Where footing digs go wrong
Footings are unforgiving. Dig them too shallow and Building Control will have you back in the trench. Dig them ragged and you waste concrete filling an over dug, collapsing trench. Bring an underpowered machine to firm Sussex clay or flinty subsoil and you lose a day fighting ground the bucket cannot bite into.
The other problem is timing. Concrete is booked, the gang is on site, and the machine has not arrived or has broken down. A footing dig has to run to a schedule, because the trench, the inspection and the concrete all stack up behind it. That is why the machine you hire has to be the right size for the depth, strong enough for the ground, and delivered on the day you actually need it.
What size digger do you need?
The depth of the trench and the hardness of the ground decide the machine. Footings for domestic work are commonly dug to around a metre, but the exact depth is set by your Building Control officer and the ground conditions on your plot, guided by the structural standards in Approved Document A, so the machine has to have headroom in its reach.
The 5 tonne for house footings
Our 5 tonne mini digger is the machine most groundworkers reach for on footing work. It digs to a depth of just under four metres, so it clears typical strip and trench fill foundations with room to spare, and it has the breakout force to handle firm clay and stony ground. At just under two metres wide with a short tail radius, it stays manoeuvrable on a working site while giving you the bucket power a footing dig needs. The site itself describes this machine as ideal for site clearance, earth moving and house footings, which is exactly the work it is built for.
The 3 tonne for tighter plots
Where access is limited or the plot is small, our 3 tonne mini digger is the sensible choice. It reaches a dig depth of over three metres and stays just over 1.5 metres wide, and its boom can be offset so you can run a footing trench tight alongside an existing wall or boundary. That offset is exactly what you want when you are digging footings for an extension against the house, where a fixed boom would not let you get close enough.
