Metal roof: expert advice on the selection and installation of a roof

Recommendation points

• Profile type, dimensions and appearance
• What is the most durable metal tile?
• Production secrets
• Complex roofing issues
• Subtleties of installation

Metal roofing is well-deservedly popular: a large selection of colors and textures, low cost, simple installation technique, no need to create a complex roofing cake. However, do not rush to purchase the first available or the cheapest cover. We will help you understand the variety of material and tell you about the nuances of installing metal tiles.

Profile type, dimensions and appearance

Although the aesthetic component of the metal tile does not affect its durability in any way, the selection of this material should begin with the determination of the desired shape and size of the profile. There are two main reasons for this:

1. All the same, metal roofing is an economy class coating, which is famous for its ability to naturally imitate roofing from piece tiles. Therefore, it will be much easier and more correct to choose a roof covering that matches the architectural features of the building, and then give preference to a covering with sufficient security for local conditions..
2. Metal shingles are not included in the category of exceptionally durable coatings, but at the same time they allow to cover the period between roof overhauls. The service life that the coating provides should be chosen equivalent to the rest of the elements of the roofing system: protective membranes, insulation and waterproofing.

When choosing a profile shape, you don’t need to be greedy for new items. The “younger” a certain type of wave, the less developed the production technology. For example: the profiling and bending of the classic Monterrey profile has been carried out for decades, the main pitfalls have been identified, and the shortcomings of the production technology have been eliminated. In general, we can say that the fewer bends in the tile with sharp corners and small radii, the less the structure of the coatings is disturbed during the molding process..

What is the most durable metal tile?

When choosing a metal tile, the most “dark” question is the composition and performance of the protective coating. The next most important is the quality of raw materials – galvanized steel sheet. The optimal combination of these two indicators ensures a long service life of the roof..

Let’s start with the simplest aspect: a sheet for the production of metal tiles can have a steel thickness in the range of 0.4–0.5 mm. This indicator has little effect on weather resistance; with an increase in the thickness of the metal core, only the mechanical strength increases. The manufacture of metal tiles from a sheet with a thickness of 0.45 or 0.5 mm is justified in cases where the profile has an increased height and wavelength, respectively, a more rare lathing is required. Do not forget about galvanizing – the density of the internal protective coating from 140 to 250 g / m2 is considered the norm² with obligatory surface passivation before applying the primer. Under the polymer-protective coating, the zinc layer practically does not thin, but its thickness is of direct importance for the protection of cut edges..

Finally, you should learn how to choose the right protective and decorative coating. This is quite difficult, because most of the polymer compositions are protected by patent law, their composition is not disclosed, and therefore it is rather difficult to assess the real performance characteristics. However, a reliable manufacturer will always meet halfway by providing a comparative table along with the ability to choose a material with a specific type of coating for the manufacture of a specific type of rolled metal. For example, the Metal Profile Company manufactures products with a dozen protective coatings, so there are no problems with choosing a roof for specific tasks and operating conditions.

And yet, what type of protective coating should you choose for your roof? You can set the task of selection to the manager of the supplier company, that is, describe the operating conditions, indicate the climatic region, supplement the initial data with your own notes – the presence of nearby chemical plants or thermal power plants. It is even better if you are able to check the choice of a manager yourself, taking into account a number of general rules:

1. For roofs in the open sun, it is better to abandon Plastisol in favor of Pural or PVDF – they also have higher color fastness, and the maximum temperature reaches 100 ° C.
2. If the roof has low insolation (shade from trees, high latitude), fading resistance is not particularly important for the roof. However, in the case of shading the roof with trees, you should take into account the possibility of falling broken branches and choose a material with a high resistance to mechanical damage (PUR) or with a significant thickness (Plastisol).
3. If atmospheric moisture has an aggressive effect, which is usually associated with emissions from nearby enterprises or the location near the sea coast, the coating must additionally have a high resistance to corrosion. Fortunately, most modern polymer coatings are quite consistent with these qualities, you just need to avoid the cheapest polyester.
4. For each coating, its operational life is determined, which, as already mentioned, should at least approximately correspond to the durability of other roof elements.
5. The presence of texture on the surface can play a significant role in the behavior of the snow cap and ice, this point needs to be clarified for the correct choice of snow holders.
6. To avoid damage to the polymer coating during delivery and installation, it is recommended to pay extra for applying a protective film.

Production secrets

In general terms, the process of manufacturing high-quality metal tiles is as follows:

1. Coated steel sheet is produced by a foreign company with qualifications measured by decades of practical experience.
2. Sheets are delivered to regional points of production, the rolls are compact and therefore the logistics overhead are minimal, the material is not damaged during transportation.
3. Modern equipment is used to form metal tiles, the shape of the profile and the length of the sheet of which is free to determine the customer.

Let’s go back to the example of the Metal Profile Company: the source material is supplied by the world’s leading manufacturers from Sweden, Great Britain and Southeast Asia. In a number of cases, the production of coiled steel with a protective and decorative coating is practiced at domestic enterprises in order to reduce the cost. Metal tiles are formed on a distributed network of manufacturing plants equipped with certified equipment, with multi-level quality control. Thanks to this scheme, there are no obstacles for individual work with each consumer..

But here are the factors that characterize the production process of a low-quality product:

1. Purchase of sheet from Chinese suppliers that do not provide proper control over the observance of production technology, galvanization rate and the composition of polymer protection.
2. Delivery from abroad of already formed sheets, which are 15–20% more expensive than domestically produced products, are subject to the risk of damage, and besides, they cannot be delivered in the required molding.
3. Rolling sheets on equipment with an exhausted production resource, as a result – difficulties in aligning locks, violation of geometry and associated installation difficulties.

Complex roofing issues

The above questions about the choice of metal tiles are just the tip of the iceberg, the roof is not limited to one coating. Even the highest quality material with an incorrect layout of the roofing pie and violation of installation rules will manifest itself only from the worst side. This does not suit a responsible manufacturer, therefore, together with the supply of the main material, he assists in the correct choice of materials for insulation, waterproofing and vapor barrier, as well as additional elements.

Ideally, the process is as follows: the customer sends the manager a drawing of the roof truss system, indicating all the actual key dimensions, according to which the coverage rate and its optimal format are calculated, the specification of extensions for the protection of abutments is determined. If the delivery of the material is required as soon as possible, the calculation is based on the length of the measuring sheets, otherwise the material for the roof is made individually. How long does it take? It all depends on the production capacity of the enterprise: for “garage” production it is 2-3 weeks, and for a company that has covered every 5th metal roof in the CIS – from 3 days to a week, depending on the region.

The issue of object tracking should be raised first. If managers refuse to calculate at least the material for the roof for free, the developer is forced to do it on his own or apply for architectural design services.

Subtleties of installation

The final stage of roofing – installation itself – is not always possible to carry out by professional roofers. The advantages of metal tiles in this regard are obvious: an average construction team will cope with its installation, however, for this a number of conditions must be observed regarding the preparation of the supporting roof system:

• the slope of the rafters should not be less than 14?;
• it is necessary to cover the rafters with waterproofing, which is fastened with a vertical counter-lattice, which provides ventilation air;
• the lathing should be carried out with lumber of the same thickness with a uniform pitch corresponding to the length of the wave row;

As for laying the coating, here the list of basic rules is somewhat wider:

• the fastening of the metal tile to the crate is performed using roofing screws with neoprene sealing washers;
• the self-tapping screw is screwed in strictly perpendicular to the coating and tightened until the washer expands by 1–1.5 mm;
• fastening is performed in every second wave in a checkerboard pattern;
• the laying of metal tiles begins only after fixing the brackets of the drainage system and installing the droppers;
• the order of laying the coating – starting from the bottom row, mainly from right to left. The lower edge of the first row is aligned with the dock so that it hangs over the gutter by no more than 1/3 of its width;
• at the vertical joints of the sheets, fastening is required in each wave row. On slopes with a slope of less than 30? it is recommended to put sealing tape in the locks;
• the metal tile allows walking on it, but only in soft shoes and only when the foot is placed in the deflection of the wave;
• valleys and abutments to walls or chimney wells are made by means of two strips – the lower waterproofing and the upper decorative;
• the upper convergence of the slopes is trimmed taking into account the ventilation gap and covered with a ridge profile of a rectangular or circular cross-section;
• for metal tiles, it is necessary to install ventilation outlets, snow holders and walk-through ladders.

These rules are well known and are indicated in the installation instructions of any manufacturer, however, you should always take into account the peculiarities of working with a specific material. The obvious advantage of the Metal Profile Company: if necessary, you can be provided with full consulting support in the framework of working with a certain type of metal tile. This makes it possible both to install the roof on its own, and to attract low-skilled labor under personal technological control..