Saturday, November 2, 2013

Air and duct sealing along with blower door testing

Wow, several months since an update.  No, we have not been sitting around and not working on the house.  It was actually "done" some time ago, but I have not gotten around to updating the blog.

So here it is, preparing for one of my most anticipated moments.  Final air sealing and duct sealing.
Air sealing has been completed during the construction phase, but the attic access needs sealed up.  So to do this, I take the drywall lid and install 2 rows of peal and stick neoprene depressible gasketing. 

I then install blocking on the side and a pull latch on each side to suck the gasket down and seal the attic access.  This will create an air tight hatch.
 Energy Star 3.0 certification requires several building techniques to be met, but also a series of testing.  One is the blower door test and the other is duct leakage.  I was confident I would hit the 3.0 @ 50 pac test requirement, but I was anxious to see if I hit my goal of less than 1.5, or better yet, 1.0.
Below they are setting up the blower door.  They install a sealed enclosure over a doorway and a fan sucks the air from the house.  It measures how much air is pulled through the house, and ultimately how much air is pulls from the exterior through cracks.   

 Here is the controller that measures the air leakage.  He did 2 tests, one at 25 pascals and another at 50 to verify each result.  The yielded the same thing.  Every point counts in this test, as very leaky homes are about 5.0+ @ 50 pascals, "tight" is at 3.0 (where most new homes test out around), very tight is 1.5, and one of the most stringent testing methods done by Passivhous requires .6, which is incredibly difficult to achieve and rarely done without taking extreme measures to the home's construction.  The numbers on the controller get converted with some basic math based on my homes total volume.  The testing worked out to be 1.08 @ 50 pac!  While it wasn't the 1.0 I was after, it was very close and I was satisfied with the results.  The tester new the home would be tight, but he didn't think it would be this tight.  He said it ranks in the top for tightest homes in 300 mile radius they test in.  He said hes only done one in the last several years that was below 1.0. 

 Energy Star 3.0 requires duct testing and leakage 8% or less of the square footage of the house.  This means I need to have a cfm leakage result of 95 cfm or less for the total house.  So my role of the build tested out well, lets see how the subs did.

Well the contractor "sealed" everything up well, or so I thought.  The first test was completed, and we were over 800 cfm leakage!!!  A lot of times they can run a smoke test, find the minor leaks, seal, and retest.  Obviously 800 cfm is far to big of an amount to seal up real quick.  So I called the mechanical contractor to come back, seal things up better, and retest.  They were not overly cooperative as they thought they "sealed it better than any house they have done".  While I would probably agree, that doesn't mean other houses they have done were good enough and certainly doesn't matter to the ES testers.  So they came back and did some more air sealing, although very minor, but I took it upon myself to do quite a bit. 

Walking around with the rater he pointed out leaks around the registers and how they can add up to a significant amount of leakage.  So I needed to seal them up.  Here is what I did.

Here you can see inside one of the returns.  The blocking and pans are completely caulked off and taped off.  While its not pretty, it seals the air so each room can have proper supply and return. 

Below you can see tape around the registers to the flooring.  The cracks around the registers and subfloor leak a lot of air, or it forces air between the subfloor and the finished floor.  The tape sealed this joint and directs all air into the space.  The registers also have foam gasketing around the perimeter of them to create a tight seal with the register to the tape.

With that being done, it was time for the 2nd test on the ductwork, so I scheduled it and crossed my fingers.  I could not be there for the 2nd test, but a guy from the mechanical company was there. 
Test started, and did not go well again.  It tested out at around 500 cfm leakage, so we cut just over 300 cfm off by sealing up the registers.  However to the readers out there, realize that but just sealing up the registers, I recaptured approximately 1.5 BEDROOMS worth of conditioned air to be directed into the space they were intended.  This obviously increases efficiency of the hvac equipment as it brings and maintains your rooms at the proper temp.  Regardless, still a ways from the 95 I needed, so a 3rd test will be required (and more money).

They set up a smoke machine this time and found leaks in the ductwork.  Apparently the thermal pans on the returns were leaking like crazy.  (thermal pans are the shiny cardboard looking ductwork used for returns.  It is leaky, hard to seal, and they were not supposed to use them, but did anyway, seen here).

The rater recommended ALL pans removed, resealed, caulked and taped, reinstalled.  Obviously the mechanical contractor did not think this was necessary and did not want to do it.  I actually agreed.  I did not think the pans needed removed either, but could just be resealed.  I made a deal with the contractor and said I would take care of all sealing and testing, if he pays for the retesting.  He agreed, so I got to work.

below you can see the register foamed to the subfloor and the mastic (contractor did) around the duct joints.

 Where the thermal pans return to the subfloor, the joints were pretty leaking and hard to seal any other way, so I simply foamed them,  Filled the gaps nicely.

 Below you can see how thermal pans are hard to seal to framing.  Crossing a beam they need to be sealed to it.  There were cracks along this entire pan where it was leaking, so I resealed it completely.
Well, I thought I was complete, so I scheduled the 3rd test, needing that 95 max leakage.  They showed up, and taped off all registers (just the same they do all testing).  They then install a fan from the furnace to suck air through the ductwork. 

He inspected everything again, thought it looked "significantly better", and we retested. 
180 cfm.  Got a nice lump in my throat.  Still nearly 100 over.  So we set up the smoker and went to work seeing if we could find it.  After letting it run for a while we went upstairs to see if anything was leaking.  Not a spec of fog upstairs, which was great.  However the fog was building pretty quickly in the basement but we could not find it.  Finally, the rater randomly see this:

As you can see above, 4 pex water lines and several wires are going through a joist, which is meant to be part of the sealed return duct.  These were not sealed at all, so there were 8 holes on each side, so 16 total holes right here.  I grabbed the caulk gun and filled them up.  Can not believe I missed these holes when I was sealing.
So we ran the test again, and it came in at 67 cfm leak!  About 6% leakage.  Happy day for me, for them, and now the testing is complete for Energy Star certification.  Paperwork is filled out, so time to submit for review.  (now I wait for the large rebates coming my way!!)


  1. So if I hire a builder does it matter if I get Energy Star 3.0 certified other than knowing I have an "efficient" home? Sorry for bombardment of questions, I am still learning a lot!

  2. not sure I completely understand your question, but you do not need to be ES 3.0 certified for your home. The reason to be certified, in my specific instance was for large rebates from utilities. An efficient home was a goal from the beginning, and from a construction standpoint the house is about 30% more efficient than the Energy Star 3.0 requirements anyway, but if I am already beyond that, why not get certified!

    1. awesome, yeah thats what i meant, just simply for rebates for your DIY project. I will try to get certified anyway for affordable heat bills :P Thanks for the reply!