Monthly Archives: February 2018

Air Tight – Certified!

February 26, 2018

Well the results are in and they are phenomenal.  Patrick (my HRV consultant)  came by on the 16th to do the duct-blaster test on my HRV supply and exhaust ducts.  I am thrilled to advise that both are air tight!  Not bad for my first try!!

– 5o Pa is standard test pressure

Zero CFM is unusual and my tester advised this had only been achieved once before in his test history.

Patrick and I setting up the duct blaster on the exhaust run

There was a scare when we first ran the air flow test on the exhaust run as the gauge was indicating 16 CFM of leakage.  While this would have still been an acceptable result and would have represented a hole that was only 1.6 square inch in size, Patrick could see I was disappointed.  So we pressurized the system and started introducing theatrical smoke to trace where the hole(s) were. During this process, I noticed that the only termination I had sealed with red tuck tape instead of Metal Foil tape, had a giant gaping hole between two strips of tape.  This was the same tape covered termination I could not get sealed in the videos showing the testing of the HRV Duct Sealing.

I knew I should have replaced that junk!  5 minutes later we had the gauge reading zero and I was vindicated. I am proud that I achieved this result on my very first attempt at installing air ducts.  If I can do this, anyone can!

After confirming that both circuits had zero leakage, we then tested the longest runs in the exhaust side and confirmed we had adequate flow through those branches.  I had 112 CFM through the 6″ grill in the master bedroom en-suit , 73 CFM through the 4″ grill in the upstairs hallway bathroom , 115 CFM through the 6″ basement sauna grill, and 80 CFM through the basement 4″ shower room grill (the four farthest points in the system).

Love it when a plan comes to fruition!  To give you an idea on how long these runs are, the en-suit is a run that includes a bull wye, standard wye, two 45 and seven 90 degree elbows, for a total equivalent run of around 125ft.  This would have been an equivalent run of  161.5 ft if I had used the standard 1.5 radius elbows instead of the special order 2.0 radius elbows.  The basement sauna had a total equivalent run of about 110 ft.

As the code only requires 20 CFM for a continuous exhaust flow in bathrooms and my consultant only needed to see 55 cfm on the 4″ lines to ‘pass’ me, these results are awesome and should allow the evacuation of moisture and smells with only short bursts of the HRV in high gear, leading to increased efficiency of the system.

Although I now have approval to proceed on the building enclosure, it is still too cold for membrane application so I am instead working towards pouring my basement slab. On Feb 7th, 90 bundles of 2″ and 10 packs of 3″ Rockwool ComfortBoard 110 were delivered and my nephew Jonathan and I moved all of the packs down to the basement the following day.

Stacks of Rockwool mean only one thing – I have some work ahead of me.

After a long weekend away from the site, I started detailing the interface between the footing membrane and the to be installed vapour/soil gas barrier installed between the sub slab insulation and the 4″ concrete slab.  This is a difficult detail to make air tight because of my use of an air permeable ICF block (Durisol).  So I came up with a plan to attach a 12″ membrane to the back side of the footing fabric, that will then extend over the top and seal to the surface of the sub slab membrane.  I also extended the bottom side of the membrane down and sealed onto the bare concrete footing, so that the air flow could not by-pass this interface.

Membrane is first attached directly to footing so I am ensured an air tight connection

Membrane is then folded back over itself and up the wall. The sticky side is now facing away from the wall. The fastfoot membrane is then primed

The release film is pulled off the black membrane (except for top 4″ which will be used to see to soil gas/vapour sub slab membrane) before sealing the fastfoot to it.

Seams on the two layers are staggered and all is carefully cut around plumbing penetrations.

I first had to add the PEX pipe to all the traps that will later be connected to a trap primer and distributor. In this case, because the PEX was running in gravel, I ran through a 1″ PVC pipe that I heated with a torch to provide the required flexibility to form. I would not due this for a ‘supply’ pipe, but for a sleeve, this worked just fine.

I have completed most of the main house and am now working on the bonus room below the garage.  As this room will also house the sub-slab insulation testing lab, I have test panels utilizing mineral wool in 4″ and 10″ thicknesses and test panels containing 4″ of XPS and 4″ of EPS. I hope to have this room including all instrumentation finished by the weekend and the last of the main house finished by early next week.  The balance of the week will entail installing the soil gas/vapour barrier and some form work needed for the slopped floors in the areas of the floor drains.  Then we will finally be able to set up the pour!

Thanks for visiting.

“If your actions inspire others to dream more, learn more, do more and become more, you are a leader.” —John Quincy Adams (1767-1848) 6th Us President

“The moment you accept responsibility for EVERYTHING in your life is the moment you gain the power to change ANYTHING in your life.” —Hal Elrod (born 1979) Motivational Speaker

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Small Victories!

February 9, 2018

Well folks, I am very pleased and extremely relieved to advise we have worked through the roadblock imposed by the Municipality last October regarding my building envelope.

I today delivered the final required letter of assurance filled out in a manner acceptable to the staff and now have authorization to proceed on completing my building envelope.  I am so grateful to Pierre-Michel from Busque Engineering, for helping me navigate through this latest impossible roadblock erected by the local Municipality.  I am also thankful to Nathan Proper from Tacoma Engineering, for his continued assistance as my registered professional of record.  I am also thankful to Murray from Building It Right, for helping guide me through this process and rattling some trees in the background.

What has been most upsetting during this process is that both the engineer who came to site from RDH and Pierre both questioned why the District had any concerns, as what I was doing was well above and beyond code requirements and demonstrated best practices for building envelopes.  It is my belief the road-block resulted from the inspectors not being comfortable/experienced with advanced envelopes, which in my view is a sad commentary on the training they are receiving.  What is frustrating is that they do not appear able to recognize the same barriers in an advanced envelopes (one incorporating exterior insulation) as those required by code minimum builds.

Both systems have a primary water shedding surface (cladding, flashings, windows & doors), and a secondary water resistant barrier (sheathing membrane, foil face membrane, and again flashings).  The code refers to this as the ‘two planes of protection’.  Usually, the dwellings being inspected have these two layers in fairly close proximity (they are only separated by the rain screen strapping – either 3/8” or ¾”).  However on a dwelling incorporating exterior insulation, there is a larger gap between these two layers, to account for the thickness of the insulation (in my case an additional 6” gap).

BUT, does this larger gap change the function of the two barriers???  Of course not.  While it does make the sequencing a bit more important (and challenging), usually requiring all components to be built up at the same time so that they can overlap each other appropriately, it does not significantly change the basic function and installation details of each barrier.

To me, it appears that homes built to the Part 9 of the Building Code are going to become extinct in the very near future.  As Municipalities adopt the new Provincial Step Code program that encourages higher performance structures, it is clear to me that Municipal Building Departments may not have adequate man-power or training to address the inspection needs of these new constructions, and instead of raising their game, are instead negating their responsibility in my opinion, and transferring it to the building community in the form of requiring professional overview of the build by engineers and now even architects.  This is going to make single-family construction, on average, a LOT more expensive.

Is this the right direction to be going??? Does it align with the goals and intent of the code officials in Victoria and Ottawa???  I know what I think, would love to hear your thoughts.

With this all being said, I AM EXTREMELY GRATEFUL that my building department compromised with me and reverted back to their original decision to only require an engineering sign off (instead of also an architect).  I really did not have it in me financially or emotionally, and do not have the time to start all over at this late stage of the build, to bring on an architect!

Thanks for visiting!

“Have patience. All things are difficult before they become easy. ” —Saadi (1200-1291) A Major Persian Poet And Literary Of The Medieval Period

“If you don’t stick to your values when they are being tested, they’re not values: they’re hobbies.” —Jon Stewart (born 1962) Television Host, Writer, Comedian

“Dreams and dedication are a powerful combination.” —William Longgood  Author

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Sealed Up Tight

February 7, 2018

Today I finished the last of the installation and sealing of the HRV supply and exhaust return ducts and preparing them for air tightness testing.  This leaves only the fresh air and exhaust ports from the HRV unit through the exterior building envelope to the outside to complete, something I will do as I am installing the exterior insulation in those areas.

The installation of the ducts was actually the easiest part of this system.  The sealing of all the joints actually took longer than the initial installation.  All in all I spent about 75hours planning the system (including planning route through structure as I was designing floor assemblies), 25 hours in total picking up materials and working with the vendors (I had several special orders that did not come in at once and you may remember that Eneready stopped selling these units and it took some time to come up with a solution), then 85 hours on the initial installation, followed by 98 hours partially disassembling into large sub-assemblies to fully seal all seams before doing final re-assembly.

One of the best practice components I incorporated into this system was the special order 2.0 Radius elbows.  This was recommended by Eneready and further motivated by some web research I did at

Equivalent Length of HVAC elbows

First notice the difference between elbows with a 1.5 centre line radius (CLR) and a 2.0 CLR. For instance, the 6″ 90 elbow with 1.5 CLR represents 12 FEET of equivalent duct length!! where a 2.0 CLR elbow only represents 7 feet.  Close to a 50% reduction for the same turn in direction.  Also note in the footer “Unlike friction losses in straight duct, fitting losses are due to internal turbulence rather than skin friction. Hence roughness of material has but slight effect over a wide range of moderately smooth materials.”

2.0 radius elbows compared to 1.5 radius elbows

It was this information that led me away from an even more expensive smooth walled ‘Die-Stamped’ elbow package, but based on the above information I did invest over $3000 in the longer 2.0 radius elbows to ensure that my system uses as little energy as possible (very low head pressure), and is as effective as possible in moving the required volumes of air to and from rooms without any turbulence or whistling.

But spending a lot of money on components would be a total waste of money if you did not also seal all the joints very well.  This is why I put so much energy into first assembling the system, utilizing the most efficient routing and as large duct sizes possible, before disassembling into sub assemblies that were then easy to seal with tape and mastic to ensure a finished air tight installation.

Hanging the sub assemblies from the floor trusses made sealing these awkward shapes much easier.

But sometimes, it was still awkward to get into the right position.

This was the largest sub assembly (15′ long) I sealed as one piece.

My sealing strategy, as recommended by Patrick Sommer (consultant recommended by Eneready HRV), has been to first seal the seam with good quality foil faced HVAC tape (I used Nashua Multi-Purpose Foil 322 HVAC), then to screw together the main joints with at least 3 screws, and then finally over sealing with duct mastic (I used fibre reinforced Hardcast 321 Duct Seal).  This three part approach ensures a strong-air-tight joint.  Patrick liked the tape to go on first and then the screws on the main seams.  This allows the screws to self seal as they go through the tape.  However, this approach does run the risk of tearing the tape as the two layers of duct being fastened, push away from each other during the screwing process.  When this happened, I would need to apply another layer of tape over the ripped areas.  In hindsight, I would probably screw the joints first and then apply the tape.  Any ripping of the tape over the screw head can easily be sealed with mastic in step three.

There was one location where I was not going to be able to seal the exterior side of the joint in any way.  This was an elbow where the one end was sandwiched between a metal beam on one side and a floor truss on the other.  It took quite a bit of effort to just rotate this elbow into this location.  So for this one location, I sealed from the inside. I could reach in the ends of the elbow and used the mastic to seal all of the gores.  For the connection to the straight duct, I also screwed and taped this joint.  I am confident, that this will allow this joint to also be 100% air tight.

Step 1 – seal internal face of gores with mastic. I also used a ball been hammer to flatten the crimps as much as possible to ensure a tight connection between the duct and elbow.  In this photo you can see I have also screwed the seam from the inside out.

I used hex head screws that were the same size as a standard bit and held them in place with a bit of tape to access this confined location.

I then tapped the main seam between the elbow and duct.

Before finally sealing the joint with mastic.

I also had one location where the assembly was not going to fit within the standard bays of my floor truss.  And you should never cut a floor truss/joist structure without an engineered solution.  Fortunately, TriForce publish a truss repair guide for just these instances.

TriForce Repair Guide for Cut Web

I used two layers of 5/8” plywood as an upgrade to the ½” requirement.

You should NEVER do this unless you have an engineered solution available. Fortunately I did, as there was no way I was going to get a 7″ wye to fit through this location.

Finished repair ready for installation of wye

There was a lot of cutting of the straight lengths and I found the fastest and cleanest way to cut these were to first mark the pipe using a jog and then cutting off with an angle grinder with a thin blade.  Just remember to run a file over the edge so there are no burs that will cut through the tape.

A band clamp makes an excellent marking jig for round pipe. Just need a few sizes for all of the diameters you are working with. I would then mark with a felt before cutting off with an angle grinder.

In the spirit of performing a professional installation, I also invested in a couple of large diameter hole saws instead of hacking out the holes using a saws-all

When assembling any air ducts, you generally work from one end of the system to the other.  But there are times where, say due to structural interference, you need to work from two directions meeting in the middle.  For these locations, I found a slip joint to be effective.

I made a slip joint in two locations using two lengths of duct telescoped into each other. I fastened one end to the installed components before I then screwed a block of wood to the other end to hammer slide it across into position (is usually too tight to slide by hand)

As part of my build documentation, I also created three short videos describing and demonstrating how I sealed these ducts and then demonstrating with theatrical smoke, what happens when you do not seal your ducts or do a poor job at sealing them.

In the first video I go through the sealing of the system and explain and show why it is so important to seal as you go.

In the second video, I share my astonishment that the assembly is still not air tight after sealing with just tape.

In the last video, I demonstrate how I seal and reinforce wye’s and offer some general tips in installing and sealing HVAC ducts.

There you have it, my prescription for an air tight and energy efficient HRV system.

Thanks for visiting and I look forward to any comments you may have.

“Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.” —John Quincy Adams (1767-1848) 6th Us President

“The key to everything is patience. You get the chicken by hatching the egg, not by smashing it. ” —Arnold H. Glasow (1905-1998) An American Author

“Integrity is choosing courage over comfort; choosing what is right over what is fun, fast, or easy; and choosing to practice our values rather than simply professing them.” —Brené Brown (born 1965) American Scholar, Author, And Public Speaker

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