Tag Archives: insulation

Breeze hunting

When we give tours of our deep energy retrofit and I am asked about our insulation methods, I always point out that the insulation is only as good as the building is air tight. And I am only repeating what is being preached in the weatherization, energy retrofit and green building community.

Take a day like yesterday, with freezing temperatures and a wind chill factor as low as -20 degrees Fahrenheit. Imagine yourself all bundled up in a very warm down coat, except your front zipper doesn’t quite work for six inches and leaves a small gap. If you go and walk into the wind, you will be chilled by the cold air blowing through the faulty zipper. That little gap completely negates the warming factor you would expect from the coat.

It’s sort of the same with insulation. If I have air blowing through my insulation, I have spend a lot of money (on insulating), but won’t get the performance that would have justified the investment.

Needless to say that I was rather alarmed when I detected some drafts at our newly installed 1st floor windows. To make sure the drafts were real, I had our friend John Bergman help me trace them with a smoke pen, and mark them with a piece of blue tape.

It turns out that the idiom “The devil is in the details” is not just a saying.

A number of the leak locations coincided with the shims we used during the window installation. We were very careful to foam around the newly installed windows, but some of the shims were not foamed in.




Luckily, this took only a step ladder and a can of spray foam to correct.

I thought I was pedantic about the window installation and air sealing, but it looks like I haven’t been pedantic enough.

Related posts:

1st floor replacement windows

1st layer – closed cell insulation

Finishing the job

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2nd floor perimeter framing

Its not just a framing job, like it was on the 1st floor. This is a framing and insulation job at the same time.

Let’s look back at the 2nd floor insulation strategy.

Because the 2nd floor exterior wall consists of two wyth, rather than the three, we have a little more room for insulation. We air sealed the building with two inches of closed cell foam. Following the foam, we planned on two layers of rock wool insulation, one layer behind the framing and the second layer between the studs.

This assembly gets us to a R-value of 40 at almost the same cost of the R-28 insulation assembly from the 1st floor.

Back to the job on hand. I decided that I should try to install the first layer of rock wool together with the framing, to keep things simple. The question was, how?

For once, it turned out to be simpler than expected. We put the framing together as usual and lifted the sections into place, making sure the bottom plate was in its final position. We tilted the top of the framing section into the room. That gave us enough space to start stacking the first layer of rock wool between the framing and the closed cell insulation.

Once all the rock wool was stacked behind the tilted framing section, we pushed it into a vertical position and attached the top plate.

The attic, the space between the ceiling joists and roof joist, was a little more complicated because it is a tight space. But we followed the same principles.

What is left now is to install the second layer of rock wool between the studs.

Once it is all done, this will be a very cozy apartment!

Related posts:

1st floor perimeter wall framing

Double duty

2nd floor closed cell installation

Blower door test – before insulation

2nd floor insulation strategy

2nd floor closed cell installation

3rd layer – rock wool insulation

Insulation preps – plugging the 3” gap

Insulation preps – 3” thermal break

Insulation update

The insulation riddle is back

Following the control layers

Insulation riddle resolved

Insulation – how much is needed

Insulation – which material cuts it

Insulation – starts with moisture management

Insulation – lots of conflicts

Insulation – how it started


Utility room pipe insulation

We have diligently insulated the pipes in our plumbing system, including all hot and cold water pipes. If you want to know why, you can read up on the rationales in the blog post [LINK] “Plumbing – energy conservation (part 1)” and “Pipe insulation.” And, I shouldn’t say “we,” because Cathy did all the insulating.

We did the same thing for the PEX tubing feeding our hydronic heating system – or more simply put – the baseboard radiators.


This should help with our energy saving efforts and assures we get the precious hot water where we want and need it: At the point of use, such as the faucet or the radiator, instead of losing it along the way to the delivery point.

But one key area has not received any pipe insulation yet – the source of the hot water, the utility room. All of the piping running from our boiler to the hot water buffer tank, to the domestic hot water storage tank, and to the heating system manifolds, are still sitting there naked without their winter coats.

And this really matters, particularly when you have large hot water storage tanks like we do.

An argument against hot water storage tanks you may have come across is about “standby loss.” That’s the thermal energy that should arrive at your faucet or radiator, leaking from the storage tanks and heating up the utility room.

The hot water storage tanks come insulated, which reduces the standby loss. But the various plumbing connections to or from the tank (a minimum of four) are not. They effectively siphon the heat out of the tank along the metal plumbing lines. Just put your hand on one of those connections at your hot water tank – but be careful not to get burned!

Cathy came to the rescue to control that thermal energy bleeding. She put her skills to task and insulated the entire plumbing system in the utility room with closed cell pipe insulation.

Not an easy job, considering that some of the tubing was hidden behind the tanks and in very awkward corners. Plus, the connections at the storage tanks were rarely a uniform pipe size, but tend to step down, which required a lot of puzzling with the corresponding pipe insulation sizes.


Does this stop the heat bleeding? No. But it minimizes it and slows down the heat loss, whether through standby or the delivery process. That in turn allows for more hot water to be delivered where we need and want it – at the point of use.

Related posts:

Plumbing installation – pipe insulation

Pipe insulation

Plumbing – energy conservation (part 1)

Wrestling the unruly

Radiator déjà vu


Blower door test – after insulation

It was time to face the music – or better, the roar of the blower door fan.

Quick recap: We applied for an insulation rebate. To qualify for the rebate, we were required to demonstrate an energy savings of at least 30%. The energy savings are in part calculated on how leaky or air tight a building is.

John, from Chicago Home Performance, conducted a blower door test prior to any insulation and air sealing. That pre-improvement test is used as the baseline to calculate the energy savings. It turned out that our 2nd floor was pretty drafty at 4,763 cfm50 or 13.9 ach50.

The preparations

A lot of work has been completed since that first test:

Were we done with all the air sealing tasks? No – not yet. I still needed to install an insulated back door from the kitchen to the porch and replace the remaining double hung windows with new insulated glazing units (IGU’s).

But – with the insulation rebate deadline approaching, these items just had to wait. We needed to get the post-improvement blower door test done – quickly!

The test

John set up his blower door equipment, just like he did for the pre-improvement test. He fired up the fan – and he didn’t get a reading at first!

The blower door fan has two flow rings (A and B) and a lid that covers the center.


The building was so leaky during the pre-improvement test that John had all of the flow rings on the fan removed.


Fast forward to post-improvements: We had tightened up the building so much that, with all flow rings removed, there wasn’t enough airflow velocity through the fan to yield a valid reading. John increased the velocity by constricting the airflow with the flow ring A, and eventually with the flow ring B.


That finally gave us a valid reading:

720 cubic feet per minute at 50 pascal (720 cfm50) or 2.1 air exchanges at 50 pascal (2.1 ach50).

That is an 85% reduction compared to the 4,763 cfm50 or 13.9 ach50 of the pre-improvement test.

Needless to say that our air sealing and insulation work paid off. We were all surprised – pleasantly surprised!

The meaning of…

What does 85% reduction in air leakage or 2.1 ach50 mean? It would be more than enough to meet the energy rebate requirement of 30% energy savings. But how does it compare to other projects or standards?

The recently published International Energy Conservation Code (IECC 2012) requires buildings to meet 3 ach50 for climate zone 5 (Chicago is in climate zone 5).

The Canadian R-2000 program mandates 1.5 ach50, while the Passive House standard requires 0.6 ach50. The latter is a hard one to achieve, even in new construction.

The Green Building Advisor blog post “Blower Door Basics” by Martin Holladay mentions that “a 2002 study of 24 new Wisconsin homes showed a median air leakage of 3.9 ach50” and “new home builders in Minnesota routinely achieve 2.5 ach50.”

Mind you, these are results for new construction. Tightening up an existing building is considered to be notoriously more difficult. So I think we are doing pretty well with our 2.1 ach50 – although I would like to get it down to 1.5 ach50.

Maybe we will get there once we install the drywall, tape and mud it, once the new kitchen back door is in, and once we have all the new replacement windows installed.

To learn more about blower door tests, read the following:

GreenBuildingAdvisor.com – Blower Door Basics

Wikipedia.org – Blower door

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Double duty

The closed cell spray polyurethane foam (SPF) came in handy while solving a problem with the attic insulation.

We used salvaged four inch XPS boards under the roof joists in the attic. Because salvaged material is rarely perfect around the edges, I was left with gaps where the boards meet.


These gaps needed sealing to prevent warm air and moisture from migrating into the insulation assembly. The associated energy loss — and even more so the wetting of the roof assembly — would be counterproductive or even dangerous.

Taping over those gaps didn’t seem feasible. I thought about using spray foam cans to fill the gaps. That would would be a big and expensive job.

Sealing the seams with closed cell SPF, however, is relatively straight forward, particularly with our installer and his attention to detail.


During the SPF installation, the installer “over sprayed” the top of the wall to properly seal the interface between the XPS boards and the masonry wall. From there he moved on to the ceiling, and sealed the joints between the boards with foam.

I got the gaps between the boards closed up. But it doesn’t entirely solve the problem of air or moisture from migrating into the roof assembly. There will always be some imperfections, leaving small pathways. My plan to manage that moisture is a good subject for another blog post.

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2nd floor closed cell installation

It is time to make nails with heads, screws with threads, and foam with no gaps!

I covered the technical aspect of the 2nd floor insulation strategy, why we decided on two inches of closed cell spray polyurethane foam (SPF), and the importance of ending up with the right vapor permeance rate. We also had some excitement with our first blower door test, a prerequisite for the insulation rebate we are after.

It was time to get started with the hands-on part — the actual closed cell foam installation.


This is a good time to talk about skills. Not mine – but the skills of the SPF installer.

I had three different installers on this project. One for the garden unit, another one for the 1st floor, and Kent’s Thermaseal for the 2nd floor. I now wish I would have known about Kent’s crew when I started this project, because he would have done all floors for us.

Take a look at the video below. The cured spray foam surface may look a little rough and wavy. But believe me, that is the smoothest, most even closed cell application I have seen. It is incredibly difficult and takes a lot of skill to keep the spray foam at a consistent depth.

This experienced installer first sprays lines 16 inches on center, which he uses as depth gauges, and then sprays out the space in between.

Attention to detail

I have written about the potential consequences if the attention to detail is deficient during a SPF installation.

I didn’t have any of those issues this time around. You can see in the video how the installer is pacing himself, allowing for the foam to expand and cure, before he continues with the next pass.

He “over-sprays” at the bottom of the wall, an important detail that eliminates weak spots at this transition and change in planes.

If you carefully watch the video, you can see the installer using a depth gauge – a needle set to two inches which he pokes into the foam to see if he has reached the specified spray depth. The use of that depth gauge is not that remarkable. But the fact that the installer goes back to where he poked into the foam and applies another pass to seal up the pin hole he created, is remarkable. And he did that consistently.

That kind of attention to detail tickles me!

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2nd floor insulation strategy

I had a frantic few weeks, working my way through the to-do-list in preparation for the spray polyurethane foam (SPF) installation. It was frantic for a number of reasons.

We had the opportunity to take advantage of a $1,750 insulation rebate, which was available through Energy Impact Illinois. This particular rebate period ended on August 21, 2013, which meant that I was under the gun to get everything ready and installed in the weeks prior.

Aside from the preparations, I had to decide how exactly we would insulate the 2nd floor perimeter walls.

Insulation assembly

The first floor walls had three rows of brick (three wythe), but narrowed down to two wythe on the second floor. That freed up an additional four inches in depth toward the interior, which allowed me to consider alternative insulation strategies compared to the 1st floor and garden unit.


The solution we came up with has roughly the same price tag as the 1st floor insulation, but an R-value close to 40 (compared to R-28 on the first floor)

insulation-section-10 insulation-section-11

Two inches of closed cell SPF on the masonry wall will provide us the critical air sealing. It also exceeds the minimum recommended insulation depth to prevent moisture accumulation in the wall assembly. At two inches of SPF, the dew point during the winter months will be located mostly within the foam. This prevents condensation, or more precisely, the wetting of the interior wall assembly and potential for mold growth.

Following the two inches of closed cell foam, we will have a contiguous layer of 3 1/2 inch rock wool batts stuffed behind the interior wall framing. The wall framing itself will be filled with another layer of 3 1/2 inch rock wool batts.

The closed cell SPF has an R-value of 5.2 per inch, while the 3 1/2 inch rock wool batts are listed at R-15. With two inches of the closed cell foam and two layers of the rock wool batts, the total R-value for the insulation assembly comes in at R-40.4.

Vapor permeance

As always, the moment you think you are done is also the moment where it gets interesting.

Only a couple of years back, I had no concept of what vapor permeance is or means. This project gave me a shove and pushed me deep into this subject matter.

To assure the long term integrity of the masonry walls, I’ve had to maintain some level of drying potential, to the inside as well as to the outside of the building. That means I have been very picky about what closed cell foam product I’ve used. The higher the vapor permeance rate of the foam, the greater the drying potential into both directions.

Most closed cell foam products have a permanence rate of less than one at a depth of two inches. This would turn them into effective vapor retarders (Class II or Class I) and as such disqualifies them from this project.

I’ve had my eye on one product with 1.3 Perm at three inches (Class III vapor retarder). At the targeted spray depth of two inches, that permeance would be even higher and provided an acceptable drying potential. But I then I had to find a reasonably priced contractor that would offer to spray it.

This is where the story got really long and complicated. Maybe I should shorten it a little: We found that contractor.

Rebate requirements

The insulation rebate is not paid out in good faith, but is performance based. To qualify, a minimum energy reduction of 30% must be accomplished.

The verification of the energy reduction is a two step process.

  1. A qualified energy rater will conduct a blower door test before and after the insulation installation. The test will show to what extent the building envelope has been tightened up.
  2. The data from the blower door test and information about the insulation assembly will be used to model the projected energy reduction, which must fall at or below the required 30%.

What is that blower door test? And can we meet the 30% reduction? More about that in the next posts.

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Shrinking a long to-do list

There is a hint of excitement in the air. We have worked our way dangerously close to another milestone – the 2nd floor spray foam installation.

Whenever a task approaches that has a significant and permanent impact of the project, the preparation list become exceedingly long. The spray foam insulation is such a task.

It is a good idea to fix up any damage on the interior masonry walls and have them in prime condition before we cover them with polyurethane spray foam. We needed to insulate the attic, first with rock wool, then with XPS foam board so that we can seal the edges with spray foam.

Prior the the attic insulation, we had to complete the roof reinforcement in the dining room and kitchen area, and rebuild the load bearing wall with the appropriate vertical blocking.

Once the attic was done, we tackled the 2nd floor window buck repairs, and adjusted the kitchen window. We couldn’t do this with the spray foam on the walls.

We now have two windows left – the south facing windows.

window-02 window-03

These are probably the original double hung windows which are, from an energy standpoint, in terrible shape. A blower door test revealed how leaky they were.

The remedy: Triple glazed insulated glazing units (IGU’s) that are as good as airtight.

window-04 window-05

Yep, and what you see there around the replacement windows is spray foam. More about that in the next post.

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Closing the gap

The attic is insulated. It is now time to think about the wall insulation – or better the preparations needed prior to the wall insulation.

The purpose of the wall insulation is not just to provide thermal resistance, but also seal the building envelope to the point where we have eliminated unwanted air infiltration. A layer of closed cell foam sprayed onto the masonry wall will provide that air seal , filling all small nooks and crevices.

Dealing with the bigger gaps rests on our shoulders. And the biggest gaps are found around the old windows.

window-10 window-11

A couple of windows have most of their window sill missing. The only remaining evidence are some half rotten wood pieces that turn into dust upon touching. All those sills that still were in one piece had their age imprinted in them, similar to the weather and hard work imprinted on the face of an old farmer.


If I think about it, it’s amazing that these sills have lasted 111 years!

We have some experience replacing sills from our work on the 1st floor. There, the window bucks were in good shape, though. Something I can’t say about the 2nd floor windows.


Some moisture induced damage and rot was evident, particularly at the bottom of the buck. That damage was more pronounced on the west facing windows (the weather side) than on the east facing ones.

What to do? My friend Drew made the decision for me, more or less. He clearly was not in the mood to fuss around and strongly recommended to remove the old bucks and replace them. And that is exactly what we did.

Actually, in most cases we were able to save and/or reuse the top plate of the buck. We also used what was left of the old sills as a template to transcribe the notching for the side pieces. This allowed us frame a new buck with the exact same dimensions and in the exact same location.

An important detail, considering that we need to reuse the existing double hung windows until we can afford more efficient replacement windows.

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Attic insulation – foam board component

The attic is stuffed with rock wool, but that is only two thirds of the story.


The other one third is the XPS foam board insulation that is mounted to the bottom of the roof joists.


Material challenge

We had narrowed the material choices down to foam board, either XPS or ISO. This wasn’t the challenge. But where to find the material for a reasonable price, and at what thickness, was.

Let’s break this down.

We needed a total of four inches of foam board insulation under the roof joists. Working with four inch thick foam board would be the most efficient and require the least handling. Two inch foam board is much more common, but would require twice the amount of handling.

And foam board doesn’t come cheap. The common sizes (such as two inch boards) appear more economical compared to less common sizes (such as the four inch boards).

Salvage with a capital S

You would think that the well of good fortunes on this project had dried up by now. Yet it still had a little surprise in store for us.

While scouring the salvage markets for insulation and reaching out to my fellow green building nerds, I landed a positive response from our friend John Edel. He is working on his own sustainable building and manufacturing project, called The Plant, and was trying to find a good home for a whole bunch of salvaged four inch XPS foam board insulation.

attic-26 attic-27

The insulation came from the walk-in coolers and smokers of the old meat processing plant, which he now is converting into a urban food production hub. The XPS insulation was faced on both sides and ideal for the attic. Not only that, but he actually had enough boards for us to finish the job.



The four-inch boards required the least amount of handling – but we still had the maneuvering issue to deal with. The only way to get the boards into the attic and under the roof joists led past the ceiling joists. We had to be strategic about what board sizes we could fit through the ceiling joists into the attic and how we staged the installation without boxing us in and leaving attic sections inaccessible.

The rear section of the attic was again easier to manage as we had no ceiling joists in the way. We still had to be strategic about the staging and mindful about the fitting in the corners and around the vertical blocking.


How did we attach the four inch boards to the ceiling joists?

We pulled the facing off one side of the boards. That side (the blue side) faced down.

I purchased a large box of two inch diameter plastic washers, specifically developed for foam board insulation installation. The washers have two small prongs that allow us to push them into the foam board where they stay put.

I also purchased a large box of 6 inch screws – a special order over the internet. The screws were long enough to reach through the four inch boards and the 1/2 inch XPS strips under the roof joists. That left me with 1 1/2 inch that I could sink into the joists.

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