Screw Pile Foundations - Why Size Matters
I’ve never seen such a big screw. When it comes to anchoring a garden room to the ground, size matters!
We chose to go with screw piles rather than concrete because they are so much better for the environment.
What’s the matter with concrete?
Concrete is a significant contributor to carbon emissions worldwide. Making concrete requires heating to very high temperatures, using large amounts of energy, mostly powered by fossil fuels. Up to 40% of the carbon emissions from construction comes from production of concrete.
As if that’s not enough, in order to make concrete raw materials such as limestone, clay and other minerals have to be quarried. Every stage of a quarry’s life cycle is a cost to the environment. Loss of natural carbon sinks, loss of biodiversity, noise, air pollution and disruption of natural streams and springs. And none of this is reversible.
In addition, the manufacture of cement requires a huge amount of water. Not to mention that when using concrete for a foundation, the most fertile layer of the earth – the topsoil – has to be removed. And the hard surfaces created by concrete contribute to surface run off of water, soil erosion, water pollution and flooding.
Apart from that, it’s fine!
How do screw piles work?
Very large 4 ft screws – that look exactly like any other screw – is spiralled into the earth, either by hand or with a machine. The people putting them in must be strong and very fit. When ours were put in, the installer stood on top of each screw to help push it down. That may be just the earth in our garden is stony, but they must have to be ready for anything. (see below for how it worked)
Screws are placed along all the edges and in the middle of the desired space. Wood is then placed over them in a grid pattern and attached with screws and bolts. This forms base of the building.
Why did we choose screw piles?
We laid a concrete foundation for our recent kitchen extension before we knew screw piles were an option.
If you’ve ever been part of laying a foundation or watched it from a distance you know it requires a massive lorry with the concrete churning away, a shute and as many people and wheelbarrows as you can muster. Ours went in on an extremely hot day and it was pretty miserable for everyone involved.
Once the concrete is in place, it has to dry out before it can be walked on. Time of year will determine just how long that takes. Doing this work in the winter time can make the wait a real drag!
On the other hand, the screws are installed in one day and you’re away!