Guide · 7 min read
Groundworks for Modular and Offsite Homes
Modular and offsite homes need a foundation built to tight tolerances, with services brought to exact positions and crane and delivery access planned before the units arrive.
The short answer
With modular and offsite construction the building is manufactured to fine tolerances, so the base it lands on has to match. A foundation that is a few millimetres out of level or position creates problems that cannot be corrected once units are set.
The civils scope is therefore front-loaded: platform, foundation, drainage and service positions all have to be right, and complete, before delivery day.
What changes compared with a traditional build
The work itself is familiar; the discipline around it is stricter.
- —Levels and setting-out tolerances set by the manufacturer, not general practice
- —Service entry points positioned exactly where the module design expects them
- —Drainage connections completed and proven before units land
- —Crane standing, outrigger loading and delivery routes designed into the site setup
- —Hard standing and access strong enough for low-loader deliveries
- —Sign-off on the base before manufacture is released for delivery
Foundation options
Modular and light gauge steel systems commonly sit on a reinforced raft, a strip and rising wall arrangement, or pad and ground beam foundations, depending on the manufacturer's design and the ground conditions.
The engineer's design governs. Our role is to build it to the stated tolerances, record the achieved levels and confirm the base is ready for delivery.
Programme and delivery day
Delivery slots for manufactured units are fixed well in advance and hard to move, so the civils programme has to protect that date. Weather contingency, drying time for concrete and utility lead-in times all need building into the plan.
A pre-delivery walkover against the manufacturer's checklist — levels, dimensions, service positions, crane access, ground bearing — is the last step before units arrive.
Frequently Asked Questions
How accurate does a modular foundation need to be?+
To the tolerances the manufacturer states, which are typically tighter than traditional construction. Achieved levels and dimensions are recorded and checked before delivery.
Do you prepare crane access as part of the works?+
Yes — hard standing, access routes and crane standing areas can be built into the civils package so delivery day is not held up by ground conditions.
Are services installed before the units arrive?+
Drainage and ducting are normally brought to the exact positions shown on the module design and proven before delivery, so final connections are straightforward.