Insulating The Floor In A Wooden House: An Overview Of The Technology Of Thermal Insulation Works

In buildings made of wood the problem of indoor climate is particularly acute. Due to the desiccation of the floor boards and the appearance of cracks, where drafts roam, the heat loss indicator can reach 30%.

Saving heat costs will help to timely insulate the floor in a wooden house, especially since it is realistic to perform thermal insulation without involving specialists. You should agree that this approach to solving the problem will allow you to save a decent amount of money and significantly improve the thermal efficiency of the house. Do not think you can do it yourself? We will help you to navigate in a variety of methods of insulation, and give practical advice on the choice of insulating material. In addition we will describe the technology for working with the most popular materials: sawdust, expanded clay aggregate and foamed polystyrene.

Content of the article:

  • Methods for performing thermal insulation
    • Method #1 - installation of insulation from above
    • Method #2 - insulation from the basement side
    • Method #3 - double floor installation
    • Method #4 - warm floor system
  • The importance of hydro- and thermal insulation
    • Requirements for thermal insulation materials
    • Popular materials for thermal insulation
  • Specialities for working with popular thermal insulators
    • Pecialities for working with sawdust
    • Performing thermal insulation with expanded clay
    • Specialities for working with techniques for working with expanded clay
  • Conclusions and useful video on the subject

Methods for thermal insulation

The thermal insulation can be laid directly in the living room or from the basement. In the first case it is customary to talk about thermal insulation from above, in the second - thermal insulation from below. In addition, it is possible to use other methods of insulating the floor, which will be discussed in more detail a little below.

Method #1 - installation of insulation from above

In this case, the insulation is laid directly in the room. It is quite easy to perform such works, but a number of problems may arise.

Disadvantages of the \"surface\" mounting of insulation:

  • the height of the walls decreases;
  • the lower layers of the insulation are not sufficiently heated;
  • the insulation layer is stressed, therefore a stiffer material must be selected.

In view of the above mentioned difficulties, when answering the question how to properly and easily insulate floors in wooden houses and cottages, the specialists recommend this technology only in special cases.

It is necessary, for example, if under the building is a shallow basement or the building stands on a monolithic slab.

Insulating the floor in a wooden house: an overview of the technology of thermal insulation works

Between the layer of thermal insulation material laid on the lag and the final coating it is advisable to leave a small gap to ensure free passage of air flows

Work on laying thermal insulation begins with removal of baseboards and finishing floor, as necessary to gain access to the lag. After that, the support beams are inspected.

Detected rotten areas must be removed by replacing them with suitably sized pieces of new beams, which are fixed with galvanized metal angles or channels.

A skull beam is reinforced on the lower edge of each joist. Planks or wooden boards, about 30 mm thick, are laid on the prepared structure without fasteners. The finished construction must be treated with antiseptic.

The length of each piece should be 10-20 mm less than the pitch of the joists.

Waterproofing, insulation, vapour barrier, counter-batten creating a ventilation gap, and finally the finished floor is laid.

Insulating the floor in a wooden house: an overview of the technology of thermal insulation works

If the finished floor is of tongue and groove board in good condition it may be used again. To facilitate subsequent reassembly it is advisable to number the boards when dismantling

Method No. 2 - Insulation on the basement side

The option of insulating the floors in a private wooden house from below, the protective covering is installed between the frame elements and the upper finishing layer.

There is more laborious work than laying insulation from above, but the result offers several advantages.

The main advantages are:

  • the height of the room remains unchanged;
  • the thermal insulation layer is not affected by the load of heavy furniture standing on the floor, allowing the use of any type of material regardless of its rigidity;
  • the thermal insulator embedded underneath provides frost protection not only for the top layer but also for the whole floor frame - this reduces the risk of moisture ingress, increasing the service life of the construction.

This option is well suited for frame structures mounted on pile and pile-screw foundations.

Condition for such technology is the presence of a cellar, basement or other subsidiary premises under the house.

Insulating the floor in a wooden house: an overview of the technology of thermal insulation works

Lower insulation is usually made with joists. On these boards with dimensions of 5*10 centimetres, boards are put and then other insulation layers as indicated in the chart

The following procedure is recommended:

  1. First of all, the old rough floor must be removed in order to have access to the floor boards.
  2. The joists should be cleaned of debris and inspected for condition, replacing damaged pieces as described above.
  3. A perimeter of the ceiling should be laid with a vapor barrier such as a membrane. If materials in rolls are used, the width of the strips overlapping each other must be more than 10 cm.
  4. A 30*30 mm skull bar must be nailed to the side walls of each joist. It will support the thermal insulation material and create a ventilation gap between it, and the finished floor.
  5. After that, install the thermal insulation, the thickness of which should not be greater than the height of the beams. Depending on the type of thermal insulation, it is reinforced with mounting glue, foam or cross struts.
  6. A layer of waterproofing is applied over the thermal insulation layer, which is suitable as roofing felt or a normal polyethylene film.

The final step is application of the finishing coat: planks, waterproof plywood or other materials.

Method #3 - installation of double floor

To reduce heat losses in wooden structures double floors are often applied. In this case, the first thing to be done is the installation of joists. Untrimmed boards are fastened to these to form a so-called subfloor.

Insulating the floor in a wooden house: an overview of the technology of thermal insulation works

When making double floors, it is important to ensure that the subfloor boards fit tightly to each other and the gaps are filled with fitting foam. To grout the gaps in the finish coating, you can use putty compositions designed for wood

Further installation of beams made from a thinner beam. The space between them is filled with thermal insulation material. Then the finishing floor is laid, made of tongue and grooved boards.

If desired, the finishing decorative coating is also used. Between the two wooden layers it is convenient to place service utilities: corrugated pipes with cables, water mains.

Between laying the rough floor, you can use various kinds of smooth or embossed floor coverings that have a high degree of thermal insulation. These materials are even preferable, as they do not accumulate debris.

This layer is attached with a bushylate adhesive, applied to the material in strips, with all joints being glued down.

For more details on the technology of insulating the floor on joists, see this article.

Method #4 - warm floor system

The \"warm floor\" technology, which also uses traditional insulators, is very popular, which is quite logical. It provides uniform heating of the entire floor covering, which effectively realizes a comfortable room temperature and reduces its humidity.

Insulating the floor in a wooden house: an overview of the technology of thermal insulation works

When choosing a floor heating design, it is best to opt for a variant that allows the heating temperature to be adjusted. This will not only maintain a comfortable temperature in the room, but also ensure economical consumption of electricity

There are two variants of such systems, in which heating is done with water or electric current.

Water flooring construction is carried out in the following sequence:

  1. Prepare the foundation by installing concrete slabs or a cement screed.
  2. The surface is covered with selected insulation, which may vary from 2 to 10 cm in thickness.
  3. A reinforcement mesh is laid on top, on which the piping system is mounted and fixed with plastic clamps.
  4. Further on, the surface is filled with a special material and, if necessary, a carpet pad is arranged.
  5. The final stage of the water floor installation of the finishing coat may be considered.

Electric underfloor heating  it is the same as the above described variant, but the heating element here is a cable stretched on a metal mesh which is firmly connected to the floor boards.

The laying techniques and wiring diagrams of the electric heating system are described in detail here.

Alternatively, the heating source is infrared film materials which are laid directly on the thermal insulation layer covering the screed.

The importance of waterproofing and thermal insulation

It must be emphasized that to properly insulate floors in wooden houses you must not forget to install hydro/thermal insulation layers.

The waterproofing coating is designed to protect the structure from moisture that falls on the warm surface when cold air flows in. Water particles that penetrate into the wooden elements lead to the development of fungus, mold, and eventually the destruction of the structure.

Insulating the floor in a wooden house: an overview of the technology of thermal insulation works

Water and vapor barriers can be used with moisture barrier membranes that allow air masses to circulate, trapping moisture inside. A polyethylene film can be a budget substitute for specialized materials

Vapor barrier layer is just as important. Electrical equipment running in the house and people in the rooms are constantly releasing heat. The heated airflows from the rooms that pass through the structural floor come into contact with the cold air masses.

This leads to condensation, which can result in the wood swelling and rotting.

Requirements for thermal insulation materials

There are many types of thermal insulation, ranging from simple natural materials to complex synthetic compounds.

In order to make the right choice, a number of factors must be considered, namely:

  1. The thermal conductivity. The higher the value, the lower the heat loss will be.
  2. History of use. This determines after what period of time it will be necessary to repair and replace the material.
  3. The weight of the insulation. Too heavy variants are not recommended for frame houses.
  4. Moisture resistance. This factor is particularly important if the structure is located in a low-lying or swampy area or if houses are built in humid climates.
  5. Unheated room under the floor.Farmer insulation is preferred in a cold basement.
  6. Work difficulty level. Ease of laying can be considered a definite advantage.
  7. Fire resistance. Insulation must not burn or support combustion or emit gases that are dangerous to health when heated.

The material's ability to resist mould, fungi and other destructive biofactors should also be taken into account.

Insulating the floor in a wooden house: an overview of the technology of thermal insulation works

When choosing a thermal insulation material, it is useful to use a comparison of the most important indicators. However, you should not forget the peculiarities of the different types of insulation

A last but not least, the cost of the thermal insulation material is an important criterion. You should not chase the cheapness: expensive products are usually easy to install and have a long service life, which saves on labor costs and repairs.

Popular materials for insulation

The most commonly used insulators include:

  • silts;
  • ceramsite;
  • wool;
  • foam;
  • foamplex.

Sawnwoodis still quite popular for thermal insulation work. It is an environmental friendly, accessible and inexpensive product, moreover it is easy to apply in places difficult to reach.

But it has disadvantages: sawdust tends to cake over time leading to loss of quality, it is also affected by micro-organisms, fungi, insects.

Keramsitea loose material resulting from clay or slate firing. This fully ecological material in ball form has a high thermal insulation value.

It is frost proof and has good fire retardance. The disadvantages of expanded clay are its relatively high weight and the fact that this material settles, which leads to house shrinkage and a drop in thermal conductivity.

Mineral woolis one of the best insulating materials as it does not catch fire or deteriorate when exposed to biofactors. As well as having good thermal insulation values, it also has sound proofing properties.

Disadvantages are the low mechanical resistance and the deterioration of the insulation properties when exposed to water or steam and therefore special attention to vapour/water proofing is required.

Insulating the floor in a wooden house: an overview of the technology of thermal insulation works

Pfoam is a foamed plastic material coated with foil on one or both sides. Due to its flexibility, it is suitable for use in complex room configurations and can also be combined with other types of insulation

Foam plasticis widely used. It retains heat easily, efficiently preserves heat loss, has sufficient mechanical strength, long service life.

We must remember, however, about the negative qualities of this material: when burning, foam emits toxic substances, in addition, it is capable of absorbing water, which leads to lower performance.

Pfoamplex. A relatively recent material that quickly gained popularity. This type of insulation consists of expanded polystyrene boards with excellent insulating properties. Easy to install, the boards do not burn and are not susceptible to bioorganisms.

Other synthetic and natural materials are also used as insulators, among which are Isolon, Penofol, Ecowool, Corkwood, Fibrovit.

Performance of popular insulators

The laying of different types of thermal insulators has its own particularities as can be seen in the three popular materials.

Performance of sawdust

Sawdust can be used directly by filling it in the space between the lag, but it is better to use it in mortar form. For this purpose, a mixture of five parts sawdust and one part cement or clay is made and diluted with half the quantity of water.

Brushed glass or special additives directed against rodents should be added to the mix prepared.

The spaces between the joists must be carefully and thoroughly filled with the freshly prepared mixture. The layer must be very even, otherwise there will be \"holes\" in the protective covering, and as a result the floor will remain cold.

Insulating the floor in a wooden house: an overview of the technology of thermal insulation works

If ordinary sawdust is used for thermal insulation, before starting the work it must be well dried and treated with antiseptic; dry lime may also be added

Insulation with expanded clay

A cheap type of insulation is claydite, work with which also has special features. In this case, an additional layer of sand is performed. This material is carefully and evenly applied to the substrate, and then carefully compacted.

Fill liquid mastic on the sand layer as a waterproofing, and then backfill expanded clay, while making sure that the coverage is as even as possible. Next, a vapour barrier is installed, on top of which the final finish is laid.

Keramzite is quite a heavy material, so it is not recommended to use it when insulating buildings on a frame foundation.

Insulating the floor in a wooden house: an overview of the technology of thermal insulation works

For thermal insulation with expanded clay it is better to prefer a multi-fraction material whose elements vary in size, weight and other characteristics. In this case, the pellets adhere more tightly to each other, so there are no pronounced voids in the layer

Special techniques when working with foamlex

Pfoamlex is a frequently used insulation option. Its use requires precise adjustment of the plates, which creates a barrier to cold air penetration. Sheets are placed between the joists, and for maximum adhesion are attached with mounting adhesive to the floor and between themselves.

Lightweight foamlex insulation is considered the best option for thermal protection of the floor in a frame house. It provides minimal load on the foundation, thus avoiding shrinkage of the structure.

Insulating the floor in a wooden house: an overview of the technology of thermal insulation works

Penoplex plates are convenient to use for both upper and lower thermal insulation. Since this material is impermeable to water, the installation of waterproofing in this case can be skipped

Conclusions and useful video on the subject

The following video demonstrates the process of insulating a house on the joists using mineral wool:

Video review detailing modern types of thermal insulators:

In order to properly perform floor insulation, it is important to carefully select the material, considering its features and the specific design of the structure. Equally important is the observance of the installation technology recommended for this type of insulation, as well as the careful execution of all stages of work.

You have experience insulating a floor in a wooden house? Please tell your readers what insulation material you have used and if you are satisfied with the result. Comment on the publication and participate in discussions - the feedback box is below.

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