During the construction of a house of bricks or blocks, reinforced concrete basement and interhesive floors are preferred. We tell about the types of structures and how to build overlap without errors.
Reinforced concrete floors are better tooling the sound and are almost not susceptible to vibrations compared to wooden beams. They are very durable, withstand the load from the masonry partitions, stairs, massive furniture, which facilitates the solution of planning tasks. There are shortcomings, first of all related to the need to attract powerful equipment and a significant number of workers, rent special devices and equipment. Reinforced concrete floors usually require additional alignment, sometimes insulation and almost always cost more designs based on wooden beams.
In order not to overpay and do not save to the detriment of quality, first of all, the pros and cons of various technologies for the construction of such overlaps should be found out.
Prefabricated slab overlapping
In low-rise housing construction, finished slabs of overlappings are used mainly three types: PC (with round voids), PB (multi-profile impellent molding) and SFO (flooring plates lightweight). PC plates and PB are released with a thickness of 220 mm, while the second are characterized by a more accurate geometry and the best surface quality (they are subjected to rough grinding). The plates pHo, a thickness of 160 mm, are considered optimal for private construction, as the walls and the foundation are loaded less, they simplify the insulation of the edge of the overlapping zone and at the same time, by strength (carrier ability), only slightly inferior to PC types and PB plates. Plants offer products of dozens of sizes, although the most common slabs 100, 120, 150 cm wide, the length of which varies from 2.4 to 9 m with a 10 cm increments (but this does not mean that the amount of 9 m can be blocked without additional supports).
The width of the reference platform for plates in the walls of the brick should be at least 100 mm. When mounting, the slabs are placed on a layer of solution. If there are no factory caps on voids, the holes should be sealing along the heads of the plates.
In the houses of light blocks (foam concrete, polystyrene bonts, arbolite, porous ceramic) for the perception of the load from the collector plate flooding the monolithic w / b belt 200 mm width and a height of 100-150 mm.
For the device, the movement in the monolithic or collection-monolithic overlap is installed by the edge formwork and enhance the reinforcement frame
The main advantages of overlapping from finished plates - high installation speed, the possibility of production of work in winter (at a temperature not lower than -10 ° C) and precisely known strength characteristics of the plates, the production processes of which are strictly regulated and carefully monitored.
On the other hand, the fixed size of the slabs somewhat complicates the task of the designer, and their rectangular shape is forced to abandon some non-standard architectural solutions (radius walls, polygonal erkers, etc.). Difficult drives: you have to resort to expensive diamond cutting, mount unloading rigels. Finally, you will need to rent a crane and enlist the help of experienced installers to prevent errors when positioning the plates. Plates pnto with delivery will cost approximately 1700 rubles. For 1 m2, and the cost of their installation - from 3500 rubles. Behind the stove.
Most factory plates have edge grooves that make it easier to seal joint
Monolithic slab overlap
This design is easily adapted to the form of the building and can be built without the use of the crane. By tightness, it exceeds the team, so the air noise isolate better and prevents the leaks (which in the country house also happen and threaten no less sad consequences than in the city apartment).
When designing a monolithic slab, it is guided by the standards - SP 52-101-2003, SP 52-117-2008 and SP 63.13330.2012. At the first stage, it will be necessary to build a formwork from plywood, female or other shields with a support on beams and racks. The unavailable formwork from the professional flooring will speed up construction, but in the future it will make it difficult to finish the ceilings.
After assembling the formwork on the entire overlap area, the two-level framework from reinforcement with a diameter of at least 10 mm with a calculated reinforcement coefficient is welding.
Precast plates from light reinforced concrete are extremely rare. The main drawback is low moisture-resistance
The process of pouring concrete must be carried out as a short time, bossing the factory mixture with the delivery of the car. Independent preparation of concrete is unacceptable, because at the same time not to avoid numerous "cold" seams, which will be much reduced the strength of the slab. It is extremely undesirable to build a monolithic overlap during the cold season, because it is due to increasing costs and is fraught with a decrease in the reliability of the structure. For today, the price of a device of 1 m2 of monolithic w / w overlapping with a thickness of 200 mm (work and materials excluding finishing alignment) is about 5 thousand rubles.
Main stages of mounting monolithic overlap
On top of the formwork shields spread the rolled waterproofing and mounted the reinforcement frame, knitting the rod with wire. Filled sales concrete. The formwork was removed in 20 days when concrete scored 80% of strength.
Collected monolithic overlapping
This long-known technology in the new version suitable for low-rise construction is offered today from Marko, Teriva and Ytong. Its essence is that first the spills overlap the skeletal beams of the factory manufacture. Between the beams (with a support for their side shelves) lay the solid flooring from the lung blocks. This design serves as a non-coated formwork, on top of which mounted a mesh from the reinforcement. Then poured a concrete mixture with a fine-deficing filler; The thickness of the layer above the blocks should be 50-70 mm. It is advisable to use a commodity concrete, however, it is allowed to prepare a mixture on their own, the main thing is to prevent "cold" seams when concreting beams.Collected-monolithic technology makes it possible to do without powerful lifting equipment (for lifting beams, the mass of which does not exceed 120 kg, you can use manual winches) and the shield formwork, and in addition - to save time and money on an aligning screed device. The cost of beams and blocks is about 1,400 rubles. For 1 m2, and the finished overlap will cost approximately 4500 rubles. per 1 m2).
The main stages of the assembly and monolithic overlap
First of all, it is raised to the walls and installed in the project position reinforcement frames of beams. Next, they laid blocks of light concrete, and on top of them - the reinforcement grid. The beams must be pushed with racks, otherwise they can be deformed. Poured a concrete mix.
Installation of monolithic overlap will facilitate the formwork with adjustable racks. True, the cost of its rent is quite high - from 1600 rubles. for 50 sq. M per day
How to strengthen holes and loops
Pieces for stairs, hatches, sewer and ventilation pipes, chimneys must be provided when designing and performing overlap during installation. According to building standards, the holes of significant sizes (with sides or a diameter of 300 mm or more) in monolithic plates should be founded by additional reinforcement with a total cross section of at least the cross section of the working fittings, which is required by calculating the plate as solid.
With the plate slaughterhouse, it is desirable to use special plates with holes (alas, they are poorly adapted for low-rise buildings) or provide support columns and / or unloading beams. Without such a strengthening and verification, the calculation is allowed to perform only holes within the distance from one ribbon rib to another (in hollow slabs you can not cut solid parts).
How to make butts without cracks
The famous sickness of panel high-rise buildings - cracks on the ceiling at the joints of the plates of the collection overlap, occur both when the building shrinkage and in the process of its operation. This trouble is not always possible to avoid privileged. But you can try. The key to success will serve high-quality plates with a bearing capacity, careful leveling of the reference site and a uniform distribution of the load on the overlap: you can not build heavy brick partitions on the second floor and install fireplaces with facing.
As for sealing joints of the plates, it is important to use high-quality materials and not to leave emptiness that negatively affect the insulation of air noise. Usually, a tubular seal is installed at the bottom of the seam (in principle, a polyurethane foam can be used), and then the cavity of the grade cement-sandy solution is not lower than M250, ideally cooked on the basis of a strained waterproofing cement.
More than 25 mm width gaps are performed using monolithic casting technology using a removable or intimidated formwork and mandatory reinforcement.