‘Value Engineering’ brings return in basement construction
Basement construction is no simple task, particularly when dealing with double or triple storey basement designs. Robin Knowles, Managing Director of London basement construction company Knowles, says 'value engineering' at the start of a project helps save space and maximises return on investment (ROI):
Architects are creating increasingly sophisticated basement designs which incorporate double, and even triple, storey basements. With such complex engineering processes at these depths under high value properties, value engineering by experienced basement construction firms is essential at the start of a project.
It is common for a structural engineer to over-engineer the structural design of a basement and loose significant potential usable space. Experienced value engineering will lead to more space, reduced construction costs and increased property values.
Knowles gives a recent example of a client who approached a less experienced construction company before finding Knowles. The first engineer planned to add an internal liner reinforced wall using underpinning, plus a reinforced wall.
Robin Knowles explains:
In a geographical location where space equates to £1,000 per square foot, this would have resulted in a £130,000 loss of space, unnecessary materials adding a further £50,000, plus an additional £30,000 saving on the ground floor RC slab to the final project cost.
Although a combination of underpinning and a reinforced wall may sometimes be necessary, it wasn’t in this instance,” says Robin Knowles. As a more experienced company working to a ‘value engineering’ philosophy, Knowles was able to reduce the cost for the customer at the very start of the project.
Alternatively, if the temporary works in supporting the building prior to or during the main works are not carried out correctly, the building may also be unsafe and increase the likelihood of damage to neighbouring structures.
In order to meet the highest standards of safety in basement design and construction, underpinning must be carried out perfectly, particularly with double or triple storey basements where there may be a pool or even an elevator for vehicles.
A key consideration in the design and construction process is the lifespan and preventing future problems such as damp.
Choosing the correct waterproofing method according to the site characteristics and design requirements will prevent groundwater from seeping into the basement over many years and causing damp, as well as preventing structural damage from excessive hydrostatic pressure.
There are two main methods of waterproofing. 'Tanking' uses cement based renders and slurries and 'cavity drain membranes' are sheets of Polyethylene that cover the structure like a studded sheet, keeping moisture out and letting it flow into underground sumps and drain away from the building.
It is also possible to over-engineer, which can be problematic explained Robin.
This is why it’s critical to hire a knowledgeable and experienced engineer with specific knowledge of basement construction, to get the best price and outcome.
That is what ‘value engineering’ really means.