Construction of houses

Installation of slate: step by step instructions

Roofs, for the installation of which asbestos slate is used, have been highly popular in the construction industry for many decades, and, despite the fact that in recent years many modern roofing materials that meet all the requirements have appeared on the market, asbestos-cement sheets still do not lose their relevance. Due to the relatively low cost of the material, its chemical inertness and resistance to static loads, neither roofing iron nor metal tiles have the right to compete with it. The aesthetic properties and technical parameters of slate, as well as the ease of installation and long service life, are in no way inferior to those of its more expensive counterparts, which also has a significant impact on the popularity of the roofing material. The steady popularity of slate, like any material used in the construction industry, experienced ups and downs, but the use of slate in country and individual construction revived when multi-colored asbestos-cement sheets went on sale. But their appearance did not affect the popularity of classic slate, which, having stood the test of time, did not lose its consumer. The first question that arises before the master when it comes to slate is how to lay this roofing material. Like any construction process, slate laying includes several stages, each of which is characterized by certain nuances. Their observance plays an important role in the effectiveness of the final result, and, accordingly, the duration of the operating life of the roof. In this regard, in this article we will answer the question: “How to cover the roof with slate?”.

Slate: basic information about the material

Slate is a traditional roofing material produced on the basis of asbestos cement and is characterized by high mechanical strength and durability. Today, there are both flat and corrugated slates on sale, as well as models released in multi-colored versions. Asbestos-cement sheets cannot be classified as environmentally friendly materials, since it has been proven that asbestos can harm human health during operation. Given this circumstance, slate can only be used for outdoor work..

Important! Wave slate can only be used for installing roofs with a slope, the angle of which must be at least 22 degrees. If the roof slope is small, it is necessary to carry out additional sealing of the joints, increase the slate overlap and use additional fasteners. To preserve the integrity of the slate sheet, holes for fasteners must not be punched, but drilled.

Important! Material based on asbestos cement is supplied in packages where slate sheets are laid with polyethylene. They should be kept in this form until they are used in work..

Before laying the slate, experienced craftsmen recommend covering it with acrylic paint, which helps to extend the operational life of the material. The service life of unpainted material is about 20 years, while slate coated with acrylic paint lasts several times longer..

Before we answer the question: “How to lay the slate?”, It should be noted that the installation of slate, like any other construction activity, requires preliminary planning. With this in mind, first of all, it is necessary to consider all possible options for the shape of the future roofing, since this is a determining factor in the calculation of slate.

Important! Roofs, for the installation of which sheet materials are used, can be flat, that is, single-slope with a slope of no more than 1-2 degrees, non-attic (single-slope and gable with a slope of no more than 7%), as well as attic, the design of which implies a slope of more than 40 degrees … It is important to know that experts do not recommend giving preference to intermediate options (for example, roofs with a slope of 25-35 degrees), since it is in this case that the maximum amount of snow accumulates on the roof. The modern development of building technologies makes it possible to equip complex roofing structures of any configuration, including those with four slopes, however, it is recommended to choose a simpler geometry for arranging slate roofs.

The advantages and disadvantages of slate: what you need to know about a slate roof?

The peculiarities of modern equipment and the development of innovative technologies have significantly improved not only the appearance of the slate, but also its operational characteristics. Among the main advantages of slate are the following:

  • Frost resistance and resistance to sudden temperature changes;
  • Resistance to high humidity;
  • Good UV tolerance;
  • The ease of installation activities and the possibility of their own implementation is another reason to pay attention to this roofing material..

Despite a wide range of advantages, slate also has certain disadvantages that significantly complicate the installation activities and are the reason for the refusal to use this roofing material..

Disadvantages of slate:

  • Relatively large weight of slate sheets;
  • The fragility of slate requires accuracy in the process of transporting material and installation activities;
  • Slate is made on the basis of asbestos cement, which contains asbestos, which has a negative effect on human health;
  • Taking into account the previous factor, you need to know that during the installation of a slate roof, provided that cutting of the slate is required, it is necessary to use personal protective equipment.

Important! Experts recommend treating the cut line with acrylic paint.

How to choose slate: basic rules

In most cases, domestically produced slate is used at construction sites, the dimensions of which are regulated by GOST 30340-95:

  • for six-wave slate: sheet thickness is 5, 6 and 7 mm; width – 1125 mm;
  • for seven- and eight-wave slate: sheet thickness – 5 and 8 mm; width – 980 and 1130 mm, respectively.

The length of the sheet regardless of the type of slate is 1750 mm.

Knowing the brand of slate, you can determine not only the number of waves, but also the height of the wave, which is the distance between the crest and the bottom, as well as the step of the wave, which is equal to the distance between any points of adjacent waves. Let’s consider this on the example of 40 / 150-8 brand slate. 8 in this case means that this slate is eight-wave, 40 mm – wave height, 150 mm – step length. These parameters must be taken into account when calculating slate, since when laying apart, implying the imposition of waves of vertical sheets, the consumption of six-wave slate exceeds the consumption of eight-wave. This is due to the width of the wave step, which in the six-wave slate is somewhat larger than that of the eight-wave slate, and therefore, the area of ​​the material going to the overlap increases..

Sediment collection system is another factor influencing the order of slate roofing. If you plan to equip a gutter under the overhang of the last slate row, it is enough to carry out the installation in such a way that the slate sheets of the last row protrude no more than 200-250 mm beyond the facade line. If you prefer a direct-type water discharge system, which provides for the discharge of water from the roof directly to the local area, the size of the ledge should be at least 400-500 mm.

Slate roof installation technology: main stages

Installation of a slate roof is carried out in several stages..

  • Preparatory measures, including the calculation of the required amount of material, as well as its purchase and delivery to the construction site;
  • Installation of the rafter system and the process of arranging the lathing under slate, combined with the laying of waterproofing materials;
  • The final stage is the installation of roofing material. He is the most responsible, since the quality and duration of the operating life of the roof depends on him..

How to calculate the required number of slate sheets? Key recommendations

Before you put the slate, you need to calculate the amount of material that will be required for the installation of the slate roof. To find out, it is necessary to carry out simple calculations, the procedure for which will be discussed below:

  • First, the length of the roof slopes is multiplied by their height;
  • The result obtained, corresponding to the area of ​​the roof, must be divided by the area of ​​the slate sheet;
  • As a result of these calculations, we received the required number of slate sheets, which must be increased by 10%, which is due to the technology of installing the slate roof, which provides for its overlap.

Preparatory stage: arrangement of supporting structures

The preparatory stage includes the installation of the lathing, for the arrangement of which it is necessary to prepare material from durable types of wood, but it is not necessary to choose oak or larch. This is due to the fact that slate is a fairly light material, and therefore any dense wood can be used for mounting the lathing. Before installing the slate with your own hands at the stage of arranging the lathing, the wood must be processed from rot.

It is important to note that, before the start of installation activities, the slate must be stored indoors in its original packaging and in a horizontal position, being folded with plastic wrap..

Having decided on the design and the slope angle, before installing the slate on the roof, it is necessary to lay the rafters, for the manufacture of which a 50×180 bar is used. Installation of rafters is carried out in such a way that the narrow side is vertical.

For the manufacture of lathing, it is recommended to use a 15-25 mm unedged board or 60×60 timber, which is installed perpendicular to the rafters.

Important! If you use boards to make the lathing, the distance between them should be from 200 to 1250 mm. In the case of using bars, they must be laid in such a way that each slate sheet rests on at least three bars, that is, the distance between them should be approximately 400-450 mm.

If you plan to equip a gutter, it must be installed before installing the slate sheets. On the sheets of the last row of the roof, it is necessary to nail a strip of metal to the bottom edge, the width of which is 300 mm and a thickness of 2-3 mm, necessary to prevent chipping of the sheets. A layer of waterproofing material must be applied to the metal strip from the inside and outside. In the places where the slate is fastened in the metal, the required number of fasteners is drilled.

Important! To improve the operational characteristics of the attic roof, experts recommend laying a vapor barrier membrane under the slate..

Slate laying technology: expert recommendations

It is important to know that horizontally located adjacent slate sheets must always be laid with an overlap, which can be one or two waves, while the latter option is more expensive, but it is he who guarantees higher strength characteristics of the roof. Due to the fact that when fixing more than two sheets of slate at one point, problems often arise, there are several ways to solve them, and, consequently, methods of laying roofing material.

The most popular method of installing a slate roof is “staggering”, which implies laying each new row with a shift relative to the previous one. Thanks to the use of such a technique, there is no coincidence of the overlaps of the waves in each of the rows, as a result of which, at each separately taken point, only two sheets can be joined. To carry out a shift in this case, it is necessary to trim several waves from the outer sheet. The disadvantage of this method is that during the installation of the last vertical rows of slate, an uneven roofing edge is formed, which needs additional alignment.

As for the eight-wave slate, there is a more practical modification of this installation method for it. In accordance with it, it is necessary to cut in half all the first sheets of odd horizontal rows (i.e., into 4 waves), which will lead to a fairly clear (through a row) repetition of the displacement lines and a more aesthetic appearance of the roof. In addition, using two sawn halves of a slate sheet, you can start installing two rows at once. After you have installed the first sheets, including the halves, you can simply lay the sheets horizontally without worrying about offset, since the shear formation occurs naturally. However, trimming may be required during the end edge alignment process..

If you are concerned about wasting material, your most preferable, albeit more time consuming, may be non-offset laying. In accordance with this technology, in the case of laying sheets from left to right, it is necessary to trim the corners of the sheets forming the upper row of the roof by at least 100 mm along the wavelength, and not less than 120-140 mm along the wavelength. In this case, the bottom corner is cut from the side covering the previous sheet of the horizontally oriented row. Experts say that thanks to the use of this technique, the most optimal overlap of all sheets of material is achieved, not only horizontally, but also vertically..

In the process of laying slate, it is necessary to use nails, self-tapping screws or special screws, characterized by the presence of an enlarged cap and a rubber gasket under it.

Important! To prevent damage to the roofing material during installation, it is necessary to mark the slate in advance and drill holes in it for fasteners. It should be remembered that the diameter of the hole should be 2-3 mm larger than the diameter of the self-tapping screw or nail..

Holes for fasteners should be located as follows: the first hole is in the lower corner of the slate sheet, the second is in the second overlapped wave, the third is symmetrical with respect to the previous one, that is, in the second overlapped wave. The final sheet of the row, located horizontally, must be additionally secured in the area of ​​the sixth (penultimate) wave.

Important! It must be remembered that regardless of the type of fasteners, they must be installed in the crest of the wave, since other placement of screws or nails will cause premature (and rather rapid) destruction of the roofing. At the same time, taking into account the magnitude of the vertical overlap between the rows, 120-150 mm recede from the transverse edge of the row.

How to maintain the integrity of the slate: basic safety rules

In the process of laying slate, it is important to observe not only the technology of installation measures, but also safety precautions. In order for the roof to be able to be cleaned during operation, as well as to carry out similar work on top of the slate, it is necessary to install wooden scaffoldings, complementing them with transverse strips-steps. If the installation of the roof is carried out on a building higher than 6 m, a fence made of metal reinforcement should be provided around it. In order to gently lift the slate sheet to the construction site, experts recommend using a block system and a nylon cable. If the installation of the roof is carried out on a low building, assistants can submit the material.

Important! Moving on the mounted pavement must be done carefully. For free movement along the slate roof during its repair or maintenance, lay wooden ladders on it, thanks to which the load will be evenly distributed.

In the process of work, it is necessary to use safety cables and other devices. As for safety precautions when working with asbestos-cement materials (cutting and drilling slate), they imply the use of personal respiratory protection (respirators) that will protect the respiratory system from harmful dust.

To equip ridge, cornices, roof joints, pipe joints and similar areas, experienced craftsmen recommend using commercially available special elements made of asbestos cement, after installing and fixing them with cement and bitumen mastic, you do not have to worry about the strength of the roof being installed. Sometimes wooden boards or galvanized strips are used for these purposes, however, due to the low aesthetics and inefficiency of this method, it has not become widespread..

If all technological stages of laying this roofing material are observed, the operational life of a slate roof without repair (except for emergencies caused by external influences) reaches 50 years or more..

Slate roof care rules: highlights

Slate coating needs simple maintenance, which will significantly extend its operational life.

Its main provisions are as follows:

  • Inspection activities and roof cleaning must be carried out twice a year – before and after the precipitation season;
  • Despite the fact that even a broom can be used to clean the roof, these activities can be significantly accelerated by using an electric pump;
  • In winter, it is recommended not to neglect the need to clean up ice and snow;
  • If you are unable to take care of the roof yourself, use the services of specialized teams..