flashing

Like any house, tin box has a number of holes in the roof to allow plumbing and mechanical vents to draw noxious, humid or lint-filled air out of the building. Each of these penetrations provides an opportunity for rainwater and critters to come inside, and so we need to use flashing to provide water-tight seals around the vents. All but one of the vents (the plumbing vent shown here) are protected by the overhang of the upper roof, which provides a comforting redundancy. The vent pipes are flashed with Dektite pipe boots, which adjust to fit a wide range of pipes, and which have a flexible base to accommodate different roof types. The pipe boots are held in place by mechanical fasteners and made watertight with a bead of sealant.

ductwork

Our mechanical contractor began installing ductwork this week. The segment in the living and dining rooms (pictured here) is the most prominent piece in the house, and it was the first to go up. It will remain exposed, along with the structure and the electrical conduit.

The ductwork has a layer of insulation between two walls of metal to keep the air as cool or hot as possible between the air handler and the register. This kind of ductwork is more expensive, but the insulation makes the system more energy efficient and prevents condensation building up on the ductwork, and the metal lining inside helps keep the air free of dust and mold.

The ductwork also responds beautifully to the changing light conditions inside the house:

best practices

A very helpful document from the Department of Energy (who also sponsor the Solar Decathlon competition) which we've been consulting is Building America Best Practices Series: Volume 1. Builders and Buyers Handbook for Improving New Home Efficiency, Comfort, and Durability in the Hot and Humid Climate. It is available online as a free PDF file.

utilities

Two subcontractors were at the site today. Our HVAC (heating, ventilation and air conditioning) contractor had a crew at the site digging trenches for the refrigerant lines that run from the air handlers inside the house to the condensers outside (image at left and following). The electrical contractor had his guys digging trenches to run conduit under the slab to each of the rooms in the house, at which point the electrical wire will branch out through the walls. The last picture shows the conduit passing through the space where the concrete contractor will pour the edge beam.