails

Once the waterproofing film has been applied, use the same galvanized nails to secure it with additional 3 by 5 cm rails that are nailed on top of the rafters. And already atop: a crate, with specific dimensions for every type of roof material.

We seal the joints

There is only one rule that applies to all film waterproofing materials: all joints should be in rafters. However, different kinds of adhesive materials use their.

Ordinary films, for instance, are just taped together and then sealed with dispersion.

Regarding the joints of the roofing waterproofing with extra components, trim the film and carefully adhere its edges to the closest bars in the roof sections where the pipes and antennas are positioned. Take the most common adhesive tape or, better yet, a bilateral self-adhesive tape to accomplish this:

Modern membrane installation technology

We advise applying two layers of membrane if your roof has a long yendov or a relatively small angle of inclination.

The cornice overhang must be precisely parallel to the modern volumetric membranes. The mounting locations should be overlapped by at least 7 cm on each subsequent roll, and the overlap area should be sealed with special glue.

Position the membrane 5–10 cm above the roof that will eventually be installed. Make sure the slips stay in the corners.

Whole sets of adhesive are used to seal modern membranes. Despite the fact that tape is not necessary because some of these films already have sticky edges.

Position the membrane over the lending canvases with the same overlap, and secure with nails or brackets. Every excess in Endov.

If you will be in the way of attic windows, follow the manufacturer’s recommendations and avoid them just like you would pipes. The guidelines are mostly as follows: Apply a membrane to a window box that is 5 cm wide when working with an attic window. As shown in the picture, tighten and switch all of the connections. By the way, these windows frequently come with special seals.

Choosing Waterproofing Film Installation Steps
1. Consider Climate and Roof Type. 1. Clean and Dry the Roof Surface.
2. Select High-Quality Materials. 2. Measure and Cut Film to Size.
3. Ensure Compatibility with Roofing. 3. Apply Adhesive or Heat Seal.
4. Check Durability and Warranty. 4. Secure Edges and Seams.
5. Verify Installation Techniques. 5. Inspect for Proper Coverage.

Selecting the appropriate waterproofing film for your roof is essential to guaranteeing weather resistance for an extended period of time. First, take into account the local climate as well as the particular needs of the kind of roof you have. Varying degrees of durability and resistance to elements like UV rays and temperature changes are provided by different materials.

Meticulous attention to detail is essential during installation. Make sure the surface is clear of any debris that can reduce the effectiveness of the film and that it is dry and clean. Make sure that all edges and seams are properly sealed to stop water seeping in. To ensure optimum performance, be sure to carefully adhere to the manufacturer’s instructions.

You should do routine maintenance to make your waterproofing film last longer. Check your roof from time to time for indications of wear and tear or damage, like tears or punctures. As soon as possible, fix any problems to stop water intrusion, which over time can cause expensive repairs and structural damage.

You can increase your roof’s resilience and longevity by selecting a premium waterproofing film and applying it properly. This proactive approach adds to the overall safety and value of your property in addition to protecting it. Never forget that careful installation and high-quality materials pay off in the long run.

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Alexandra Fedorova

Journalist, author of articles on construction and repair. I will help you understand the complex issues related to the choice and installation of the roof.

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