Low cost and rather long service life have made slate roofs quite popular in construction at the present time. This article talks about how the roof is covered with slate, what materials are used and what positive and negative qualities they have.
The main types of slate
Natural or natural roofing slate is a tile obtained by splitting mountain layered rocks, mainly shale.
The roof material has been used in construction since the Middle Ages, and even today you can find buildings and structures covered with natural slate back in those days.
In modern construction, slate is practically not used as a material for roofing, and slate refers to materials made from asbestos cement.This is especially true for corrugated sheets (asbestos-cement slate).
In the manufacture of slate, a mixture consisting of 15% short-fiber asbestos and 85% Portland cement is used, which ensures a long roof life and good resistance to fire.
Asbestos-cement slate is one of the most common roofing materials due to its low cost (several times cheaper than sheet metal or tiles) and ease of installation.
The positive qualities include good frost resistance, low thermal conductivity, resistance to negative environmental influences, fire safety. In addition, this material is easy to process and has a long service life (several decades).
The production of asbestos-cement slate sheets consists in the manufacture and subsequent hardening of a mixture that includes Portland cement, asbestos and water.
Another type of slate roofing is asbestos-free slate, which has the following characteristics:
- fairly low weight of 0.2 kN/m2;
- increased elasticity;
- good resistance to temperature changes;
- resistance to various biological and corrosive influences;
- effective sound insulation;
- slight deformations due to temperature fluctuations;
- Fire safety.
The installation of asbestos-free slate sheets is carried out similarly to the installation of asbestos-cement sheets, and their fastening can be done using special nails, the color of which matches the color of the coating.
Recently, the material called "Euroslate" has become more and more widespread.
This imported material has a higher cost, but this is offset by its environmental safety, low weight, long service life and attractive appearance. There are a number of varieties of euroslate, such as nulin, ondulin, guta, ondura, etc.
All of them are popular due to their lightness, ease of installation, wide range of color shades, as well as the ability to cover various elements of the roof, such as ridge, plums, pipes, valleys, etc. . The main disadvantage of such materials is their rather high cost.
Advantages and disadvantages of slate coating
Despite the fact that a wide variety of roofing materials are presented on the construction market, slate is the most popular of them for the construction of country houses, cottages and summer cottages.
This is primarily due to its rather low cost, and in terms of technical and decorative characteristics, it may not be inferior to more expensive materials, such as roofing iron or metal tiles, and also has a significantly longer service life than a wooden roof that has risen in price recently.
We list the main advantages of slate roofing:
- high service life;
- increased resistance to fire;
- hardness, allowing the slate roof to withstand the average weight of an adult man;
- in the hot season, a slate roof heats up much less than roofs made of metal tiles and corrugated board;
- good electrical insulation;
- soundproofing, well muffling the sounds of rain and hail;
- relatively low cost of the material;
- high resistance to corrosion.
The negative characteristics of slate include the following:
- the composition of the material contains asbestos, which negatively affects the human body, as well as cement dust, fiberglass, etc. When working with slate, it is necessary to use special means to protect the respiratory system;
- over time, a layer of moss forms on the surface of the material;
- significant physical effort when laying the material, due to its significant weight;
- fragility, due to which care should be taken during the transportation of slate to the installation site.
The basis for the construction of a slate roof is a crate made of bars, the cross section of which is 5x5 cm for sheets from a regular profile or 7.5x7.5 cm in the case of reinforced profile sheets.
The pitch of the crate is 50-55 and 75-80 centimeters, respectively.
The laying of sheets is carried out starting from the eaves in the direction of the ridge, while the overlap of each upper row to the lower one should be 12-14 cm.
Important: in the case when the slope angle exceeds 30º, the overlap can be reduced to 10 centimeters.
In each row, the joints should move one wave in the longitudinal direction.
To fasten the sheets to the crate, nails or screws with rubber sealed gaskets and galvanized caps are used. Overhangs of cornices are made of roofing iron or sheets of asbestos cement.
Recommended ramp angle slate roofs ranges from 25 to 40 degrees, while an increase in the angle of inclination leads to an increase in the water tightness of the roof. In addition, keep in mind that steeper slopes require more roofing material.
Important: the minimum angle of inclination of the slope when arranging a slate roof must be at least 12 degrees.
Depending on which slate is used, roofing materials have their own subtleties when laid on the roof surface. For example, in the case of using rubber slate, it is very important not to make a mistake with the dimensions of the transverse and longitudinal overlap.
Rubber slate is most often laid on slopes with a small angle of inclination to allow movement on the roof.
For such roofs, as well as in the case of trees growing near the roof, more overlap should be made than with large angles of inclination or the absence of vegetation.
This is due to the fact that the leaves, needles and seeds of trees can be blown out by gusts of wind under the overlap of the slate sheet, where they will swell, absorbing air moisture.
This causes the vented part to rise, resulting in a space that more debris can enter, etc. The end result is a significant rise in the edges of the slate sheets, which causes the roof to get wet in the event of an oblique rain.
This process will last for a long time, but as a result, slate roof repairs will have to be done much earlier than the required time.
In order to avoid such troubles, the overlap should be increased, as well as fastening with nails closer to the overlap of the slate sheets, hammering them not along the crest of the wave of the sheet, but along the gutter.
And then slate roof repair you won't need it for long!
Did the article help you?