Roof Caps For Bath and Kitchen Exhaust Ducts

At 1/1/2025, add realization that intermediate duct penetration adapters must become mandatory with all ducted exhaust. Add a new cap requirement: A cap shall be detachable from the roof without need of attic access.

When re-roofing, find the protruding adapter rim convenient for slicing or stab-breaking membrane and shingles to the duct circle. Never misalign a roof cap to the sheathing penetration.

Roofers are accustomed to high-vent caps that simply slide down from the roof for cap or shingle maintenance, with removal of a few gasketed screws. A proper ducted path must have full penetration of the roof sheathing. Compliance in this is often forced by use of a cap with a stem. It is increasingly hard to find offered duct caps without stems. A diligent fan installer will tape and/ or screw the fan-duct termination to the stem. If a cap must always be detachable,  we need to introduce duct penetration adapters. Let there be no offering of caps with stems.

I want these things in the roof cap of a bath or kitchen exhaust duct:

1. There is no compromise of two layers of sealing against roof leakage in water down-flow from the roof.
2. There is no possibility of siphon action, with leakage from water flow driven upward on the roof.
3. There is back-draft protection at the roof, that can not mechanically jam.This is also effective protection that small pests do not find refuge in ducts below. Design of the back-draft protection shall ensure materials don't degrade , free of service needs for minimum 25 years. Jamming open with excessive grease carry in kitchen exhaust shall be warned-against, including provision of easy from-roof maintenance procedures.
4. Screening of maximum 1/4" mesh keeps out larger pests.
5. The cuts through roof sheathing and shingles must be of minimum size matched to that of a served duct.
6. Positive means shall assure that a cap is not misaligned with roof cuts and served ducting in a way that compromises flow capacity, structural integrity and safety of the roof, and water-tight integrity.
7. The cap screen, body interior, and the back-draft protection shall be easily serviceable from the roof, without compromise of watertight integrity.
8.  A cap must be detachable from the roof without need of attic access. This is already true of vents not served by approaching ducts.

I will now detail innovation in which all of these wishes are achieved. Readers should appreciate this for the fact that these wishes are not always achieved, especially those of Items 1, 2,3, 6, 7 and 8.

Suggestions and background here are based on lifetime commitment of always to do better in each new installation, and are abbreviated from  a photo album summary  more-instructional to manufacturers I wish to influence. Where I offer invention, I intend always to prove existing practice and to fully disclose details, to ensure free availability to all, not allowing a competing patent.

Imagine a better way to cap a bath or kitchen exhaust duct at the roof, with a flow-check flapper upon an intermediate “penetration adapter.” The penetration adapter seals against water flow down the roof, superior to a one-piece cap. The adapter demands less release and reset of surrounding shingles. The cap, a powered fan or any other roof device needing roof penetration, serves only as a rain cover of the smallest-possible, neat hole cut through roof sheathing.

Shown is a 6” Famco roof cap, BK6BK. With an 8" dia. circular nibbling of the base plate, I have discarded the factory center, a 2" length of 6" pipe crimped into the plate, sealed imperfectly with a bead of caulk. My spun-aluminum penetration adapter has same 6” ID, now bearing the Famco cap's flapper and silencing seat.




The common injection-molded plastic 4" bath fan cap of manufacturer Air Vent is now produced by many regional injection molders, branded Gibraltar presently in sales at Home Depot, and only with stem.  Famco offers the cap with a detachable stem. I would install the Famco cap thus, with reliance on the duct penetration adapter to deflect water accumulated on the roof.

At $24.95 plus shipping, this cap is awfully expensive compared to $11.00 paid steadily over many years for caps labeled Air Vent Inc., 4" RCV, made at Portland Oregon molder M&N Plastics and sold by Beacon Building Products. At this time, only Famco offers a plastic cap useful to me. I can buy a Broan 634 4" steel cap without stem for about $40, a price that has not changed in eight years. 

Prefer a plastic cap, and implore some changes to the Famco product. Introduce the adapter plate. Fix the injection mold to delete the stem option and to add bakk wings that better repel up-driven rain.

Add the wings. Get rid of a twist in the cast base that defies screen installation.

Please visualize topside completion with this Summer 2016 photo for a 4" bath fan duct, with an injection-molded cap.

Here is an underside view of that cap, Norwesco RCV4 . One should wish for tolerance of some misalignment between the cap center and the smallest-possible roof cut, but an oversize square below a flapper-check here is not as helpful as size of the cap might permit. I suggest there should be about 2" diametral clearance between pipe and cap paths in which there is no performance penalty, in placing the cap to suit the shingle pattern.

Where the cap bore is about 3/4" above the roof bore in this installation, I think there is some added flow resistance.

Where Norwesco and Famco 4" and 6" plastic caps without stem are nearly identical and with a lot of misalignment potential, find argument that their flapper function should be transferred to a roof penetration assembly. Enlarge the crown and the opening of the base of their caps as in steel Broan 636 (up to 4" ducts) and 634  (up to 6" ducts), and their cheaper knock-offs at Home Depot. With this innovation, offer convenient duct joining means for the Broan steel caps. Get rid of jamming-prone rectangular flappers.



See here better trial placement of a duct for a pilot hole of a 4" bath fan duct.

Where I can now adjust the lengths of duct pipes, I am free to make a large shift of hole location to best align with shingles. An extra hole a short distance down-roof is of no consequence.

The added crossing 2x4 that accept cap mounting screws are not in my way, and help in the strapping of the duct. Wood blocks to drywall ensure worker force upon ducts does not threaten the friction-only elbow coupling to the penetration adapter,

The topside completion photo for this job is the third graphic in this post. With no constraints of underside arrangement, 1/2" plywood only, The Norwesco RCV4 roof cap top edge was tucked under a shingle course.


Here, accepting a pilot hole centered between skip sheathing boards, the tuck under a shingle course did not work out. Remember, the roof cap is only a direct-rain cover, in combination with the roof penetration adapter.

In the photo above, see steel/ EPDM washers cannibalized from inappropriate roofing screws. I shall never need more than 1x backing under plywood roof sheathing. Use 1 5/8" deck screws with independently-purchased 1/2" OD steel/ EPDM washers. Choose washers Made In USA, Aztec Washer Co., Poway, CA. And, know this choice is offered through chance, not through manufacturer and re-seller diligence. Read on, below.






























Wanting only the washers, I first purchased qty 100 of a too-small 3/8" OD washer from Raw Products, via Amazon.
Neoprene EPDM Washers 18/8 SS - #8 (OD .50) Qty-100
 $10.74  |   Qty : 1  |   Sold by Raw Products Corp 
$10.74 wasted. What next? I'm lucky to live in metro-Portland, Oregon, large-enough to support quite a few fastener store-fronts. At Oregon Bolt, Inc., persisting by phone I found admission  they had qty 300 of 1/2" washers like those on also-sold 2" roofing screws. I bought qty 100 of washers maybe a bit thin, identified as 15BW050STL, 8 X 1/2 BONDED SEALER WASHER AZTEC H. 

I can not select this washer at the Aztec web site . I will hope that anyone may find 1/2" gasketed washers, somehow.

Here are two more variants of 4" bath fan roof cap placement, allowed with penetration adapters. Cap placement must cope with existing or new holes, independent of shingle patterns.

Now record the Famco BK6BK cap installation on this roof, for exhaust of a kitchen microwave oven, in place of an unsuitable static vent. Here is the static vent, with poor proximity to a plumbing vent.

I must employ this roof cut, placing the Famco cap as far as possible from the plumbing vent.

Here is trial placement of the flappered 6" roof penetration adapter.

The better roof opening is quite long, requiring several "shingle bridges" above and below the penetration adapter. Add plywood strips below the roof sheathing to strongly engage 1 5/8" deck screws that retain the roof cap.

Here is the topside completion of the modified Famco cap.

Here is the efficient and secure 6" duct, installed in a now nicely accessible attic.

Here is the actual cap arrangement employing three shingle bridges, and the flappered penetration adapter. The elongated opening could have been mended using a one-piece cap, but there is more-assured mending of found shingle hacks and excess opening of the roof sheathing, before the cap is placed. In a new installation shingle and roof cuts are smallest-possible and are simple circles perhaps cut with a hole saw. In a re-roof the penetration adapter is more-easily laced among shingles, with unambiguous trimming needs, then the rain cover/ roof cap with no trimming of shingles, all with accuracy.

Here, a 4" bath fan duct is rigidly fixed to the roof with sheet metal screws. Added 2x4 bridging  accepts roof cap mounting screws, and compensates for lost plywood stiffness with the 4 1/8" dia. sheathing cut.

See an edge of the not-stiff 15/32" sheathing plywood, 4" below the lower support here. Walking upon a displaced plywood edge may rip roofing membrane.

Here is an installed 14" Costco solar attic fan, employing a penetration adapter and very-much-needed 2x4 sheathing reinforcements. There is no ducting to this fan, but a penetration adapter is yet a good idea. The fan as a rain cover is easily detached from the roof, at four mounting screws, leaving a rimmed hole that might be bagged against rain for fan service. 

Here I began the 14 1/2" sheathing cut with swing of deck screws to cut shingles about a center pivot. The silly fan manufacturer prescribes an 18" square opening of the roof sheathing. I protest:

Slow Progress In Solar-Powered Attic Ventilation January 29, 2014

And at January 2025 edit here, still find no progress.

Use roof sheathing reinforcements generously. 

Find that a penetration roof cap can be useful in curing the common occurrence of a misplaced attic ventilation high vent. No duct. This intermittent leak with a wind-driven siphon, in my home, was repaired in November 2011, by an understanding and highly reputable roofer under my instruction.

See the repair at 1/10/2025, never again leaking.:

Here is another important use of a penetration adapter, in passive control of dangerous radon levels in my rental home:

Here is the suck of the perforated pipe in the gravel channel, sealed under ground covering. The female side of a spun-aluminum 4” roof penetration piece joins the buried pipe as male. Double-backed butyl tape durably and sealingly bonds the adfapter to the ground cover.  The male end of a two-ft warm air pipe sealingly engages the penetration adapter.

Here is the gravel channel and pipe fitting, before gravel-filling and sealing of the ground cover:

Home Energy Scores, Zero To 100

From RMI Blog, the blog of Rocky Mountain Institute :

A Leap Ahead for Energy Efficient Homes Down Under 

Watch this YouTube video , and learn of a superior approach to home energy-efficiency rating, employed in Australia. Ratings are based on actual energy consumption, and range from zero to 100, as applicable to the efficiency potential of any unique home.

I hope I can employ this too, in my assessment of auditing usefulness to my existing-homes weatherization customers. The Home Energy Score creator is Tendril, Inc. , in Boulder, CO. Tendril. Inc. reports their HES has been applied to 31,000,000 homes. Compare this to the achievement with US Dept. of Energy HES, applied so far to 37,000 homes. Know the greater achievement in Australia is driven by much higher fair-market cost of energy to residents of Australia. 

Energy Data


Take advantage of the 300 data points Tendril processes on each individual home.

Surely, I can learn to do this.

Amazon Discussions, LED Downlighting

Let's follow and guide the public discussion of LED downlighting at Amazon Discussions as "LED retrofit for recessed lighting." 

https://www.amazon.com/forum/home%20improvement/ref=cm_cd_fp_ef_tft_tp?_encoding=UTF8&cdForum=Fx1MQVH99VVS61W&cdThread=Tx2J9FH9SEYSYKD 

I hope we can overcome the wasteful obsession with residential lighting as of point-source bulb form. In a point-source expression of LED light, more than half of input energy is simply wasted. The cheapest trick is in very thick obscuring plastic that glows, looking like the incandescent improvement of candles and gas or oil lamps that are history. Let's hope all point source bulbs will be history.

In commercial applications we have not tolerated antique bulbs, for several decades. Why should residential lighting be different?

My Trial Of Home Energy Auditing

I hope to report here, my experience with home energy auditing, using US DOE Home Energy Scoring, as a challenge to continued do-nothing weatherization in my community. I will do this at no cost to my customers, for a limited time only.

The contribution of one more capable contractor must matter, where about 27,000 existing homes are sold in the Portland market, each year. Compare this to HES audit accomplishments reported by US DOE , a nationwide total of 37,000 existing home audits in a three or four year period since 2012, by 350 auditors. Among foolishness of the Portland mandate, is inability of a pool of competent contractors, to perform even a small fraction of the required audits.

To become licensed to perform Home Energy Score audits to a new City Of Portland mandate, I may choose among paths spelled out in an application form from Oregon Department of Energy, dated 4/25/2016.

https://www.oregon.gov/energy/RESIDENTIAL/docs/HEPS/Proof-of-training-for-Home-Energy-Assessors.pdf

Where all paths must follow the US DOE instructions, How To Offer Score , step through them here.

1. Work with a Home Energy Score Partner.
To offer the Home Energy Score, Assessors work directly with Home Energy Score Partners. Interested Assessors should contact a local Partner  for information about joining their program. Or, you can reach out to another organization that is not yet a Partner and ask they become one.

In Oregon, I may choose as local Partner, Oregon Department of Energy , then following their rules cited above.

2. Hold a relevant credential.

If you hold a certification as a home inspector, HVAC contractor, or other residential professional, then you meet our minimum qualifications to become a Home Energy Score Assessor. The table below gives some examples of relevant credentials, however this is not an exhaustive list. Contact your local Home Energy Score Partner  to find out more about the minimum qualifications they require. 

In Oregon, this partner is again Oregon Department of Energy . Confusion arises here, where Oregon Department Of Energy fails to list quite a few allowed paths. These additional paths include:

U.S. Green Building Council LEED: Green Rater or Green Associate, a path costing just $250. I find this uninteresting, where LEED has no interest in existing homes.

North American Board of Certifed Energy Practioners: PV Installation Professional, again irrelevant to me.

I infer that US DOE requires acceptance of any interested professional.  As a superior weatherization professional, with more than 20,000 hours of proficient practice I am a qualified professional, and need not be burdened with further investment of my valuable time and small cash reserve.

By the fewer Oregon Department of Energy paths, professionals exempted from further cost burden include home remodelers of no proven skill in weatherization, The free path of the National Association for the Remodeling Industry, NARI, is open to any worker of a dues-paid business. Find only two such doing insulation, Gale Contractor Services and USI JB Insulation, listed as NARI members through Oregon Remodelers Association. Gale, the more likely to join a rater game, was caught and reported by me , for blatant fraud and has remarkably bad grades at Angie's List. At Angie's List I am very-visibly superior to JB Insulation for both quantity and quality of service.

If I found reason to join ORA/ NARI, I would be out $945 for dues and for irrelevant training. Again, any Gale or JB Insulation employee would pay nothing in this path to becoming a licensed rater, and would do so with inferior motivation to serve the public interest.

Look at  BPI Paths


To become BPI certified is not honorable, and costs much more, if with traditional purchase of a rating as a Building Analyst, Envelope Professional. 

It seems the little-knowledge BPI certification to only do home energy scores is simply a no-fee passing of US DOE rater examination. Then pay to BPI $200 one time and $25 for each audit billed. This is nothing but theft from home owners. BPI cares not whether one behaves honestly, or knows much of anything. I will never submit a penny in such thievery. I believe BPI is a criminal organization.

Become BPI Certified Building Analyst:

http://bpi.org/bpi_raters.aspx 

Oregon Training Institute Office
27501 SW 95th Ave., Suite 980 (Building C9)
Wilsonville, OR

http://www.warmandsafenow.com/event_mgr/pages/registration.php?id=772  

BPI Building Analyst; Envelope Professional - Wilsonville

Five days, 9 am to 5 pm, guaranteed pass as a Building Scientist.

(1/30/17 – 2/3/17)

Available Seats: 8

Price: $3790.00

This expensive path has been chosen by most of the rating advocates who showed up at Portland's City Hall. They have paid up, mostly as unearned income to BPI, to be privileged weatherization Generals under HPwES. And, there may be too few of them to fulfill the new Portland audit mandate.

However I might end up serving the public interest as a rater and critic, I must offer my choice of how to rate, from among those allowed by Portland's mandate.  Look at the ordinance words at pages two to three:

http://www.portlandoregon.gov/bps/article/620857 

K. “Home Energy Performance Score System” means a system that incorporates building energy assessment software to generate a home energy performance score and home energy performance report. Examples of home energy performance score systems include, but may not be limited to, the U.S. Department of Energy Home Energy Score, the Energy Performance Score (EPS) or the Home Energy Rating System (HERS). 

I choose US DOE Home Energy Score, for reasons including absence of a tax upon my customers.

 Here is an example HES graphic:

HES scores rise with efficiency improvement to a maximum of 10.

I reject EPS:

Energy Trust of Oregon/ Earth Advantage Institute/ Cake Systems wants auditors to use EPS, not the US DOE Home Energy Scoring. Cake Systems has a fee schedule very similar to that of BPI, and also does nothing to earn this tax upon home owners.

What does an EPS report look like?

EPS scores fall with efficiency improvement to a minimum of zero, and have no high limit, though a maximum of 200 is depicted. A home owner under the City of Portland mandate is as likely to receive an EPS report as a HES report, and will not attempt to understand the numbers, or do anything good as a result of the tax upon the buyer.

I reject HERS Scores:

There is a HERS score possibility too. What does that look like?

A HERS score looks something like an EPS score. See that a home may have a negative number with site power generation. Such scoring is criticized for perhaps not doing diligence with efficiency, before crediting the perhaps-temporary privilege of some odd power generator.

I don't care about HERS scores as Energy Rating Index, ERI, for new homes only:
Here is another example graphic where HERS for a new home is identified as the Energy Rating Index, ERI, prescribed by International Code Council, ICC, for 2015 International Energy Conservation Code, IECC:

The energy-efficiency improvement of any existing home is not definable by HERS/ ERI.

In energy matters, ICC is not at all concerned with a home that is no longer subject to approval or not, by some Jurisdictional Authority. Except for meaningful snares of plumbing and electrical codes, a remodeler is not at all required to improve a home. A flipper may cash out a house without any efficiency improvements. Those who permit this may be more guilty of hurting buyers, than one flipper.


Comment at August, 2018:
I performed math studies of US Department Of Energy Home Energy Scores, and recorded observations here:
http://energyconservationhowto.blogspot.com/2017/07/the-odd-insulation-math-of-us.html 

Where none of my infrequent-now existing home customers have had an interest in silly HES numbers, and I found no means to conduct supervised scoring, I am done with scoring. I do exemplary opportunity assessment and real work in weatherization.

I support  myutilityscore.com ,  with  reporting of actual energy costs as the information to be shared by realtors , for all homes, not just those for sale. 

Comment at March 2023

How might actual energy costs be studied? Please consult my post Fresh Air is Free, dated March 4, 2023,  reporting annual actual energy costs in my home diligently recorded to the present over a span of fifteen years. Prior to January 2020 I lived in the house with frugal heating, winter thermostat setting 55°F. From 2012 home energy efficiency was progressively improved from poor to remarkably outstanding. From January 2020 the home has been occupied by renters, with winter thermostat setting probably 70°F, and annual heating cost about $450 for a 1000 sf single-story home. Learn now whether this qualifies as an exceptionally good conservation score.

Compare the $450 number to an American Gas Association tabulation for 2020 , $639 average annual natural gas cost for homes in Oregon. As I assuredly know, my home is exceptional. Do make comparisons with comfortable thermostat settings. See details in my chart: A super-efficient home with thermostat at 55°F will have savings unfairly limited by base charges. Natural gas in Oregon through 2022 has been weirdly inexpensive. A 25% cost increase is in effect in 2023, and dollars per therm will continue to increase. Cheap natural gas has been an awful deterrent to weatherization.

My Observed ACH50 Numbers in Pre-1990 Existing Home Weatherization

This review of my blower door experience is in challenge of numbers near 30 ACH50, found in example Home Energy Score Reports, issued by US Department Of Energy, Better Buildings Program in years 2015 and 2016.  The reports are both for fictitious homes in Arkansas, built 1970, perhaps with little consciousness of energy efficiency.

 2015 Example:
v2015_HEScore_BB_example_12-15-15.pdf ,  a two-story home 1800 sf with 8-ft ceilings, testing in at 4200 CFM50, 17.5 ACH50. I did not remember confronting so large a number, before.

2016 Example:
Home Energy Score Report Example.pdf , of about November 2016, a single story home with ten-ft ceilings, 1500 sf, testing in at 6500 CFM50, 26 ACH50.

If such large numbers are not fictional in lax construction for milder-weather Arkansas, it does not suggest that huge savings from air sealing justify blower door madness, in Portland, Oregon. Few weatherization contractors in this area will accomplish real tightening of more than 3 ACH50, and some with their building scientist pedigree as blower door believers, will charge more than $2000 for the deed. Yes, at such unjustified cost, it is not worth doing. For a 1000 sf Portland home with an inefficient gas furnace, even with $2 per therm applied cost of natural gas heat, the savings per ACH50 reduction, in preheat cost of fresh air, are only $10 per year. Please see my Insulation Math . Annual savings of 3*$10 = $30 per year at cost of $2000 are a poor investment. At best, the present value of savings through a twenty year horizon are 44*$30 = $1320.  Please find that *44 payback multiplier (vs. *20) in this blog post .

At fair sealing cost of $300, the return is excellent. Abhor a blower door and test-in, test-out , with this. A blower door is almost never employed as the guide of important sealing measures. The value in tightening a home is in just acting in a permanent way, upon every sealing opportunity one sees, in dealing with evident drafts, and in the course of preparation to add insulation. Preparation must include all treatment of home integrity including plumbing, wiring and roofing deficiencies, that would be obstructed by the added insulation. Wiring includes anticipated communications wires and upgrades to permit most-efficient LED lighting.

Where I have spoken out as an Energy Trust Trade Ally, I have asserted that blower door testing with public support should be done rarely, for a stated purpose. Results should then be freely shared, so that we can accelerate consensus on further testing investments. This narrowing of test practice and sharing of paid-for results, never happened. My own sharing here, from my own investment, is a start.
My Test Results
I owned a Minneapolis blower door from 8/15/2008 to 5/16/2009, to dutifully employ it for air sealing test-in and test out in qualification of customer rebates. Finding no other resource, I trained myself with measurements in my 1955 single-story ranch home, 986 sf. I quickly found a stable, repeatable 1330 CFM50 Baseline result. This is 10.1 ACH50, a bit more drafty than the 7 ACH50 target for a healthy home. Tightening my home would take more than three years of staged effort, never to need or to again employ a blower door.

Higashi, October 2008:
The first test in a customer home was done 10/17/2008, a larger single story home, testing in at 1625 CFM50, 14.4 ACH50. The home tested out 11/10/2008 at 1410 CFM50, 12.5 ACH50,  with $27 per year saving of cost to heat makeup air. This was in sealing and insulating of poor solid-steel HVAC ducts of both attic (return) and crawl space (heated), with no other evident opportunities. An air sealing rebate of $215 was paid at a foolishly-offered $1 per CFM50 reduction. The work did not include any discovery under blower door conditions. The crazy ducts block crawl space access and are likely to be detached and again to leak, soon. I did not feel good about this, but always seek the maximum offered rebate for a customer.

Bronner, November 2008:
The second test was done 11/24/2008, testing in to check work of one notorious HPwES crew. who failed to do any apparent sealing, missing quite-large opportunities including a garage wall holed by long-ago car impact of a wood pile. The test-in was 3740 CFM50 in a complex 1937 two-story home, 11.8 ACH50. The test out 1/19/2009 was 3050 CFM50, 9.6 ACH50, but this large improvement, not earned, is thought to be due to closing the door to a conditioned basement, not likely the condition in other tests. I became fatally disenchanted with my blower door here. A blower door show would never be of any use to me in finding anything, and only wasted a half day of progress. I immediately sensed that prior testers in a home always used their blower door only as a marketing scam, not understanding readings at all and doing nothing useful by the testing; always spending more time in testing than in crude and unguided “sealing.”

Costello, December 2008:
The third test in a customer home was done 12/12/2008, testing in at 760 CFM50 in a small single story ranch home, a tight 7.0 ACH50. There were no sealing opportunities and no test-out, where the attic was insulated and the crawl space was sealed and conditioned.

Levine, February 2009:
This is a typical bungalow home with top half-story weirdness, with result 2300 CFM50, 12.0 ACH50. There were no sealing opportunities in my attic access and insulation work, and no test-out.

Three jobs have shed light on other contractor’s misuse of a blower door, and the magnitude of home leakage that might be found in the majority of existing homes, which were built before 1990.

Wheeler: (January 2010)
This is a 914 sf single-story home built in 1951. It was evaluated as one of 200 homes in a 2008 pilot program of assigning Energy Performance Scores, EPS, in existing homes. The assigned EPS score of 80, was done with PTCS duct sealing  and with R30 insulation of the crawl space by an independent contractor. A blower door test-in of 3670 CFM50 was reported. Extremely large 30 ACH50 was not computed, and was not attributed to a fallen-down duct in the crawl space. That duct was simply reattached by the CS insulation contractor, who may have needed to remove and then reset, all ducts. At May, 2010 and no longer owning  a blower door, I just thoroughly fixed things in the attic of this home. Fixes included replacing broken HVAC solid steel ducts much in the way and frequently stepped-upon, that had been gauze-wrapped and gooped as evident teaching of PTCS that goop fixes anything; the goal is cheapness independent of durability and safety against traffic hazards. I would hereafter have complete disdain for PTCS and EPS.

Weigand: (May, 2010)
This is a 1400 sf single-story home built about 1970. It was  my second confrontation with one notorious HPwES crew, which reported 4220 CFM50, 22.6 ACH50. This extremely large infiltration, not flagged for concern, is in part the result of construction with exterior walls open to the attic. I thoroughly insulated the attic of this home, with preparation including replacement of many poor solid-steel HVAC ducts, sealed air tight. I was not allowed to cap the exterior walls.

Chamberlain: (October 2011)
This is a 1590 sf single-story home built in 1973. This was  my third confrontation with one notorious HPwES crew. The home tested in at 3392 CFM50 (20 ACH50), and tested out at 2248 CFM50 (13.2 ACH50). The very large CFM50 change, 1144 CFM50, at paid cost $450, might have qualified an air sealing rebate of more than $1000, but in the end this home owner did not get any air sealing rebate. The achievement not rewarded, was fraudulent, with perhaps-deliberate misuse of a door to generate most of the reduction. Negligible sealing was achieved in the attic, leaving test-in of about 20 ACH50. My very thorough and imaginative sealing surely reduced leakage by more than half, less than 10 ACH50, but in this Energy Trust did not care. I could not engage a volunteer to do the test out as a learning exercise.


More than 30 ACH50  is possible then in pre-1990 existing homes, where testing is with detached HVAC ducts. Absent detached ducts, numbers much more than 12 ACH50, are not in my experience. I did try to employ my blower door just before it was sold, in a 3500 sf three-story home in Northeast Portland, and found I would have needed several blowers to generate minus fifty pascals test conditions. The evident problem was balloon frame construction, and my interest in testing was over. I can ony suggest that this home with hydronic heat, no heat ducts, was well under 30 ACH50 test-in.


In the course of this exercise I discovered writing by Allison Bailes III PhD, Energy Vanguard, upon discoveries in his Atlanta condominium, built around 1970. Higher infiltration numbers are to be expected in multi-family homes, but his blower door numbers surprise me. 
(At July 18, 2016)
http://www.energyvanguard.com/blog/how-i-achieved-a-21-increase-in-airtightness
Here find test-in at 29.6 ACH50, where part of a bathroom ceiling is missing. Ceiling patched, and with some air tight sealing of exterior walls, the number is down to still-large 20.8 ACH50. Despite advocacy for and practice of blower door testing, Mr. Bailes seems to despair of further reducing his condo fresh air supply.

He had previously found that Celotex exterior sheathing under a brick exterior of the complex was severely buckled. 
(At April 26, 2016)
http://www.energyvanguard.com/blog/air-flow-pathways-in-a-leaky-bathroom-wall 

Here is the report of fixing the exterior sheathing leakage, at a bathroom wall only.
(At May 23, 2016)
http://www.energyvanguard.com/blog/how-to-fix-a-leaky-underinsulated-exterior-wall 


Also in the course of this exercise I found that homes built from 1994 to 2004 are notoriously leaky, due to cheapening of exterior sheathing, at least in New Zealand . The leakiness refers first to rot problems. We in USA too have cheapened exterior sheathing in reliance upon house wrap, and have had lapses in provisions to screen and drain falling water. Where this is thought the concern of building science, a blower door operator will not be depended upon for solutions.