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The installation of a metal tile roof is a multi-layered “pie,” where the wooden batten serves as the load-bearing base, critically important for the longevity and reliability of the entire structure. This type of roofing is deservedly popular due to its aesthetic appearance, relative ease of installation, and excellent performance characteristics. However, achieving these benefits is only possible with strict adherence to installation technology at every stage, from calculations to the installation of additional components. A properly installed batten ensures the correct geometry for laying the sheets, ventilation of the under-roof space, and even distribution of loads. Ignoring technical standards and rules can lead to coating deformation, leaks, reduced roof life, and damage to the truss system.
Design and Calculation of the Roofing System
The design of a metal tile roof begins with an accurate calculation of all loads that the structure will experience. Constant loads include the weight of the roofing pie itself: the truss system, batten, insulation, waterproofing, and the metal tiles themselves. Temporary loads account for the mass of snow cover typical for the particular region and wind pressure. All this data is regulated by building codes and rules (SNiP), and based on this, the cross-section and pitch of all wooden structural elements are determined. A crucial stage is the calculation of the slope angle of the slopes, which directly affects the choice of metal tile type and the requirements for joint tightness.
Based on the calculations, a detailed drawing of the future roof is drawn up, which includes a plan of the truss system and the batten. The plan must indicate the locations of all additional elements: attic windows, ventilation outlets, chimneys, and snow retention systems. For each such element, it is necessary to provide for reinforcement of the batten or the installation of additional bars. Simultaneously, the calculation of the required amount of materials is carried out: metal tiles, additional components, waterproofing membrane, fasteners, and lumber for the batten and counter-batten. A reserve of 5-10% is always added to the obtained quantity for trimming and possible defects.
Preparation of Materials and Tools for Installation
The quality of materials directly determines the durability and reliability of the entire roof structure. For the wooden batten, lumber from coniferous species is primarily used, dried to a moisture content of no more than 18-20% and treated with antiseptic and fire-retardant compounds. The antiseptic protects the wood from rot, mold, and fungus, while the fire retardant increases its fire resistance. For the main batten, bars with a cross-section of 50×50 mm or 40×50 mm are usually used, and for the counter-batten — 30×50 mm. The wood must be even, without signs of blueness, warping, or falling knots.
Metal tiles are chosen based on aesthetic preferences and climatic conditions. The highest quality are sheets with a protective coating of pural or plastisol, which have high resistance to ultraviolet radiation and mechanical damage. In addition to the roofing itself, it is necessary to purchase in advance the entire set of additional components: ridge and end strips, abutment strips, lower and upper valleys, eaves strips, and elements for organizing penetrations. The required tools include a jigsaw or metal saw, a screwdriver, roofing screws with sealing washers, a measuring tape, a level, a hammer, a marker, and a string for snapping lines.
Installation of the Truss System and Waterproofing
The truss system is the load-bearing frame of the entire roof, and its installation requires particular precision. Rafters are installed with the calculated pitch (usually 600-900 mm) and attached to the Mauerlat or the top frame of the building using metal angles, plates, and brackets. The upper ends of the rafters are connected at the ridge purlin, which provides rigidity to the entire structure. After installing all the rafters, the geometry of the slopes is checked: the diagonals must be equal, and the planes of the slopes must be even without deflections or humps.
A vapor-permeable waterproofing membrane is rolled out and fastened over the rafters. It is laid in horizontal strips from bottom to top with an overlap of 100-150 mm. The membrane sheets should not be taut; a sag of about 20 mm between the rafters must be provided to compensate for thermal deformations and possible condensation. The membrane is attached to the rafters using a construction stapler or galvanized nails. The overlap areas are additionally taped with a special connecting tape to ensure complete tightness. The lower edge of the membrane must extend beyond the edge of the eaves board to drain moisture into the gutter.
Installation of the Counter-Batten and Ventilation Gap
The counter-batten is a key element that provides ventilation for the under-roof space. It is created by nailing bars with a cross-section of 30×50 or 40×50 mm along each rafter leg on top of the waterproofing membrane. It is the height of the counter-batten that determines the size of the ventilation gap, which is necessary for free air circulation from the eaves overhang to the ridge. This airflow effectively removes excess moisture coming from the internal premises of the house, thereby protecting the insulation and wooden structures from getting wet and deteriorating.
Installing the counter-batten requires careful control. The bars must be even and fastened strictly parallel to each other. Galvanized nails or screws are used for fastening, with a length exceeding the thickness of the bar by 30-40 mm to ensure reliable fixation to the rafters. In areas of complex nodes, such as valleys or abutments to walls, the counter-batten may require the creation of an additional frame for the correct installation of planks and ensuring ventilation. At the ridge, the counter-batten bars from the two slopes should not butt together tightly; a gap must be left between them for air exit.
Installation of the Main Wooden Batten
The main batten serves as the direct base for attaching the metal tile sheets and must be installed with the highest precision. The batten pitch is not universal and strictly depends on the type of metal tile profile and the length of its wave. The manufacturer provides an exact diagram of the batten pitch for each profile brand, which must be strictly followed. Usually, the first bar from the eaves is installed with a smaller pitch than the subsequent ones to form a more powerful eaves overhang.
Installation begins with the eaves board, which is thicker compared to the other batten bars. This is necessary for reliable fastening of the end parts of the sheets and eaves strips. Then, according to a pre-marked scheme using a template, all subsequent bars are nailed. Each batten element is carefully leveled horizontally using a level. In the areas of the valley and around attic windows, the batten is made solid to reinforce the structure and facilitate the installation of flashing and abutment strips. All wooden elements must be securely fastened to the counter-batten using nails or screws.
Installation Features in Valleys and Around Pipes
A valley is the internal angle formed at the junction of two slopes, and this is the most vulnerable place for leaks. Installation here requires special attention. It begins with the installation of a solid deck made of boards at least 500 mm wide from the internal angle in each direction. A lower valley strip, designed for water drainage, is laid on top of this deck. Its installation is carried out from the bottom up with an overlap of 150-200 mm. The edges of the strip are bent under the eaves strip, and the joints are coated with sealant.
A solid base made of boards is also created around chimney pipes and ventilation outlets. The waterproofing membrane is led onto the vertical surface of the pipe and glued to it using a special tape. Then, the lower abutment flashing is installed, which is led under the valley strip or onto the batten. After laying the metal tiles, the upper decorative abutment flashing is installed over it, the edges of which are tucked into the profiled sheet. All joints and connections in these units must be sealed to eliminate any possibility of moisture penetration.
Fastening Metal Tiles and Laying Technology
Laying metal tile sheets is the final and most crucial stage. Installation starts from the end of the slope or from the valley. The first sheet is aligned strictly along the eaves overhang and temporarily fixed at the ridge and at the eaves. It is important to maintain the correct overhang of the sheet beyond the eaves strip: usually, it is 40-50 mm to ensure effective water discharge into the gutter. Subsequent sheets are laid with an overlap of one or two waves (depending on the profile) and connected to each other at the ends.
The sheets are fastened to the batten using special roofing screws with an EPDM seal. The screws are screwed strictly perpendicular to the plane of the sheet into the lower part of the wave, directly under the transverse stamped rib. It is unacceptable to fasten into the upper part of the wave, as this violates the tightness and strength of the structure. The screw consumption is usually 7-9 pieces per square meter of coating. For cutting sheets, a jigsaw with a fine-toothed metal blade or nibblers is used. The use of an angle grinder with an abrasive disc is strictly prohibited, as it damages the protective and decorative polymer coating.
Installation of Ridge, End, and Eaves Strips
After laying all the metal tile sheets, additional components are installed, which complete the roofing and ensure its tightness. End (gable) strips are installed on the edges of the slopes and attached to the end board and to the crests of the metal tile waves. They protect the under-roof space from wind blowing and the ingress of atmospheric moisture from the side, and also give the roof a finished aesthetic appearance.
The ridge strip is mounted at the junction of two slopes at the very top point of the roof. Before its installation, it is recommended to install a seal or ventilation tape, which prevents birds and insects from inhabiting the roof but does not hinder the free circulation of air for ventilating the under-roof space. The ridge strip is fastened with screws into the upper crests of the waves every 200-300 mm. The eaves strip, in addition to its decorative function, directs the flow of rainwater from the waterproofing membrane directly into the gutter, protecting the fascia board and eaves elements from getting wet.
Installation of Safety Systems and Gutter System
For safe operation of the roof and protection against snow avalanches, the installation of snow retention systems is mandatory. On metal tile roofs, tubular snow guards are most common, which are mounted at a distance of 300-500 mm from the eaves overhang. They are attached directly to the batten through the metal tile using long screws into pre-reinforced areas. The number of rows of snow guards depends on the length of the slope.
The gutter system is an integral part of the roof structure and is mounted on the eaves fascia board before the installation of the eaves strip and metal tiles. The brackets for the gutters are installed with a slope of 2-3 mm per linear meter towards the water intake funnel. The pitch of the brackets usually does not exceed 600 mm to ensure sufficient strength of the system when snow and ice accumulate. The installation of downpipes is carried out at a distance of 30-50 mm from the wall of the building using clamps securely fixed to the capital structure.
Operation and Maintenance of the Finished Roof
A properly installed metal tile roof requires minimal but regular maintenance to maintain its performance qualities throughout its service life. At least twice a year, in spring and autumn, it is necessary to conduct a visual inspection of the roof, clean the gutters and funnels from debris and leaves. During inspection, special attention is paid to the condition of the protective polymer layer for chips and scratches, which must be promptly touched up with paint to prevent the development of corrosion.
The reliability of the screw fastenings should be checked periodically, especially after strong winds, and tightened if necessary. It is also important to monitor the condition of the seals in the ridge elements and abutment strips, as over time they can lose elasticity and require replacement. When moving on the roof for its maintenance, it is necessary to wear soft shoes and try to step only in the lower part of the wave, where the batten is located, to avoid deformation of the profile. Following these simple rules guarantees long and flawless service of the roofing.