What is a Norwegian roof and do you need one? Green roof How to make an earthen roof
“Green roof” (grass) - the most ancient roofing material. This is the roof of a building that is partially or completely covered with vegetation and soil mixture.
This idea originated in Northern Europe and Russia. Residents of Scandinavia have long insulated their homes with natural materials, pieces of moss. In Russia, thatched roofs were covered with turf to prevent fires.
Rebirth, forgotten design solution, is associated with the name of the German architect Karl Rabitz. He revived the concept of the “green roof” by introducing a house with green space instead of a traditional roof at the World Exhibition in Paris in the 19th century.
The most simple solution The issue of roof gardening is container gardening. With this system, plants are placed in boxes or containers.
A “green roof” is a way to emphasize the owner’s sense of style. It will give your estate a unique, original look.
“Green roofs” are divided into two types – intensive and extensive. Intensive method, more complex and requires special care. But on such a roof you can create not only a green lawn, but also relax on it. The extensive look is unpretentious and can be located on roofs with a slope of up to 45 degrees. Access to such roofs is limited.
Research conducted by scientists in the Scandinavian countries (and primarily Norway) has convincingly proven that grass roofs can significantly reduce the level of air pollution and enrich it with oxygen and moisture. The most important thing is that the grass carpet of the roof creates a special energy in the home, where a person, tired of modern hectic life, can again feel in harmony with nature.
However, greening your roof is beneficial not only from an environmental point of view, but also from an economic point of view. In particular, a roof with grass covering helps to save heat and energy resources, can significantly reduce temperature fluctuations in the home, and improves the sound insulation of the building.
With your high thermal properties The “green” roof is due, first of all, to the air gap formed between the stems of plants.
Unlike modern roofs, heating up to 80°C on hot days (which causes air movement and, as a result, contamination with dust particles), a grass roof heats up to only 25°C, and thanks to convection, practically does not lose heat. In addition, due to the “breathing” of plant roots, the temperature of the grass, even in frosty conditions, is always above zero. The heat emitted from the walls of buildings is also partially absorbed by the grass carpet of the roof and accumulated by the soil layer and the moisture contained in the plants.
Thanks to these properties, houses with a green roof have an excellent microclimate. In the summer, a pleasant coolness reigns in such a home. In essence, a grass roof carpet is a kind of natural system conditioning.
Finally, a green roof is an excellent self-cleaning natural air filter. After all, grass perfectly catches dust particles, and rain washes them away again.
In our country, greening roofs is a new direction in landscape design. But every year the “green roof” finds its fans and pleases more and more admirers with its appearance.
How to make a grass roof like this
The construction of a grass roof is similar in most cases. This is the carrier truss structure and the sheathing is made of non edged boards, on top of which turf was laid.
Instead of the waterproofing widely used today from rolled bitumen or other materials, a layer of birch bark was laid on the sheathing, on top of which turf was laid in two layers or a soil mixture was poured for sowing it with grass seeds.
However, before touching on the technology of laying bark and turf, it should be noted that the dead weight of a green roof is about 250 kg/m2. This means that the shear load (especially on roofs with steeper slopes) can move the entire grass covering down. To avoid this, fencing was an indispensable structural element of green roofs. Their function was traditionally performed by turf fencing beams or boards laid along the overhangs - the so-called turf holders.
At the same time, the construction of the roof when creating a grass carpet had to ensure unhindered drainage of rainwater from the roof slopes. To do this, it was necessary not only to choose the right shape of the turf holders, but also to attach them to the sheathing accordingly.
Strips of birch bark were laid overlapping each other. In the overhang area they were laid in 5...8 layers. At the same time, the strips released from under the fencing beam and placed on it were laid outer side up. This was done in order to ensure effective water drainage and protect the sod holder and the end parts of the sheathing boards from moisture. In addition, the bark, laid with the outer side up, is an important decorative element green roof.
To increase the service life of the roof, the bark on the rest of the roof was laid with the outer side down, since its inner side provides more effective protection lathing from the mixture of sigumic acids contained in the soil.
To protect the turf laid on the sides of the pediment from wind and water erosion, natural stones. Later, pediment wind elements, which were used as logs, began to be used for this purpose. They were laid so that the ends protruded above the ridge. The logs were joined crosswise. And since the logs were the same thickness as the sod holders, together they formed a kind of wooden frame for the entire roof.
In another option, a wind board was used to protect the grass surface from erosion. It was fastened with wooden dowels and covered with birch bark from moisture. Sometimes, instead of bark, a horizontally laid covering board was used.
One of important elements traditional grass roofs - a wooden gutter, which was made from boards screwed together at right angles or hollowed out from a tree trunk.
The weak point of grass roofs is the openings (particularly for chimneys). To prevent water from flowing down the walls of the pipe into the house, stone slabs protruding beyond the pipe were walled into its masonry.
Rice. Roof with grass covering in the pipe junction area 1 - traditional design; 2 – modern design.
At the same time, sheets of birch bark were placed under these slabs, diverting the flow of water to the roof. Stone slabs on the side of the slopes they were arranged in steps, which contributed to more efficient drainage of rain or melt water from the pipe walls.
A log is used as a fencing element, supported by a stop hook secured under the sheathing. In this case, the hook, cut into the log of the upper crown, is secured under the sheathing, and the round timber itself lies completely on the birch bark. To prevent water from accumulating on the roof, the sod holder has slots for drainage.
The round timber, in turn, is also lined with birch bark. Despite the presence of such moisture protection, the sod holder still needed to be periodically replaced with a new one.
For example, when attaching a stop hook on top of the sheathing, a space is created between the birch bark and the turf holder to ensure effective drainage of water. And when attaching the enclosing element using a dowel, special slots were provided in the sod holder for water drainage.
Another interesting solution is when the fencing beam is attached to the side, with a distance of 5 cm from the edge of the overhang, which also ensures rapid drainage of water.
In all these cases, the turf holders are protected by birch bark. The overhang zone itself is covered with several layers of bark.
You can also use the option of fastening the enclosing beam using a powerful dowel embedded in the end of the rafter. This fastening method was used for roofs with hanging rafters, protruding beyond the overhang by approximately 12 cm.
Often, in order to save wood, instead of logs or beams, boards 3...4 cm thick and 12...16 cm wide were used to fence the grass covering, depending on the thickness of the green roof.
To ensure water drainage, holes or slits measuring 3x3 cm were made on the lower edge of the board every 20 cm. On the side in contact with the turf, they were expanded, giving the shape of a funnel. Sometimes boards were installed without drainage holes. In this case, they were fastened so that they protruded 2...3 cm beyond the overhangs. To do this, as a rule, they used persistent steel corners, which were screwed to the sheathing with screws.
The main task of any roof is to retain heat in the house and protect it from wind, rain, snow, ultraviolet rays and other adverse atmospheric factors. However, there is an acute shortage of places for construction and environmental problems megacities have led to the fact that additional tasks are assigned to modern roofing. One of the modern fashion trends in modern architecture is to create a “green roof” where you can arrange a flowering lawn and even grow the necessary vegetables and herbs.
What is it?
Not all city residents have the opportunity to fully relax in a forest clearing or enjoy the mountain air - often there is simply no time for such trips. Multi-storey buildings, cramped streets, exhaust fumes from passing cars and hot asphalt have a negative impact on people every day. That is why the owners of private houses and cottages work tirelessly to ensure that their homes are as close to nature as possible - they use environmentally friendly materials in construction and arrange flower beds, lawns and rockeries.
Very interesting technological solution came to Russia from the Scandinavian countries- this is a “turf earthen roof”, which is quite often built on small houses in Norway. This design assumes the following: the roofing material is covered with a clay bedding, and it serves as the basis for the formation of a turf layer 10-15 cm thick, where grass is planted. Such houses looked very attractive, however similar design requires additional strengthening of load-bearing supports - not only is the soil “pie” itself quite heavy, winter period snow masses were added to it, and not every building could withstand such a load. That is why turf roofs have almost ceased to be installed over time. Perhaps this idea would have remained an idea if landscape designers these days had not remembered the forgotten Scandinavian traditions.
Nowadays, “green roofing” is far from uncommon in big cities. Roofs partially or completely planted with living plants can be found in shopping complexes, office centers and luxury residential high-rises. Not long ago, the fashion was picked up by the owners country houses, which began to actively plant green surfaces outbuildings in summer cottages.
Peculiarities
Like other types roofing systems, eco-roofs are similar to a layer cake, although its components differ in some operating features. The creation of a green roof must guarantee reliability and practicality important criteria: foundation strength, good protection from water and reducing heat loss. The roofing “pie” of this type of roof has the following layers:
- base– it can be made of wood or concrete, most importantly, it must have a large margin of safety, capable of bearing the weight of the earth and the plants themselves;
- waterproofing layer extremely important for reliable protection buildings from moisture ingress, plants require regular watering, so quite high demands are placed on the strength of this layer;
- barrier mounted above the waterproofing material to prevent roots from growing into the main roof of the building. If it is not installed, the plants will take root in the previous layer and damage it;
- drainage used to evenly distribute moisture over the entire surface of the roof, retains some of the water, preventing the plantings from drying out, and removes excess moisture through the drain;
- filter– a layer of geotextile that limits penetration fine particles into drainage;
- geogrid installed to prevent the earth from “scattering away” under the influence of rain and strong wind;
- substrate– the soil itself, which is poured onto the geogrid in a layer of 5 to 20 cm; its thickness depends on what exactly you plan to grow: for ground cover flowers a layer of 5 cm will be enough, but for growing vegetables you will need about 20 cm.
Pros and cons
Large-scale landscaping is one of the necessary conditions existence in the frantic rhythm of modern megacities built of concrete and glass. At the same time, narrow streets do not allow the creation of flower beds and flower beds in cities - as a rule, small areas of parks and squares are allocated for this. That is why the installation of a green roof solves a very important problem - it allows you to significantly improve the environmental situation and at the same time make the most efficient use of useful space.
The advantages of this technology include the following factors.
- Strengthening the structure – vegetation layer reliably protects the roof from various mechanical damage, temperature fluctuations and adverse effects natural phenomena. A roof “covered” with a green layer can be used for more than 20 years. However, let's not forget that this is only true for reinforced structures with a large margin of safety.
- Effective use of rainwater and storm water – soil can retain more than 30% of precipitation. A green roof reduces the likelihood of flooding. In addition, the water, instead of being drained into storm drains, is used to irrigate the surface and contribute to a good harvest.
- Exceptional thermal insulation characteristics – a layer of turf is considered a very suitable material for this purpose; it retains heat in winter, prevents heat from penetrating into the house in summer, and also promotes effective air circulation, thereby forming favorable microclimate indoors.
- The soil absorbs noise well, so the inhabitants of the house can be sure that they will not be disturbed by the sounds of rain or hail.
- Organization of a recreation area– an attractive roof can become a harmonious place for family leisure and meeting with friends in a comfortable environment.
Owners of modern mansions often equip small pools on such roofs and install sports equipment. In addition, a green roof improves the overall environmental background, gives garden plot stylish and extraordinary look.
Despite the obvious advantages, the eco-roof also has disadvantages.
- Heavy weight– drainage and soil give a load of approximately 50 kg per square meter. meter, this leads to a significant increase in pressure on the floors of the building.
- High cost– green roof equipment is intended to be used only environmentally pure materials, and they are quite expensive. Therefore, installing a green roof is much more expensive than installing a conventional one.
- Complexity of installation technology– the construction of an eco-roof and the corresponding increase in pressure on the supports requires the mandatory preparation of a design project, created according to accurate calculations of the permissible load parameters on the floors. It is impossible to do this without such planning skills, so you need to seek help from specialists.
Please note that experts do not recommend converting an existing roof into a green one, since the old foundation and existing floors may simply not withstand significant additional load.
The installation of such a roof is suitable for new houses, where the necessary strength of the supports is laid down at the design stage of construction work.
Varieties
Depending on the parameters of using eco-roofs, intensive and extensive types of landscaping are distinguished.
Extensive roofing
Such structures are created on pitched roofs with an inclination angle of no more than 45 degrees. The design features of these buildings are such that they do not provide access to the roof. Accordingly, it cannot be used normally. For greening roofs, low-growing perennials are used, which sod the covering and create a decorative appearance and at the same time protect the roof from mechanical influences and precipitation. Used for planting unpretentious plants, which do not require special care and abundant watering - natural precipitation is enough for them to fully grow and develop.
Extensive roofing provides several landscaping options.
- Low vegetation cover– in this case, the soil height does not exceed 6 cm, the ground is planted with drought-resistant ground cover plants of several types, thanks to which it is possible to achieve continuous flowering from May to October. This is the simplest and easy way landscaping;
- Green roof – the roof is designed like a lawn; roll types of coverings are often used for this purpose.
Intensive landscaping
Involves the installation of an eco-roof on flat surfaces that can be used by building occupants. Such buildings have access to the roof, are equipped with a parapet that protects against possible falls, and special paths for comfortable movement. Here you can grow not only a grass lawn, but also plant large shrubs and even fruit trees. Of course, such a design requires special attention during construction and operation. This garden needs the same care as above-ground gardens and flower beds.
Laying technology
Green roofs can be created in absolutely any climatic region. In itself, installing such a roof with your own hands is not complicated, but it is labor-intensive.
The layers of the eco-roof are:
- base;
- vapor barrier;
- insulation;
- waterproofing;
- protective layer;
- drainage system;
- filter;
- priming;
- plants.
As a base, insulation, as well as vapor and waterproofing insulators, you can use the most various materials. In any hardware store there is now wide choice in a wide price range.
The easiest way to complete the installation of an eco-roof is to use roll lawn as a finishing coat. If the roof is straight or its angle of inclination does not exceed 10 degrees, then the seeds can be planted directly into the ground. If the slopes are steeper, then during the rainy season and snowmelt, an unpleasant phenomenon such as a landslide may occur. To prevent the soil from “sliding” down, layers of soil are placed between special barriers.
A very important part of a green roof is the installation of a drainage system. It is very important to understand the importance of proper drainage: since water cannot enter the house, therefore, it needs to find a way out in some other place, otherwise it will remain in the roof and simply turn sour. This will lead to root rot and plant death.
Geotextiles, as well as sand or small crushed stone, are used as the main drainage. Additionally, a drainage system will be installed.
As a rule, one of the proposed options is used.
- Drainage slabs– plastic panels profiled type, which are attached to each other and mounted over the entire surface of the roof. The mechanism of action is as follows: water accumulates in the “blades” of the panels, and if there is an excess amount of it, it flows into the slabs located below. Thus, the water is cascaded down and then flows into the drainpipe.
- Drainage mats They have a similar principle of operation, but are faster to install. In addition, mats enhance waterproofing. This method is not good for all types of roofing; it is not applicable to flat or very steep roofs.
- Drainage boxes– drainage flat roof involves the use of special systems that facilitate the forced removal of moisture from the roof, as a result of which water enters the funnel. and from there - into storm sewer systems.
Under the term " green roof"It is customary to understand the roof of a building or structure on which specially planted vegetation is located.
Advantages of a green roof:
- Protects buildings from overheating
- Reduces air temperature in cities in the summer (on average, up to 1 0 C);
- Provides oxygen supply;
- Reduces overall background noise from 2 to 10 dB;
- Eliminates the rapid spread of fire along the roof surface during fires;
- Allows rational use of available space;
- Additional layers reliably protect waterproofing from accidental mechanical damage;
- Reduces air pollution.
- The downside is the increased cost.
Green roofs are a type of roof that is in use.
By exploitation it is meant that the roof, in addition to its main construction functions, is also used for some purpose useful to humans. For example, it is a resting place with installed benches, flower beds, barbecue facilities, a swimming pool, and a fountain. Or it serves as an observation deck, parking for cars or even for a helicopter.
Structurally, green roofing is usually performed on an ordinary, flat roof. In some cases, it is possible to install a “green” roof on pitched roofs, but with an inclination angle of no more than 35 degrees. When installing a “green” roof, special attention should be paid to the exceptional reliability of the material used for waterproofing. His wrong choice or non-compliance with technology can become fatal mistake, which will entail significant financial costs for repairs.
An enlarged green roof can be imagined as consisting of two components: parts:
- flat roof - let's call it the base for the green part;
- the actual “green” part.
Options for the first part (flat roof) are described in detail in our article.
There are several options for the second, green part.
Which one should be preferred depends on the climate, as this affects the amount and frequency of precipitation, and on the type of vegetation, since different plants require different amounts of moisture and also have various sizes root systems.
The green part options differ from each other in the following parameters:
- the presence of certain technological layers in its composition;
- order of layers;
- layer capacity (ability to hold different quantities moisture);
- "brand" of materials used for these layers.
For example, let’s consider the simplest version of the “pie” of all two parts of the “green roof”.
Roof type: classic, insulated, soft.
The roof is in use, i.e. There is supposed to be a lawn on it for seeding with grass.
Explanations for non-specialists:
The following sequence (from bottom to top) is usually called a classic pie:
- Roof base.
- Vapor barrier layer.
- Insulation layer.
- Slope-forming layer
- Waterproofing layer.
Not classic pie- This inversion. It differs from the one described above in the location of the insulation relative to the waterproofing. You can read more about inversion cake in our article.
Therefore, in all our interpretations of exploited roofs, this pie same for all options further finishing coating, including “green”. We make deviations only at the request of the customer.
Typical layers of the “green” part of a roof with landscaping are (from bottom to top):
- Root protective film
- Drainage membrane.
- Separating layer made of nonwoven material- layer of geotextile.
- Soil layer for green spaces(prepared)
- Lawn, meadow grass, bushes, trees
Let's take a closer look at their functions.
Soil layer- nutrient medium for plants. Different for different plants.
A separating layer of geotextile prevents soil from penetrating into the lower layers and being washed out over time. The material is synthetic and does not rot.
Drainage membrane- creates a gap between the soil layer and the waterproofing layer, thereby providing conditions for the free flow of water to the elements of the drainage system (funnels, scuppers). The design of the membrane allows some of the water to be retained and nourish the plants. Membranes differ from each other in this parameter. For different types plants need membranes with different “capacities”.
Root protective film- prevents plant roots from destroying the waterproofing over time. Eat waterproofing membranes, which is not afraid of roots. But it won’t be superfluous to put the film on.
Examples of green roofs
Since any roof in use usually has several additional layers on top of the waterproofing layer, if problems with leaks arise, repairing such a roof turns into a rather troublesome and costly matter. Therefore, for roofs in use it is very important to use reliable and high-quality waterproofing materials. The most reliable material today is Resitrix (Resitrix, Germany). To be convinced of this, it is enough to hold a piece of it in your hands. None of the materials existing on the roofing market has such a thickness of 3.1 mm!
Roofing of any type and purpose completed by Resitrix is a task solved once and for a lifetime.
Today there is an alternative system of maintained (green) roofs. This is the so-called “false floor” system. Its essence is that the system is entirely mounted on adjustable supports.
The advantages of this system are as follows:
- Lightweight design for extensive landscaping. Light weight per base
- Modularity and readiness of units and solutions. Combination of different types of coatings
- High speed of work
- Possibility of laying communications. Water, electricity, etc.
- Possibility to change places different coatings. Quick disassembly if necessary
- Absolutely quick drying of surfaces after rain
Our company installs flat roofs of any purpose and type.
- Operated roofs
- Flat roofs
- Green roofs
- Ballast roofs
- Inversion roofs
- Waterproofing terraces
- Waterproofing balconies
When building their homes, humanity has made grass roofing since ancient times. In some cases, this type of roofing is called earthen. This type of roof does not present any complexity and the construction scheme is not difficult.
There is, however, one an indispensable condition: the weight of such a roof is quite large, so the roof rafters must be as reliable as possible. If structures are being built from logs, beams, carriages, then a grass, heavy roof is even preferable - with its additional weight, the building being erected will go through the shrinkage process much faster. Also, the crowns will close together much more tightly.
You can divide the types of grass roofing into the following types:
- Turf.
Reed.
Shingle (wooden).
Slate.
Tiled.
Copper.
How to make a grass roof
Let's highlight the main components of a grass roof.
First of all, absolutely any vegetation can be used for styling. But hard-leaved is still better.
Next, lay a dense layer of earth (peat, turf), waterproofing is possible if necessary. Also, there is no way to do without insulation. Do not forget about drainage - it is acceptable to use gravel or crushed stone.
Please note that geogrid is used for large roof slopes. It makes sense to cover the drainage layer of crushed stone with a layer of geotextile.
Let's consider eco-friendly look laying a grass roof.
The construction of a grass roof is similar in most cases. This is a load-bearing rafter structure and sheathing made of unedged boards, on top of which turf was laid.
Instead of the waterproofing widely used today from rolled bitumen or other materials, a layer of birch bark was laid on the sheathing, on top of which turf was laid in two layers or a soil mixture was poured for sowing it with grass seeds.
However, before touching on the technology of laying bark and turf, it should be noted that the dead weight of a green roof is about 250 kg/m2. This means that the shear load (especially on roofs with steeper slopes) can move the entire grass covering down. To avoid this, fencing was an indispensable structural element of green roofs. Their function was traditionally performed by turf fencing beams or boards laid along the overhangs - the so-called turf holders.
At the same time, the construction of the roof when creating a grass carpet had to ensure unhindered drainage of rainwater from the roof slopes. To do this, it was necessary not only to choose the right shape of the turf holders, but also to attach them to the sheathing accordingly.
Strips of birch bark were laid overlapping each other. In the overhang area they were laid in 5...8 layers. At the same time, the strips released from under the fencing beam and placed on it were laid with the outer side up. This was done in order to ensure effective water drainage and protect the sod holder and the end parts of the sheathing boards from moisture. In addition, the bark, laid with the outer side up, is an important decorative element of a green roof.
To increase the service life of the roof, the bark on the rest of the roof was laid with the outer side down, since its inner side provides more effective protection of the sheathing from the mixture of sigumic acids contained in the soil.
To protect the turf laid on the sides of the gable from wind and water erosion, natural stones were laid on the edges of the gable. Later, pediment wind elements, which were used as logs, began to be used for this purpose. They were laid so that the ends protruded above the ridge. The logs were joined crosswise. And since the logs were the same thickness as the sod holders, together they formed a kind of wooden frame for the entire roof.
In another option, a wind board was used to protect the grass surface from erosion. It was fastened with wooden dowels and covered with birch bark from moisture. Sometimes, instead of bark, a horizontally laid covering board was used.
One of the important elements of traditional grass roofs is the wooden gutter, which was made from boards screwed together at right angles or hollowed out from a tree trunk.
The weak point of grass roofs is the openings (in particular for chimneys). To prevent water from flowing down the walls of the pipe into the house, stone slabs protruding beyond the pipe were walled into its masonry.
At the same time, sheets of birch bark were placed under these slabs, diverting the flow of water to the roof. The stone slabs on the side of the slopes were arranged in steps, which contributed to more efficient drainage of rain or melt water from the pipe walls.
A log is used as a fencing element, supported by a stop hook secured under the sheathing. In this case, the hook, cut into the log of the upper crown, is secured under the sheathing, and the round timber itself lies completely on the birch bark. To prevent water from accumulating on the roof, the sod holder has slots for drainage.
The round timber, in turn, is also lined with birch bark. Despite the presence of such moisture protection, the sod holder still needed to be periodically replaced with a new one.
For example, when attaching a stop hook on top of the sheathing, a space is created between the birch bark and the turf holder to ensure effective drainage of water. And when attaching the enclosing element using a dowel, special slots were provided in the sod holder for water drainage.
Another interesting solution is when the fencing beam is attached to the side, with a distance of 5 cm from the edge of the overhang, which also ensures rapid drainage of water.
In all these cases, the turf holders are protected by birch bark. The overhang zone itself is covered with several layers of bark.
You can also use the option of fastening the enclosing beam using a powerful dowel embedded in the end of the rafter. This method of fastening was used for roofs with hanging rafters protruding beyond the overhang by approximately 12 cm.
Often, in order to save wood, instead of logs or beams, boards 3...4 cm thick and 12...16 cm wide were used to fence the grass covering, depending on the thickness of the green roof.
To ensure water drainage, holes or slits measuring 3x3 cm were made on the lower edge of the board every 20 cm. On the side in contact with the turf, they were expanded, giving the shape of a funnel. Sometimes boards were installed without drainage holes. In this case, they were fastened so that they protruded 2...3 cm beyond the overhangs. To do this, as a rule, they used persistent steel corners, which were screwed to the sheathing with screws.
World - unusual thing. Traveling around the world or looking through photographs in magazines, you often come across unusual and unusual things. For example, grassy roofs are especially attractive - wooden houses, covered with green grass - like a piece of meadow on the roof, that’s when you begin to feel unity with nature.
You begin to wonder whether such a miracle is possible here, in our region; and if so, how. To answer these questions, you must first understand what earthen roofs are, where they came from, and what are the features of the creation technology.
A little bit of history
Grass roofs appeared in Norway and the Faroe Islands in ancient times. "Grass" roofing (Turf - roof or "torvtak") is traditional type roofs of Scandinavia.
It is worth noting that the appearance of such roofs in these countries is not accidental; this is due to the climate. After all, it is through the Faroe Islands and near the coast of Norway that the warm Gulf Stream flows; thanks to the Gulf Stream, with its warm air flow, Norway has a milder climate than would be expected for a state at this latitude. In summer there is a large amount of precipitation and high humidity.
But the main essence of a “green” roof is that it is alive - it must be constantly wet.
However, what is the secret of this grass roof?
Construction of a traditional earthen roof
If we take the original grass roofs, which were made in ancient times, then the situation is like this: they didn’t invent special materials - they took what was at hand - the boards (the base of the roof) were first covered with birch bark, as a waterproofing, so that water would not seep into inside the home. It was laid with the “yellow” wrong side up, and then, to secure it, the whole thing was sprinkled with turf (no nails were used). The result was a turf, grass roof.
And most importantly, why was this design not lost and became popular in these countries? Of course, the main thing was not the beautiful view (although the roof looks extraordinary), but the fact that such a roof design better retains heat in the house. It was convenient and economical: building material at hand, such roofs did not require special care and served for a long time. In addition, such green roofs - good camouflage buildings and structures from enemies.
Now, of course, they no longer use birch bark, but the principle has been preserved.
Placed on the roof sheathing waterproofing material and geotextiles that prevent plant roots from sprouting (you can use foundationalin - it simultaneously provides waterproofing and prevents sprouting). Then the geogrid is laid and backfilled drainage layer(this could be crushed stone, expanded clay). The grating is necessary to prevent the entire earthen structure from sliding off the roof. In addition, sides are installed along the edges of the roof, which also prevent the earth from sliding.
Now the turf is laid - first, a layer of turf is laid on the drainage layer with the roots up, and the second layer of turf is laid with the roots down. This is necessary for good adhesion so that the structure does not crumble. There are options when, instead of a “roots up” layer, they take geomats - a roll of polymer fibers, the surface of which is uneven and rough, which ensures good adhesion of all layers of the structure.
It is clear that in order for the structure to be stable and not slip, there are certain restrictions - firstly, the slope of the roof, which should not exceed 28 degrees. Its increase is not recommended, because there is already a risk of sliding, but if the slope is designed too small, then excess water will stagnate and not go away.
It should also be noted that such roofs are non-operational, i.e. do not require any movement on it, but earthen roofs do not require any special care. The main thing is that the substrate is always moist and does not dry out. This is probably why these roofs are very common in Norway and the Faroe Islands. There are legends that they used to let sheep onto the roof to “cut” the grass. Of course, you don't actually need to put any sheep on your roof, but stories like this increase interest in grass roofs.
Now in the Scandinavian countries there are “meadow” nurseries. They specialize in growing herbaceous seed mixtures from local genetic material for a variety of green roofs. All that remains is to cut out the turf and lay it on the roof surface. The load from the roof is about 250 kg per square meter, and in winter the roof weight is 400-500 kg per m² due to snow.
So, Scandinavian roofs became possible thanks to the following conditions:
- The high humidity and raininess of the Norwegian climate. That is why green roofs retain their unchanged appearance and have a bright, rich grass color;
- The composition of the substrate is peaty soils, important indicators that need to be taken into account;
- Quality installation and use of high quality and sustainable materials.
Possibility of use in our region
Now let’s think about whether the same analogue is possible in the conditions of our zone (more precisely, in the city of Nizhny Novgorod).
The main problem that needs to be solved is providing and maintaining sufficient humidity, as well as selecting the optimal composition of the substrate
Climatic conditions in Nizhny Novgorod typical for central European Russia. Summers are warm, with periods of heat, winters are moderately cold. According to the city weather station, the average annual precipitation is about 600 mm with predominant precipitation during the growing season. By comparison, the Faroe Islands have an average annual rainfall of over 1600-2000 mm per year, predominantly in the form of rain and drizzle. Moreover, more than 260 days a year are rainy. Unlike our continental climate, the Faroe Islands have a temperate maritime climate. In Norway, cities along the coast (for example, Bergen) have approximately the same high rainfall and similar climate conditions.
It is clear that in our region the technology of creating green roofs simply by cutting out turf from meadows and laying it on the roof will not be successful (without irrigation systems and proper care). In the absence of watering and maintenance, a green roof will quickly lose its decorative effect and will not perform the desired functions. The most effective and economical way is to use ready-made special peat substrates.
Therefore, there are two ways to solve the problem of creating optimal humidity:
- Establishing an additional irrigation system that will prevent the soil from drying out;
- Creating a green roof from drought-resistant plants(juvenile, sedum).
If you go deeper into history, then in the territory Ancient Rus' there were analogues of the Scandinavian “earth roofs”. However, the technology was lost, while in Europe it was preserved and developed.
Technology for creating green roofs using drought-resistant perennial plant species
This technology is quite simple, it is popular and standardized in many countries. Green roofs are being created throughout the USA, Canada, Germany, Great Britain and Scandinavian countries. In Russia, green roofs are also becoming popular. On at the moment, many foreign companies are starting to create “green roof” projects in Russia, and, accordingly, Russian companies are adopting foreign experience.
As real example You can consider the project of the ZinCo company; in 2013, it carried out a project for landscaping the pitched roofs of five pavilions-kiosks in Gorky Park in Moscow. Each roof is unique due to the use of various varieties of sedum and sedum.
Two types of green roofs were installed on the pitched roofs - the “Sedum” and “Blooming Meadow” pitched roof systems.
The "Sedum" system is a landscaping system with low growing plants and substrate height 60 mm. Sedums and other perennials are designed to create a solid green or multi-colored (several colors) cover. And with the help of the “Blooming Meadow” system, the roof can be given an individual character. These plants do not require special care once they are planted on the roof. The most important thing is that the design solution of the “Seduma” and “Blooming Meadow” systems is easy and inexpensive to operate. After installing such roofs further exploitation occurs with minimal human intervention - 1-2 times a year!
"Pitched roof" system using sedum
Roofing cake and materials used:
1. Plants of the Sedum family;
2. Substrate >50 mm above the drainage and storage element;
3. Drainage and storage element;
4. Moisture-accumulating mat;
5.Waterproofing with anti-root effect;
System characteristics:
- Tilt angle: 10°-20°;
- Height: 130 mm;
- Moisture retention volume: 38 l/m2;
- Weight (including moisture saturation): 145 kg/m2
Let's look at the concepts:
Anti-root layer (WSF 40 film) - this layer is laid directly on the waterproofing layer, ensuring its protection from root germination;
Protective moisture-accumulating layer (SSM 45) - protects the waterproofing from possible mechanical damage and acts as an accumulator of additional moisture;
Drainage-accumulation layer (floradrain FD 25/40) - accumulates optimal quantity moisture necessary to ensure the life of plants and regulates the outflow of water;
Filter layer (TG system filter) - provides water filtration, preventing fine particles of the substrate from entering the drainage and storage element and thus protecting it from silting;
The composition of the substrate (in which plants are planted on the roof) was developed by ZinCo and is its know-how. The substrate for green roofs ZinCo contains the necessary plants nutrients, does not cake, does not compact during long term, allows water and air to pass through well and provides plants with a favorable habitat.
In conclusion, I would like to point out that the main advantages of installing a turf roof are: very aesthetic and decorative look;
- use only natural materials;
- the possibility of creating a special microclimate in the area near the house;
- good thermal insulation qualities of the roof;
The disadvantages include:
- heavy weight, and, as a result, the need to use powerful rafter systems;
- high labor intensity repair work in case of leaks;
- quite high material costs.
Creating a turf roof is also possible in middle lane. A grassy roof will have an attractive decorative appearance if you use lawn mixtures with drought-resistant lawn grasses, the substrate is a special peaty composition, and also provide additional watering to maintain the moisture of the roof soil. Alternative solution is the creation of turf roofs using ground cover, drought-resistant perennial plants (sedum and sedum varieties with a variety of colors). Such roofs no longer require special care or additional watering.
