We have a cathedral ceiling in our house about 24 feet high. We would like to drop about the top eight feet of the ceiling down to about 16 feet high, by basically building a wall and ceiling in this area. Will this area need to be insulated?

 

Hi reztab and welcome to the forum,
The challenge with drop ceilings is they leak air like mad. If you insulate, you will be creating a cooler space above the new ceiling that will have the potential to create condensation on the current existing ceiling. You are kind of inbetween, but you still get enough cold in winter to be cautions about where the thermal barrier is placed. That thermal barrier should be a combination of your insulation, air barrier (like sheetrock), and vapor barrier. All in the same plane and in contact with each other.

If the existing ceiling is well insulated, go with just the drop. If you are trying to add an insulation layer, you will need to re-think how to build it.

Bud

 

Hi Bud.

Thank you for your reply. I am not too sure about the insulation on this part of the roof. As the house was built in 1978 there is probably some insulation between the rafters but it would be anyone's guess as to how much. I am just thinking that the dead air space would have some insulating properties or am I crazy?

 

Can I jump in with something?

Bud....I don't think rez meant a drop ceiling..like for a basement. I'm pretty sure he meant a framed ceiling with sheetrock and all.

Rez...will this space be ventilated or sealed to the existing?

 

Not crazy, but it would be a trap for moisture/condensation. The warm air inside your home can hold excess moisture. When the air comes in contact with a cooler surface it can deposit some of that moisture and that creates the potential for mold.

You are probably correct based upon standard construction requirements in 78. They would have thought the builder was crazy if he was using R-60 back then.

Is your objective to reduce heating costs and increase comfort or to eliminate the visual appearance of the high ceiling?

If you are after heating costs, a little investigating to see what is there and I can calculate your potential savings for different fixes. My suspicion is, I can recommend better places to spend that improvement money where it will yield greater savings.

One of the primary objectives of energy planning is to sort out the fixes to where you can capture the easy ones first and then plan the rest for when it coincides with other changes. Things like replacing siding are a great opportunity to add extra wall insulation and possibly new windows.

Let us know where you are going and we can offer some suggestions. There are also some home owner versions of heat loss calculators that you can play with if interested.

Bud

Edit: I always loose the typing races . I'll wait to see what he says. You are probably correct. Since I just repaired a home with an actual drop in ceiling, that is what came to mind.

 

Yes, this will be framed in with sheetrock and sealed to the existing walls. I am not doing this for any type of energy savings but just to get rid of the high ceilings and it will also create the feeling of another room space, since this is in the great room. I guess as a plus I won't have all of my heat rising up to 24' anymore. It is all wasted space anyway.

 

Now I see where you are going!
Leaving the sheetrock and insulation that is currently there, in place and then adding a new ceiling with addtional insulation is at risk for a cool space and potential moisture problems.

Are the current rafters vented from soffit to ridge vent or other? If this is vaulted on two sides, adding a new ceiling and removing the old sheetrock and insulation would create a conventional attic space. Then lots of new insulation and making sure the current ventilation is adaquate, and you would be all set.

Will there be any access to this space, say from adjacent 2nd floor space or other attics?

Bud

 

This was only vaulted on one side. The back side of this space is attic and there is insulation on the wall in this area of the attic. There will be no access into the area.
Soffit vents are minimal in this area of the house.
Another thought we have is putting a "SolaTube" through this area as this room is typically very dark.

 

Since this new space backs up to an existing attic space, I would recommend converting the new space to unheated attic and opening it up to the existing attic. Sealing in a dead air space is an unknown and as one who works on a lot of houses, access is desirable. I would not perform an energy audit on a house where I could not access all spaces. And energy audits are moving towards mandatory, i.e. when you buy or sell.

It's your choice, but from 600 miles away, that's the best I can do.

Bud

 

Bud,
Thanks for your help. I will take all of this into consideration. I really don't want to create problems for myself down the road.
Thanks again.