Forums | Home Repair | Home Improvement | Painting | Interior Decorating | Remodeling | Landscaping


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Building & Construction

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

Reply
 
Thread Tools Search this Thread Display Modes
Old 08-02-2011, 01:12 PM   #1
Member
 
Join Date: Sep 2010
Location: Nashville, TN
Posts: 31
Share |
Default

using XPS and spray foam together in stud bay


I posted this in the insulation section but i need to get some fast answers and i know not a lot of people wander over there so i am going to post it here as well.

I have four of my rooms taken down to bare studs and i am about ready to insulate the exterior walls. I am really like idea of the spray foam but i hate the price. Can i first use 2" XPS board and then 1-1.5 inch of closed cell spray foam to get 3.5" of insulation and still retain the value of spray foam? This may be a stupid question but i have searched and searched and i cant find anything about it anywhere.

I am looking at the DIY spray foam kits and they are around $1400 for 1200 board feet. That comes to about 1.16 per foot not counting waste. Foam board is about $.50 per foot and is closed cell. If this would [COLOR=blue !important][COLOR=blue !important]work[/COLOR][/COLOR] would the spray foam stick to the smooth surface of the XPS?

by the way I am in nashville tn and the home is 1200 sqf main floor and a 1200 sqf basement (70% below grade) all brick/block.

Thanks
Brad
diybrad is offline   Reply With Quote
Old 08-02-2011, 02:51 PM   #2
Member
 
Join Date: Jan 2010
Location: NW Louisiana
Posts: 71
Default

using XPS and spray foam together in stud bay


Hi Brad, I think you are on the right track using a combination of foam and some other type of cheaper insulation. Research the following terms on the internet: "Hybrid Insulation System", "Flash and Fill Insulation" and "Flash and Batt Insulation". Also for anyone doing new construction check out this method of insulating: http://www.buildingscience.com/docum...s/high-r-value

Last edited by jrepp44; 08-02-2011 at 03:15 PM. Reason: Correct Spelling
jrepp44 is offline   Reply With Quote
Old 08-02-2011, 03:14 PM   #3
Member
 
Join Date: Sep 2010
Location: Nashville, TN
Posts: 31
Default

using XPS and spray foam together in stud bay


i have seem the flash and batt type of hybrid but i still havent seen a XPS version of it or if it has been tested. The problems i have read about with the flash and batt scare me with moisture issues. what i read talked about the vapor barrier being behind the fiberglass insulation and that could cause condensation in the wrong place.

My rooms are already gutted due to a moisture and what was starting to be a mold problem. I have corrected the moisture problem but now i am looking for the most efficent i can get will a medium budget. That is where the XPS and spray foam idea came from. Moisture can get past that (or should i say probably wont).

has anyone ever used or seen it before? In theory it sounds good.
diybrad is offline   Reply With Quote
Old 08-05-2011, 10:08 PM   #4
Registered User
 
Join Date: Mar 2009
Posts: 9,872
Default

using XPS and spray foam together in stud bay


What kind of sheathing is on the walls- OSB, plywood, Celotex.....?

Is there a gap- air space between the sheathing/brick?

Use the AC much?

Gary
__________________
Clothes taking longer to dry?
Clean the dryer screen in HOT water if using fabric softener sheets.
They leave a residue that impedes air-flow, costing you money.
Clean the ducting in the last six months? 17,000 dryer fires annually!
Gary in WA is offline   Reply With Quote
Old 08-06-2011, 08:26 AM   #5
Member
 
Join Date: Sep 2010
Location: Nashville, TN
Posts: 31
Default

using XPS and spray foam together in stud bay


Quote:
Originally Posted by GBR in WA View Post
What kind of sheathing is on the walls- OSB, plywood, Celotex.....?

Is there a gap- air space between the sheathing/brick?

Use the AC much?

Gary

Its not none of the three. It is some sort of MDF or fiberous sheeting that is 1/4 thick. The there is about a 1/4 to a 1/2 air gap between the brick.

So from the outside to the inside it goes: brick, air gap, 1/4" board then the stud bay. there is no type of house wrap or air barrier.

The air gap goes up to the soffits down to the breather holes before the block foundation.

we do use the AC. we keep it set on 72-73. outside temp at worst gets to 95-100 with high humidity. in the winter we keep it around 68 if that matters.

If you have any reason that i shouldnt do this let me know. I already put the Dow XPS foam board up and i plan on spray foaming with closed cell next weekend.


Thanks
Brad
diybrad is offline   Reply With Quote
Old 08-06-2011, 08:08 PM   #6
Registered User
 
Join Date: Mar 2009
Posts: 9,872
Default

using XPS and spray foam together in stud bay


Your Zone, if #4, requires only R-10 cavity insulation (minimum). I would be worried when adding the SPF after the rigid of being too low in the permanence rating of drying to the inside effectively. Rigid foam at 2" = 0.75 perms (about same as asphalt paper faced f.g.), SPF at 1-1/2" = 0.9 perms, combined let very little moisture through. Why so much foam? You want a vapor open inside (no poly), to dry both ways. When sunshine drives the water in the brick inward, you want a permeable cavity insulation not to stop the moisture in the cavity; http://www.buildingscience.com/docum...n-brick-veneer
Echo: http://www.greenbuildingadvisor.com/...moisture-walls

You are in Zone 4, not really a cold climate: http://www.buildingscience.com/docum...s/?full_view=1

http://www.buildingscience.com/docum...commendations/

Read these recommendations and follow the links given throughout, in a location similar to yours; http://www.rlmartin.com/buildingscie.../charlotte.htm


Gary
__________________
Clothes taking longer to dry?
Clean the dryer screen in HOT water if using fabric softener sheets.
They leave a residue that impedes air-flow, costing you money.
Clean the ducting in the last six months? 17,000 dryer fires annually!
Gary in WA is offline   Reply With Quote
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





Top of Page | View New Posts

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