Sunday, August 12, 2012

Up she goes!

     Out of the ground and underway.  Brent and his crew started framing last week.  The Smart framing techniques have prove a little challenging, keeping studs joists and rafters aligned.  Also correct header sizing, everybody wants to keep adding a safety factor instead of trusting the numbers.  We're working throught that and the other thing that we have to keep checking is the Energy Star Thermal Bypass checklist for anything going on the exterior walls.  For instance Jeff made a good catch earlier this week noting that "Don't we need to have an air barrier going around the stairs?" This just before they started framing in the stairs!  The learning curve has been a little steep for everyone.  People are a little jumpy around the site hoping they haven't missed something that would cost a point or worse a pre-requisite.

     I've attached a few pictures to show some of the framing.  Another item to note is the use of Structural Insualted Sheathing (SIS) instead of OSB.  The 1/2" SIS gives us an additional R-3 after the foam has stabilized.  Over this we will be placing another 2" of Poly-iso foam rated at R-12, then housewrap, then 3/4" furring strips to mount the siding on.  The use of two layers of foam insulation  and offsetting the seams during installation, significantly decreases the amount of air infiltration.  Also in typical construction with OSB as the sheathing and fiberglass ("filterglass") insulation in the wall cavity, creates a situation where the back side of the OSB is warmer than the exterior face thus creating a surface for condensation to collect.  OSB + Condensation = a bad situation over time if the OSB does not have adequate time and air flow to dry out.
    



     Right now, I'm pretty well exhausted.  Building this house is fun even if it is a little draining mentally.  But not only are we building the house, I'm trying to get the pavilion started, we're looking at rescuing a couple of old barns to re-locate to the farm and I have a stone chicken coop to build before winter.   Yeesh!  I'll keep more coming. 

Wednesday, July 11, 2012

Ok so it have been awhile and a lot has happened since the last post.

First thing is we changed General Contractors.  Tom is still doing the site work at the farm but Tom Doyle of Doyle Home is now the GC.  Jeff is a custom home builder with 20+ years of experience.  Again no "Green" experience but he has really taken on the challenge and things are moving forward at a fast pace.

Secondly, if you remember we were shooting for an initial HERS (Home Energy Rating System) score of about 40 points.  Keep in mind the average resale home in the United States scores about 130.  A score of 100 is considered the average for new construction built to code.  So an existing home, as an example, is roughly 30% more inefficient than a new home.  So a score of 40 would theoretically make our house 60% more efficient than a new home.  The score is derived from an energy model created by the HERS rater.  The model takes into account all of the wall components, roof components, window U-factors, energy used by appliances etc.  We were then able to utilize the energy model to try out different insulation and material combinations to achieve the best energy efficiency and most bang for the buck.

Having said all of that, our preliminary HERS rating is a 41!  Kudos to the design team and thanks to Scott and Alex for working with us to get the information to us in a timely fashion so we could make our decisions!

Thirdly, we started digging today!  we've got a big hole in the ground but the foundation looks more like a foundaiton for an outhouse with a basement!  Somehow we'll fit.  It's certainly larger than the fifth wheel we're currently in!

As  a side note check  out the pictures from Horse Progress Days.   This was in Clare, MI a couple of weeks.  Two days devoted to Horse Power and the economic viability of horses for use on small farms.  It was a ton of fun, unfortunately my pictures of the 12 horse team didn't take!

Anyway, more to come, we're getting to the good stuff!


House features

Back again!  So here are some of the features of the house.

   The house is small, 32' x 24' footprint that equates to 1536 sf of conditioned space.  We kept the footprint small for several reasons.  First a larger house means we have to buy more stuff to fill it up thus reducing the Funstuff Funds.  We'd rather go play than buy another sofa.  Secondly, if we keep it small we can add other features to the house, LEED certification for instance.  Lastly, LEED rewards smaller homes.  Not suprisingly larger homes consume more resources, not just building materials but also heating and cooling.  They award smaller designs through the Home Size Adjuster (HSA).

   Based on informal studies and published data, within the context of LEED, a 100% increase in home size equates to an increase in annual energy usage of 15% - 50%, depending on the region.  Also the same increase equates to an increase in materials usage of 40% - 90% depending on the design.  So smaller homes can earn extra points towards certification based on the number of bedrooms and square footage.  So the SCF house will 5 points based on the square footage and bedrroms.

   We've tried to keep as many penetrations out of the exterior walls as possible.  You'll notice that the only fixture mounted on an exterior wall is the sink in the Master bath.  Believe me we tried every possible combination to get it off the wall.  The reason we kept out of the exterior walls is that every penetration is a potential air leak.  Air moving inside the thermal barrier sets up all kinds of potential problems with moisture in the walls as well as reducing the efficiency of the walls.

   "Smart Framing" will also be utilized in the construction.  Smart framing incorporates techniques such as aligning roof trusses and wall studs so that the trusses bear directly on the studs.  This eliminates the need for a second top plate on the wall.  Also no headers in non-load bearing walls, sizing headers to the exact size needed, studs and rafters spaced greater than 16" on center and no trimmer studs at window and door openings.  All of this amounts to significant reductions in the amount of wood needed top build the house.  Also less wood in the walls means more room for insulation.





 Well lunch is over, back to the grind.  More to follow.