Video: Designing a Better Wall for a Wet Climate

It’s a big day at Portland Built as we officially launch our new video documentary project! The goal is to help visitors better understand the technology, products, and businesses behind the site.

For our first effort we went to the Live/Work project to discuss wall assembly design, thermal bridging, and insulation.

A big thanks to Jeremy Dunham at Polara Studios for his help in producing our first segment. Share your thoughts in the comments area below.

UPDATE: For those of you with an iphone, or if you just prefer the YouTube experience, here’s another version of the video. We’ve had to cut out some sections in order to meet YouTube’s 10-minute maximum length. (click on the image to watch in HD)

Insulation: A Tight Fit Equals Big Savings

Insulation is probably the best place to spend money when it comes to getting a return on investment. It’s cheap, installs quickly, and can make a real difference in the bottom-line costs of operating a home.

We recently hired Noe Gaxiola of Vale Insulation Group (503.799.4436) to insulate the interior of the Live/Work project. Noe came highly recommended by my friend, Jennifer, who worked in the industry for many years.

Like many of the trades on the project, Noe went above and beyond the call on our project. He sealed every single nook and cranny of the building with an expanding foal sealant. This will help keep the heat in and – more importantly – keep cold air OUT. “Air infiltration” is widely recognized as one of the biggest causes of heat loss, and Noe went to extreme lengths to ensure an air-tight building envelope. Here’s a close-up of some his work around an exterior window (the foam gets trimmed once it dries):

Foam Insulation Close Up

What really impressed me about Noe’s work was that he provided a lot of value for a very reasonable price.

While it may appear that insulation is just about stuffing stud bays, there’s actually quite a bit of art/skill to installing the bats properly. In fact, many studies have shown that a major loss of heat is attributed to poorly installed insulation. High R-value insulation does little good if the insulation is crammed and crushed around electrical, plumbing and other obstacles. A good installer like Noe pays careful attention and FITS the insulation in every void.

Big thanks to Noe and his small-but-mighty crew at Vale!

Second Floor Insulation

Post Script: There are a LOT of options for insulating a home (blown in cellulose, reccyled cotton, closed and open cell foam, etc). We even considered foam at one point. It’s superior for preventing air infiltration, and would have been the best choice for our vaulted ceiling. Unfortunately, the cost differential between fiberglass and other technologies was a budget buster.

Live/Work Update: Exterior Trim

It’s been a while since the last post…the delay mostly being due to the fact that I’ve spent every waking moment on the electrical system.

The good news? We passed our inspection on the first try! For an experienced electrician, this is not a big deal. But for a DIY homeowner, this is almost unheard of. I did have some great help (lots of books) and some great advice from the “right” people. Thanks to everyone who contributed to my ever-expanding knowledge-base.

Windows and Doors

Doors and windows arrived last week and the crew at Bronze Construction started installing right after the product arrived on-site. I should mention we took a bit of a risk here: while Bronze had a track-record for rough framing, they aren’t exactly a dedicated window/door/siding crew. But, after a few conversations with the owner, my contractor decided it was worth the risk.

Our decision to go this route was based on several key factors. First, there was cost. Most of the siding bids we had received were out-of-this-world expensive. And while siding isn’t necessarily easy work, our budget couldn’t afford the figures we were seeing. Santos (Bronze) was much more reasonably priced.

The second factor wass the fact that Bronze had a good track record on the Live/Work project. During rough framing, they fixed mistakes without nickle-and-diming us to death (I won’t mention other subs who weren’t quite so stellar). At the end of the day, Santos’ guys were good at framing and the business owner stood by his work. That’s worth a lot, and I was willing to place my bet on these guys a second time around.

Flashing

A big part of the windows and doors is flashing. And this project had a flashing system unlike anything you’ve probably ever seen. To put it in simple terms, we have a layer of plywood, then a layer of tyvek, then a layer of pink foam. On TOP of the foam sits the windows and trim work. To keep the water from running inside, we cut back the foam and tyvek to the wall, then ran “z” flashing to the face of the head trim. Any water that got behind the foam would run down the tyvek until exiting the building via the z-flashing. A picture (or video) is needed to tell the story, but for now suffice to say we’ve created perhaps the most redundant rain barrier known to man.

Window Flashing Detail

The down side to this system is that it takes a bit of time to install, and the crew needs to be extra careful not to cut the tyvek in the wrong spot. Once again, I’ve been impressed by the Bronze crew, as they seem to have managed to get everything in place, in the RIGHT place. Kudos also to my contractor, Rory Read, who spent vast amounts of time explaining and supervising.

Live/Work Update: Roof, Electrical, Plumbing, House Wrap

It’s been a busy month at the Live/Work project. After the guys at Bronze finished framing, we started in on roofing, plumbing, electrical, and the exterior house wrap. Let me just say that the addition of the roof (thanks T-Mix!) was a huge blessing, especially with the recent spat of bad weather.

The Electrician Arrives

I’ve made the decision to tackle the rough-electrical myself. The project budget dictated some cuts, and doing the wiring made the most sense. It’s not for the faint of heart – up and down ladders, drilling holes, pulling wire…it makes for a long day. There’s a good reason electricians get paid well – they generally earn it! That said, I’m happy with the decision. It’s enabled me to make small changes to the lighting, plug placement, and switches. All of this would have been difficult (or expensive) if someone else were wiring the project.

Wrapping it Up

Another big change you can see in the photo above is that we’ve started to wrap the house. We went round and round over our final wall details, and finally settled on a system that’s affordable, energy efficient, and weather resistant. Here’s a simple graphic showing how the exterior wall works:

Exterior Wall and WrapThe idea here is to accomplish several things. The Tyvek (house wrap) prevents water from reaching the plywood. This is a fairly typical use of the product – you’ll see it used over and over in new developments because it’s cheap, goes up quickly, and keeps the water out (mostly). What’s different about this configuration is 1) the use of plywood instead of OSB and 2) pink foam board (R5) on the exterior.

Thermal Bridging

The purpose of the pink board is to prevent thermal bridging. Thermal bridging occurs when you have a material with poor insulation characteristics that touches both a warm and cool surface. In home construction, the primary source for thermal bridging are the 2×6’s used in the stud walls. Because studs touch the exterior envelope AND the interior drywall, they act ass conduits for heat loss. The pink board creates an insulated envelope that reduces the heat loss, while also reducing air infiltration and providing a second layer of water protection.

Flir, a company that makes thermal imaging cameras, has some great shots of this in action on their website. Here’s just one example showing the “cold” 2×4’s in the wall:

Exterior Walls Thermal Bridging

My contractor, Rory Read, has also spearheaded several advanced framing techniques to better insulate the home. Thes have included things like 24″ spacing on studs, hangers for door and window headers, and hollow-corners when possible. I’ve really come to appreciate the level of detail he put into making sure the house was an energy efficient as possible…without breaking the bank.

Vent Pipes Never Looked So Sexy

On my last trip to the Harpoon House I observed a cool strategy for getting plumbing out of the walls. Why would you want to do this? For one, insulation improvement. The more stuff in the walls, the less insulation can fit in the cavity. More insulation = more efficiency = lower heating/cooling bills.

Here’s an example of a simple yet brilliant way to deal with one of the most common pieces of plumbing: a vent pipe. By running the pipe outside the house and behind the siding, the homeowners have effectively increased their wall’s R-value without adding significant additional costs. Since the home’s design already included a rain screen, bumping the siding out another 2″ meant they could run the pipe up the side of the house.

Harpoon House makes use of SIP panels, so this makes even more sense (SIPs are pre-fabricated, preinsulated panels). The fewer holes and tunnels you put in the panel and insulation, the fewer opportunites for air intrusion and heat loss. Kudos to the Harpooners!

Live/Work Update: Framing!

This has to be the most satisfying part of the project thusfar – seeing the walls raised and the building begin to take form.

The crew from Bronze Construction arrived today in force. In almost no time, they had the sill plates in place and the first wall established. It’s amazing to watch a team of experienced framers work together…especially when you consider the 26 degree weather (and did I mention wind chill?).

Fortunately, nothing slowed these guys down. In fact, things might have progressed a little TOO quickly when we realized the wall studs were nailed 16″ on center (as opposed to the 24″ we had specified). A BIG kudo to Bronze’s owner, Santos, for agreeing to make it right. His guys tore out the studs and replaced at the correct distance.

One Wall Framed!

Why is this important? Well, for several reasons: first, less material means a slightly more eco-friendly approach to framing. Secondly, and perhaps more significantly, the 24″ centers allows us to use more insulation. Wood has a very low R-value, and the more you have, the less efficient the building.

And, speaking of efficiency, I’m glad to see my contractor, Rory Read, has made some great strides in reducing the amount of wood used throughout the project. One example is in the headers above the windows. By specifying metal brackets (instead of 2×4 jacks) we’re reducing the amount of wood in the wall and allowing for even more insulation. Rory’s actually done a lot of research in this area, and I’ll follow up with a post on some of these techniques. Our goal is to build a highly efficient building at a reasonable budget.

Here’s a shot of the building at 5:00:

CRW_0565

Insulation: Calculating Your Cost and Savings

One of the big revolutions in building technology has been the significant increase in insulation. And I’m not just talking going from R-13 walls to R-21. No, what I mean are the super-insulated buildings you see in both LEED and Passive projects (often with walls as high as R-40!)

The revelation, of course, is that energy is an increasingly expensive commodity, and that insulation is one of the cheapest, easiest to use building materials available. Simple changes to the design and framing can have a dramatic impact on energy use…to a point where homes can be heated by the equivalent of a hair dryer! Yes, that’s right – imagine heating your home with just a few hundred watts…

Slab-Insulation

How much is enough (or is there such a thing as too much)?

Of course we all have a budget, so determining the “right” amount of insulation is critical. At the Live/Work project, we were recently faced with this dilemma. The plans called for 2 1/2″ thick insulation under the slab perimeter, and 1″ in the field. Since this idea of multiple thicknesses for insulation seemed somewhat silly (it was easier to just insulate the same thickness across the field) we ordered 2″ for everywhere under the slab.

However, after giving this some more thought and research, we considered adding more than one layer of foam. The question was: how much makes sense?

Do the Math

To help decide how much foam we needed, we performed a series of calculations based on the loss of heat per hour (BTU) and assumed a number of heating days per year. Here’s how we started:

  • Assume 50 degrees outside, 70 degrees inside (20 degree differential equals “Delta T”)
  • 1000 sq ft of surface
  • Formula to calculate BTU loss: 1/R-Value x Delta T x Area.

Now, we were planning on using 2″ board across the surface – this would provide us with an insulation value of R-10. Pretty much standard building code these days. However, passive houses use as much as 16″ of foam (R-80), so we needed to dig a little deeper in our analysis.

  • 2″ Pink Board (R-10): 1/10 x 20° x 1,000 sq ft = 2,000 BTU/hr – This was our baseline
  • 4″ Pink Board (R-20): 1/20 x 20° x 1,000 sq ft = 1,000 BTU/hr

Ok, so I’m not sure what a 1000 BTUs looks like, but loosing 1000 of them per hour sounds significant. But what about the cost?

  • 2″ Pink Board = $1,097 per 1000 sq. ft.
  • Subtract the cost of gravel that will no longer be required under the slab ($216)
  • Total additional cost for 2″ board = $877

Next, we needed to calculate the cost of a BTU. This is a little tricky, since the gas company measures in “gas units” and “therms.” So, to avoid getting even more geeky than what we’ve discussed so far, it boils down to this:

  • 1 Therm = 100,000 BTUs.
  • In Portland, using NW Natural, at current rates, the cost of 1000 BTUs per hour is roughly .015 cents (based on NW Natural’s recent rate reduction – it had been closer to .017 cents per 1000)
  • If you’re using electricity, based on the rates in our NE neighborhood, your cost is roughly .027 cents per hour.

The next calculation gets even more subjective and is based on the number of heating days per season (in other words, out of 365 days per year, how many days require you to use the home’s heating system).

  • Based on a 150-day season, running the system 24 hours a day, our annual heat loss cost is $54 (gas) at 1000 BTUs per hour.
  • At that cost, and factoring in the $877 for extra foam, it would take us 16 years to obtain payback on our additional 2″ of foam.

In the end, we decided to split the difference and go with 3″ of insulation, achieved by two staggered sheets of 1″ and 2″ foam. This decision was made for two reasons. First, going to 4 full inches of foam was a bit of a budget buster. With the 16 year payback, it was a tough sell, especially considering that this math was based on several factors:

  • We’re assuming 24-hour occupancy of the lower floor. Since the lower area will be used primarily as an art studio, its use will be much more limited in duration.
  • We’re assuming a 70 degree constant temperature. In reality, a working studio space doesn’t need to be nearly this warm, as the act of working and moving around the space diminishes the need for higher temperatures.

One of the other reasons we decided to go with the 1″+2″ foam combo was that it would allow us the benefit of staggered seams. In other words, by overlapping the sheets of foam, we’d achieve a benefit of greater vapor resistance than if we had just used a single layer of 2″ or even 4″ foam.

Additional Resources

There’s a lively discussion of this topic over at the Green Building Advisor. Just as we discovered, there is a tipping point for insulation where the cost of installation starts to outweigh the benefits. Other resources include (of all things) a great page from Fairbanks Natural Gas which shows how to compare the cost of natural gas to other heating sources. Of course, if you are factoring in CO2 emissions, there’s more to consider than just dollars and sense.

And, to get some perspective, here’s a photo of what 16″ of foam looks like (Photo credit: GreenBuildingAdvisor.com)

16" of Foam Used Under the Slab

Live/Work Update: Slab Insulation

Over the last few days the concrete crew has been hard at work putting in place our under-slab insulation. The pink board (also known as extruded polystyrene or EPS) serves several important purposes. First, it’s a barrier between the slab and the ground, minimizing heat loss. Since we’re using a radiant hydronic heating system, it’s critical that we insulate to prevent heating the earth.

In addition to serving as an insulator, the pink board also acts as a water vapor and moisture barrier. In Portland, water is a BIG deal, so it’s critical we do everything possible to limit the amount of moisture entering the structure.

Foam and Rebar

Our strategy for insulating the slab involved 2 layers of foam, staggered so that the seams don’t overlap. Our theory here is that by overlapping the panels (and using a sheet of plastic underneath) we’ll dramatically reduce the path for moisture to enter the slab. Our total R-value for the insulation is around R15 (a layer of 2″ foam and a layer of 1″ foam).

In the photo above, you can also see the slab rebar, as well as the rough-ins for our plumbing. We passed our plumbing inspection (yeah!) and are setting up to pour on November 25th (weather permitting). Take a look at the gallery to see more photos from the recent concrete pour and plumbing rough in.

Also, for a more detailed post on why wee weent with 3″ of insultation, check out this post.