How to install metal roofing over shingles

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How to install metal roofing over shingles

metal roofing

The final stage of construction of the house is the laying of the roofing system and the outer covering. It is it will take the brunt of the load from precipitation, so for this purpose should use only the best materials available. We will tell you how to cover the roof with metal roofing with your own hands, step by step.

Advantages of the material

Before you know how to properly put metal roofing, you should better familiarize yourself with its features. It is one of the most popular types of roofing material.

The main advantages:

  1. Relatively low weight. The mass of one meter of tile is approximately 6 kg, which significantly reduces the load on the roof pie, walls and base of the building.
  2. Resistant to the damaging effects of the environment. Protected against corrosion, the metal can withstand the effects of ultraviolet rays, water, snow and hail.
  3. Aesthetics. The finished coating is distinguished by its external appeal. Manufacturers offer products in a variety of shapes and color options.

Metal roof tiles are not affected by fire, and their service life exceeds 40 years with proper care. The only threat to fire safety are wooden beams, but if treated with flame retardants, they also will not be able to catch fire or support combustion.


How to properly lay metal tile depends on what type it belongs to. Existing models differ in the length and height of the wave. The thickness of steel determines the index of ultimate strength and durability, as well as the cost.

Available varieties differ in a number of parameters:

  1. Profile type. The shape of the outer surface can be symmetrical, asymmetrical, or trapezoidal. They do not differ in quality, so the choice depends only on personal tastes of the building.
  2. Protective coating. To achieve the required indicators of strength, metal is coated with an anti-corrosive composition based on zinc, aluminum and other materials. Spraying gives reliable protection against contact with air, which causes the formation of rust.
  3. Decorative coating. It is selected on the basis of the style of decoration of the building, as well as on the basis of the personal taste of the owner. Its task is to give the coating a spectacular appearance, while providing additional protection from the environment.
  4. Decorative coating is made of different materials. The most affordable is polyester. It is good for any climate, but it is easily damaged under mechanical impact. A more durable option is plastisol, a polymer material based on polyvinyl chloride. It is unaffected by corrosion, but in hot regions it melts in the sunlight.

Pural well protects against corrosion and easily withstands adverse weather conditions. Therefore, before roofing a metal roof with his hands using this cladding must take care not to subject it to plastic deformation. A better option – PVDF. This coating withstands mechanical damage well, does not burn out in the sun and is able to last more than a dozen years.

Tips for working with metal shingles

When laying the roof for optimal results, you should follow the correct slope – 14 degrees. With this arrangement, precipitation will not linger on the roof, but also the roofing pie will not be too small for the house.

Consider a number of other recommendations:

  1. Do not use a grinder to cut shingles. When you come into contact with the rotating disc at high speed, there is localized heating of several hundred degrees, which causes the protective layer to break down;
  2. When working with roofs of complex shape should buy a large stock of material. After the cut is left a lot of unnecessary scraps;
  3. The places of cuts are painted with a quality paint that can permanently protect the metal from corrosion. Do not miss this point, because otherwise the coating can quickly rust and deteriorate.

Anyone who knows how to properly cover the roof with metal roofing, always working as carefully as possible, without stepping on the surface with your feet. This is done using a lightweight ladder, on which the master moves.

When installing waterproofing, protecting against the formation of condensation and its absorption into the thermal insulation layer is mandatory. To do this, cut a piece of necessary length, taking into account the overhang (20 mm), and fastened to the rafters through the stapler staples. During independent installation you will need the following tools:

  • hammer;
  • screwdriver;
  • tape measure;
  • 3-meter level;
  • scissors designed for cutting metal parts.

Before you put a metal tile on the roof, it is necessary in advance to make calculations and purchase building materials in excess. Particular attention is paid to caulking the gaps through which moisture passes.

metal roofing

How to calculate

Such work is carried out with a clear planning process, so first of all a project of the roof is developed. To do this, accurately measure the slopes of the roof, calculate the number and length of valleys, ridges and other components. In the plan is made a scheme of drainage.

Based on the collected data and the specifics of the chosen technology of laying, it is possible to know how many building materials required for the job. The homeowner can perform calculations on their own, or, having collected the data, contact a specialized firm for the sale of roofing materials. Its staff will hold them through special programs, and determine the anticipated cost.

Before you put a metal tile, you must purchase and deliver sufficient quantity of building materials in advance. In their shortage may stop construction, with the unfinished roof will be vulnerable to the effects of precipitation.

What will be needed for construction

Assembling a roof is a complex process that cannot be safely carried out without a number of devices. Each master, who knows how to install metal roofing, has its own set of tools and devices to ensure easy access to all parts of the roof.

Portable ladder with stops

Necessary when installing the first eaves strips and gutter system. In its upper part are movable legs, which can be positioned at a given angle and rest against the wall of the house. Such a design eliminates damage to the overhang of shingles and gutters. The product is lightweight, and if necessary, it can be easily moved from place to place.


By installing them near the walls, you can significantly increase the safety of the work. The scaffolding consists of metal supports and a wooden platform that can accommodate several people. It is best to use factory models, the size of which will correspond to the height of the building. When choosing, be guided by individual conditions.

Gangway for movement on the roof

The product is similar to the usual ladder, but it is supplemented with special hooks designed to fix to the roof ridge. The ladder is installed on the finished elements of the roof so that the master does not damage them when moving. With its help it is much easier to screw in screws and other fasteners, create a frame chimney and attach snow guards.

Guides for shingles

Are made on their own, used to simplify the transfer of roofing elements on the roof. Two boards are sewed together so that their width corresponds to the size of the fragments of metal shingles. The length of the guides should be long enough to allow them to lean on the roof at an angle of no more than 45 degrees.

When using a single person places a piece of the roof at the bottom, and pushes it up. The person on the roof takes the roofing element and pulls it toward him, and then fastens it to the battens.


Before covering the roof with metal roofing, it is necessary to prepare appropriate clothing. It should be lightweight, the presence of hanging parts is not allowed, because they can get caught on ledges and or other objects. You will also need certain tools:

  • Hammer and screwdriver – they are used to hammer nails and screw in self-tapping screws;
  • A marker for making marks;
  • a tape measure at least five meters long;
  • rail-rule to help determine the location of the elements of the roof;
  • Metal scissors to separate tile sheets into parts.

All tools must be in perfect condition as the quality and speed of work depends on it.

Installation work

This stage involves the sequential execution of several stages of the installation of the roof pie. Each of them is performed according to its own rules, and requires the most responsible attitude from the master.

Installing the sheathing

This is the name of the wooden structure, laid on top of the rafters and taking on the main load. Assembled from 50 * 50 mm bars or boards 100 * 25 mm with a given step, the width of which depends on the wavelength of the shingles.

The assembly process includes several steps:

  1. At the edge of the eave board is attached, exceeding by 15 cm in thickness all the others. The next one is set 50 mm closer than all the subsequent ones.
  2. On the rafters are placed bars with a cross section of 50 mm, which will be used as an internal counter-batten. This superstructure is necessary for the formation of ventilation holes.
  3. On the inner counter-battens install waterproofing, fixing is done with a stapler. The film is not stretched tight, a certain sag should be left. Individual panels are laid on top of each other with an overlap of 15 cm.
  4. Nail the boards that make up the external counter-batten on top of the waterproofing.
  5. After the fastened elements are installed on all the eaves, fasten the remaining boards with a certain pitch.
  6. Fasten the end boards at the height of the wave of the tiles, so that they are above the general level of the lathing.

Lathing can be regular or continuous. The first option is suitable in most cases, while the full coating of boards with a gap of 15 mm is used with heavy sheathing of high thickness.

Additional boards are also added near the ridge and in valleys. To determine the best option, before laying metal on the roof, you should check the geometry of the slope and measure the exact weight of the sheathing.

Peculiarities of work with purlins

Step of laying the boards of the supporting lath directly depends on the model of metal shingles. For example, for coverage of the Monterrey type it is 350 mm. If the master does not have such information, the slats are located so that they were at the bottom point of the wave, where the fastening will be carried out.

Particular attention is paid to complex elements of the roof, such as internal corners, outlets from the chimney and other elements. In such places, a solid batten with a gap between the boards not exceeding 5 mm is installed. You will also need to install interior valleys and aprons.

Do not forget about antiseptic treatment. Each board and bar on all sides are treated with a protective spray that does not allow penetration of harmful microorganisms such as mold and fungus. They also protect the wood from insects. In order to comply with fire safety standards, wood is additionally treated with flame retardants.

Insulation and waterproofing

Before you cover the roof with a metal roof, you should decide how you plan to use the space under the roof. Non-residential space that is used as a storage room will not require additional insulation of the slopes. However, in northern regions it is recommended at least to insulate the intermediate floor.

But if you plan to install a high-quality roof with metal shingles, it will not be superfluous to take care of reliable insulation. The space between the boards and purlins is large enough to install insulation boards of mineral or basalt wool.

In this case, immediately after the installation of purlins its surface is completely covered with vapor barrier with an overlap of 15 cm sheets, and fastened with staplers. The joints are additionally closed with an adhesive tape. Insulating material is laid in the openings between the joists, and then it is also covered with vapor and wind barrier, and covered with boards of counter-battens.

Before you mount metal roofing tiles, you should pay attention to the weather forecast. Work in the rain or snow is not allowed, since the insulation easily absorbs moisture, losing its operational properties. After completing the work with purlins and insulation, the master proceeds to the laying of shingles.

How to assemble a metal tile

The process is not particularly difficult, but the master must be persistent and prepare for painstaking work, because mistakes will lead to a decrease in the quality of the coating. Installation begins with the fixation of the first slat on the thickened board. The assembly is carried out with an overlap of 10 cm. Peculiarities of the beginning depend on the type of roof:

When working with a gable roof, you can start from either end;

In a hipped roof the boards are recruited from the highest point, and lead to the two sides;

In a complex work also begins with any end, but when you reach the complex structural elements, they need additional trim.

When laying the sheet is carried out beyond the line of the eaves by 40 mm. When laying from right to left, the next piece is laid overlapping the previous one. Otherwise, it is laid under the previous one. When laying each new piece, make sure that they are strictly aligned with the bottom line.

Fixing is done with self-tapping screws designed to work with metal shingles. They are made of galvanized steel, and are complemented by external coating and a wide cap. Such a design gives reliable protection against corrosion, both for the fastener itself, and for the roof.

In the lower part of the screws are installed on each bend of the wave, which ensures a secure fit. Above it is enough to fasten through one wave. Install the screws so that they are positioned exactly in the middle of the bar or board.

Features of the process

Since the valley is expected to have an additional load, in this place the sheets are fastened on each wave to a solid purlin. Since several sheets are docked at this point, they must be fastened so that they form an even angle.

A separate technique is provided for the equipment of chimneys:

this functional element is supplemented by a solid batten, attached directly to the brickwork;

the pre-cut sheet of shingles is fixed to the battens, the adjacent ones are laid so that an even angle is formed;

the joint is concealed by decorative elements attached with screws;

For maximum tightness, the steel plates are attached so that the upper slat was tight to the surface of the chimney, and the joint is covered with sealant.

If everything is done correctly, at the junction of the top sheets formed a gap in which you can install a sealant.

Common mistakes

If the work is performed by a group of people who have no real experience and have only theoretical knowledge, small or serious violations of technology are possible. As a result, the strength and durability of the roof significantly reduced.

Working with self-tapping screws

Most often, inexperienced craftsmen make a mistake screwing self-tapping screws. If the fastener is fixed too close to the edge of the sheathing board, the wood can peel off. As a result, fixing will be unreliable – the screw will hang in the air, and the base will lose its strength.

Do not screw in screws too far from the wave, otherwise its head when clamped will lead to a serious deformation of the roof. At best this will lead to a loss of visual appeal, at worst the metal will break, and water will go inside. When installing should make sure that the screw is screwed flat – the only way to ensure maximum tightness of the head and the maximum protection from the environment.

Inexperienced craftsmen often underinflate or squeeze the hardware. In the first case, water will slowly penetrate into the interior of the roof through the remaining gap. In the second deformation will occur, reducing the service life of the roof covering. Ideally, no gap should remain between the rubber pad and the shingles.

Mistakes when laying sheathing

Laying each plank of the base under the metal shingles, you need to monitor their location. All boards are laid strictly parallel, nailing them to make sure that they are all at the same level. To do this, use a rule with a special indicator.

Do not break the step of the crate, otherwise it will be impossible to fix the elements of the roof. Do not be lazy to use measuring instruments when fixing each board and beam – this ensures maximum accuracy.

Installation of snow stops

These elements are designed to reduce the load of precipitation on the roof in the winter. In their presence, the snow will descend from the roof without causing damage to the sheathing and the surrounding area. Their number depends on the length and slope of the roof. The longer the slope and the steeper the slope, the more rows are needed.

For fixing after even before the roof is laid, select an appropriate place on the first and/or second wave from the eaves. These elements are placed behind the eaves and fixed with special fasteners so that they pass through the bottom of the wave and enter into the boarding on 15-20 cm.

Familiar with the technology of laying shingles inexperienced person well be able to cope with its installation. To do this, it is sufficient to strictly follow all instructions, and work very carefully. Those who are not confident in their abilities or do not have enough time, it is much better to turn to professionals.