Drilling Specifications for Prefabricated Slab Roofs

Drilling on the roof of a prefabricated slab house must strictly adhere to the following specifications to ensure structural safety and installation quality:

1. Drilling Direction and Rebar Protection
Prefabricated slabs contain embedded prestressed rebars. Drilling holes randomly can easily compromise structural stability. Drilling perpendicular to the slab is strictly prohibited, as this can cut at least two rebars, reducing local load-bearing capacity. If drilling is necessary, drill parallel to the slab and ensure internal rebars are not cut. If rebars cannot be avoided, contact a professional to evaluate reinforcement solutions and avoid handling it yourself.

2. Drilling Operation Specifications

• Control Speed and Clear Dust: Start drilling at a low speed to prevent the drill bit from slipping. Clear dust from the hole promptly during drilling to avoid accumulation that can affect the tightness of subsequent anchor installations.
• No Water Drilling: Prefabricated slabs may contain embedded plumbing lines. Drilling with water can cause leaks and reduce the grip between the anchor and concrete due to a damp hole wall, leading to fixation failure.
• Avoid Critical Areas: Before drilling, confirm that the hole location does not contain hidden structures such as pipes or concealed beams. Use a metal detector for assistance in locating these.

3. Anchor Installation Specifications

• Size Matching: The outer diameter of the anchor should be slightly smaller than the drill hole diameter (typically 1-2 mm smaller), and its length should be slightly shorter than the hole depth (reserve 2-3 mm) to ensure full embedding and tight contact with the hole wall.
• Tap Gently into Place: Use a rubber mallet to tap the anchor gently. Do not strike it directly with a hammer to prevent concrete fragmentation around the hole wall, which can cause loosening.
• Check Fixation: After installation, gently shake the anchor to confirm it is secure. If loose, redrill and choose a new location; avoid forcing fixation.

4. Special Scenario Handling

• Heavy Item Installation: For heavy items like water heaters or large cabinets, reinforce the floor slab in advance. Methods include bonding carbon fiber sheets, adding steel beams, or increasing support points to enhance load-bearing capacity.
• Small Hole Installation for Lighting: Prefabricated slabs are hollow in the middle with a thickness of about 15-20 mm. Use an 8 mm impact drill to create holes and insert wooden plugs for fixation. Control drilling depth to 2-3 cm to avoid penetrating the floor slab and affecting the upper-layer waterproofing. If rebars are encountered, change the location; do not force drilling.

Precautions: Before drilling, obtain the house's structural drawings to confirm the direction of the prefabricated slabs and rebar positions. If uncertain, commission a professional agency for non-destructive testing. Wear safety goggles and a dust mask during operations to ensure safety.