This installation was one of the more complicated installations, the configuration of a box frame, also referenced as a Picture frame configuration. The box frame involved four steel beams mechanically connected together to present a very strong load bearing frame resistant to both vertical and side loads.
Box frame installations are generally deployed when clients want to removal a wall, end-to-end, without the two piers sticking out of either side of the room. So imagine you open two rooms, and you want a flush wall between the two rooms on both sides, to make the room look as if it were one pre-constructed room, then you would install a box frame of steel beams.
The advantages of box frame steel beam installations, is that they can also bare the load of other secondary beams that splice off the frame to support secondary rooms, floor structures and openings.
For this project, structural calculations were prepared by a third party engineer arranged by the client. Based on these working items we procure the correct steel beams ready for installation.
The load bearing wall was constructed of single skin brickwork with internal timber rafters supporting the two floors above. Normally single skin masonry over one floor does not require large steel beam installations, however, this single skin wall was the spinal wall of the property and elevated three stories above the ground floor. A loft conversion was also structurally weighted onto this wall, so the loading was at maximum for this style of property.
Installation of acrow props is carried out to remove the load from the internal walls to facilitate installation of the box frame beams.
- 2No 203 x 203 x 42 colum beams
- 2No 203 x 203 x 52 span beams
- 1No 152 x 152 x 30 single span beam – supporting the first floor landing and bedroom
Once the box frame has been installed, the next phase is to brick up the space above the top span beam to place the load of the spinal wall onto the box frame. The final 50mm of wall section is dry packed with a dense mortar mix to reduce shrinkage for the connection of the box frame.