Q&A: A Forum for Green Building Experts and Beginners

In 1985 I had a greenhouse design project through the Louisiana solar design association at LSU. I used an aluminum scissor hinge to open a vent window. It was operated by a wax-filled cylinder that had temperatures etched on the side and you set its range by screwing the cylinder in or out (clockwise or counter). The hinge was passive and worked excellent with about a 5 degree offset. The greenhouse was dismantled by another class and I never got the hinge back. It couldn't have cost much seeing I was a poor student at the time. Ever ran across these and are they still available?

Hey Martin;
New member and my first question! I've been following blogs, become a fan, and I'm on board/planning to build with exterior rigid board, using a mini-split, and concrete floors for mass.

I have read several posts regarding off gassing off 2 part foams both closed and open cell....However my question specifically relates to using the Great Stuff Dow Expanding foam around HVAC supply vents. My concern is any off gassing that may occur around these supply vents if I use this foam. I have some minor gaps that I was going to seal to enhance the air barrier. But have concerns regarding any off gassing AFTER the foam has completely cured.

Anyone have any insights into this.

I've read several posts lately mentioning a "5:1 outside to inside perm ratio with the goal of creating walls that can dry to the outside" for cold climates. Does anyone know what the ratio (along this line of thinking) would be for mixed-humid climates? It seems the goal would be to dry to both sides...but it also seems that opens the chance for moisture problems at both extremes of the year- we get 90 degree summer days with a good deal of humidity and single digit winter nights.