How to Build the Roof of a Prefabricated Slab Building

The method of constructing the roof of a prefabricated slab building should be selected based on specific needs and structural characteristics. Common methods include flat roof with skylights, pitched roof paving, and anti-seepage treatment, as detailed below:

1. Flat Roof with Skylight Structure

If additional lighting or ventilation is required on a flat roof, a circular skylight tray design can be adopted. First, install a circular skylight tray in the middle of the roof. The tray is typically made of metal or preservative-treated wood, ensuring a secure connection to the main structure. The tray is fixed to the roof frame with beams around its perimeter, with the beam spacing calculated based on the span, generally not exceeding 1.5 meters to distribute the load. When covering the top with thick wooden planks, choose preservative-treated boards with a thickness of no less than 3 centimeters, and connect them to the tray with bolts or rivets. This method is suitable for low-rise residences or spaces requiring extra lighting, but attention should be paid to waterproofing around the skylight, which can be achieved by applying waterproof glue or laying waterproof membranes at the plank joints.

2. Pitched Roof Paving with Prefabricated Slabs

For pitched roofs requiring drainage, prefabricated slabs can be directly used for paving. First, determine the roof pitch, generally recommended to be no less than 15° to ensure natural drainage of rainwater. The prefabricated slabs are arranged one by one along the slope, with a 2-3 centimeter gap left between them for filling with waterproof mortar or sealant. To prevent the slabs from sliding, horizontal members such as concrete barriers or metal angle irons should be installed at the top and bottom of the slope, with a height 5-10 centimeters higher than the thickness of the slabs. This method offers high construction efficiency but requires strict control over pitch accuracy to avoid water accumulation and leakage.

3. Anti-Seepage Reinforcement Treatment

Regardless of the roof type, enhancing anti-seepage properties is crucial. It is recommended to lay a layer of steel mesh on the roof base, with a steel diameter of 6-8 millimeters and a spacing of 15-20 centimeters, to strengthen the bond between the concrete layer and the base. Then, pour a 6-8 centimeter thick layer of crushed stone concrete with a strength grade of at least C20. During pouring, use a vibrator to compact the concrete and avoid voids. The concrete surface should undergo secondary polishing to reduce capillary pores, and finally, apply waterproof coating or lay waterproof membranes to form multiple waterproof barriers. This method can significantly extend the roof's service life, especially suitable for rainy regions or buildings with high waterproofing requirements.