Insulation riddle resolved

February 4th, 2010
Written by Marcus de la fleur

I spent a lot of time last October and November researching appropriate insulation options. In the post “Insulation – how much is needed?“, I described the SPF (spray polyurethane foam) phenomenon of diminishing returns.

I somewhat understood the concept of this effect, but had no information on the actual process or cause. So I asked whether anyone had more information on this.

Lo and behold, I received a comment on the post from a gentleman called R. Tom:

“… a report that illustrates a scenario that uses Fourier’s steady-state heat flow equation to evaluate the performance of a typical wall area with a prescribed R performance value. The results are quite profound… it indicates, basically, that the first inch of [SPF] insulation represents 80% of the heat flow reduction in the system, the next inch 9%, the next inch 3%, the next inch 2%, the next two inches 1% each and the next four inches only 1%! So in the first 2″ you are getting 89% of the total performance realized in your [SPF] insulation assembly.”

The report R. Tom mentions is a publication by Icynene Inc., describing the testing process, providing the math and plotting the results in various graphs.

My first thought was: “Is this for real?” I forwarded the report to a mechanical engineer I respect and asked for his opinion. He agreed with the rationales and results of the report.

Here is what my sleepy little brain cells retained. There are three types of heat flow:

Conductive heat flow
Convective heat flow
Radiant heat flow

The R-value is a measure of the conductive heat flow resistance through a material, but ignores the influence of convective and radiant heat flow. SPF insulation has an R-value of 3.6 per inch thickness (as per the report). If properly applied, SPF can eliminate air infiltration (or convective heat flow), and thus delivers up to 89% of the total performance in the first 2 inches. I think I sort of get this.

My second thought was: “How does this impact our project? Do I need to rethink our insulation strategy?” The answer is yes. Now that I understand the effectiveness of the first two inches of SPF and the decline thereafter, I would like to look again at various insulation materials and their performance, cost and environmental footprint.

PS: I found a great website that explains SPF in plain language:

Tags: economics, insulation
Posted in research | 5 Comments »

Door follow up

February 2nd, 2010
Written by Marcus de la fleur

I can’t get the issue of the heat loss through a standard steel door frame out of my mind. I keep thinking of potential condensation issue, associated moisture problems and what difference a frame with a thermal break could make.

Then, just the other day, I found myself staring at a perfect example of heat transfer, heat loss, and subsequently condensation. It wasn’t a typical steel door frame, but an aluminum frame window. Still the same principles apply.

In cold weather, the aluminum frame loses heat to the outside, cooling down below the dew point on the inside, which causes the condensation.

On the vertical surface of a typical steel door frame, the condensate is likely to run down and collect on the floor. Here it could cause moisture problems, such as rust at the bottom of the steel frame, and could also lead to mold growth.

It is good to have come across a visual reference on what the problems looks like. Test data on a thermal break frame are encouraging and could, I’d like to think, eliminate this problem of excessive heat loss and condensation.

Tags: energy, insulation, water
Posted in research | No Comments »

Sound asleep?

January 31st, 2010
Written by Marcus de la fleur

While researching exterior doors for the basement, I visited a number of home improvement stores, but not by choice!

I started online, looking for available products. I found some products alright, but little meaningful information on their energy performance. Recently, some stores added eco or green categories to their product lists, which filter eco or green items (in my case qualifying exterior doors). I am still left guessing what eco or green means, because no or little definitions are offered.

Depending on the store, you may or may not learn if the door is Energy Star qualified, but there is no word anywhere on the NFRC rating or the products R-value or U-value. To get this information I had to go into the store and look for the labels and ratings on the actual product.

In these days of a $1,500 Federal Tax Credit, green building programs and incentives, this information (such as the energy performance on a door) determines if a product cuts it or not. Wouldn’t you think that the retailers would fall over themselves, including this information on their product web pages?

I have the suspicion that somebody in the marketing department is sound asleep!

Tags: energy, insulation
Posted in research | 1 Comment »

Confusing doors

January 26th, 2010
Written by Marcus de la fleur

I wrote about the masonry repair work around the basement front door.

That work is done, but I still need a new door and looking for one quickly turned confusing.

I started with a visit to various home improvement stores. What I found were exterior rated doors with a 24 or 22 gauge steel skin, insulated foam core and wood frame. The good news is that these doors are typically Energy Star qualified and are eligible for the $1,500 Federal Tax Credit.

The bad news is that they don’t offer enough security and could easily be kicked in. That is what happened with the original door, which had not only a steel skin but also a light gauge steel frame! We consider the basement front door to be the most vulnerable to a break-in, as it is tucked away in a little staircase alongside the house.

I wanted to know where the professionals get their doors and asked my contractor friends. The first thing I learned is that I am probably looking for a commercial grade door rather than a residential door.

Commercial doors come with a heavier steel skin (typ. 18 gauge) and sound steel frame (typ. 16 and 14 gauge). There is no kicking in this door without getting the attention of the whole block.

That takes care of the security, but what about the energy side? We put a lot of work into good insulation and efficient windows. Having a poorly insulated exterior door would leave a gaping hole in the building shell and defeat the investment into an efficient building envelope.

While visiting and talking to a number of commercial vendors, I had to be very persistent with my inquiry about insulated doors. Once they noticed that I was serious, various product information appeared from back office filing cabinets.

Door examples:

I had to be even more persistent on the door frame! What is the point on spending close to $500 on an insulated door, when an uninterrupted (one-piece) steel frame turns into a thermal highway? During wintertime, such frame has energy loss, condensation and moisture problems written all over it.

Ceco Door - Thermal Break Frame

It turns out that, after all, there are steel frames with built-in thermal breaks and that the frame profile can be filled with spray foam insulation.

Next question: How energy efficient are these commercial grade doors or assemblies?

Almost all residential doors come with a NFRC rating and tell you whether they are Energy Star qualified. This allows the consumer to compare apples to apples and determine if the product qualifies for the $1,500 Federal Tax Credit.

Commercial grade doors, on the other hand, exist in their own world, with no NFRC rating or Energy Star labels. I even called the manufactures and checked! What is provided are two R-values (calculated and operable), which differ by a factor of three to four. Confused? Me too!

Why does this matter?

Because the NFRC rating and Energy Star labels are prerequisites for credits in the Chicago Green Homes program (for which we have signed up) and the $1,500 tax credit. Looks like I will have a hell of a time to reconcile the security issue with the energy side. Anyone have any suggestions?

PS: If you are looking into doors and windows with the Energy Star label, note that the Energy Star program has new performance levels starting 01-04-2010. It is growing some teeth – finally!

Tags: economics, energy, insulation
Posted in research | No Comments »

Staircase(s)

January 21st, 2010
Written by Marcus de la fleur

The basement appears to be the flavor of the month – let’s stick with it for a little longer. How many staircases do you need to go into a basement?

Well, we currently have three ways to get downstairs. There is a staircase directly connecting the first floor unit to the basement. There is also a ‘front door’ to the basement [LINK – Basement front door] and a rear exit through the back porch.

That back porch is in bad shape and we plan on rebuilding it. This gives us the opportunity to improve the staircase layout as such that the first and second floor units will directly connect to the basement.

Going back to the question of how many staircases we need to the basement, we decided that one really would do the job. And that would be the one in the new back porch. I am sorry to say, but this was the death sentence for the existing stairs leading to the first floor.

Charming as that staircase was, the good news is that we now have an extra space on the first floor, which we can now convert into a closet or pantry.

Tags: basement, deconstruction
Posted in deconstruction | 3 Comments »

Rooting for removal

January 13th, 2010
Written by Marcus de la fleur

Back in April of ’09 I wrote about our decision to remove the existing mulberry tree in our front yard. It wasn’t a difficult decision, but a difficult task to complete.

We now have further reassurance that it was a good choice. While we were gutting the basement we came across and increasing number of roots finding their way up through the floor. They had a particularly strong presence in “the secret room” under the front stoop and stairs, which was very close to the mulberry tree.

While removing and excavating the existing basement floor we discovered a whole new network of tree roots, large and small, growing in from underneath the footing wall and popping out of the clay.

Mulberry tree roots don’t have the best reputation; they can be pretty aggressive. I am really glad that we took the tree down last April.

That said, not all roots may originate from the Mulberry tree! There is also a big Tree-of-Heaven (another junk tree species) very close to the northwest corner of our house.

This tree is also a little too close to the building and foundations for my comfort. The problem is that this tree is not on our property. I should plan to talk to our neighbor to find out how they feel about the tree, and if they would be open to replace it with another species a little further away from the building.

Tags: basement, trees and shrubs, yard
Posted in trees and shrubs | No Comments »

Basement excavation

January 11th, 2010
Written by Marcus de la fleur

After we had determined the basement elevations and devised a simple tool to check them, we were left with the unthankful task of excavating 4 to 6 inches of clay from the entire basement area. I remembered two old but useful principles helped me in that process:

Use sharp tools, because they make it easier to slice through the clay. I had an angle grinder handy and sharpened the spade and shovel at regular intervals. It made a big difference.
Hunker down and focus on the ten square feet in front of you. You’ll be amazed how much work you got done if you look up and back only every hour or two!

The clay is out and I have the required depth for all the new basement floor materials and layers.

I now look forward to investigating the location and state of the existing sewer lines, preparing for the interior perimeter footing drain, and getting everything ready for the soil gas (radon) removal system. After that, I can start on the actual basement floor layers. Things are moving along!

Tags: basement, flooring
Posted in general construction | No Comments »

Basement elevations

January 5th, 2010
Written by Marcus de la fleur

We have a plan on how to put the basement floor back together, but need to do more homework on the elevations.

Here is what we know:

We had a 7’-6” ceiling height, which we must preserve if we would ever like to convert the basement into a living space.

The old floor section, which we removed, measured 8” to 10” in depth.

The new floor cross section will require a depth of at least 12”. I would prefer 14” to keep the option of a 5” deep concrete slab and give me another inch of play at the ceiling height.

We will need to excavate 4” to 6” of clay subgrade to accommodate the new floor.

What we don’t know:

… is the depth of the footing wall – or – if we actually can excavate 4” to 6” without undermining the footing wall.

Step #1

Check the depth of the footing wall.

Easy! A spade and a couple of test holes, and it turns out that the footing wall extends beyond the 4” to 6” we’ll need to excavate.

Step #2

Let’s set and mark the elevations.

I used a pin to mark the finished floor elevation, measured at 7’-7” from the bottom of the floor joists. I also marked the depth of the concrete slab at 5” (in case I want to go from a 4” slab to a 5” slab), and the depth for the insulation at 4”.

All I need now is to excavate 4” from the bottom mark to accommodate the aggregate base.

Step #3

Find an easy way to check elevations during excavation.

I am used to placing pins and stringing up mason lines from which I can check the excavation depth with a tape measure. In this case though, the mason lines seem too much of a trip hazard.

Looking for an easier way, I realized that the bottom of the floor joists are pretty much all at the same elevation. They are spaced 16” on center and I could use them as a benchmark.

I got a 2×4, marked the total required depth (8’-8”) and notched it at the mark. I now can simply walk around with this “measuring stick” checking the excavation depth. Hooray for technology!

Tags: basement, flooring
Posted in general construction | 2 Comments »

How to put it back together

January 3rd, 2010
Written by Marcus de la fleur

I listed the various reasons why we wanted to start fresh with a new basement slab. I also mentioned a number of items and functions we hope to integrate into the new floor. It is time to figure out how we will put it all back together.

After some back and forth, we decided that a hydronic radiant floor heating system is the way to go in the basement. It makes sense and becomes somewhat cost effective, considering that we’ll start with a new floor slab. The system will meet the heating loads for the basement and add comfort.

Building codes, energy codes and Chicago Green Homes requirements aside, insulating a floor slab with a hydronic radiant system becomes imperative (see also Basement floor post). I already have half the insulation I need for under the slab. But that is only half the story, as I learned through my research.

I will have to create a bond break with the same XPS insulation around the entire floor slab perimeter (see detail above). It provides a thermal break to the foundation wall and prevents heat from bleeding out of the floor slab.

We will have to carefully seal the bond break at the top for moisture and radon gas control. If there is any radon, it should remain under the slab, where we will provide a controlled escape route. A system of perforated drainage pipes in the aggregate base is connected to a vent stack, helping to collect and remove any radon.

See also:EPA’s A Citizen’s Guide to Radon

Moisture control is built in at several levels. I already mentioned the seal over the bond break (see detail above). In addition, a polyethylene vapor barrier between the concrete slab and insulation prevents water vapor diffusion from the subgrade into the floor.

The aggregate base supporting the floor slab is ½ inch stone that also acts as a capillary break. The stone base prevents any water from wicking up from the subgrade towards the floor.

While at it, we also would like to include a perimeter drain along the entire interior of the foundation wall. The purpose of this drain is to keep the footing reasonably dry. The dryer the foundation wall the less moisture will wick up and diffuse into the open basement, where it may cause condensation problems.

Tags: drainage, flooring, indoor air quality (IAQ), insulation, water
Posted in design | No Comments »

Where did all the concrete go?

December 30th, 2009
Written by Marcus de la fleur

I hope you enjoyed the last post about the basement floor removal. We had fun swinging the sledge hammer busting that concrete floor. It ended up to be a lot of concrete!

What did we do with it – other than throwing it in the back of my truck?

While researching Construction Waste Management (CWM) options, I compiled a list of various recyclers. I found my go-to places for deconstruction debris (WasteBox, Inc.), scrap metals and clean wood debris (which is turned into wood chips).

A few weeks back, when I was getting masonry supplies for the parapet repair at the Illinois Brick Company on California, just north of I-55, I noticed their neighbor across the street, Lindahl Brothers, Inc. They have a huge pile of old concrete in their yard, which was the give-away that they run a concrete recycling facility.

Mine and any other concrete received is crushed, sorted and sieved, turning it into aggregate that can be re-used in construction. Eventually I will need some aggregate for the new basement slab. If I get my materials here, I may end up re-using the very concrete that we removed.

As prices for scrap metal fluctuate, so does the cost for recycling concrete. If nobody is buying the aggregate, the concrete pile gets bigger and the cost for dropping off concrete for recycling goes up. If the aggregate ‘flies of the shelves’, you may even be offered a buck to deliver your concrete for recycling.

I was very happy to get charged as little as $15 per truckload. It made the whole operation rather affordable.