Low-temperature heating, made in the screed floor, now you will not surprise anyone. Thanks to many positive qualities, such systems have often been used in modern buildings. Until recently, one question remained unresolved: how to make a water heated floor in a wooden house, because the floor beams are not designed for a screed mass of at least 200 kg per 1 m².
It is noteworthy that the best way to install underfloor heating for houses made of wood appeared recently. Let's understand this technology and find out how to properly arrange light warm floors without screed, including with your own hands.
Why is a “dry” warm floor?
What is the charm of the traditional scheme, where the underfloor heating pipes are walled in a screed? Briefly list:
- low temperature of the heat carrier (maximum - 55 ° C), which allows saving energy carriers;
- uniform heating of the concrete floor surface from embedded pipes;
- comfort from the heat coming from the lower zone over the entire area of the room.
The catch is that the water-heated floors in the wooden house retain all of these advantages, but without a heavy cement-sand screed. Judge for yourself how many functions the wooden beams of the floors perform:
- They perceive static loads from furniture and interior partitions.
- Compensate without deflection the mass of the finish coating, rough floors and insulation.
- Withstand constant dynamic effects from the movement of residents.
- They carry their own weight and serve as elements of the lateral stability of the building.
Imagine adding heavy concrete monolith weighing 1-3 tons in each room to these loads. In order for the wooden system of beams to withstand the mass of such a structure, their cross-section will have to be increased by 1.5–2 times, which will increase the cost of construction. The solution to the problem is to make the so-called floor heating system of a water heated floor, arranged in a dry way without screed and having a low weight (about 20 kg per 1 m² of room area).
The heating water circuits of wooden buildings can be monolithic in concrete under such conditions:
- when the coating of the first floor of a private dwelling is based on soil or a strip (slab) foundation;
- in dwellings of SIP panels 200 mm thick, based on a strip or pile-screw foundation;
- if the base of the floor of a chopped or frame house contains powerful beams designed for the weight of the screed.
Lightweight flooring design
A key element of warm water floors laid in wooden houses in a “dry” way is a metal plate with a groove in the form of an inverted Greek letter Ω (when viewed from the end). The walls of the recess tightly enclose the body of the pipe with a coolant, and the side “wings” of the plate increase the area of heat dissipation instead of the screed.
Reference. Plates for uniform distribution of heat flow are made of galvanized steel and aluminum. Their width can be different and is selected depending on the pitch of pipe laying (standard - for a distance of 150 and 200 mm). The product can be broken into equal parts with your own hands due to transverse notches (perforations).
Using metal diffusers, a device for a water floor heating can be performed in several ways:
- according to the technology of the famous Uponor brand, laying pipes of heating circuits in the gaps between the floorboards;
- using special polystyrene slabs for a floor heating, equipped with protruding bosses or finished grooves;
- with the burning out of recesses in ordinary polystyrene with a special apparatus;
- using sets of wooden products where grooves for heating water circuits are made.
Each technique has its pros and cons, but they are united by 3 important properties: low weight, efficiency and the absence of "wet" processes, which greatly speeds up the installation. Whatever method you choose, the “cake” of the floor remains unchanged and consists of the following layers (in the direction from bottom to top):
- The basis for laying insulation.
- Thermal insulation material.
- Heat distribution plates.
- Pipelines with circulating heated water;
- Fine flooring.
Note. When installing water-heated floors on a wooden base in a heating “pie”, a vapor barrier film and a diffusion membrane (waterproofing) can be used.
Now we will understand in detail what is better to insulate the floor and how to properly make a warm floor in a wooden house using any of the above methods. But first, a few words about the selection of components.
Material selection
Before laying heating water circuits in a wooden house, it is necessary to insulate the floors. Therefore, you have to choose 3 groups of components:
- type of insulation;
- pipe material;
- plate material.
Among the common and affordable heaters for thermal insulation of wooden structures, mineral (basalt) wool is best suited. It is permeable to water vapor, due to which it combines well with wood, gives it the ability to "breathe" and does not cause rot. Another thing is that when laying mineral wool you need to ensure the exit and removal of these vapors, otherwise it will get wet through and stop serving as a heat insulator.
Tip. It is better to use basalt fiber with a density of 40–80 kg / m³ and a thickness of at least 150 mm for insulation of the ground floor coverings, and in the northern regions - 200 mm and more. Mineral wool with a thickness of 50-100 mm will be used for interfloor overlapping. Its task is not to let heat intended for the upper rooms into the premises of the first floor and serve as sound insulation.
Polymer insulation - polystyrene, foamed polyethylene and extruded polystyrene foam practically do not allow moisture to pass through. Therefore, they must be used wisely, otherwise the wood in the places of contact with the polymer will become black and rot. The minimum thickness of materials for thermal insulation of the floors of the first floor is 100 mm, it is enough to lay 20-30 mm in the ceiling.
The following types of pipes with a diameter of 16 and 20 mm go to the warm floors without screed, arranged on wooden logs,
- cross-linked polyethylene with an anti-diffusion layer that does not allow oxygen to pass through;
- metal-plastic;
- copper.
High-quality polyethylene pipes (for example, from the Rehau brand) are no cheaper than metal-plastic and are not inferior to it in operational properties. Hence the conclusion: there is no fundamental difference between these types of polymer pipelines, they are equally good for warm floors.
Copper pipes are much more expensive than plastic pipes, and it is more difficult and longer to mount them. But, from the point of view of heat transfer, copper has no equal, and therefore it is successfully used for floor heating devices of any buildings. An important point: do not use copper heating circuits in conjunction with aluminum heat distribution plates, these metals are absolutely not “friendly” to each other.
Since the thermal conductivity of aluminum is higher than that of steel, plates of this material are more preferable (excluding copper wiring). But keep in mind that high-quality aluminum distributors are 1.5-4 times more expensive than galvanized ones.
Note. Prices of aluminum and galvanized plates from different manufacturers fluctuate in a wide range and cannot be compared, because they are made of metals of various thicknesses. Hence the advice: try to purchase thick-walled products, they are able to accumulate and transfer more heat.
Of the newly emerged materials, stainless steel flexible corrugated pipes are of interest. They are durable, mounted without welding and soldering, while transmitting heat well and can be used in lightweight flooring systems.
The calculation of the pipe length in each circuit, the laying pitch and the surface temperature is presented in a separate publication. Familiarize yourself with the methodology in order to accurately determine the amount of materials.
Uponor technology installation
The technique is widely used as the most simple and affordable in terms of cash costs. Mineral wool here acts as a heat-insulating material, you can take pipes and plates at your discretion and financial capabilities. The essence of the method is in laying wooden boards with a thickness of 20 mm on logs with 2 cm intervals for the further installation of a water heated floor, as shown in the diagram:
Note. A similar scheme can be used in any residential buildings where wooden floors are laid on logs, including over concrete foundations.
To make warm floors using this technology with your own hands, you will need a regular set of locksmith and carpentry tools, as well as special scissors for cutting polymer pipes. When arranging floor heating on the floor of the first floor (above ground or an unheated basement), perform work in this order:
- Flush with the lower edge of the beams beat the cranial bars with a cross section of 25 x 25 mm. On top of them lay the rough floors of boards with a thickness of 20 mm, as shown below in the drawing.
- Cover the draft floor with the beams with a waterproofing film (technical name - diffusion membrane) with the waterproof side down. Observe the overlap between the sheets of at least 10 cm and carefully glue the joints with double-sided tape.
- Place mineral wool plates on top of the waterproofing so that they do not wrinkle, otherwise the basalt fiber will partially lose its thermal insulation properties. The thickness of the insulation must be less than the height of the log by at least 5 cm, in order to provide a ventilation gap between the surface of the wool and the future wood flooring to remove moisture.
- Log the vapor barrier film. The polyethylene must be tightened and fixed to the tree with a stapler so that it does not sag in the gaps between the beams.
- Across the log, nail 2 cm thick boards, retreating from the wall 30 mm. Depending on the pipe laying pitch (15 or 20 cm), leave between the boards slots with a width of 20 mm for the heat-distributing plates.
- Insert the metal plates into the slots and lay out the pipes of the heating circuits along them, inserting them into the Ω-shaped grooves. To rotate the pipe, shorten the ends of the boards in this place by 10-15 cm.
- Run the ends of the pipes along the walls to the comb of the warm floor, connect them and check the tightness of the system. Cover the floor.
Work on the floor is carried out in the same order, only boards of rough floors can be nailed directly to the logs below. By the way, instead of wood, OSB boards can be used here, while hemming the ceiling of the first floor.
Important! Do not confuse the diffusion membrane with a vapor barrier film, otherwise the mineral wool is saturated with water and will cease to be a heater. Waterproofing at the bottom of the “cake” protects the cotton from getting wet from the outside, and the upper film prevents water vapor from penetrating. In ceilings, the opposite is true - vapor barrier is laid on the bottom, the membrane - on top. To remove moisture from the insulation, a 5 cm ventilation opening and products made in the walls of a wooden house are used.
Along with simplicity and cheapness, this method of installing underfloor heating systems has one drawback - pipes can be laid only with a “snake”, which is why the rooms of a wooden house have to be divided into several heating circuits in order to achieve uniform heating.
Installation Guide for Polystyrene System
This method of laying underfloor heating circuits allows you to perform work much faster and easier, since it involves the use of two-layer polystyrene foam boards with guides in the form of protruding bosses. For the manufacture of plates used polystyrene of different densities - the upper layer is more durable, the lower one is soft.
The technique is suitable for any floor with a flat surface, for example, from OSB plywood (as in houses made of SIP panels). Warm water floors on a flat wooden floor are made according to the following technology:
- Cover the logs with OSB sheets and fasten them with galvanized self-tapping screws. If the work is carried out on a wooden floor of the first floor, then between the beams it is worth laying mineral wool insulation, as described in the previous section. The thickness of the polystyrene system is not enough to fully insulate the building from below.
- Fix the damper tape on the walls around the perimeter of the room.
- Lay polystyrene foam plates on the finished surface, fastening them together on locks.
- Install the diffusion plates in accordance with the scheme and the pitch of the pipelines, fixing them between the bosses. Unwinding the pipe from the bay, insert it into the recesses of the plates.
- Cover the heating contours with plastic wrap, overlapping and sizing the canvases.
- Mount the base of the floor from gypsum fiber sheets (GVL), where subsequently lay the finishing coating (a popular option is laminate).
The details of the work are shown in the video from the Russian producer of polystyrene foam systems - Rusteplopol company:
Tip. Before laying the finish coat, connect the supply lines from the circuits to the manifold of the distribution and mixing unit and carry out leak tests (crimping) with a pressure of 4 Bar.
The advantages of figured insulation for warm water floors are obvious - simplicity and speed of installation work, the ability to lay out pipes not only with a "snake", but also with a snail. There are also disadvantages:
- high price;
- the material can bend from large mechanical loads;
- because of the gaps between the bosses, a small part of the heat is spent on useless heating of air under the floor covering.
Other pipe laying methods
Other heating products can serve as the basis for heating loops where metal plates can be inserted:
- polystyrene boards with finished grooves;
- factory sets of wooden products with cutouts for laying pipelines;
- polystyrene sheets with a density of 35 kg / m³, where the recesses are cut with their own hands using a special thermal knife.
In addition to expanded polystyrene with bosses, polymer plates with finished recesses are found in the distribution network. This option is suitable for installation on a flat surface, and inside the ceiling flush with the lags, as shown in the diagram:
Note. The disadvantages of the option are the need to cut out the grooves in the lags for the passage of tubes and the fastening of the polymer at the corners so that it does not lie on the wood. Therefore, slabs with recesses are best placed on the base of OSB plywood or aligned boards.
A big plus of wooden sets for underfloor heating is the ability of the coating to carry a large load from bulky furniture without deformation. Products with cutouts for plates are mounted on beams along with insulation, as described above (Uponor brand technology). Stacked wooden floor heating has only one drawback - the high price of materials.
Time-saving homeowners can save on the polystyrene system by buying a thermobar for burning grooves and regular high-density foam. The technology is simple: insulation plates are laid out on a level surface, after which they need to burn out the pipeline route in accordance with the scheme. It remains to install heat distributors and insert pipes into them.
Is it possible to save on materials
Since components for floor heating without a screed cost decent money, many craftsmen have found ways to do without them:
- Put heating branches inside the ceiling, directly on the insulation. Then Ω-shaped products are not used.
- Make cuts in the boards yourself, and instead of plates along the length of the grooves, roll out the aluminum foil used for baking.
- To make steel heat distributors independently on metalworking equipment.
- A wooden system for laying pipes in grooves can also be made by yourself, for example, from sheets of chipboard.
Of the options listed, only the latter 2 will save and at the same time organize effective heating. Indeed, on a sheet bending machine it is possible to make plates of any metal, only the groove profile will turn out to be rectangular, and not “omega-like”.
When laying pipes inside a wooden structure, they have poor contact with the finish coating and more warm the air around them than the room. In order for such heating to have an effect, pipes must be laid at a distance of 10 cm from each other, and the temperature of the coolant should be raised to a maximum. Then the idea loses its meaning, it’s easier to put radiators.
Thin aluminum foil serves as a poor heat flux distributor due to its thickness in hundredths of a millimeter. In addition, it crumbles over time from gradual oxidation, so it makes no sense to use foil.
There is another way to save money - to organize the heating of a wooden house with electric underfloor heating using infrared film heaters. But such a system will lose versatility, that is, you can use only electricity for heating, you will have to forget about gas or firewood.
On the pros and cons of "dry" floor systems
In conclusion, I want to note the advantages of a warm floor without a screed that can attract owners of private wooden houses:
- The design is lightweight, reliable and at the same time efficient.
- Unlike heating circuits walled up in the screed, in such a system it is easy to detect a leak and eliminate it.
- The thickness of the "cake", protruding above the upper section of the log - from 20 to 50 mm.
- Water floors with scattering plates made of steel or aluminum are not able to accumulate heat and are practically devoid of inertia. Accordingly, they quickly warm up the rooms and quickly respond to automation commands and changes in the flow rate of the coolant in the loops.
- The speed of installation associated with the absence of "wet" processes and solidification of the solution. How light warm floors are arranged in a short time, is shown in the next video:
For reference. On various Internet resources there is conflicting information about the reduced heat transfer of the flooring system compared to monolithic. Theoretically, this is true, but in practice the difference is small, and it is rather difficult to make a comparison.
The only drawback that makes home inventors to be smart with aluminum foil is the price of steel products, especially in conjunction with figured polystyrene foam. You can get around this nuance as follows: to make a warm floor in all rooms alternately, upon the appearance of financial opportunities. First you need to insulate the floor and put a comb, and then gradually mount the pipe wiring, starting from the premises where the residents stay constantly.