How to make an add-on for a change house or a construction trailer in the country

Recommendation points

• Foundation and structure binding scheme
• Assembling the frame
• Making rafters
• Completion of work

Over time, the possibilities of the summer cottage are exhausted, more useful exploited space and space for storing materials and tools are required. From the review from you will learn about ways to make a superstructure with an attic and a semi-open terrace.

Foundation and structure binding scheme

Most modular cabins are installed with little or no preparation. All work on the base can consist of uprooting stumps and removing shrubs, leveling the ground and arranging several support legs made of brick or cinder block. For a lonely suburban trailer, this approach is quite acceptable, however, the presence of a superstructure obliges you to take care of a more solid foundation, which will not allow individual parts of the structure to part.

First of all, you need to make sure that the change house is installed exactly at the level and all possible processes of soil shrinkage under the supports are completed. First, align the trailer along the back wall, where 3-4 retaining posts are usually located. If they crumble from erosion or can sag in the future, repairs should be carried out by strengthening the supports and replacing, if necessary, part of the soil under them.

There should be more supports on the side of the change house door than under the rear wall. It is better to install them in increments of no more than 120–150 cm, while the change house should rest only on half of the pillar so that the first lag of the terrace can be laid in the remaining free space. Depending on the level at which the change house door is located, the same support can be two-level, so that later the attached platform is at the correct level relative to the floor and the entrance sill.

The load-bearing base of the superstructure is made of rolled metal or sawn timber. The first is preferable, because the required cross-section of steel elements is less than in the case of using wood, but in suburban conditions there is not always everything necessary for welding metal structures. At the same time, wood will cost a little less, although you will need to work hard to make the connections correctly.

The main support points of the superstructure are located along two lines: the first runs close to the front wall of the trailer, the second parallel to the first with an indentation necessary to form a sufficiently spacious terrace. This offset can be chosen arbitrarily, but, as a rule, with a length of more than 4.5–5 meters, it will be necessary to use truss structures so that the roof is sufficiently rigid. It is most reasonable to make the terrace the same width as the trailer itself..

The most loaded elements are the racks located on the first line, because they have the main emphasis. The end posts and the roof of the trailer play an auxiliary role, taking on the eccentricity of the loads from the asymmetrical configuration of the roof. Accordingly, the supports located close to the front wall of the change house should be more powerful, or installed with a more frequent step.

The attachment of the superstructure to the trailer is not intended to transfer the main loads, but it is necessary to exclude possible shifts and securely fix the parts during their assembly. It is necessary to determine in advance in what places under the skin the frame elements are located and select the appropriate type of fastener.

Assembling the frame

The basis for the frame is a frame made of timber with a side of at least 100 mm. A grillage is assembled from it along the perimeter of the future terrace, a half-body is cut in the corners. The same method of joining is used when installing jumpers. Their number is determined by the material and the section of the floor lag, which, with a load of 70–80 kg, concentrated in the center of the span, should bend no more than 10–15 mm. To keep the grillage confidently, it is recommended to knock the points of rallying with a steel strip.

At the intersection of the grillage, frame racks are installed. For the first line, these are all the same 100×100 mm or more, for the outer row, you can use a lowered section, for example, 100×50 mm, placing the board with an edge against the wall of the trailer. A crossbar is installed on top of the posts. The crossbars located across the change house must cover it over the entire width of the roof. The planks should be installed directly above the structural members, which are usually located directly below the corner claddings. The section and type of rallying of the upper strapping are the same as that of the grillage.

There are few nuances when assembling the frame. First, there must be a support under each post, for example, a brick post. Secondly, one should abandon hardened self-tapping screws in favor of anodized ones or use ordinary nails. Thirdly, the lumber for the frame must be dry, without traces of twisting and warping, because these elements set the geometry, and it will be quite difficult to correct the flaws later..

Making rafters

Although the process of making rafters for a gable roof itself is quite simple, their installation without assistance is extremely difficult and almost impossible if there is no support under your feet. Therefore, first of all, you need to assemble the floor frame, for which you will need to install additional beams, which are better placed across the struts connecting the racks, that is, along the trailer. For the correct installation of the beams, it is enough to throw on the harness from above, performing the usual type of undercut at the intersections. By the way, in the same way, you can immediately strengthen the floor structure, the spacing of the beams in the upper and lower parts is the same – about 80-100 cm.

Note:so that the half-body undercut does not weaken the strength properties of the wood at the intersections, the parts should be fitted as tightly as possible, for which a small end plane will be a good help.

To complete the assembly of the floor, it is enough to cut out jumpers of equal length from a 100×50 mm bar and set their spacing between the beams. After that, you can build a temporary floor from boards or sheet materials, laid without fastening. On such a basis, you can safely move massive rafters and work safely.

The rafter legs are always assembled according to a template, which is the first structure assembled in the shape of the letter A. The easiest way to make it is as follows:

1. Two boards with a cross section of 50×150 mm must be laid on top of each other and fastened with one nail 100 mm from the edge exactly in the center.
2. Having unfolded the legs, they need to be installed on the extreme floor beams to determine the appropriate height and slope.
3. In place, at a distance of 60-70 cm from the top, you need to temporarily fix the crossbar on the self-tapping screws.
4. Having drawn two lines at the intersection of the legs with each other and with the crossbar, you can disassemble the structure and perform an undercut.
5. The rafter leg is assembled back, the main lintel is nailed on the opposite side of the temporary.

In much the same way, by placing the boards on the template, the remaining rafters are trimmed and assembled. The main jumpers should not be installed on them yet, it is enough to fasten the legs with a board on a pair of self-tapping screws. If the quality of the building materials used is high enough, you can trim the left and right legs separately by moving the desired angle with markings using a bevel. Raising the legs and assembling them on the roof is easier, with proper skill, you can do even on your own.

The assembly begins with the installation of the extreme rafters, between which the lacing is pulled along the top and overhangs. If you need to change the height, it is enough to slightly reduce or spread the legs, temporarily fastening them to the edge of the floor with self-tapping screws. The main fastening of the rafter system is reduced to installing two crossbars on the inside, running along the entire roof, and fixing the main rafters above the crossbars. Fastening the legs to the ceiling can be done with a hem, reinforcement with steel corners or wooden scarves in cases where the step of installing the floor beams and rafters is the same.

Completion of work

Everything that remains after the assembly of the superstructure frame and the roof support system can be attributed to cosmetic work. Depending on whether the superstructure will have a thermal protection belt in common with the change house, the composition of the roofing cake should be chosen correctly. For an unheated superstructure, it is recommended to lay a hydro-barrier, tamping counter-battens, transverse battens and the simplest roof covering, for example, a profiled sheet in the color of the trailer’s skin. For a warm roof, you will need to lay a spacer between the rafters of the insulation and a vapor barrier on the inside.

It is easiest to cover the floor of the terrace with an ordinary edged board, you can use a special terrace. To create a fence, it is enough to nail 50×50 mm bars between the posts, but no one has the right to prohibit you from installing chiseled and milled handrails with balusters. The quality and high cost of materials is generally determined by the capital of the building and its purpose. The structure of the superstructure is a standard wooden frame, which means that almost all methods used in frame housing are suitable for insulation, glazing and decoration.