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Ran D. St. Clair · 08-19-2009, 06:54 PM

Geofkaye,

I think you have a valid point about the liquid nails and FRP. I should have done some destructive testing before I got so far along. At this point the deed is mostly done, but I could get some Polyseamseal and run a bead up and down the sides of the studs to help out the liquid nails. I also meant to rough up the walls with my disk sander before gluing but got in a hurry (excuses, excuses). For the benefit of others, here is the web site for Polyseamseal.

http://www.polyseamseal.com/allpurpose.shtml

I am sure a 2 part epoxy would have been very strong, but given the slow process for putting up the individual studs it would have been onerous. Fortunately, once the plywood goes up it will effectively lock everything in place. The inner walls can't peel away from the outer walls because the floor and ceiling will get in the way.

Electrical will run up through the floor, but once inside be distributed via conduit in the walls and ceiling. It might be easier to run things under the floor, but I don't like the idea of exposed wires running around under there. I would have to put conduit under and around the frame bits, which I may have to do to some extent anyway, but mostly I want to run from the underbed boxes up through the floor and then remain in the protected environment inside the box.

I am surprised to hear you say I only need 2.5" insulation in the ceiling. I had heard a somewhat vague unscientific statement that 80% (or something like that) of heat loss was through the ceiling. Therefore I had assumed that I wanted considerably more insulation in the ceiling than the walls. At this point the rafters are already in place so I will just fill it with R-Maxx to 5 1/2" thick at the most, and less in places where the shape of the roof or conduit dictates. If I spend a little more than I needed to on insulation then it will probably be one of my smaller mistakes on this project.

Speaking of insulation, I am wondering what is your opinion of using multiple layers with aluminum foil on the layers. In the walls for example, I was thinking to use 3 layers of 1/2" R-MAXX with the foil to the inside. I don't have a good handle on the exact physics of how multiple layers of foil would relate to the reflection, absorbtion, and re-radiation of IR energy through the layers, but my intuition suggests it would be more effective than just one layer, especially if the foil on that one layer is in direct contact with the plywood of the inner walls. Once again, this is an area where I am willing to spend money.

Beyond the R-MAXX I will be using the can foam to fill cracks and lock everything into place. That and I figure a plastic vaper barrier just before I throw up the inner plywood. I am hoping that this will be one very well insulated structure, and so well sealed that I will have to pay special attention to venting to keep from dying for lack of air.

Thanks for your input. I am listening...

08-19-2009, 06:54 PM	#33
Ran D. St. Clair Senior Member Join Date: Apr 2009 Posts: 212	Geofkaye, I think you have a valid point about the liquid nails and FRP. I should have done some destructive testing before I got so far along. At this point the deed is mostly done, but I could get some Polyseamseal and run a bead up and down the sides of the studs to help out the liquid nails. I also meant to rough up the walls with my disk sander before gluing but got in a hurry (excuses, excuses). For the benefit of others, here is the web site for Polyseamseal. http://www.polyseamseal.com/allpurpose.shtml I am sure a 2 part epoxy would have been very strong, but given the slow process for putting up the individual studs it would have been onerous. Fortunately, once the plywood goes up it will effectively lock everything in place. The inner walls can't peel away from the outer walls because the floor and ceiling will get in the way. Electrical will run up through the floor, but once inside be distributed via conduit in the walls and ceiling. It might be easier to run things under the floor, but I don't like the idea of exposed wires running around under there. I would have to put conduit under and around the frame bits, which I may have to do to some extent anyway, but mostly I want to run from the underbed boxes up through the floor and then remain in the protected environment inside the box. I am surprised to hear you say I only need 2.5" insulation in the ceiling. I had heard a somewhat vague unscientific statement that 80% (or something like that) of heat loss was through the ceiling. Therefore I had assumed that I wanted considerably more insulation in the ceiling than the walls. At this point the rafters are already in place so I will just fill it with R-Maxx to 5 1/2" thick at the most, and less in places where the shape of the roof or conduit dictates. If I spend a little more than I needed to on insulation then it will probably be one of my smaller mistakes on this project. Speaking of insulation, I am wondering what is your opinion of using multiple layers with aluminum foil on the layers. In the walls for example, I was thinking to use 3 layers of 1/2" R-MAXX with the foil to the inside. I don't have a good handle on the exact physics of how multiple layers of foil would relate to the reflection, absorbtion, and re-radiation of IR energy through the layers, but my intuition suggests it would be more effective than just one layer, especially if the foil on that one layer is in direct contact with the plywood of the inner walls. Once again, this is an area where I am willing to spend money. Beyond the R-MAXX I will be using the can foam to fill cracks and lock everything into place. That and I figure a plastic vaper barrier just before I throw up the inner plywood. I am hoping that this will be one very well insulated structure, and so well sealed that I will have to pay special attention to venting to keep from dying for lack of air. Thanks for your input. I am listening...