GreenDwellingSeattle

As we continue to follow the construction at 1105 Dwell we want to take a quick look back at what we have covered so far and then to move forward as the siding is applied and the homes really start to take shape.

In past posts we have covered the Foundations, the Structural Insulated Panels (SIP’s), and the Windows on this project.    Now it is time to move on to siding and roofing, after which the majority of the interior work will be completed.   All homes are basically a layering of materials built upon a solid foundation, and all of these systems work in conjunction with one another to provide a home that is beautiful, efficient, and durable.

At key intersections, say at window openings special consideration is needed to assure that moisture is properly dealt with and directed away from the home.  You will see from the image that the window openings are wrapped with a self-adhering flashing that seals the union of materials that come together at window openings.  When the windows are installed additional flashing and air sealing will not only keep moisture from entering at these window openings it will also provide an airtight seal around them.

Moving on to preparing for the siding to be applied, the entire exterior surface of the homes (with the exception of the roof systems which we will cover in a future post) will be covered in a waterproof sheeting known as tar paper.  This is a waterproof, yet breathable material that will allow moisture vapor to move from the interior spaces out and away from the home, but will not let moisture in from the outside.  At this point another layer of self adhering flashing is applied as duplicate insurance from the intrusion of moisture.  The exterior and openings are now ready for the final layer, siding.

Dwell Development has chosen to use a combination of siding techniques at 1105 Dwell.  The grey material in the first image is called fiber cement siding.  Fiber cement siding is made of cement, sand, cellulose fiber, and fly ash.  It is fire resistant, recyclable and a particularly durable and low maintenance material.  The other they have chosen to use is called a Rainscreen Wall.

Rainscreen Walls are a siding technique that employs four major components to produce an assembly that is effective and durable.  The four components are 1) A rigid support wall (SIP’s), 2) A drainage layer (tar paper), 3) An air gap (See battens in image), and 4) Exterior siding which in this case is cedar that as you can see has small gaps between boards.  The siding in a Rainscreen wall serves primarily to protect from direct impact of rain and objects.  It is the drainage layer that is the weather proof seal of the home.  The battens hold the siding material consistently away from the homes drainage layer so moisture that does come behind the siding has a quickly and effective way to get out.  This air gap will not only aid in the transfer of moisture from the interior spaces it will also help to cool the home in warmer months through natural convective heat transfer.

Next week we will be talking about the roof top decks that these homes will have.  Especially in urban settings rooftops are an ideal place to create outdoor living space.  In this case they also offer outstanding views and a place to grow food.

These homes will offer a behind the walls tour by the architect and builder on Saturday, December 19^th.  Visit the tours page for more information.