How To Build A Basement Under A House
When retrofitting a basement, one of the most common questions is how does the house stay up while the basement is built beneath it?
The use of a method called ‘underpinning’ extends the foundations downwards by redistributing the load weight onto piles, ensuring that your house stays put whilst it is hollowed out beneath and the construction team can work safely.
There are many methods that can be used, but be careful, one size does not fit all. An experienced basement company like Knowles will be able to calculate the most efficient, strong and financially suitable method for your project.
Mass Concrete Underpinning
This traditional method of mass concrete underpinning is over 100 years old. Mass concrete underpinning strengthens an existing building’s foundations by creating another set of foundations underneath; digging boxes and filling them with cement. This is a simple method that doesn’t require heavy machinery, making it perfect for small spaces.
Beam And Base Underpinning
Underneath the existing structure, a reinforced concrete beam supported by a concrete base is built; the load of the house is then redistributed onto these bases. This is a more technically advanced method but very similar to traditional mass concrete underpinning.
This type of underpinning uses piles with a much smaller diameter and is useful for conditions where access is restrictive and minimal structural movements are necessary, also for when ground conditions are variable and environmental pollution must be minimised.
Underpinning By Expanding Resin Injection
In order to fill any voids and crevices in weak soil, a mix of structural resins and hardener is injected into the foundation ground. This is a useful method as it doesn’t require any construction or excavation.
A survey by Knowles’ specialist team will help establish which the most suitable method for your project is. With over 20 years’ experience, Knowles is considered one of the leading authorities in London basement construction, designing and building hundreds of retrofit and new build basements every year.
Get in touch with us to learn more.