Lower Beam under Precast Slab on the Roof of a Self-built House

Adding beams under the precast slabs on the roof of a self-built house can be achieved through methods such as using supporting steel bars, adding columns, and installing steel wire ropes. During construction, attention should be paid to issues such as ground levelness, concrete strength, and steel bar usage.

Beam-adding Methods

• Using Supporting Steel Bars: Pre-bury some bent supporting steel bars under the precast slabs and fix them in the ground concrete. Then, pour concrete for the beams on top. The length and diameter of the supporting steel bars should be determined according to the size and weight of the precast slabs to ensure sufficient supporting force.
• Adding Columns: Based on the size, weight, and thickness of the precast slabs, reasonably add columns under them. Connect the columns firmly to the ground concrete and regularly check their stability to prevent loosening and ensure continuous and stable support for the precast slabs.
• Installing Steel Wire Ropes: Pre-bury steel wire ropes with hooks under the precast slabs and hang the hooks on the steel bars on the ground. When installing steel wire ropes, ensure that their length and quantity are sufficient to effectively enhance the support for the precast slabs.

Construction Precautions

• Ground Requirements: The precast slabs should be placed on a level and solid ground, which is the foundation for ensuring the stability of the entire structure. If the ground is uneven or not solid, it may cause uneven stress on the precast slabs, thereby affecting the effectiveness of beam addition and the safety of the house.
• Concrete Usage: Use high-strength concrete when adding beams and maintain uniformity during pouring. High-strength concrete can provide better load-bearing capacity, and uniform pouring can avoid defects such as cavities inside the beams, ensuring the quality of the beams.
• Steel Bar Usage: Use an appropriate number of steel bars to ensure the strength and firmness of the beams. Steel bars play a role in enhancing the tensile capacity of the beams. Insufficient quantity may cause cracks or even fractures in the beams under stress.

Relationship between Precast Slabs and Beams

Precast slabs and cast-in-place beams are separate independent components. The precast slabs are directly placed on brick walls and are not an integral part of the walls, so they cannot provide tensile force and have relatively poor stability. Therefore, by adding beams under the precast slabs and other methods, the overall stability and load-bearing capacity of the structure can be enhanced.