Screw pile foundation cost: what drives the price

A foundation quote cannot be compared from one project to another without understanding what it is made of. Here are the items that really drive the cost of screw piles.

Number and sizing of screw pile support points

This depends on the structure to be supported and how its loads are distributed. Two extensions with the same footprint may need different support layouts depending on the joist spans and the type of structure.

Soil type

This determines the anchorage depth required and therefore the length of the ground screws installed. It is the most variable item, and the one that a preliminary survey makes more reliable.

Why a technical site visit changes the quote

Without a visit, a quote is based on assumptions. With a visit, it is based on observations. The difference between the two is paid for in variations to the contract.

Site access

The installation machine must be able to reach every support point. Restricted access, a slope or a narrow passage affects the equipment used and the time on site.

Frequently overlooked items

• the soil survey, where required;
• locating underground utilities;
• pile caps and connection parts to the structure;
• the installation report and monitoring records.

Compare like with like

Ask for every quote to itemise these costs. A lump-sum price with no breakdown makes any serious comparison between two offers impossible.