The Hansen House Part 3: Concrete Slab/Radiant Heat

The month of July has been very busy at the Hansen House.  Once the insulated foundation was complete the plumbing pipes, as well as mechanical conduit piping, were laid out, run and installed. Plumbing pipes have to be run at a slight downhill slope so that the waste in the pipes can drain properly. Weld-On P-68 primer was used to help join the pipe and fittings.  This low VOC product is compliant with LEED Green Building Rating System and can be credited towards indoor environment quality. The same GreenGuard rigid insulation that was used with the foundation walls was installed before the slab was poured.  These products contain up to 30% post-industrial recycled content and help reduce energy consumption and improve durability. On top of the 4 inches of insulation the rebar was laid out in a checkerboard pattern used to reinforce the concrete and prevent cracking.  The PEX tubing for the radiant floors is also attached to the rebar structure. PEX tubing is a tough, flexible plastic that is easy to layout in loops and bent around corners.  The PEX tubing is where the warm water is circulated to heat the radiant floors. Select floors throughout the Hansen House will have radiant heat.  The PEX tubing for the radiant heat will run to the manifold in the mechanical room.  Here it will be heated with an electric water heater and pumped back through the piping.  The electric water heater will be run on energy generated from future solar panels. The concrete is then poured over the PEX tubing and rebar. Using products made from recycled materials is a standard operating procedure for HJLCMS.  The concrete for the Hansen House was made with 20% fly ash and is sourced locally.  This recycled material content is closely tracked should the need for LEED certification be considered. Fly ash makes the concrete more durable, water-resistant and stronger.  Fly ash shrinks the environmental footprint of concrete because it reduces the amount of water and Portland cement in the mix. Once the concrete had set, the power trowel was run over the surface to smooth out any imperfections and get a tight, glossy finish.  The more passes with the power trowel will give you a more glossy finish. The broom finish on the concrete floors for the wrap around porches gives a unique and distinguishing feel to these outside areas. A material called River Jack was added to the concrete as the aggregate giving the East porch a textured surface. Check back for the next post as the crew begins to frame out the garage.

Open Building Methods

A note from HJLCMS’s president and founder, Hugh J. Lofting, on open building methods… We, at HJLCMS, practice “open building” methods of construction.  This concept considers a housing project is never completed; it is always under construction.  In order to achieve these goals we think of ways to make access to electrical, plumbing and HVAC easy and adaptable in the building.  One of the obvious ways to achieve this is to use “open web” floor joists.  As long as there are access ports to the floor joists, it is easy to add mechanical and electrical needs in the future.  Another principle of open building that comes into play is spanning the entire width of the buildings in order to reduce the need of bearing walls.  This is also achieved with the open web floor joists.