Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Insulation

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 01-12-2014, 04:21 PM   #1
Newbie
 
Join Date: Oct 2013
Posts: 14
Rewards Points: 10
Default

Raleigh basement insulation


Hi all,

I'm planning to frame and insulate the basement in my new-build house in Raleigh, NC soon but am trying to figure out the best insulation method. The house has a walkout basement where the back wall is floor to ceiling 2x6 framing and the side walls are a combination of both, with stepped up concrete as you go further into the grade. All concrete is poured, no blocks. Prior to backfill a perimeter drain system was added as well as black spray tar and then some type of thin wool insulation nailed to the concrete. Right now there is no insulation on the interior of the walls. From what I can gather this seems to be the preferred method of insulation:

1. XPS foam board glued directly to concrete. All seams taped or spray foamed.
2. 2x4" framing placed right on top of XPS.
3. Standard unfaced fiberglass batts between studs.
4. Drywall.
5. NO dedicated poly vapor barrier, the XPS is serving that function.

On the 2x6 walls (back walk-out portion and stepped half walls) I would just do FACED fiberglass batts. Again no poly vapor barrier.

So my questions are as follows:

1. Is this the best insulation method?
2. How thick does the XPS need to be? What I don't like about this system is I lose some inches all around depending on the XPS thickness.
3. Are the fiberglass batts necessary on the concrete portions since they'll also have XPS?
4. How do people feel about turning the 2x4 framing on edge to save some room space? Of course I'd have to lose the fiberglass batts, or maybe put some XPS in those cavities instead?

The goal here is to have some finished heated space and some shop space. But I want even the shop space insulated such that someone else could finish (really just apply flooring) that area off and use as living space.

Thanks!
Todd


Last edited by Todd1561; 01-12-2014 at 04:25 PM.
Todd1561 is offline   Reply With Quote
Old 01-13-2014, 04:44 PM   #2
Newbie
 
Join Date: Oct 2013
Posts: 14
Rewards Points: 10
Default

Raleigh basement insulation


Anyone have any thoughts?

Todd1561 is offline   Reply With Quote
Old 01-13-2014, 08:17 PM   #3
Registered User
 
Join Date: Mar 2009
Posts: 9,967
Rewards Points: 2,000
Default

Raleigh basement insulation


Zone 4, Wake county; http://energycode.pnl.gov/EnergyCode...rth%20Carolina requires R-10 XPS (2").

Add the strapping of 2x2 over the foam board, no need to cavity fill with any fibrous insulation, leave it empty. Glue it in 1'sq. grid patterns, canned foam the perimeters. Tape will loosen as the FB shrinks- eventually; better still; furnace mastic/fiber tape on joints for air-tight, or canned foam. Add a strip of FB under the bottom plate for thermal/air/capillary break; may want to use a 2x4 on edge for attaching base later... second thought; NA the FB under as you are new build (requires poly) and not a cold climate.

No vapor barrier or retarder above or below grade for your Zone 4; http://www.buildingscience.com/docum...commendations/

Gary
PS. Welcome to the forums!
__________________
If any ads are present in my answer above, I do not condone/support/use the product or services listed, they are there against my permission.
Gary in WA is offline   Reply With Quote
Old 01-13-2014, 09:02 PM   #4
Newbie
 
Join Date: Oct 2013
Posts: 14
Rewards Points: 10
Default

Raleigh basement insulation


Gary,

Thanks for the input and for the welcome, sounds about like what I was thinking. And I'm glad you don't think the fiberglass batts will be necessary now that I've calculated the cost of just the XPS I'll need! And yes there is poly under the slab, forgot to mention that. Another thing I forgot to mention is the ceilings are 12' tall. Do you think just 2x2 will be adequate for studs? I'll want to be able to hang drywall and some cabinets. 12' seems like a long span for a 2x2, not to mention trying to find a straight one that long! I'm wondering if I should do 2x4 on their side with a few concrete spikes evenly on each stud? What about doing 2' centers instead of traditional 16"? Oh and does traditional faced (or should I do unfaced?) batts sound ok for the foundation walls that are above grade 2x6?

Thanks again,
Todd
Todd1561 is offline   Reply With Quote
Old 01-13-2014, 09:59 PM   #5
Registered User
 
Join Date: Mar 2009
Posts: 9,967
Rewards Points: 2,000
Default

Raleigh basement insulation


You need to at least read a little of the links.... lol; No vapor barrier or retarder above or below grade for your Zone 4; http://www.buildingscience.com/docum...commendations/

I would pin the 2x2 anyways.... 12' wall- use 2x4 with 2-1/2' pins. 24"o.c. is fine. Add backing at cabinet top rails.... add XPS at rims; How to insulate rim joists simply

Air seal any holes in top plates they may have missed. ADA the drywall; http://www.buildingscience.com/docum...wall-approach/

Gary
__________________
If any ads are present in my answer above, I do not condone/support/use the product or services listed, they are there against my permission.
Gary in WA is offline   Reply With Quote
The Following User Says Thank You to Gary in WA For This Useful Post:
Todd1561 (01-14-2014)
Old 01-14-2014, 08:44 AM   #6
Newbie
 
Join Date: Oct 2013
Posts: 14
Rewards Points: 10
Default

Raleigh basement insulation


Yeah yeah sorry. I know you said no vapor barrier but it doesn't seem like kraft paper is considered to be much of a vapor barrier these days. But I'll be sure to use unfaced batts in those walls. Thanks for the links, I'll be sure to do the rim joists as well

Todd1561 is offline   Reply With Quote
The Following 2 Users Say Thank You to Todd1561 For This Useful Post:
Gary in WA (01-14-2014), Windows on Wash (01-14-2014)
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Basement Exterior Above Grade Insulation purpasadu Building & Construction 6 02-28-2012 05:42 PM
Insulation in basement floor joists and integrated garage speedster1 Building & Construction 3 12-07-2010 06:44 PM
Old Home - Basement addition insulation vapor barrier question 1870 Building & Construction 0 10-14-2010 08:36 AM
basement insulation advise needed bmartin5150 Building & Construction 1 04-27-2009 05:56 PM
Installing new insulation in my basement and removing the old moldy insulation. Fixitgeorge Remodeling 3 10-17-2006 09:33 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.