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Posted: 11/30/2013 7:28:11 AM EST
Quick and possibly easy question: should I insulate my basement ceiling?

House is new (2006) construction. Basement is conditioned and all exterior walls are framed out, insulated and have a vapor barrier over them. We are in the process of finishing it out with a family room, two bedrooms, bath and partially finished laundry room and unfinished utility/HVAC room. The family room and bathroom will have heated tile flooring. I've been doing some reading and it seems that it is NOT recommended to insulated the ceiling in this case.
Link Posted: 11/30/2013 7:49:53 AM EST
[Last Edit: 11/30/2013 7:52:46 AM EST by PzIvF2s]
If you do, you can't use paper faced insulation for code. It needs to be bare or the plastic wrapped for the fire code.

I haven't done it myself, but I was reading an article that said that all floors and walls should be insulated. When I redid the house, I added sound deading insulation in the interior walls and it's cool as heck especially since we had the kids. Nap time is less stressful.

Edit: check this out: This old house
Link Posted: 11/30/2013 10:27:18 AM EST
That article is one I read. They basically say that if it's a conditioned basement, insulating the ceiling isn't worth it and may be detrimental.
Link Posted: 11/30/2013 11:01:26 AM EST
Ya, the biggest bang for your buck is to do the basement floors and walls. I installed DRIcore at my parents at that made a huge difference for the.

I think I'd like to put the sound deadening insulation under my first floor just to cut down on the sound, both if you drop something on the hardwood or if I'm working on something in the basement.

Not sure if your seen this stuff before, but it's pretty easy to work with:

http://www.dricore.com/en/aboutus.aspx
Link Posted: 11/30/2013 11:07:50 AM EST
I'd be more worried about that vapor barrier on the walls.

Have you read the articles at building science?
Link Posted: 12/1/2013 12:59:29 PM EST
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Originally Posted By kallnojoy:
I'd be more worried about that vapor barrier on the walls.
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Why? That's how all houses are built here.
Link Posted: 12/2/2013 4:03:59 AM EST
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Originally Posted By pokey074:

Why? That's how all houses are built here.
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Originally Posted By pokey074:
Originally Posted By kallnojoy:
I'd be more worried about that vapor barrier on the walls.

Why? That's how all houses are built here.


Likely is code and may be good enough, but read the articles on the Building Science site regarding basement insulation best practices.

Ex: http://www.buildingscience.com/documents/information-sheets/basement-insulation

Allowing below grade walls to dry to the inside is one of the key elements, as is eliminating condensation within the wall cavity.

A vapor barrier prevents drying towards the interior as well as rarely is much of a barrier to interior moisture due to the inevitable penetrations.
Link Posted: 12/4/2013 2:33:48 AM EST
[Last Edit: 12/4/2013 2:55:17 AM EST by NotMrWizard]
We bought a house with a basement about 5 years ago. The previous owners finished the basement. They insulated the ceiling, then drywalled it. Personally, I wish the ceiling was just a false ceiling instead of drywall, to allow for accessibility if it's ever needed. But the insulation is definitely a sanity-saver with the kids. The family room and television is directly below our bedroom, and without the insulation, it would be unbearable.

There is one section of the basement that is a store room and also contains the furnace and well pump, unfinished, and the ceiling is not insulated. You can definitely tell a difference when you are inside of it, being able to hear much more sound transmission through the floor from upstairs.

I also run a dehumidifier in the basement. I keep it right about 50% humidity. The house is newer, I think about 15 years old now, and from what I can tell (by the unfinished store room), all of the basement walls are insulated, with vapor barrier that was glued along the bottom.

ETA: There are also supply and return vents in all the basement rooms (family room, office, bedroom, and store room), so there is an air exchange going on during both the heating and cooling seasons.
Link Posted: 12/4/2013 3:54:58 AM EST
Ya, I run a dehumidifier all summer in the basement. Summers up here get really muggy, and then I run a cold air humidifier on the first floor in the winter since it gets so dry. I installed hardwood throughout the house, so I have to watch swelling and shrinking.

I would bet that you'd really need insulation if you were running one of those fancy multi-zone auto baffled systems. My buddy had his basement finished and they wrapped the ceiling in drywall, no insulation I don't think they insulated, but the covered up all access to the duct dampers, so he can't balance his system any more.

I've also read about insulating only the ductwork in an attempt to preserve air temp within the duct as it's been pushed through the system.

I TRIED to close up all the seems and gaps in the ductwork, but it's an older home and they pretty much slaughtered it together. I probably should really take it all down and rerun it, but God, that's a lot of work....
Link Posted: 12/4/2013 11:24:55 AM EST
[Last Edit: 12/4/2013 11:26:27 AM EST by jjc155]
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Originally Posted By kallnojoy:
I'd be more worried about that vapor barrier on the walls.

Have you read the articles at building science?
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this

The wall needs to be able to dry to the inside. a non permenable VB will eventually trap moisture and mold.

When I have finished basements I have used rigid insulation sandwiched between the poured basement wall and the stud wall. the rigid is semi permiable and allows the wall to dry to the inside.

J-
Link Posted: 12/6/2013 8:47:40 AM EST
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Originally Posted By jjc155:


this

The wall needs to be able to dry to the inside. a non permenable VB will eventually trap moisture and mold.

When I have finished basements I have used rigid insulation sandwiched between the poured basement wall and the stud wall. the rigid is semi permiable and allows the wall to dry to the inside.

J-
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By jjc155:
Originally Posted By kallnojoy:
I'd be more worried about that vapor barrier on the walls.

Have you read the articles at building science?


this

The wall needs to be able to dry to the inside. a non permenable VB will eventually trap moisture and mold.

When I have finished basements I have used rigid insulation sandwiched between the poured basement wall and the stud wall. the rigid is semi permiable and allows the wall to dry to the inside.

J-


This!
Im guessing that the vapor barrier is poly sheeting? If so i would remove it and also any fiberglass insulation against the block/conc wall. Its a mold problem waiting to happen.

If you want insulation against the block/conc go with rigid

Link Posted: 12/6/2013 12:34:16 PM EST
Just had a contractor over last night to get a look before drywalling. He said it was done properly: fiberglass insulation with vapor barrier over it.

/shrug
Link Posted: 12/6/2013 12:48:19 PM EST
Link Posted: 12/6/2013 7:47:30 PM EST
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Originally Posted By pokey074:
Just had a contractor over last night to get a look before drywalling. He said it was done properly: fiberglass insulation with vapor barrier over it.

/shrug
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just cuz it may be code does not mean its done correctly, lol

J-
Link Posted: 12/7/2013 6:30:47 AM EST
Rigid on below grade.

Thick enough to try and get the freeze line inside the rigid insulation.

This is just another variation on 'flash and batt with sprayed on foam.

Enough foam to bury the 'frost line'(32 F point in the insulation stack) inside the rigid, fiberglass to get to the final R value.
Link Posted: 12/14/2013 2:09:07 PM EST
I used Roxul.
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