paper igloo architecture and design

Concrete slab pour

March 26, 2014

Today saw the pouring of the power floated reinforced concrete floor that is both our foundation and ground floor finished surface. This forms a 'raft' style foundation, which due to the amount of reinforcement within it, allows our internal load-bearing walls to be placed anywhere, as the load is then distributed across the slab and down into the ground below over a larger surface area than with conventional perimeter strip foundations. Using a more conventional system would have required additional strip foundations under each internal load bearing wall. As almost all of our internal walls are load-bearing, we chose to use the Isoquick insulated formwork system which requires a raft foundation, as this removes the need for additional 'internal' foundations that penetrate the insulation layer and create difficult junctions to thermally break.

The concrete was pumped into place, spread, levelled and then finally, after several hours waiting, power floated. As we don't want a shiny surface or exposed aggregate it was not highly polished. At the end of the evening a penetrating sealer hardener was spray applied, which reacts with the concrete and helps the curing process, as well as providing a water-proof sealing coat over the whole floor. The whole process took place on a single day & evening.

Now we just need to wait a few weeks for it to harden and strengthen, then we can begin the timber frame!

The concrete pump in place over the slab area

The start of the pour...


Filled and levelled up to the correct depth

The holding down straps around the perimeter

The power-floating machine waiting to begin

After the first pass with the power-floater

Spraying the sealer hardener into the evening