Roof Addition for Old Prefabricated Panel Houses

Roof addition for old prefabricated panel houses requires selecting an appropriate method based on the house structure, budget, and needs, while strictly adhering to construction specifications and safety requirements. The specific methods are as follows:

I. Roof Addition Methods and Construction Points

1. Concrete Cast-in-Place Roof

   • Construction Process: Clear debris from the roof, use a high-pressure water gun to wash away dust from gaps, inspect and fill loose areas in the joints of the prefabricated panels, and apply an interface agent to enhance adhesion; arrange 6-8mm diameter threaded steel bars with a spacing of 15-20cm in both directions, elevate them by 2-3cm with concrete spacers to ensure the thickness of the protective layer, and implant short steel bars around the perimeter to connect with the original structure; continuously pour C25 grade concrete from one end, insert a vibrator between the joints to eliminate air bubbles, cover with plastic film for curing for 7 days after pouring, choose to construct in the morning and evening in summer, and add antifreeze in winter; conduct a 24-hour closed water test after completion to check the waterproofing effect.
   • Applicable Scenarios: Houses requiring long-term stability and with an allowable budget, but with a relatively long construction period.

2. Prefabricated Panel Roofing

   • Construction Points: Use factory-produced cement prefabricated panels or lightweight sandwich panels for on-site installation, ensuring good sealing of the joints and focusing on waterproofing to prevent leakage.
   • Precautions: It has specific requirements for the overall design and structure of the house, with relatively high costs, suitable for scenarios pursuing construction speed and with sufficient budget.

3. Other Roofing Methods

   • Tile Roof: Suitable for pitched roof designs with good drainage performance, but ensuring the tiles are staggered and laid without leakage requires high construction skills.
   • Metal Roof: Using color-coated steel tiles or aluminum-magnesium-manganese alloy panels, it is lightweight, easy to construct, and highly corrosion-resistant, but may generate noise in extreme weather conditions.
   • Light Steel Structure Roof: With light steel members as the framework and covered with panel materials, it has high strength and good seismic performance, but requires waterproofing and thermal insulation treatment.
   • Green Roof: Planting vegetation on the roof provides thermal insulation, but requires consideration of the house structure's load-bearing capacity, waterproofing, and irrigation system design, suitable for scenarios with high environmental protection needs.

II. Key Precautions

1. Structural Safety Assessment
   Old prefabricated panel houses may have issues such as through-cracks and hollowing on the roof surface. Before adding a roof, it is necessary to assess the load-bearing capacity of the original structure to avoid collapse due to excessive loads. For example, if the gaps between the prefabricated panels are too large (up to 4 cm) or there are height differences, repairs should be made before construction.

2. Waterproofing Treatment
   Regardless of the method used, waterproofing at the joints is crucial. A waterproof layer should be applied on the surface of a concrete cast-in-place roof; the joints of a prefabricated panel roof should be sealed; for a tile roof, ensuring the tiles are staggered and laid without leakage is essential; and for a metal roof, waterproofing at the joints and edges should be handled.

3. Professional Construction Advice
   Roof addition projects involve structural safety. It is recommended to consult professional architects or engineers to select a plan based on the actual situation of the house, climatic conditions, and budget. For example, although a concrete cast-in-place roof is reliable, it has a long construction period; while a prefabricated panel roof has a fast construction speed but high costs.

4. Budget for Old House Renovation
   If the original roof has hidden dangers such as hollowing and cracks, a budget should be reserved for base treatment (such as removing the hollowing layer and filling gaps) before implementing the roof addition project to avoid potential safety hazards later.