Don’t Forget the V in HVAC

V stands for ventilation and if you don’t control it you are in big trouble.

“Ventilation is the one thing that if you truly understand it, you can save yourself from that dreaded callback in ten years.” Al CobbThis goes for the owner of a SIPs house as well as the installer. The Department of Energy’s National Laboratories did a study and found that SIPs walls are 15 times tighter than stick-framed walls.  This is great news for the performance of SIP walls but if the HVAC contractor hired for the job doesn’t fully understand just how well a SIPs house can perform, how tightly it controls airflow, big problems can develop.

This is a recurrent theme. If we don’t understand the emerging technologies used in our own homes and how it relates to bulk water management, the homes we live in will fail and bite us in the butt as well as the pocketbook. Cobb says that the common practice of designing our HVAC systems for the worst-case scenario is stupid. What’s worse is that HVAC systems that are designed for worst-case stick-frames homes are routinely applied to the best case performance of SIPs.In gross terms this means a 10-ton ventilation system will be applied to a house that demands only 3 tons. In real terms this means you might have a machine in your mechanical room that resembles a semi truck when all you need is a Volkswagen.

Bear with me as I take the deep dive.

 

When an oversize system tries to cool a small space (or a large space that is well sealed) it cycles on for a only short time before it reads that the air is at the target temperature and shuts off. But what it doesn’t do, what it doesn’t have time to do, is condition the air. In rough terms, conditioning the air means bringing it to the proper humidity. This means that while the air is cooled to the proper temperature, the humidity continues to rise out of control.

If the system is properly sized this doesn’t happen. Instead of cycling on and off, a right-size system works at a lower capacity for longer intervals. This gives the system time to remove the moisture from the air. So instead of creating a room that is wet and clammy at 67 degrees it creates a room that is drier and more comfortable at 72 degrees.

This allows for a whole host of benefits of air quality.

Enough of science. Here is a flipbook of the fun we had today.

Beer 30

Why Houses Rot

The fact is rot is not a SIPs house issue; it’s a modern house issue. As we strive to make houses that have tighter envelopes with less air infiltration and that are more efficient, as we strive to build houses that put less demand on HVAC systems, as we strive to build houses that cost less to live in and put less demand on the earth’s resources, as we strive to create house that are built green, we put more demand on our building systems and reduce our acceptable margin of error.

Here’s how that works.

This is my house.  

 

It’s a 200 year old colonial where air flows in and out freely. Let’s just say there is plenty of indoor-outdoor transition because there is not a stitch of insulation in it. This is not a good thing for house efficiency. If I decided to insulate the entire structure, replace the windows, and seal all the doors I might have a warmer house but I might create big problems. Say I missed a spot. For argument’s sake, say I left a two inch hole in the corner of an upstairs bedroom. All the air that used to move in and out of the entire structure would now try to rush through that small hole in the bedroom wall.

This winter all the moist, warm air in the house would be trying to get out that hole. As it mets the sub-zero air coming in from the outside, the moisture in the warm air would condense. Water droplets would form on the inside of the wall. It would seep down the wall cavity and soak the insulation. It would pool on every horizontal surface and waterlog inside the wall. If, when I insulated, I added vapor barriers on the interior and exterior surfaces (not unheard of), the water would be trapped inside. Rot and mold would take hold. If I didn’t’ notice right away the problem would go unchecked and half my wall would rot away while I was playing in the snow.

 

Photo courtesy PDPhoto.org

This is a microcosm of the building efficiency evolution over the last thirty years: good intent and innovation applied without a complete understanding of bulk water management. SIPs are a flashpoint for problems because the envelope is so tight that small lapses, like an improperly sealed roof vent, create big problems like a rotten roof. The #1 weapon we have to combat problems in a tight house is a good HVAC system that is designed for the house (I will have more on HVAC in upcoming posts). But first we have to seal the house and this is where the techniques of SIP installation really hit the ground. This is what we learned today.

First and foremost, create tight joints.

Use an approved sealant on all the seams.

 

Spline or block all seams.

Use straps to pull the panels together tightly.

Secure panels with the right screws.

 

Don’t let things slide.

This joint went together easily and looked fine from the outside but when we looked at the bottom, we saw a gap from the overburn of the EPS. The thing to do here is mark the gap where we will see it later, then fill it when we go back to foam the joints.

I was exposed to so many good things today it would be impossible to cover it all. Here are just a few pictures I snapped along the way. Enjoy!

Notch your Speed Square for easy marking.

Charles H Byrd III, professional SIPs installer: “I’ve been installing sips for years and this is my second time through the course. I’m still learning stuff.”

$$$$$ The Cost Equation Clarified $$$$$

The question that came up almost immediately when I first started looking into SIPs was: Why do they cost so much?

The answer I kept getting was that you have to compare apples to apples. That wasn’t good enough for me so I would press the issue but couldn’t get very far. Frustratingly they didn’t want to come out and talk directly about money . They (I’m using  “they” to protect my sources) would say you can’t compare SIPs to stud framed walls.Today Al Cobb was able to explain the cost equation to me in terms that are simple to understand.

If you want to build a structure that has very low insulation demands, say an outhouse in Arizona, it is much cheaper to build it with stud framing. If you build it with SIPs it will be more insulation than you can use.

Outhouse

If, on the other hand, your energy efficiency standard is very high, say a heated privy at the North Pole, you may never be able to achieve a level of acceptable comfort with studs stuffed with all the batt insulation you can find. However, if you build it with SIPs, the inherent insulated value would keep your toes and tush so toasty you could read the entire New York Times in comfort.

North Pole Put simply, SIPs are the most cost effective way to achieve a premium insulated structure. I had promised notes on Best Practices and Learning from Our Mistakes but today those subjects were covered in a business overview. I’m going to hold off for now. Al Cobb promised me that he will go over some juicy worst case scenarios before the class is finished.

Some pictures of class.

Me after a day in class.  

Note on this blog: I’ve embedded links to the site but they are not as visible as I would like. If you look carefully the words in blue are hot links.

SIP School Gets Real

This is my last cramming session before things get real.

And like in college, I have to deal with some distractions. 

But enough of distractions. The itinerary for the first day is…

The points that sound interesting are the points of Best Practices and Learning from Our Mistakes. I expect to have good notes on these topics.These two topics are of special interest to me because in my casual conversations with builders I have been surprised to hear how many of them expect to build with SIPs, if not in their next project, in a project coming up soon.

Al Cobb told me that he thinks the biggest thing holding back the SIP industry is a lack of trained installers. I think that says a lot about the state of the home building industry. Things are changing fast. Not many of the people I have talked to are asking what’s wrong with traditional stud framing. Most people are asking how do we make building better and keep up with the mandates of a changing world.

Here’s a note on my bias: I am not a proponent of a specific building system, but I am a proponent of using the best methods and practices available to us. As the posts follow I will hedge them in advance. The point of this exercise is to get inside the SIP building method. It’s important to keep a critical perspective but as I consider the pros and cons of SIPs it’s just as critical for me to take a deep dive; to take off my flotation devices so to speak. It’s up to you all to keep me honest. I welcome the diversity of points of view. If you have questions about what I post or disagree with what I am saying, post a comment.

I’ll leave it at that and see you all tomorrow.

SIPs raise big questions

Building with SIPs raises a whole host of questions; a never ending stream of what ifs, what abouts, and I never thought of thats.

I bat these questions around in conversations and online and make lists of questions for the industry experts. I’ll get to these questions…

But first I digress.       

 

My grandfather was an ironworker. He worked the day he died and I never met him. My father was a rivet catcher until he said FU to that and never looked back. More power to him and my growing up sheltered. I huffed dust as a framing and finish carpenter until I laid down my own nail gun and started banging away at a keyboard. I look back every day and love every minute of it. What I had and what I have.

              

It works for me because I still have the connection to shelter. Our shelters evolve with us and we evolve into them. For most of us, our shelter is our single biggest investment and asset. Also for most of us, it’s our single  biggest consumptive item. It’s our biggest black mark on the earth.

And it’s the place we can make the biggest positive impact. 

What are SIPs and what do Frank Lloyd Wright and Alden B. Dow have to do with them?

SIPs are basically big Oreo cookies with foam on the inside and OSB on the outside. Now that I’m thinking about it, I think a SIP is more like an ice cream sandwich. They are structural so they don’t have stud framing and they go up FAST; days as opposed to weeks and weeks to months.

To the non-initiated (which I am) building with SIPs raises tons of questions. But let me get to the flash and flame first: Frank Lloyd Wright.

–Some of the earliest examples of sandwich-panel technology can be found in the Usonian Houses designed by Frank Lloyd Wright– Michael Morley, Building with SIPs.

OK so who invented them? According to SIPA  (Structural Insulated Panel Association) SIPs were invented by engineers at the Forest Products Laboratory (FPL) in Madison, Wisconsin, in the mid 1930’s. But SIPs may never have made any news if it weren’t for a student of Frank Lloyd Wright; Alden B. Dow  (son of Dow Chemical founder). Dow started experimenting with insulted panels in the 1950s and built the first Styrofoam houses in Midland, MI, in 1951. While the history is compelling, I am really interested in the uses that people are coming up with today.

Stronger Lighter Faster SIPs are coming. Are you ready?

Am I ready? This is the question I asked myself when I got this assignment.

Immediately I knew I was going to need a better grasp of the subject than I could get by simply visiting a job site and taking a few pictures. So I decided to attend a SIPs installation certification course . I signed up a month ago and had anticipated putting in tons of research. I wanted to be the expert on SIPs before I even went.I wouldn’t say I’ve procrastinated but of course Turkey day is here and I’ve only got the next few days to get myself informed about SIPs before the real fun begins on November 27th. My first day at SIP school… In the mean time, here are a few pics of some SIPs.

   

Are SIPs for real?

 Fine Homebuilding Assitant Editor John Ross

I’m on a gonzo journalism assignment for Fine Homebuilding Magazine (or as gonzo as we get in the annals of serious how-to). In this blog I’ll bring you the chronicle of my investigation into what some are saying is the next generation of residential structures.