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King post walls

King post walls

How to build and procure king post walls

If you are not familiar with king post construction and the processes required to construct your king post project, we can support you with the process.

The first thing to do is collect all the information the structural engineer needs to design the wall together, this includes the following:

• Wall lengths and heights
• Retained soil type
• Subsoil type
• Arrange for a site investigation if required if no subsoil information or a historical bore hole is not available.
• Arrange for a topographical survey if the site is complex.
• Define the use of land being retained to work out any surcharge loads
• Define any vertical loads being placed on the wall
• Water table information

On completion of the structural design

The process after the king post retaining wall has been designed is as follow:

• Organise the working drawings
• Schedule out the posts and panels
• Obtain prices for the posts and panels
• Write up an installation tender document
• Obtain ground worker and or piling contractor’s proposals
• Prepare a gantt timeline chart
• Make a plan to procure the materials and installation team.

King posts working drawings.

A working drawing is required to set out the posts in accordance with the design, layout and any site constraints.

The detailed setting out dimensions are then used to schedule the panels. Lengths of walls normally end with an odd-sized panel.

The drawing will detail the wall section and show where height variation occurs.

When several wall heights are required, the steel section of the post may vary. The detail of the posts needs to be communicated on a drawing to prevent errors on site.

The setting out of the wall is important to get right. The working drawing is normally drawn over the topographical drawing for accuracy of location and levels.

To stop the panels from sinking into the ground over time. The panels sit on top of the post embedment concrete. It is important to communicate the bottom of the panel level on the drawing.

The bottom of panel levels can be quite tricky on sloping sites.

Overlaying the setting out on the topographical survey drawing helps to get the levels correct.

King post procurement

A king post retaining wall consists of steel posts, concrete panels, an excavation machine with an auger attachment or a piling rig, ready-made concrete and labour.

There are several ways you can procure a king post retaining wall.

• Employ a main contractor.
• Employ a groundwork or piling contractor.
• DIY project management.

Employing a main contractor would be considered when the project is large and has a value over £250,000. The main contractor would be responsible for managing the works and employing a subcontractor to carry out the work.

Employing a groundwork/piling contractor directly. They would buy the steel and concrete panels and install the king post retaining wall.

Do-it-yourself project management involves buying the steel posts and concrete panels and employing a contractor to install the posts and panels for you.

The most economical method is DIY project management. You can buy the steel and panels using the schedules produced from the working drawings yourself. This saves the contractor from putting on a profit from this element of the work.

The risk with King post-construction projects

Any civil engineering project comes with risk. The risks include:

• Inclement weather causing delay
• Hitting underground obstructions, causing more work and delay
• Problems getting materials, labour and plant
• Accidents causing delay

When contractors price a project, these risks are taken into consideration, and the cost is added to cover them. If you project manage the works, you will be taking on these risks. 

Risk is something to be aware of.

If you are not competent in construction and project management, it is best to employ a contractor who will take the risk on board and manage it.

Alternatively we can support you with project management.

Learn more

• About king post retaining walls
• King post retaining wall design
• King post panels
• King post retaining wall costs and cost drivers
• King post case study with costs

 

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