Conversion of Walls to Beams in Prefabricated Panel Structure Houses

Converting walls to beams in prefabricated panel structure houses is feasible and is relatively common in the renovation of old rural houses. The purpose is to expand space by using beams instead of load-bearing walls to eliminate wall obstructions. The specific construction methods are as follows:

Hole Drilling and Grouting

• Preliminary Preparation: First, tie the steel bars at the bottom, provide reinforcement support, and install formwork. Since holes cannot be drilled in prefabricated panels, if the panels need to be handled, they can be directly lifted away or knocked down. Locate the positions for drilling holes on the floor slab, similar to the formwork installation method for new house carpentry. At the same time, provide support for the entire floor slab underneath in advance to prevent issues with the floor slab after the wall is removed due to its inability to bear the weight.
• Grouting Operation: Pour the mixed concrete directly into the drilled holes. If the beam is long, multiple holes need to be drilled to avoid voids and exposed steel bars in the poured beam.

Side Formwork Grouting

• Formwork Installation Points: When installing formwork, install one piece vertically and the other piece at an angle. The angled surface is for convenient grouting. Nowadays, there is a small concrete conveying machine. Simply drill a few holes at the edge of the formwork and pour the concrete into the installed formwork through a conveying pipe.
• Steel Bar Processing: Whether for beams or columns, steel bars and stirrups should be prepared in advance. When making beams, prepare beam steel bars according to the length of the beam, i.e., make beam steel bars at a ratio of dividing by 10. Use 25 deformed steel bars for the bottom steel bars, along with secondary steel bars and waist steel bars. For the stirrups of house beams, there are 4 - 5 per meter for newly built houses and 5 - 7 per meter for wall-to-beam conversions. When binding the waist steel bars, they should not be bound in the middle of the house beam stirrups but at a position 15 to 20 centimeters from the bottom steel bars.

Maintenance Requirements

The poured beams require careful maintenance. The side formwork can be removed after 24 hours, but the bottom formwork and supports should remain for at least half a month in summer and at least 20 days in winter before removal, and they should be watered daily for maintenance. In addition, there are also cases of reinforcing prefabricated panel houses by adding large beams, such as using two 20-unit steel bars to make a 500 large beam. There is also a case in Hubei where the load-bearing walls of a two-story prefabricated panel house were converted to beams to transform it into a workshop. After the conversion, the bottom wall below could be removed after 15 to 20 days, and the entire first-floor space was fully opened up.