Friday, September 16, 2011

Smelling Asphalt

For a whole week I've been trying to decide what material to use to waterproof my brick and stone walls. Brick and stone are porous, so at some point in the wall system there has to be a "moisture barrier" to prevent water from migrating through the masonry and into the house.

The first option, suggested by my consulting builder, was a product called Karnak 220. It's a black, asphalt based, liquid-applied coating. So I scheduled to meet with the guy who would apply it to go over exactly where I did and didn't want it. Then I texted my boss to let him know I would be a little late that day for a meeting about waterproofing my masonry. My boss texted back, "That's a big step. Watch the VOC's!"

For the uninitiated, that stands for "volatile organic compounds," which emit nasty little molecules that can be inhaled. The green-building revolution of the past decade has declared war on VOC's, and I think for good reason - they are not good for human lungs. Now you can find even big-name brands of paint offering "low-VOC" and "no-VOC" options. No-VOC paint is quite impressive - it goes up wet with no smell whatsoever.

It was just a plain oversight on my part to have not considered the VOC level of this waterproofing material. In my case it is especially important since this coating will be facing the interior of my house. This type of waterproofing is usually applied to the outside surface of a concrete block wall that will be later concealed with a brick veneer. VOC's are not so significant in that case since they are not emitted towards the interior spaces of the building. In my case the only things separating my Great Room from this potentially hazardous coating is some insulation and wood boards. My boss's little reminder sent me on a search for a low-VOC alternative.

I've always wanted this house to be a healing place, not just for the spirit but for the body. This is part of the reason I'm using all-natural materials as often as possible. It's like the architectural equivalent of organic food. The body God has designed for us should be respected and honored by not just how we eat and exercise but the materials we surround ourselves with day in and day out. The building industry, like the food industry, has come to rely heavily on the use of various chemicals that turn out to be harmful to people and nature in general. In recent years we have seen this begin to change, but there is a long way to go. Still most of our buildings are built with drywall, carpet and paint that contain adhesives, formaldehyde and other chemicals that emit gases not good for us to breathe. A Church House should be a respite from all that, a "breath of fresh air" in all kinds of ways, not least the physical.

Assuming that the asphalt in the Karnak material would send its VOC content soaring, I looked elsewhere immediately. I found a liquid-applied moisture barrier from Dupont that is advertised as low-VOC. I called about it and found out that the cost would be about three times that of the Karnak. A bit steep, but I was ready to use it if it meant better IAQ ("indoor air quality" - another buzz-phrase from green-building culture). While I waited to receive an exact price from the company for my project I looked up the VOC content of the material on their website: 25-30 g/L. I'm still not sure what those units are, but I learned that the lower the number the better.

So just out of curiosity I looked up the VOC content of Karnak. None listed on the website. Ahah! I thought - too high to even mention. Still curious, I called Karnak. I said I was interested in a low-VOC coating, half expecting them to say "Low WHAT?" They surprised me by offering the Karnak 100 or 220 - the latter being the one my builder suggested. I asked for the VOC level. He said "20 g/L, at the most." That's lower than the "low-VOC" Dupont product.

I called the Karnak applier I met on site that day to ask if he could put some of the product on a scrap brick for me to see and smell. I was thinking that even if the VOC level is low, I still didn't want to smell asphalt in my Great Room. Also Karnak seemed to give conflicting messages on their website, saying in one place that the product has no odors and no fumes, and in another place to be careful about inhaling the product in enclosed spaces. So today I smelled the asphalt.

I detected only a hint of tar in the brick he coated today, and not even a hint in a brick he coated yesterday. He had told me earlier that the product has a little odor when wet but not at all after it's dried. He also left a bucket of the stuff on site so I could read the info on the side. There I found its actual VOC content: 10 g/L.

So I think that issue is settled - Karnak is cheaper AND has less than half the VOC content of the Dupont product. Oh yeah, and also I got a call from Dupont just today saying that they cannot offer their product for the "residential market" at this point, but only for commercial projects. Again I'm amused and annoyed at the way the building industry seems to think the physical properties of water are different for "commercial" and "residential" buildings. I need moisture protection just as much as they do! Eventually I'll learn to just start calling this project a church - which is considered "commercial" in that it is not (supposed to be) "residential."

There is another issue though - vapor permeability - that I'm weighing out with a few other products, and I won't dare bore you with the specifics of THAT consideration. It's even more technical than this one was. Rest assured there will be some kind of coating on my brick and stone next week; and I think - probably, at this point - it will be Karnak 220.

It's been a few days since I wrote the above. Now the waterproofing for the brick walls is complete:

Notice it's not black. Because it's not Karnak. I had become more concerned about Karnak's lack of vapor permeability. This could cause condensation to form on the inside of my brick and stone walls, which over time could soak my insulation and rot the wood studs. I needed something that would stop liquid water but allow water vapor to pass through.

For a few hours I was excited about just using a low-VOC acrylic paint. Spray on several coats and it will keep out water, AND acrylic is vapor permeable. I ran it by my boss, who also thought it was a great idea - for a few hours. Then we both realized that in a few years it will crack and peal, and there will be no way to re-paint since it's inside the wall.

Then I happened upon "Perm-A-Barrier," a liquid waterproofing product specially formulated to be vapor permeable. It is also low-VOC. Then I saw the price tag. This would cost even more than Dupont's Tyvek, many times more than Karnak. But again, I was willing to sacrifice for the right product.

At some point in the midst of all this my boss suggested looking into a cement-based coating that we specified for the exterior of a Meineke Center a couple years ago: "Thoroseal." I was initially skeptical, but as I re-read the information we had on it the more right it seemed for my situation. What about VOC's? I called the company: ZERO VOC's. Well, except for the admixture; that has a whole 1 g/L. Done deal there. How about cost? And is it locally available? And can my guy apply it? I called him; he had never heard of Thoroseal. I called my consulting builder, who had also never heard of it. I started to worry. After all, this step has to be completed before framing starts, which is set for next week.

But to my surprise the company's website showed a distributer here in Wilmington. I called and found out that Thoroseal was the least expensive option yet, cheaper even than Karnak. And anyone can apply it. And they didn't even ask if I was using it for a commercial or a residential building! I like equal-opportunity building material distributors. So that gray stuff on my brick walls is Thoroseal.

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