How to Distinguish Prefabricated Floor Slabs in Houses

You can use the following methods to determine whether a house has prefabricated floor slabs:

First, check the construction year. Generally, houses built before 1998 mostly have prefabricated slab structures, and houses built 15 years ago also often use prefabricated slabs. This is because, under the early building technology conditions, prefabricated slabs were widely used due to their fast construction speed and relatively low cost. With the continuous development of building technology and the increasing requirements for building quality, cast-in-place slabs have gradually become the mainstream.

Second, observe the floor slab structure. Prefabricated slabs usually appear as regular blocks, and the gaps between the slabs are quite obvious. This is because prefabricated slabs are pre-made in factories and then transported to the construction site for splicing and installation. In contrast, cast-in-place slabs are formed by pouring concrete on-site, resulting in a flat and seamless overall appearance.

Third, tap the floor slab and listen to the sound. Gently tap the floor slab with a hard object. If the sound is crisp and has a long echo, it may be a prefabricated slab. This is because there are cavities inside the prefabricated slab, and the sound will produce an echo when propagating inside. On the other hand, since cast-in-place slabs are solid concrete structures, the sound propagation is relatively dull with a short echo.

In addition, check the house design drawings. If you have the design drawings of the house, you can directly check the type of floor slab structure. The design drawings will clearly indicate whether the floor slab is made of prefabricated slabs or cast-in-place slabs, which is the most direct and accurate way of determination.

You can also look at the pipe-laying areas. In a house, if there are columns or reserved holes, it is likely a prefabricated slab structure. This is because prefabricated slabs can have holes reserved during production to facilitate the subsequent laying of pipes. In contrast, cast-in-place slabs need to reserve pipe positions during concrete pouring, and generally, there will be no obvious columns or reserved holes.

Finally, examine the interior walls of the house. If there are no beams on the walls and no columns at the intersections of walls, it indicates a prefabricated slab structure. Prefabricated slabs rely on the walls for support during installation, so there are usually no beams above the walls and no columns at the intersections. In contrast, cast-in-place slabs are poured together with beams and columns, so there will be beams above the walls and columns at the intersections. Moreover, drilling holes in the floor slab is also a method of determination. During the production of prefabricated slabs, there are usually holes with a diameter of about 8 centimeters every 3 centimeters or so. Use an impact drill to make three holes in the floor slab at intervals of about 5 centimeters. If you hit a cavity while drilling, it means it is a prefabricated slab.