How to properly organize ventilation in a wooden house? Why you can’t build a house on stilts Foundation ventilation on screw piles

A wooden house on stilts is a construction method that is very popular in a number of different countries around the world, including in Russia, where it has been actively used for more than 5 centuries. Today it is especially in demand during the construction country houses and country houses.

• Durability - the service life of such a foundation can easily reach up to 100 years, it all depends on the design of the house, the type of soil, and also the piles used tree species. In addition, the piles are quite easy to repair if necessary or can even be completely replaced, which makes their service life almost endless;
• Low cost - no piles required for construction a large number of building material, depending on the total area and weight of the house, wooden or concrete piles are used. The material used in the construction process is also not expensive; usually round timber from coniferous trees, pine, larch or spruce is used as piles;
• Practicality and efficiency - on peat soils, it is possible to build houses exclusively on stilts. Screw piles for a wooden house will ensure the absence of dampness inside the building, and if the home is located in close proximity to rivers, it can save it from a small flood. Provided that the piles are installed in accordance with the necessary requirements.

In a house on stilts, problems such as mold or mildew never arise, all thanks to excellent ventilation. Piles are also an excellent solution for the construction of wooden buildings in areas with a large slope. Also, even after completing the so-called zero cycle of the foundation, there are no difficulties with connecting all the necessary communications to the house;

• Functionality - under the house, installed on high stilts, you can easily organize an additional room, a summer kitchen, a place to park a car or just a small gazebo;
• Speed ​​of construction - perhaps no other type of foundation, both for wooden and stone buildings, can compare with piles in terms of laying speed.

Flaws

Piles have fewer disadvantages than advantages, however, they still exist; let’s consider the most significant of them.

• When installing piles, there is a possibility that some of them will fall into softer areas of the ground, which in the future can lead to their uneven subsidence, which can lead to serious damage to the house installed on them. In order to avoid this, you should study the soil in the area for installation of piles as carefully as possible.
• Low-quality materials - especially often low-quality material is used in the production of screws, as a result of which the metal from which they are made is not able to withstand an aggressive environment for a long time, and becomes unusable after 25-30 years. When installing wooden piles, it is important that they are made of larch, oak or pine, tree species with the highest strength, and wooden piles must also be treated with special antiseptics.

Wooden houses on screw piles began to be built relatively recently; the fact is that screw piles are made of light and durable metal, which are literally screwed into the ground, due to which their service life is significantly increased. To erect such a foundation for a dwelling, a large number of people are not required, since the structure does not have much weight and a small team of two or three people can handle its installation. Otherwise, screw piles have all the same advantages as wooden ones, but at the same time they are devoid of almost all of their disadvantages.

If there is a need to expand the house through an extension, in most cases it is recommended to give preference to a pile foundation. Since this will significantly speed up the entire construction process, as well as install communication structures under the new part of the house in the most convenient way. It is especially recommended to make an extension on stilts to a wooden house if it is some kind of non-residential premises, such as a terrace, veranda or porch.

Sometimes the extension can be quite large, not much different from the size of the house, and sometimes even larger than it; in this case, screw piles are especially suitable, as they can easily support even a huge structure. At the same time, everything will be produced quickly, inexpensively, and at the same time, the safety margin will last for centuries. However, despite all the obvious advantages, before building an extension on screw piles to a wooden house, it is recommended to consult with specialists.

Note!!! It is not recommended to combine screw piles with a strip foundation, since the latter is highly susceptible to the influence of the soil and the processes occurring in it. While screw piles are installed to a great depth exceeding the thickness of soil freezing, due to which they remain almost completely static throughout their entire service life.

Basement of a wooden house on screw piles

Base wooden house on screw piles in itself does not look particularly attractive, but its finishing may seem to many to be a very difficult task, which is impossible to carry out without the help of specialists. In general, everything is correct, it is better to turn to professionals, especially if you do not have confidence in your own abilities, but if you wish, you can easily cope on your own. Finishing the basement of a house on stilts is only slightly more complicated than finishing the basement of a house on a strip foundation.

Here are a number of tips that you can follow to easily give an attractive look to the base of a house built on stilts:

• When installing a base, this is especially true on heaving soils, it is advisable to leave a small gap of 15-29 cm between it and the ground, which will avoid troubles in case of ground movements. On denser, sandy soils there is no need to leave a gap. If desired, you can take measures to drain the soil under the house or replace the soil under the base with sand; this will also allow you to do without leaving a gap. The main thing is not to forget to leave the vents;
• Insulating the basement of a house on stilts is a very labor-intensive and expensive task, but there is no need for it as such. It is enough to properly insulate the floor, and good ventilation under the house in any weather will avoid the appearance of dampness and mold.
• Most suitable finishing materials For the base of a house on stilts, the following are considered: corrugated board, fiber-glass slabs, siding; you can also use special decorative grilles made of wood or metal.

That's all you need to know about the house on stilts. This is a reliable, time-tested construction technology for alternatives that simply does not exist on some soils. In addition, if you add an extension to a wooden house on stilts, even a porch, a huge terrace, or even a multi-room building, this structure will last for a very long time and will not require a lot of time and money for its construction.

Why is that? Let's find out!

The main problem with a pile foundation is that you voluntarily increase the heat loss of your home. Exactly the same story awaits you if you do strip foundation and leave a ventilated subfloor (instead of insulated floors on the ground).

When there is soil under the floor of your house, its temperature, as we know, is constant throughout the year and is approximately +7 degrees. As soon as you raise the floor into the air (on stilts or tape), the temperature underneath becomes close to the street temperature. That is, in the first case, your temperature gradient does not change throughout the year and is approximately 15 degrees (+22 indoors, +7 ground temperature). In the second case, during a cold winter, the temperature gradient between the floor indoors and outdoors will be more than 40 degrees! That is 2.5 times more. And these are the most natural heat losses.

If we take the standard cottage 10x10 with a ceiling height of 3 meters, it turns out that by raising the floor above the ground we increase the area of ​​the enclosing structures that come into contact with the cold environment by 30%. And if we want the floors in such a house to be warm, then we will need to use 300-400 mm thick insulation (and if we make floors on the ground, then we will need 2 times less insulation).

You can object and suggest insulating the base around the perimeter. Yes, you can do this and at first nothing bad will most likely happen. But if you do not leave any ventilation, then all your logs will quickly rot from moisture, and if mistakes are made during the installation of vapor barriers, the mineral wool insulation will become saturated with moisture, which will lead to it no longer performing its functions. And if you make ventilation, the air temperature under the floor will practically not differ from the outside temperature.

For this very reason, a foundation on metal piles and a house for permanent residence are completely incompatible things. And I’m not even touching on such issues as shaky floors (if the performer saved on deepening and tying, which is found everywhere) and the need to climb several steps before entering the house from the street (the lower the entrance to the house from ground level, the better ).

A foundation made of metal piles is justified only in one case - you are building a tourist center and its remoteness from civilization does not allow you to bring concrete or cement to make a monolithic foundation. Or if you want to build a seasonal cabin for weekend getaways. Also, you can’t do without a pile foundation in the permafrost zone, but that’s a different story.

If you are building a house for permanent residence, forget about the pile foundation. And about the tape s wooden floors forget it too. Use the type of foundation in which your floors will be in contact with the ground (through the insulation). Of course, you can make a strip foundation with insulated floors on the ground, but if it is possible to make a USHP-type foundation, there is no point in messing around with floors on the ground (this is more expensive and more difficult). If the terrain does not allow the use slab foundation- make a concrete basement. The same applies to cases when you definitely need a house with a basement. In exceptional cases, it is possible to build a house on reinforced concrete piles.

More details about why a permanent house needs to be built on an insulated foundation Swedish stove can be read.

Addition: Since you are constantly asking me what I think about standard modular houses on screw piles, I will insert here this video, which I already showed in the comments:

Literature for self-study:
Värmeförlust genom platta på mark - en jämförelse av kantbalkar

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There are several opinions about pile-screw foundations. Some consider this option ideal for relatively light frame houses and log houses, while others criticize it, citing their own arguments. Let's together understand the myths that exist about foundations on screw piles.

Myth one: a pile-screw foundation is unreliable

In fact, there are reviews from homeowners that a house built on screw piles wobbles, sways, and the piles themselves begin to protrude. So, unreliability is not a myth at all, but the pure truth? Not really. If problems arise with a house built on a pile-screw foundation, it means the construction technology was violated! We wrote about what it should be like optimal size screw piles. In addition, the reasons for instability of the house may be:

• Insufficient depth of piles;
• The diameter of the piles is not large enough;
• Excessively deep pit;
• Small number of piles;
• Weak-bearing, too soft soil;
• Errors in calculating the load on piles.

If all technologies were followed, calculations were made accurately, and installation was carried out by professionals, there will be no problems with the pile-screw foundation! In this case, it will be possible to say for sure that the unreliability of such a foundation is a myth.

Myth two: a pile foundation can be erected in just a day

Of course, installation of screw piles is much faster than pouring concrete foundation. However, this is not to say that you can cope in just a day! This is not always the case. Firstly, professionals always carry out test drilling and test screwing. This is necessary to find out the characteristics of the soil. It may be weak-bearing, too hard or rocky. The presence of stones in the soil will seriously complicate the screwing of screw piles, and in some areas the soil can be so strong that even metal will not withstand. In addition, sometimes it is impossible to use a drill and other special equipment on the site. In this case, the construction time for the foundation is also delayed.

Myth three: screw piles will rust within 10 years, the house will not last long

Experts say that a correctly selected screw pile will last at least 50 years. Service life depends on the following parameters:

• steel grades;
• metal thickness;
• quality of metal protection - painting, galvanizing, anodizing;
• soil aggressiveness.

In saline and acidic soils, metal rusts faster. In addition, special paint should be used to protect it and an anti-corrosion coating should be provided. You should not use cheap compounds.

Myth four: during installation, the blades of the pile may break off, causing it to sag

This can only happen in two cases - low-quality screw piles were initially selected and the installation technology was violated. If the soil is strong, rocky, and the installation was carried out harshly, then, of course, the blades can be broken. However, if you choose high-quality piles and do everything according to the rules, there will be no problems.

Myth five: you can install a pile-screw foundation only in the warm season

Not true! In winter, the soil, of course, freezes, but a small top layer can be removed using a chipper and you can easily install piles. Experts say that in winter it is often even easier to work, and no potato beds interfere with the plot. As for pouring concrete at sub-zero temperatures, we have dedicated this topic.

Myth six: screw piles are a new technology, not yet proven by time

In fact, pile foundation construction has been known since ancient times. True, then the piles were driven into the ground. In 1833, Irish civil engineer Alexander Mitchell patented a device called the "screw pile". Unlike conventional piles, screw piles are screwed into the soil. Initially, such piles were used for the construction of piers and lighthouses, then the scope of application expanded significantly.

In Russia, screw piles have been known since the beginning of the last century, in particular, they were widely used in the field of military construction, in permafrost conditions. That is, we are not talking about any new product! Research in the field of application of screw piles has been carried out more than once, including in the USSR, the advantages of this technology have been proven by specialists. True, screw piles began to be used in Russian low-rise residential construction later; previously they were considered the prerogative of the construction of industrial and military facilities.

Myth seven: all screw piles are the same, they differ only in price

Absolutely false. Piles differ not only in quality, size, metal thickness, and the presence of corrosion protection, but also in their scope of use. For example, there are piles created specifically for heaving, waterlogged or permafrost soils. In addition, they can be cast or welded. So you should choose based on your needs, preferably in consultation with specialists.

Myth eight: you can screw in screw piles without a pit

Professionals consider this a violation of installation technology, recommending that a small pit be made. This is due to the fact that the top layer of soil is usually the loosest, and the blades of the pile at the first stage loosen the soil until they reach denser layers. Often, without a pit it is completely impossible to screw in a bladed pile. In addition, concrete can be poured into the pit to strengthen the structure.

Myth nine: screw piles are ideal for building a house on a slope

Yes, this option occurs quite often. However, a house on a slope can also stand on other types of foundations; before choosing a foundation, it is important to conduct geological surveys. Pile foundation may be the simplest choice in this case, but it is by no means ideal.

Myth tenth: the floor of a house on a pile-screw foundation will be cold

This myth is connected with the fact that cold air will circulate under a house standing on stilts. However, if the floor is reliably insulated, the problem can be easily solved. And ventilation, by the way, will prevent the floors from starting to rot.

Foundation ventilation will protect your basement from premature destruction caused by decomposition building materials, impregnated with condensate of water vapor. After all, it is in the condensate that those colonies of aggressive microflora (mold, fungus, etc.) “live”, which, sooner or later, will destroy the entire basement structure.

Therefore, it is customary to install ventilation openings - vents - in the body of each foundation, except, perhaps, for the slab version of the foundation.

Ventilation of the foundation of the house

In this article we will look at the nuances of ventilation of pile and strip foundations, starting from calculations of the dimensions of the vents and ending with the practice of arrangement and operation ventilation ducts.

Ventilation in the foundation of a house - how it works

Any ventilation, as an air exchange process carried out in a certain volume, is based on the mechanical or natural impulse of the influx and exhaust of air masses.

1. Mechanical urge involves the use of injection equipment in the air exchange channels - fans, compressors, and so on. This is an extremely effective, but very energy-intensive method of ventilation.
2. Natural urge uses an almost inexhaustible and free source of energy - the forces of nature itself - to activate the air exchange process. Air exchange occurs due to the pressure difference between the supply and exhaust or the temperature difference between the ventilated and ambient environment.

Ventilation under the foundation works only due to the natural impulse of flow. Moreover, it’s not even a matter of temperature or pressure differences - everything is complicated with foundations. The principle of operation itself is based on the elementary “blowing” of the basement space with ordinary winds, the gusts of which rage in the atmosphere all year round.

And this is, perhaps, the most reliable ventilation option: after all, with proper selection of the dimensions and location of the vents, drafts provoked by the wind will “stretch” the entire basement space of the house, providing multiple air exchanges in the foundation area.

Foundation ventilation device

Calculation of vents based on the area of ​​the base

Effective foundation ventilation in wooden house or a brick building is possible only if there is an influx of a sufficient portion of air masses. In turn, the volume of inflow depends on the dimensions of the ventilation holes - vents. Thus, the efficiency of the entire ventilation system serving the foundation of the building depends on the size of the vents.

Therefore, in building regulations there is a special section devoted to calculating the dimensions of vents. Moreover, the easiest way to determine these dimensions is to compare the area of ​​the ventilation hole and the area of ​​the basement of the building. IN building regulations SP 54.13330.2011 even indicates the proportion of such a comparison – 1:400.

Example: if the area of ​​your floor (basement) is 100 square meters, then the area of ​​the vents sufficient to service such a base cannot be less than 0.25 m2 (1/400 x 100).

At the same time, it is necessary to understand that vents are arranged exclusively in pairs, located along one axis - this enhances the energy of the draft. Because of this, the total number of vents cannot be less than 4 pieces (one hole in each “wall” of the base tape). Therefore, the area of ​​one vent is determined by dividing 1/400 of the floor area by the recommended paired number of channels for ventilating the base.

Example: if the area of ​​the vents is 0.25 square meters, and the number of channels cannot be less than 4, then the area of ​​one vent is 625 square centimeters (0.0625 m2).

However, both the number of vents and the location of these ventilation holes are determined solely by the type of foundation.

Placement of foundation vents

Ventilation of pile foundation

Foundations on piles or short pillars involve the construction of a strip plinth that blocks access to the supporting elements of the foundation structure. Moreover, vents can be installed both in a finished base and in a belt under construction.

Ventilation arrangement during the construction of the basement is carried out as follows:

• First, the dimensions of the vents are determined.
• Next, when the base tape reaches ½ of its height, “bookmarks” are made in opposite walls for the vents, placing them at a distance of a quarter of the length of the façade from each corner. In most cases, “backfills” are bricks or channels made of wood that are not reinforced with cement mortar. profile pipe, placed in the formwork when pouring the tape.
• After completion of the construction of the tape, the bookmarks are removed from the body of the enclosing structure, opening the vents.

From the point of view of ease of arrangement, the installation of vents during the construction of the plinth strip looks preferable to the operation of “cutting through” ventilation ducts. After all, when cutting out the vent, it is necessary to use a special tool - hammer drills, grinders, drills with special attachments - with the help of which they pierce a fairly strong wall of the tape. Let's say right away - this is very hard work.

Foundation ventilation on screw piles

Ventilation of strip foundations

From the point of view of the process of arranging vents, the strip foundation is arranged in a more complex way than the pile version of the foundation. Indeed, in addition to the external tape that holds the walls of the house, inside such a foundation there are special partitions on which the internal interior partitions are based.

Therefore, the process of forming ventilation ducts in strip base as follows:

• First, the number and dimensions of the vents are calculated.
• Next, the formwork is assembled for pouring the foundation strip.
• Upon completion of assembly, the formwork is filled with reinforcement and mortar to ½ of the height of the foundation.
• After this, wooden blocks wrapped in roofing material are placed in the required places - at a distance of ¼ of the total length of the front or side section of the tape from each external corner.
• The same bars are laid in the internal sections of the foundation strip, placing them along the axis of the future ventilation duct.
• Next, you need to fill the formwork with mortar to the calculated height of the foundation.

After a week, you will remove the formwork and push out the wooden block from the tape, which will slide out of the roofing felt wrapper, opening the air channel.

Design for pouring a strip foundation

Operating rules for foundation ventilation

In the test above, we figured out how to make ventilation in the foundation. However, even the most effective ventilation will not give the expected result if the system is not used correctly.

The construction of a building begins with the construction of the foundation; at this stage it is determined where the vents will be made, in the foundation or in its base. Vents in the foundation of a wooden house are special ventilation holes in the above-ground part of the foundation, which are made in order to prevent the appearance of dampness in the basement (underground) in the summer and the accumulation of natural gases such as radon. That is, their direct purpose is ventilation under the floor on the first floor.

It is worth noting that the basement rooms must be connected for air exchange (air circulation). As a rule, ventilation ducts are located in the foundation or its base under the basement floor or below. Vents are usually closed for the winter.

IN summer period When moisture and gases accumulate in the basement of the house and evaporate from the soil, part of the foundation and the lower part of the floor of a wooden house becomes overgrown with mold and starts rotting processes. That is, if you do not make a vent in the foundation, it will quickly begin to grow mold and slowly collapse.

Proper production of ventilation

To have a dry basement, good ventilation is necessary. Such ventilation in the foundations is included in the design when organizing the formwork. To organize the vents, it is necessary to take into account their location above the ground. The height of the vents from the surface should not be less than 30 cm, so that in the spring melt or rain water does not leak through them.

It is likely that in some cases, the ventilation holes will need to be made higher if the height of the foundation allows. It all depends on the climate and the amount of snow. Please note that for ventilation purposes you cannot use wooden beams. For vents, it is better to use plastic or asbestos pieces of pipes with a diameter of 110-130 mm, mounted in concrete (at the stage of pouring it).

In addition to moisture, radon can accumulate in the underground space. Most moisture and gas enter there in winter. After all, the soil under the house does not freeze. To prevent such problems from arising, they arrange vents.

Boxes and beams are pulled out from the foundation no earlier than a month after it is laid. During this time, they “stick” to the concrete, and it is difficult to knock them out. For this operation you need to perform the following steps:

1. After the concrete has dried, take a metal drill and drill into the block on both sides, in the center or around.
2. Then take a wood drill and drill a hole through, and the drill should not be more than 2.5 cm.
3. Having made a through hole, you need to use a semicircular chisel to expand the hole from the center in any direction.
4. Then, using a straight chisel, the frozen side is beaten off.

The procedure for removing beams clogged in this way is quite labor-intensive. Therefore, it is better to use other methods, for example, vents can be made using metal boxes instead of bars, since it is easier to knock it out of the foundation. You can also use it for this sewer pipes. In this case, the ventilation vents are positioned strictly one against the other.

Peculiarities

For high-quality arrangement of the ventilation subfloor, the windows are covered with special lattice covers (made with your own hands from meshes or gratings). This is done to prevent animals from entering the house through the vents. The diameter of the boxes is selected in proportion to the ventilation covers. If the vents are not made in advance, they are drilled using diamond core bits.

The shape of the holes can be very different: square, round, triangular. But, as a rule, they are made rectangular. The vents must be positioned evenly, at equal distances from one another. If the house is cold, it is better to close the holes. But in wooden houses they are not closed under any circumstances, especially if the house is new.

If there is no ventilation or blocked openings, you may incur costs associated with repairing the foundation or cleaning the walls from the resulting rot and mold.

A little about the positive aspects

Unlike other methods of organizing ventilation, vents have much more advantages. The main ones:

• long service life;
• low price;
• reduction of heat loss;
• environmental cleanliness;
• practicality.

None of the other methods of ventilation can compare in efficiency and practicality with vents.

Calculation

The optimal number of ventilation windows should be one per 2-3 meters. It is worth considering where the wooden house is located; if it is located on a hill, then two vents will be enough, for a house in the lowlands from four. It is advisable for homeowners who are building a house to know the local wind rose diagram (a diagram of the wind regime in a certain place based on long-term observations) so that the ratio of air flows on each side is not a problem. Let's look at an example of how to make the calculation.

Let's say the dimensions of the foundation are 5 by 6 meters. The planned dimensions of the vents, which have a rectangular cross-section of 20 by 25 cm. It is necessary to calculate the minimum permissible number of windows and correctly position them along the walls.

The required area of ​​the vents is determined by the formula:

S = F/400 = 30/400 = 0.075 m2,

where: F – basement area.

The required number of vents is determined as follows:

N = S/P = 0.075/0.05 = 1.5 ≈ 2 pcs.

where: P = 0.2x0.25 = 0.5 – area of ​​one vent.

It turns out that you need 4 holes to avoid unventilated “bags”. They can be placed on the short or long side of the house. But the best ventilation will be if the vents are located on the short sides. The height above the ground is not lower than 30 cm from the ground.

Ventilation in a wooden house

Foundation ventilation wooden houses is arranged in embedded foundation beams. They are usually cut down between the first and second crowns, or between the foundation and the floor log. They do this like this:

• mark the places where there will be ventilation vents;
• make cuts in embedded foundation logs;
• make the holes in the form of boxes.

This work can be performed by specialists if necessary. Especially if you need to do the vents after you forgot to do them in advance.