Superb Blower Door Test

 

It was a quiet week at the Sumac Grove.  For the most part we watched the insulation dry.  We brought in two large commercial dehumidifying units which have been operating for nearly a week now.  The relative humidity (RH) has gone down from 74% to about 34%, but the insulation is still quite damp.  We will run the equipment through the weekend and see how it is doing.  We have been using a hygrometer with a long probe which measures the RH deep in the insulation.  We are still getting readings in the 70 to 80% range in some areas.  We won't begin drywall until we are satisfied that the moisture levels are low enough.  

Michael Holcomb of the Alliance for Environmental Sustainability came out to perform and inspection of the site before we install the drywall.  This inspection is a prerequisite in LEED for Homes.  While he was there we ran the blower door test to measure the air volume that can be attributed to air leaks in the building envelope.  

The blower door is a canvas frame with an exhaust fan built into it that is fit firmly into a door opening.  All openings in the home are closed as they would be in normal operations.  The exhaust fan is hooked up to a computer.  There is a small flexible hose that goes through the canvas frame that samples the air pressure outside the building, and another one inside to measure the air pressure on the inside of the building.  The fan is turned on to create a negative pressure in the building.  The pressure differential between the two measurements is measured by the computer and calculated against what it knows the volume of air generated by the fan speed to be.  This is an image of a typical blower door testing apparatus.


The new air infiltration guidelines for energy efficient homes that Energy Star has just published established a benchmark of 3 Air Changes per Hour (3 ACH).  Passive House requires a maximum leakage rate of 0.6 ACH.  Michael measured 0.26ACH, less than half of the Passive House requirements.  He has never seen a measurement so low, and we were thrilled to know that all of the design elements we incorporated and the work we invested to obtain the airtight design were vindicated.  



Last week the drywallers installed the drywall in the basement, the garage, and the ceiling of the house.  Judy and I spent the weekend blowing in cellulose insulation over the garage ceiling.  Though we probably will not use it very often, the garage is insulated well enough that a small 1,500 watt electric heater will make it possible to work on projects in the winter.  The garage was designed to include a workshop at one end, and space can be expanded by removing the cars.  The Clopay overhead garage door is insulated with 2" of foam with insulated glass for daylighting and is scheduled to be installed tomorrow.  

As we waited for the insulation to dry we finished up a few details.  The last of the blocking for the barrier free design requirements has been installed.  We put reinforcing members in to accommodate the future installation of grab bars.  We have almost finished up with the exterior insulation and lath.  They were just finishing up this gable this morning, and should finish the east gable next week. 

The turning point

In spite of the short work week we got a lot done.  The heat was turned on with only a few troubleshooting issues with the controls and only a few minor leaks in some of the piping connections.  We have had three sunny days in a row, and the added solar gains have warmed up the home very quickly.

The "wet blown" insulation was installed in the walls on tuesday, and the attic insulation was installed on Wednesday.  Wet blown insulation has a moisture content and a mild adhesive in with a recycled cellulose material.  Chemicals are added to inhibit mold and insect infestation.  With the 10" wall thickness, the weight of the insulation causes it to sag, so they added horizontal baffles to reduce the settling.  There is still a little bit of settling at the top in some areas which will be repaired in the next few days.  

 

To extract the water from the insulation and accelerate the schedule, we rented two industrial dehumidifiers to work over the weekend.  We have set a goal to get the moisture content down to the same residual levels as the wood studs which will be determined with a moisture probe.  We have turned the heat up to about 80 degrees to bake out the moisture from the insulation for a day or two, and then will turn the temperature down.

 

 The attic insulation is blown in dry.  It is slightly over two feet thick providing an "R" value of 90.  We will install a little bit more over the garage ceiling. The space is designed to be used as a workshop, so we have insulated the walls and ceilings in the event we want to use the space for a winter project.   We have a 2" thick insulated overhead door that we expect to have installed next week.

 

The drywall was delivered this morning, and the board hangers finished the basement and started the garage.  Tomorrow they will install the ceiling in the main house.  No board will be installed on the walls until we are confident that the moisture content in the wall is stable.

 

 

The metal roof was completed shortly after this picture was taken.  The metal roofing end up being symmetrical over the front entrance.  No amount of planning could have been as effective as plain good fortune.  

 

The exterior rigid insulation proceeds at a slower pace.  The plaster lath installation is very labor intensive.  Installation of the lath on the north elevation is complete, and work begins now on the south elevation. 

Next week we hope to have the garage door installed, blow in attic insulation over the garage, finish up some wiring connections, continue with installing the plaster lath, and install the track for the large pocket doors.

Closing in

We have had a short production week with many of the crew members taking extra time off for the holidays.  In spite of this we have accomplished a great deal.

 

The carpenters have completed the installation of the foam on the north wall with the exception of the garage and will have the better part of the south wall complete today.  They should be able to finish the rest of the insulation and fiber mesh lath by the end of next week.

The electricians temporarily wired all of the mechanical equipment so they can be started up.  The well, sump pump, heat pump, heat recovery ventilator, and hot water heater are ready to go. 

The geothermal crew completed the installation of their piping to the heat pump and filled the lines with water and a 25% solution of an environmentally friendly antifreeze.  We turned on the well to bring in water to fill lines for the heating system so we hope to have the heat on by Friday.  The hot water heater was installed today which is the last major component needed to start up the heat pump and begin warming up the floors.  The temperature controls are turning out to be fairly complicated, but we should have them operating at least on a temporary basis by the early next week.

The metal roof is done on the north side and they have started on the south side.  The gutter we designed to go over the front entrance will be especially useful.  The little bit of snow that had accumulated on the roof, melted, dripped down on the sidewalk, and frozen into a skating rink, will all but disappear after it is installed. 

The plumbing inspection was completed, followed quickly by the final building inspection without issue.   We are now ready to start insulating and are scheduled to start next Tuesday.  One code requirement is a carbon monoxide (CO) detector normally located near the bedrooms.  Since we have no equipment in the home with a combustion source, the building inspector is allowing us to locate the CO detector near the entrance to the garage to allow air quality monitoring from vehicle exhaust.  To further assure that we do not have CO infiltration from the garage, we have installed an exhaust fan in the garage that will be tied to the lighting control timer for the overhead garage door opener.  The fan will start up when the overhead door opens, and shut off when the light goes out.   

 

The transom for the front door arrived, although without glass.  We needed the transom frame in order to begin drywall and exterior trim.  The picture shows the transom in place with foam in place of the glass.  The black material on the door frame is foam pipe insulation that is a protective cover for construction traffic. The picture also shows the four inches of foam with the joints of each layer staggered so that air infiltration is virtually eliminated.  

The tub and shower both finally arrived .  Unfortunately the shower was bigger than the door opening, so we had to remove the garage door and frame to get the shower inside.    

  

The next week will be a turning point in the project, marking the start of the finishes stage.  We will have a warm, dry, insulated building with a possible start on the drywall installation.  

Roofing Started

The electrical and mechanical inspections are complete.  The plumbing inspection is waiting for the tub and shower to arrive.  The manufacturer delayed shipment another week without letting us know until the day we were expecting it on the site.  This one element has put us about two weeks behind schedule. 

Production fell victim to holiday stresses with contractors tapering off their schedules in anticipation of the holiday weekend.  For my part; I had been told by the electrical inspector that the light fan combination unit did not appear to meet code for use in a bath or shower.  The next day I removed the original fixture and discovered the markings the inspector had been looking for clearly marked on the inside of the fan housing.  Then, completely unencumbered by the thought process, I proceeded to dismantle the light/fan and attendant ductwork, and re-frame the opening for the new fixture I had purchased.  A couple of hours latter, it finally dawned on me that I needn't have done anything. I dutifully re-installed all of the original ductwork and the light/fan combination... After I took some time to get some lunch.  Are the Holidays here yet????

We did get the soffit and fascia completed on the front and back, and started to install the soffit on the west gable.  We began installing the 4" of foam insulation on the west gable as we discovered a construction detail for the soffit and fascia was inter-related to the installation of the foam sheathing.  Here they have installed the "Spiderlath" to hold the foam in place against the wind.  Spiderlath is a fiberglass alternative to metal lath for the cement stucco that we will be installing in the spring.  We need at least 72 hours without freezing conditions for the stucco to cure properly.

 

 

The roofing started yesterday.  This is the end result of about four hours of work in the field.  A good deal of time is spent in the shop fabricating the panels and trim.  Though this shows the north side of the house, the panels are fabricated to accept the solar panels we have selected.

We installed blocking for all of the cabinets, towel bars, and toilet paper holders.  With studs on 24" centers, you cannot rely on having a stud nearby to fasten cabinetry to, so wood blocking must be installed to provide anchor points for cabinets.  We also framed in the access ports to the hydronic heating controls. 

 

All of the light fixtures have been ordered, and most of them have arrived with only a couple on backorder.  The remaining fixtures should be here in plenty of time for installation.  We are storing them in the spare bedroom at the apartment, so it appears we won't be having any company for the next couple of months.   

Though next week will be short, we expect to have the roofing complete, the plumbing inspection completed, hopefully we can get the final inspection, and then order the insulation.  At this point it would be victory to get the insulation scheduled much less started.  The HVAC contractor is building the heating controls in his shop, and expects to have the geothermal contractors finalize the installation and fill the lines.  

This will require a choreography with the geothermal installers, the HVAC installers, the temperature control installers, the plumber, and the electrician.  The electrician will need to install the electrical disconnects to provide power to the units.  We can't start the well to provide water to fill the geothermal unit until we are confident that we can provide enough heat to prevent it from freezing, so all of the controls, the power to the unit, and piping must be complete and operational.  The hot water heater still needs to be installed and the plumbing completed to provide water to the HVAC unit. 

 

If you look closely around the front entry you will see a string of Christmas lights framing the front door.  Judy is particularly pleased with this first solar powered contribution to the home.  

Hope everyone has a Happy Holiday!