Showing posts with label t-mass. Show all posts
Showing posts with label t-mass. Show all posts

Saturday, August 11, 2007

Going Vertical



I got to witness the first big concrete pour on Thursday--very impressive. There must have been 9 or 10 concrete trucks showing up every 20 minutes or so, for over 3 hours of pouring.

It was hot and it was humid, and the crew worked their butts off. It was also somewhat humbling to find out it took a solid week to set up the forms to accomodate the T-Mass insulation, the wire reinforcing mesh, etc. Concrete guys probably like corners less than any other building trade, because it's a beast to get every form perfectly square with all the zigs and zags the walls make. Sorry guys!
The construction economies I had expected ("I'll just pour the T-mass walls and I won't have to insulate, paint or install vapor barriers" would seem to have disappeared. Aesthetically, t-mass was still the right way to go, and I still expect to save money heating and cooling the place due to the tightness and the thermal mass effect of the concrete.

Above is a panoramic photo taken 2 days after the pour, comprised of 5-6 regular shots, so don't be thrown by the bowed walls that are artifacts of the stitching-together process. There were some glitches with the aggregate hanging up and creating some voids, which is an issue with the above-ground parts and particularly those on the inside, so we'll have to come up with a touch-up approach that looks authentic and not "appliqué" – my architect's personal bête noir.

Sunday, July 22, 2007

Collaboration



Many contractors; I feel important.

The out-of-place Bimmer is mine, but will someday feel at home with the kitchen guy's Mercedes wagon (hmmm).

Barry, the general contractor, invited the key trades to meet with me and the architect, and with each other. The concrete guy won the show-and-tell award with a four-foot square sample of the T-Mass wall construction, with the Pella windows guy coming in a close second with donuts.

Kidding aside, having this kind of a kick-off meeting was a terrific idea. We caught all kinds of minor inconsistencies and omissions, and might have saved a couple bucks of rework and change orders in the process. Everyone now has a face to associate with a name, and for those that stuck around, I bought lunch at the local restaurant and cheese emporium.

Saturday, July 07, 2007

Concrete Momentum, and Panic

Momentum is the force that gets difficult projects done and keeps people from changing their minds. It breathes life into all sorts of undertakings ("Relationships are like sharks, they need to keep moving forward to stay alive. What we have here is a dead shark." --Woody Allen in "Annie Hall.")

This project ("Chartier Hermitage") has been in the works for a couple years now, and almost got built last Fall, but it lost steam when we couldn't resolve some key issues. The biggest decision was how to build and insulate the concrete walls. Concrete has essentially no insulating value of its own (although it acts as a thermal mass, like a stucco wall), and there a few ways to keep out the cold:

  • Conventional insulation on the inside--frame a wall against the inside concrete surface and fill the openings with your favorite insulation material.
  • Insulated concrete forms--the concrete is poured between forms made of a rigid Styrofoam sandwich. Called "ICFs" in the trade.
  • The "Thermomass" approach--another sandwich, but the reverse of ICFs. Concrete makes up the bread, and Styrofoam insulation is the filling. The two concrete walls are held together by plastic ties that don't conduct heat.

You guessed it, we're going for the third approach. This means that there can be a bare concrete wall on both the inside and outside, so the structural material is also the finished surface. ICFs force you to add another couple of layers to the wall on both sides, This has a lot of appeal for modernists, and, given that I'm paying a ton of money for this T-Mass approach, you're gonna see every inch of that concrete.

It also creates its own set of concerns:

  1. Not many foundation contractors have experience with this technology.
  2. It's a proprietary technology, so there's no price or product competition
  3. It's therefore not cheap. How much "not cheap" is difficult to say, because of #1, not many people do this. We couldn't get a true apples-to-apples comparison to the conventional approach because we couldn't find two T-mass foundation guys. So, while this project is in southern Wisconsin, our concrete guy is coming from Minnesota.
  4. The finish of a concrete wall is somewhat of a crapshoot. You can clean the forms so they shine, use the right release agent, spec the concrete recipe precisely and use fancy admixtures, but there's no guarantee that it'll come out the way you wanted.

Hence the panic. We start pouring in 10 days; until then, I'll be dreaming about concrete...