Insulation - Sealing and Insulation in New Construction

Larry Janesky from Dr. Energy Saver walks us through the process of air sealing and insulating two newly constructed condominium units. In new construction, you have many choices of insulation material to chose from: spray foam, rigid foam board, fiberglass, cellulose or a combination of these.

Insulating Two Condominium Units

There are different ways to insulate new construction. There is fiber glass baths, there is spray foam, there is sprayed cellulose which is very good, and there is blown cellulose in the attics and on the flats and on cathedrals. We're going to be doing a combination of those things here today.

Hidden Air Leaks

Here is something else that we look for, is holes that are drilled to the outside by the electricians and plumbers. As you could see, they drilled a hole here and it was in the wrong spot, so they drilled one here. You could see daylight right through it.

Garage Wall Insulation

The wall between the house and the garage has to be insulated because the garage is unheated and the house is heated, so that's where you want insulation, between heated and unheated spaces. We're using fiberglass bats in the walls, the interior walls between the garage and the house.

Cellulose Insulation Seals It Tight

But cellulose insulation is just much, much better than fiberglass bats because it seals all the air leaks. It's very dense and has an excellent R-value per inch. This wall is R-16 compared to R-13 for fiberglass at best. This is genuinely R-16.

Read Full Video Transcript Below:

Larry Janesky: Hi, I'm Larry Janesky from Doctor Energy Saver. Today we're going to be insulating these two condominium units. There are different ways to insulate new construction. There is fiber glass baths, there is spray foam, there is sprayed cellulose which is very good, and there is blown cellulose in the attics and on the flats and on cathedrals. We're going to be doing a combination of those things here today. We're not going to be doing any spray foam. The builder didn't want to have that done. But sprayed cellulose is excellent. Blown cellulose is fantastic, and we're going to mix it in with some fiberglass bats according to the builder's specification. Let's take a look. We have the windows taped off because we're going to be doing sprayed cellulose into the walls. And one of the first things that we do is we seal around the window and door frames with spray foam like that. And so we're going to seal.

You see the daylight in there? Well, that is a lot of air leakage all around that window coming in right around. The only thing that would stop that air leakage is your interior trim, which doesn't stop it. I mean it comes in around the interior trim and it contributes to drafts, and people say, "Well, I want to change my windows to stop my drafts," but it may not be the windows. It might be the space around the window that's actually leaking the most air. So we want to seal this up. In an existing home, what you could do is take off the interior trim and then foam around this shin space and put the trim back. Now, of course, you'll have to repaint the trim and re-caulk it and so forth, the nail holes and all that, so it's a bit of a project but it could be worth it because that lets a lot of unconditioned air into the house. Now, if we look here, we see daylight through the wall sheathing, and we can seal that up.

Now cellulose would do a pretty good job of sealing air leakage like that. Here is something else that we look for, is holes that are drilled to the outside by the electricians and plumbers. As you could see, they drilled a hole here and it was in the wrong spot, so they drilled one here. You could see daylight right through it. Now the siders are going to come by and they are going to cut a hole in the siding. Then the electrician will put the sconce light fixture on the outside of the wall outside the door, but there will be a hole into the wall cavity. So with sprayed cellulose, you're sealing that air leakage from that hole. Whereas with a fiberglass bat, you're going to get air leakage, cold air leaking in from the outside and running right through this cavity, making the whole part of the wall cold with a fiberglass bat. But nevertheless, when we're going around sealing windows and doors, we'll just seal up these holes, and now we don't have to worry about it. Here is a duct chase and we've got supply and return ducts going up to the attic.

If there is air that can leak through this chase, it escapes right into the attic. So this is an important place to seal around these ducts where they go through the floors and to seal the ducts themselves because you'll often get duct leakage. So if we look here, here is a hole in the duct where the ducts go right together and it's just sealed with this little flap of sheet metal so it's not sealed. And what happens is if this is the return line, it's going to suck air from this cavity which is open to the attic and it will suck unconditioned air back into the return. So in the summer, [indiscernible] air conditioned air but it's sucking 140 degree air into this hole at all the gaps in the duct, and it's just a lot harder to cool 140 degree air than it is to cool return air that might be 80 degrees from the house.

Here, we have leaks in supply ducts, and you can see that, again, the same thing. And this goes up, and as you can see, feeds all the rooms, all the supply registers on the second floor. And when this duct is pressurized and air is going to leak out of here, hot air in the winter, cold air in the summer and it's going to be lost to the vented attic. So the attic is outside thermally. Just think of it as the outside. It's vented with outside air. And so this duct leakage is going to cause the homeowner money over the years. And so these ducts should all be sealed before this chase gets closed in with drywall. Here we have the garage, and the garage is unheated, of course, so the sealing has to be insulated, and we're going to do that with fiberglass bats.

And the wall between the house and the garage has to be insulated because the garage is unheated and the house is heated, so that's where you want insulation, between heated and unheated spaces. So we're using fiberglass bats in the walls, the interior walls between the garage and the house. Now, if this had sheathing on it, if it was an exterior wall, we would blow it with cellulose because that's much better.

But this is an open frame wall, open on both sides, so we will deal with that as the builder requested. We're going to get started spraying cellulose on these exterior wall cavities pretty soon. But this is a room upstairs, the master bedroom, and we have baffling here because the wall comes up flat and then we have a soffit vent and a slope part of the ceiling that goes to the flat part of the ceiling. So later on, we're going to come in here. We're going blow cellulose insulation on top of the dry wall and a flat part of the ceiling and fill up these slopes with cellulose from the attic. And these baffles will keep that cellulose from filling the soffits and blocking the soffit vents. Over here, we have a master closet so this is going to be heated. But then, we have an attic space. This is a bit unusual but we have a big walk-in attic space right off the master closet, and this is going to be a vented space.

Now, it's not the way I would do it. We know that if we put our thermal boundary here and we made this conditioned space, that's the way I would do it. But according to the builder's specification, they didn't want to add to any more of the heated square footage of the house. They want it to be no more than 2,200 square feet so they want this to be unheated, vented from the soffits to the attic. So what we've got to do is insulate the walls between this attic space in the master closet, which we have started doing here with fiberglass bats only because they are open walls. There is a way to spray cellulose in these walls if we put a facing, matting on here, which is like the bottom of your couch, kind of a mesh, and we've stapled it on one side and sprayed the cellulose on the other side. But in this case, the builder wanted bats here, okay. So we're going to insulate this whole area around the unheated attic space with fiberglass bats, and then we've got to insulate this floor underneath. And so there is a room underneath here that we're going to insulate the floor from underneath with fiberglass bats. There is a number of different ways to do it, especially today when you have cellulose, you have fiberglass, you have sprayed cellulose, blown cellulose, and you got to spray foam. So, lots of different options.

Spray foam is your most expensive but it will get you the highest R-value per inch and do a great job of air sealing. Spray foam is definitely the Cadillac. But it adds thousands and thousands of dollars to the cost of the house. So, sprayed cellulose and blown cellulose in the attic does a great job. Stops air leaks. Stop airflow in the wall cavities very well. Not as good as spray foam but pretty good. And it's a fraction of the price of spray foam, so cellulose is a fantastic way to go. Each insulation has its place. As you can see here, we're using some bats here. We're using some sprayed cellulose here, blown cellulose there. We could use some spray foam in places. Or we could do the whole house in spray foam or the whole house in cellulose. But you try to use the right insulation for that wall, for that application that's going to be the most efficient and cost effective for you.

Sprayed cellulose insulation is very messy, and that's why we do walls on new construction. We wouldn't do this in an existing home, of course, because you have drywall on the wall and you can't get to it anyway, so we inject foam in existing home walls. But cellulose insulation is just much, much better than fiberglass bats because it seals all the air leaks. It's very dense and has an excellent R-value per inch. This wall is R-16 compared to R-13 for fiberglass at best. This is genuinely R-16. And if it was my house, I would love to have this in my walls. So we're going to continue on these two condo units and get them tight and warm. If you have a new home that needs insulation or you have an existing home that you want to be more comfortable, warmer in the winter, cooler in the summer, and lower your energy bills, call Dr. Energy Saver.

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