If you’ve ever experienced the installation of concrete foundations in the past (which we’re sure you have if you’re reading this) then you will have seen or heard about caging – or “metalwork” – along with the term plinths – or “lintels” – used on site. We can’t speak for everything in the UK or the world, but here in Manchester we will often drive piles for structural rigidity at a site’s footing, and then commence the building of cages.
But what are they for? Another fair question is “do you need them?” and the answer is entirely dependant on the piling or concrete job. When we send a technician out to inspect a site, draw up plans and quote a price for our customers in Manchester, they will quickly be able to determine whether or not the customer needs piling, caging, etc. This can be determined by how hard or soft the ground is where you’re building, how deep the footing has been dug, and what’s being built atop the foundations.
So, let’s say you’re having piling or concrete done on your project and the technician determines you need caging and plinths: here’s what comes next.
Your piling team (once all piles are driven and the next stage can commence) will arrive at the site with plenty of rebar poles, take measurements of the footing/look at the drawings, and then begin fabricating the cages at the site. Once they’re complete, the team will then start “tying in” the cages using metal wire and plastic stilts to stand the cages on when in the footing. Once completed, the cages should be sturdy enough to support the weight of someone walking along them, and as long as they don’t sink in the footing, your caging is complete and it’s time for concrete.
What about plinths? Well, on occasion a building will be designed to include large steel beams integrated into the foundations for added strength, leading from the poured concrete and making a sort-of gateway shape. Plinths allow the beams to be secured higher than the shuttering of the foundations, elevating the point of contact for the beams from being part of the concrete slab poured later on. They are caged and tied-in just like the traditional metalwork, but they protrude above the shuttering and usually resemble a cube-like shape. Later on, once the base concrete is poured and has begun to harden, the plinths that are left coming out the top of the concrete are shuttered and then poured in addition, thus creating a strong, stable platform to construct a structural beam.