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Wouldn't an extension be possible without a foundation? An extension to a house - how to quickly and inexpensively make it from available materials An extension without a foundation

Wouldn't an extension be possible without a foundation? An extension to a house - how to quickly and inexpensively make it from available materials An extension without a foundation

07.10.2023

Frame technology is a long-lasting trend in Europe and America. The costs of preparing buildings are minimal. This is much more profitable than buying an apartment in the city. Frame technology is adapted to climate change, which means it is optimally suited for the changeable Russian climate. you can build during the winter frost season and within a few months you will have a building fully equipped for living.

The key advantage of frames is proper weight distribution. Regardless of the number of rooms, the weight load on the supports is distributed harmoniously. That is why there is no need to build a massive foundation, spend money on purchasing reinforced concrete blocks and renting special equipment for digging a pit. Even an ordinary embankment, which consists of sand, crushed stone and cement, can fix and hold reinforcement and metal supports.

What designs of houses without a foundation exist?

You can get information about what types of frame houses there are, projects, photos and prices of these sites on the website of professional construction organizations. A competent company offers both a set of ready-made templates and layouts, and also works on individual orders. This is important when a building is being erected in a limited area, where it is necessary to fit a large number of rooms, but at the same time, correctly fit the structure into the composition of the garden plot.

A cottage without a foundation is much easier to modernize. We are talking about extensions in the form of verandas and gazebos. Thanks to this, you can continue the embankment or build a regular platform, which will not put an additional load on the foundation supports. This helps to create unusual solutions and implement bold architectural ideas.

When creating projects for houses without a foundation, special attention is paid to the engineering system. In such a situation, water and sewer lines are either taken outside or isolated directly under the house. This prevents serious repair costs in the event of a break or deformation of sewer pipes, which also speaks in favor of building frame houses without a foundation.

Time passes, and it turns out that the private house no longer satisfies the owners with its size and amenities. A decision is made to expand its area with an extension. We’ll tell you in this article how to do this efficiently and without extra costs.

Save money without harming quality – requirements for premises and materials

Poorly thought out design of an extension will eventually force something to be altered or completed, or added to the country house. In order to avoid getting into such a situation, we think through all the nuances, weigh the advantages and disadvantages of our idea. We start with choosing a location and size.

Each type of additional room has its own specific characteristics in connection with its use, requirements for insulation, waterproofing, and others. If a decision is made to build an additional living room in a country house, then this is tantamount to building a small house. It is necessary to reliably insulate and prevent the appearance of dampness. If you plan to stay in cold weather, you need to think about heating.

Another common type of extension is kitchens and bathrooms. The requirements for them are practically the same. First of all, we think about utilities and install them even before construction begins. It is much more convenient to lay sewer and water pipes before pouring the foundation than to dig underneath it later. The waterproofing of the floor covering requires increased attention. We are thinking about insulation, but if the kitchen is planned for summer, then you can save on this.

The house is being expanded by adding a veranda. The structure is light, serves for summer recreation, protects the entrance from wind, snow and rain. It is carried out in many variants: from the simplest in the form of a boardwalk, low walls with a roof on pillars, to complex with walls, doors, windows. No insulation is required, otherwise it will no longer be a veranda, but waterproofing the foundation is necessary.

The extension to the house must be in harmony with the main structure. If the house has external decoration, then it will not be difficult to repeat it in the attached room. All materials go well with wood, which looks great even without additional finishing. The best option would be a frame structure:

it is built quickly, literally in a few months;
does not require a capital foundation because it is lightweight;
without special knowledge and skills, it can be built with your own hands;
will cost less.

The foundation for the extension is made on the same level as the foundation of the house. When attaching a structure to a house, we do not do it tightly - over time it will shrink - but leave an expansion joint. In this regard, frame structures that do not shrink vertically compare favorably.

If the structure is attached to the front wall, the roof continues the main roof and is pitched. We choose the slope in such a way that the snow does not linger and the rain flows off. If this is an extension to a side wall, then the roof follows the configuration of the main one. The roofing material is the same as on the roof of the house, if different, it is important that they are combined.

Columnar base - fast, cheap, reliable

For the columnar foundation of the extension to the house, concrete, brick or a combination of both is used. It is made mainly for a living room or veranda. If used for a kitchen or bathroom, thermal insulation of the utility lines entering the house will be required. Since the protection concerns an average of half a meter of pipes, such expenses can be incurred, and it will still be cheaper than a strip foundation. The floor is made of boards; for concrete, you will need a lot of backfill material and a fence around the perimeter.

We start by marking the area, the installation locations of the pillars are one and a half meters from each other. A separate hole of 50x50 cm is dug under each pillar, with a depth greater than freezing of the soil. At the top we expand the pits a little: about 10 cm on each side. We fill the bottom with a 10 cm layer of sand, carefully compact it, then crushed stone or broken brick, which is also compacted.

We lay out the film for waterproofing and bring the ends to the surface. If we plan to build brick pillars, pour a little concrete mortar into each hole for the base and wait for it to set. When planning concrete pillars, we tie reinforcement at the top along the entire height and lower them into the pits. We ensure equal distance between the walls. We place pieces of brick under the bottom to raise the reinforcement by about 4 cm.

We make formwork for the base, inside which we run the film. We pour the concrete in layers, pierce each layer several times with a rod to release air bubbles. It is important not to rush, it is better to wait until it sets, then continue pouring. We carefully level the top of the column and wait about two weeks until the concrete hardens. All this time, water heavily and cover with burlap or film.

When the foundation reaches the required strength, the formwork is removed. We heat up the bitumen mastic, apply it to the pillars and immediately glue pieces of roofing felt for waterproofing. There is space left between the pillars, which it is advisable to fill in to insulate the floor. We use ordinary soil mixed with crushed stone or pieces of brick. Fill in layers of 10 cm and tamp. The technology for constructing a strip foundation is practically no different, but unlike a columnar foundation, it is solid.

Getting started - bottom frame and extension floor

So, we settled on the frame option as the fastest and cheapest. In order for wood to serve for a long time, you need to adhere to two rules: make reliable waterproofing and carry out antiseptic treatment. Of course, the wood must be well dried. For waterproofing, the most reliable means is bitumen mastic. It is possible to use several layers of roofing material, but it is short-lived.

Then we make the bottom trim. Usually 150x150 mm timber is used, but it is possible to use 150x50 mm boards. We lay them horizontally along the entire perimeter, aligned with the outer edges of the foundation. We do not connect the boards of the first row to each other. We lay the second row on top, overlapping the joints in the first.

In the boards laid in this way on the foundation, we make through holes for the studs and connect them. If it is strip, we drill and connect it on the ground, and then lay it down. To get the effect of a single beam, we knock it down with nails in a checkerboard pattern every 20 cm. The result is a binding of the required thickness, which also has additional advantages:

costs much less than beams;
It’s very easy to connect them together, but with bars it’s more difficult.

We attach the bottom frame to the beds from the same 150x50 mm boards, installed on top of the edge along the outer edge. We fasten them together and with the beds with 90 mm nails. Next we install logs made of similar material installed on the edge. The distance between them is 60–80 cm, but it all depends on the size of the frame extension: the longer the logs, the narrower we install them. They are attached to the trim board with nails, 2 on each side.

Now let's start insulating the floor. The cheapest, although not very environmentally friendly option, is tile polystyrene foam with a density of at least 15 kg/m3. Its advantage is that it is the only insulation material that is not afraid of moisture. We nail 50x50 mm bars to the lower edges of the logs, which will hold the polystyrene foam. A thickness of 15 cm is required: we use sheets of 10 and 5 cm. We lay them so that the seams of the bottom and top rows overlap.

The base is ready. We lay the subfloor on top. To prevent it from warping over time, we lay it alternating the direction of the annual rings. We look at the cut: we place one board with an arc up, the other - down. We make the finishing floor from plywood, the joints are staggered. A rough base is not necessary if there are edged tongue-and-groove boards with a thickness of 30 mm or more or 15 mm plywood. We lay it directly along the joists.

Wall installation - two assembly technologies

There are two technologies for assembling frame buildings. The first is called frame-panel, when the entire assembly is carried out on the ground, then the finished structures are installed in place and fastened together. Sometimes the frame is immediately sheathed, which makes it even stronger. Another method involves gradual installation on site. Which one is more convenient - everyone decides for himself. A shield assembled on the ground cannot be lifted alone; assistants will be needed.

We begin the construction of the frame with the corner posts. For them and intermediate posts we use timber 150×150 mm or even 100×100 mm. The distance between the racks is determined by the width of the insulation, which we find out in advance. We position the pillars so that the gap between them is 3 cm narrower than the width of the insulation. This way we will save on waste-free use of material and improve the quality of insulation without leaving gaps.

Fastening can be done simply and reliably using metal corners installed on both sides of the racks and secured with stainless steel screws. Before finally fixing the stand, we carefully check its verticality, this is especially important for the corners. One incorrectly aligned beam will cause the entire extension to bend.

Temporary bevels, which are installed from the inside and serve until the outer skin is attached, help maintain the correct shape of the frame. If the sheathing is made of a rigid and durable material such as plywood, OSB, GVK, it is capable of independently strengthening the base, which will stand securely after removing the temporary slopes. When soft material is planned for the cladding: siding, lining, then permanent braces cannot be avoided. It is better to install them two at the bottom and at the top of each rack.

At the places where windows and doors are installed, we attach crossbars. We make double racks next to them: they experience increased loads and must be stronger. The final fastening of the frame is carried out by installing the upper trim. In order not to invent anything, it can be similar to the bottom one: a bed made of two boards fastened together and the actual harness made of the same boards installed on the edge. To it, in the same way as the floor joists were attached, we nail the floor beams from 150x50 boards on the edge.

We constantly check the geometry of the entire structure, as well as the correct installation of the racks and crossbars: the racks are strictly vertical, the crossbars are horizontal.

Shed roof - design and technology

The roof of a house with an extension consists of two parts, which should be harmoniously combined into one. If the extension is built on the side, the roof will be a continuation of the main one; all that remains is to repeat its design in order to lengthen it. When an attached building is located along its length, its roof is made of a pitched roof. The slope is ensured by the difference in height of the front and rear pillars. The height of the rear ones should ensure that the roof of the extension goes under the main canopy.

The roof is supported by rafters, which we lay on beams. They are made from thick boards, to ensure fixation, we make special grooves. We cut them out on the ground according to a template so that they are all the same. Then after installation in place there will be no need to align horizontally. We treat the grooves with mastic, install them and fasten them to the walls with brackets and metal corners on studs. If the length exceeds 4 m, we install additional vertical supports.

We lay the sheathing on top of the rafters. Depending on the roofing material, we make it continuous or in increments of 0.3–0.6 m. The need for continuous wooden flooring arises when using soft material; we make sparse material for all other types of roofing. We make fastening depending on the type of roof. We fasten corrugated sheets and metal tiles with special self-tapping screws having sealing washers, and ondulin with nails with a wide head. We provide wave overlap. Don't forget about the final design: wind strips not only protect the roof, but also give it a finished look.

Insulation is a mandatory operation for an extension

Mineral wool and polystyrene foam are mainly used to insulate buildings. Mineral wool resists fire and has low thermal conductivity. They are light in weight and have a consumer-friendly release form: rolls, mats. Another popular insulation material is polystyrene foam. Its advantages: it is inexpensive, not afraid of fungus, moisture, rotting. But there are two big drawbacks: rodents love it, and in case of fire it emits toxic gases.

We carry out insulation from the inside in the following sequence:

1. We install the waterproofing, having previously cut strips of the required sizes. We fasten with staples using a construction stapler, so as to ensure overlap. We sheathe the frame completely, driving in staples every 10 cm.
2. Place insulation between the studs. We ensure a tight fit to the wooden structures, close the seams between the individual elements of the insulating material, overlapping the next layer.
3. We attach the vapor barrier, even if we use polystyrene foam. The fact is that it is necessary to protect not only the insulation, but also the wood. We perform fastening in the same way as waterproofing.
4. We cover the walls from the inside. We use plasterboard over a perfectly flat frame or OSB if there are any unevenness. It is tougher and smoothes out imperfections.

All that remains is the interior and exterior decoration, which leaves room for the owner’s imagination. A frame extension is built quickly, cheaply, lasts for decades, and can be built with virtually no outside help.

Over time, some private buildings require expansion for various reasons. For example, an increase in the number of people sitting, installing a sewer system into the house, or the need to close the front door from direct exposure to cold. Therefore, there is a need for an additional room, expanding the kitchen, creating a room for a bathroom, or simply building a veranda.

A do-it-yourself extension to a house can be made of wood, brick, or a combination that includes several building materials.

Premises requirements

To avoid having to make additional changes to the attached room, it is better to immediately think through all the nuances of the extension, since each of them requires a special approach.

Additional room

If you need to add another living room to the house, you will have to try, since this work is almost equivalent to building a small house. The floors, walls and ceiling of the building must be well insulated, otherwise the heating installed in it will not be effective - this is one of the main conditions for a living space. The second important condition for normal living is the absence of dampness in the room, which means reliable waterproofing is needed.

Kitchen or bathroom

When constructing these premises, before installing the foundation, utilities are brought to the construction site - in particular, sewer pipes. You may have to install the water supply separately.

In addition, it is also worth paying attention to the insulation of all elements of the structure, and think about reliable waterproofing of the floor.

Veranda

A veranda is a lightweight structure that mainly serves to protect the main entrance to the house from wind and rain or is used for summer recreation. It may be closed, have a door and one or more windows, and May be and completely open, that is, it consists of a flooring, low walls and a roof raised on pillars.

This structure does not require special insulation, but it will still be necessary to waterproof the foundation.

Construction of the foundation for the extension

The foundation for the extension can be strip, made of brick or stone blocks, or columnar. Each of them has its own advantages and disadvantages. To settle on one of them, you need to find out how each structure works and choose the one that is more suitable for a particular extension.

Information about building the foundation

Strip foundation

So, the strip foundation is arranged in the following sequence:

First you need to mark and trace the place where the extension will be installed. This is done using a rope, which is stretched on the ground and secured with pegs.

Next, following the markings, a trench is dug to the same depth as the foundation of the entire house. Before pouring concrete, it would be a good idea to secure the reinforcement that connects the foundations of the main building and the extension.
The width of the trench should be 100-150 mm greater than the planned wall thickness.
After the trench has been dug, further preparation begins. First, the bottom is filled with a sand cushion 100-120 mm thick. It must be compacted thoroughly.
The next layer is filled with crushed stone or broken brick, which is also compacted with a hand tamper.
Next, waterproofing is placed in the trench along the entire perimeter, which should extend to the ground surface by 40-50 cm, since it should cover not only the inside of the foundation, but also the formwork for its above-ground part.
A welded reinforcement structure is installed on the waterproofing film, which should follow the shape of the foundation, and over its entire height.
Then the reinforcement is poured with a rough concrete solution of cement and gravel to ⅓ of the height of the trench, and after this layer hardens, the next one is poured to one-half of the remaining height.

Installation of formwork for strip foundations

After pouring this layer, you can start installing wooden formwork to form the above-ground part of the foundation - the plinth. The waterproofing film is left inside the formwork, spread along its walls and secured on top of them so that it does not slide into the concrete.
Concrete is poured into the prepared formwork to the top. Then the solution is pierced in several places with a shovel so that there are no air cavities left inside it. You can lightly tap the formwork - such vibration will help the concrete to compact as much as possible.

Having completed pouring the foundation, the concrete is leveled to the required level and left to dry, sprinkled with water daily to strengthen it.
After the concrete has completely hardened, the formwork is removed and the foundation is waterproofed from the outside.
Before starting the construction of walls, it is recommended to additionally cover the foundation with waterproofing compounds or roll materials. For this process, liquid rubber, tar, bitumen mastic and roofing felt are used.

The space inside the strip foundation can also be equipped in different ways - with a concrete screed or a flooring of floor beams and joists with a wooden floor installed on them.

Video - construction of an extension to a house on a strip foundation

Columnar foundation

In addition to a strip foundation, a columnar foundation can be constructed, which is built from brick or concrete, or a combination of these materials. This option is mainly used for the construction of verandas or additional living rooms, since communications associated with water supply or drainage in an uninsulated or even open underground will require additional thermal insulation.

A columnar foundation is most often installed if it is planned to install a boardwalk.

The work is carried out in several stages:

The first step is marking the area chosen for the extension. The pillars should be one and a half meters apart from each other.

Excavations are dug for each pillar separately. Their depth should be 500-600 mm, with a square side of 500 × 500 mm. Towards the top, the pits should widen slightly - about 100 mm on each side.

Foundation pillar installation diagram

Next, the bottom is strengthened in the same way as when installing a strip foundation, using sand and crushed stone, and waterproofing is laid.
If the support pillars will be built from brick, it is recommended to lay a layer of coarse cement mortar on the bottom. Only after waiting for it to harden do they make brickwork.
If the pillars are concrete, a reinforcement structure and formwork are installed at the bottom of the pits to the height of the future pillar. The waterproofing film is placed inside the formwork and secured on top of it;
Concrete is poured into the formwork in layers. Each layer must set well before the next one is poured;
The top of the column is well leveled and sprinkled with water daily until it hardens completely;
After the pillars are ready, the formwork is removed from them and they waterproofed roofing material, which is glued onto heated bitumen mastic.
The gap remaining between the soil and the pillars is backfilled, compacting every 100-150 mm of backfilled soil mixed with crushed stone.
Several layers of roofing material are laid on each of the pillars - it is necessary for waterproofing the wooden blocks that will be laid on top of the pillars.

Installation of the base floor of the extension

If a strip foundation is chosen, both wooden and concrete floors can be installed on it. A columnar foundation without lintels requires the installation of a wooden floor.

Concrete floor

To make a reliable and warm floor screed inside a strip foundation, you need do work step by step, adhering to a certain technology.

To begin with, excess soil is selected from inside the finished strip foundation. It is first loosened and then removed to a depth of approximately 250-350 mm.
A ten-centimeter sand cushion is poured and compacted onto the bottom of the resulting pit. Crushed stone can be laid on top of it, but to insulate the screed, instead of crushed stone, expanded clay is used, poured in a layer of 15-20 cm.

Expanded clay is leveled, and a reinforcing grid is laid on it. After its installation, a system of beacons is installed on top at the selected horizontal level. Some rooms, for example, a bathroom or an open terrace, may require a certain slope of the surface to allow water that falls on the floor to flow smoothly to the drainage system.
Next, cement mortar is laid out on the prepared surface and leveled using the rule. After a day, it can be covered with plastic film - then the concrete will mature more evenly, which will give it additional strength.

When the walls of the extension are erected, any decorative covering or wooden floor can be laid on the resulting concrete base.

Floor on wooden beams

Floor beams are wooden blocks of fairly large thickness, about 150 × 100 mm in cross section. You cannot skimp on them, since the overall strength of the floor will depend on their reliability.

The beams are laid on pillars or strip foundations, on top of a fabricated roofing felt substrate, and can be secured to the concrete in a variety of ways - using through fasteners, angles and other metal fixtures. The beams at the intersection points are also fastened together using strong corners.

They will hold securely, since the wooden flooring of the “black” and “white” floors also serves as a kind of binding fastener.

Video: construction of a frame extension with a wooden floor

Construction of extension walls

Brick or frame walls can be built on a finished strip foundation, while a columnar foundation is mainly used for frame buildings. If you plan to make brickwork on the pillars, then you will have to make additional concrete lintels between the pillars.

Frame walls

The frame for future walls is erected from timber and secured to the previously installed crown beams. The beams can be attached to the beams separately, but sometimes it is much more convenient to assemble the wall elements in a horizontal position, on a flat area, and then install them in a vertical position already assembled.

To connect the frame to the wall of the house, a perfectly accurate vertical marking is made on it, along which a separate block or assembled frame element will be fixed.

For reliability, all bars are connected to each other with metal corners.

Having installed the entire frame of the extension, it is better to immediately sheathe it with boards or plywood (OSB) from the outside. Sheathing will immediately make the structure more rigid.

The upper horizontal beam running along the house is attached to the main wall using reliable metal corners or anchors.
The walls are insulated after the roof is installed.

Video: another example of constructing a light extension to a house

Brick walls

Before you start building brick walls, you need to carefully check the horizontalness of the foundation surface and, if necessary, level it to perfection. If the base is uneven, the masonry may crack due to deformation during shrinkage.
It should be noted that brick extensions are best done to a brick house. To connect the extension to the main wall, during the construction of the walls, holes are drilled in it to two-thirds of the depth, every two or three rows of masonry. Reinforcement is embedded in them, which should protrude from the wall by about half a meter. It should be in the seams of the future masonry. To ensure that the seams in these rows are not excessively wide, the reinforcement must be chosen not too thick, or you will have to make a recess in the bricks of the row on which the reinforcement will be laid.
If a brick extension is installed against a wooden wall, then a hole is drilled through it, into which reinforcement with a transverse stopper is installed from inside the house, which will hold it in the wall. The reinforcement is also installed as the wall is erected, every two or three rows.

Before starting masonry, a string is stretched along the future wall, along which it will be easy to control the horizontality of the rows, and the verticality is constantly verified using a plumb line.
The thickness of the walls will depend on what function the extension will perform. If this is a living room, then the masonry should be at least one or two bricks. If the room will serve as a veranda or utility room, then half a brick will be sufficient.
Having built brick walls, they are connected along the entire top with a concrete belt. Formwork is made for it, a reinforcement structure is laid in it and poured with concrete mortar. After the solution has completely hardened, the formwork is removed from the belt, and you can begin installing the ceiling.

It should be noted that building brick walls is not as easy as it seems, therefore, if you have no experience in this work, it is better to entrust this process to a qualified mason or choose a different type of wall.

Extension ceiling and roofing

After the walls are erected, it is necessary to make a ceiling. For it you will need beams - beams, which are installed on the upper part of the walls, at a distance of 60-70 cm from each other, and secured with special corners.

If the beams are laid on a brick building, they can be embedded in a concrete belt, having first wrapped the edge of each of them with roofing material.

The next step is to line the beams with boards or thick plywood, on which insulation will be laid on top, between the beams.

The roof of the extension can have different designs, but generally the lean-to option is chosen, which is worth considering.

This structure consists of rafters on which the roof is laid. This type of roof is quite simple to install; the main thing is to choose the correct slope angle. It must be no less than 25 — 30 degrees - this is necessary so that precipitation in winter does not linger on the surface, otherwise it can simply damage it.
Having determined the slope angle, a mark is made on the wall or façade of the roof in the form of a horizontal, even line along which the block supporting the rafters in the upper part will be attached. The lower support for them will be the previously laid floor beams or the edge of the wall. The rafters should extend beyond the boundaries of the constructed walls by 250 — 300 mm, in order to protect the walls as much as possible from rainwater.
The rafters are also secured using metal corners.
It will be more difficult to resolve the issue of roof slope if the extension is installed on the side on which the slope of the main building of the house is located, since there will simply be nothing to secure the transverse beam there. Therefore, it may be necessary to remove several lower rows (sheets) of roofing material from the roof of the house in order to use its beams to secure the rafter system and combine the overall covering.
You need to decide in advance what kind of roofing will be laid on top of the rafter system. If it is a soft roof or flexible tiles, then a solid material is laid on top of the rafters and secured, for example, plywood or frequent transverse lathing.
If large sheets will be fixed (roofing iron, metal tiles, slate, etc.), then they can be overlapped with directly installed rafters.
When the system under the covering material is ready, it is recommended to lay waterproofing on it. In the first case, plywood is covered with it, in the second, it is fixed to the rafters.
The roofing material is laid on top of the waterproofing material, starting from the bottom of the rafter system and rising to the top. If it is necessary to combine the roof, then when joining, the top row of the extension roof is slipped under the last row of the roof slope of the main building.
If the roof adjoins the upper part of the roof to a wall or the front part of the roof, then the joint between them must be waterproofed.
When the roof over the erected extension is ready, you can begin to insulate the walls and floor.

Prices for metal tiles

Metal tiles

Insulating the extension from the inside

If the room is residential, then reliable thermal insulation is indispensable. If the ceiling is already sheathed and insulated, then you can proceed to insulating the floor.

Floor insulation on beams

If floor beams were installed on a columnar foundation for the floor, then the work proceeds as follows:

Transverse logs made of smaller bars are attached to the floor beams.
It is recommended to install a subfloor on the joists; in this case, it is better to lay the boards for it as a continuous flooring, otherwise the heat will be blown out of the house.

Next, the entire rough coating is coated with a fairly thick clay solution, and after drying, a vapor barrier film is laid on it.
Mineral wool is placed tightly between the joists and expanded clay or slag is poured.

On top, the insulation is again covered with a vapor barrier, and a wooden floor made of boards or plywood is laid on it.
A decorative coating can be immediately laid on the plywood, or an infrared film floor can be installed underneath it.