Thermal Envelope & New Home Insulation

Behind The Walls Video Series: Part 5 of 12

In this installment of our 12-video Behind The Walls series, Mike Goodrich explains the thermal envelope and how we insulate our Legend Homes.

Watch the video to see how we design and build our homes to keep you more comfortable more efficiently.

Video Transcript

So we want to talk a little bit about the insulation of the home and the thermal envelop of the home. The thermal envelop is going to be the insulation underneath the floor, the insulation up the walls, [and] the insulation in the attic up above. We’re going to create and envelop basically around this home that’s insulated and sealed against the weather. That’s going to keep the inside inside and the outside outside for the most basics of it.

You’re probably used to seeing Batt insulation ( “Batt” insulation, not “Bad” insulation) on the outside wall – that’s fiberglass batts. They come in a big, long sheet. They’re installed in the wall and wherever there is an electrical outlet or pipe or another obstruction in the wall like that that insulation has to be cut and then tried to form around that. That’s very difficult to try to install in the field and it leaves little voids. Also, where it’s tucked into the stud bays there it leaves little voids.

Insulation doesn’t work unless it’s touching a surface on all six sides. We want that insulation to touch the bottom plate, the top plate, outside wall, the inside of the inside wall and the studs on both sides for it to actually work.

So we use a blown-in insulation. That’s what you see here. We put the netting up on the wall. We blow the insulation on the inside of it. It’s get behind all the electrical boxes. It’s gets behind all the pipes and around it and it’s so effective that where the same thickness of insulation is rated as an R21 and the Batt insulation is rated an R23.

So once we’ve established this thermal barrier (We’ve got some insulation underneath the floor. We’ve added additional to that and some additional insulation in the attic.), we want to make sure that the air that we have on the inside is conditioned as effectively as possible. And the way that a lot of us used to build homes was to put the furnace out in the garage and the we’d take and warm up that air out in the garage. Then we’d blow it underneath your crawl space or then we’d blow it through the attic on top and then we’d bring it back inside your home. As it’s going through the crawl space, or as it’s going through the attic, it has the possibility of losing heat. If you have a depressurization system it could pick up air that we don’t necessarily want in the home.

So the logical step was to move all of that equipment inside the home and that’s what we’ve done here. The furnace is upstairs. It’s a 95-percent efficient furnace. It doesn’t draw any combustion air. It’s a sealed unit. So we’re going to pipe in the combustion air from the outside and we’re going to pipe the bad stuff right to the outside.

And then we’re going to take that conditioned air now and we’re going to pump it within this conditioned space that we’ve created and that’s what you see here up in the ceiling. We’re pumping down into this ductwork [and] we’re running all the ductwork in-between the two floors in the home.

[It’s a] very, very efficient system. We thoroughly test ductwork connections before we cover everything up so we know we’re not going to have a lot of air leaking out of it. Basically, we’re going to create a tight envelope. We’re going to control the amount of air that we put into it, and we’re going to test to make sure that’s going to all the places we want it to.

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