How To Insulate Rim Joists Simply - Insulation - DIY Chatroom Home Improvement Forum


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

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

Reply
 
Thread Tools Display Modes
Old 11-14-2013, 02:40 PM   #1
Member
 
Join Date: Sep 2012
Location: Greater Detroit area
Posts: 466
Rewards Points: 346
Default

How to insulate rim joists simply


How should I insulate my rim joists?
But I don’t want to use the 2 bottles foam kit though
I was planning to use Roxull or rigid foam
But I’ve read so many different opinions…..that I’m lost
I’ve heard that in some areas, you cannot put the rigid foam
But it seems to be one of the most used method (using 2” foam)
I was thinking about using 2” foam + Great Stuff to seal all around, or 1” foam + GF and additional layer of Roxull
I was also planning to “fix” the foam on the rim joist with some caulk, just to keep it in place with a gap of ½” all around to seal with Great Stuff

What do you think is best?

Advertisement

french_guy is offline   Reply With Quote
Old 11-14-2013, 02:46 PM   #2
bbo
Member
 
Join Date: Feb 2010
Location: Packerland !!
Posts: 1,016
Rewards Points: 500
Default

How to insulate rim joists simply


best is really perspective.

I used closed cell foam. no worries about air leakage. but more $$ for sure.

Advertisement

bbo is offline   Reply With Quote
Old 11-14-2013, 05:01 PM   #3
Member
 
Dave Sal's Avatar
 
Join Date: Dec 2012
Location: Chicago, Illinois
Posts: 299
Rewards Points: 266
Default

How to insulate rim joists simply


I did the 2" rigid foam with silicone caulk to seal around the edges. It was relatively easy, inasmuch as squatting around in a crawl space can be. I also closed off the two outside air vents and sealed them up with the rigid foam as well. The crawl space temps now stay an average of 63 degrees all year round. Pic attached of rigid foam in place prior to caulking the edges.
Attached Thumbnails
How to insulate rim joists simply-rigid-foam-rim-joist.jpg  
Dave Sal is offline   Reply With Quote
Old 11-14-2013, 05:08 PM   #4
Member
 
concretemasonry's Avatar
 
Join Date: Oct 2006
Location: Minneapolis/St. Paul, Minnesota - Latitude 45.057 Longitude -93.074
Posts: 3,825
Rewards Points: 2,138
Default

How to insulate rim joists simply


I precut some scrap 2" XPS that was sized a little loose for the typical opening (box cutter and snap). I put a small bead of Great Stuff around to seal and then immediately jammed the XPS pieces in and left the foam to fill and adhere the XPS. I then stuffed in some fiberglass (probably not necessary) but it was handy, but Roxul would be better and you could do it at on you time table after the XPS and foam were in place.

It made a world of difference and I got rid of a lot of "waste".

Dick
concretemasonry is online now   Reply With Quote
Old 11-14-2013, 09:33 PM   #5
Member
 
Join Date: Dec 2011
Location: zentral Iowa
Posts: 1,269
Rewards Points: 624
Default

How to insulate rim joists simply


When I build, I sheath with 1" xps and I save all my window and door cut-outs. I rip them to the joist width on a table saw, then set my saw up in the basement and measure each space and cut them to length plus a bit.

I "friction fit" the pieces in, 2" thick. If I have some 2" stuff left over from the concrete walls, I'll use it up as well. I'll use a hole saw to cut out for the 2" pvc going to the furnace, and any sleeves I have for the line set, etc., then cut them in half at the hole and put them in.

No problems getting to fit tight with the friction fit, but if I have some extra free caulk, I'll caulk the edges. Then I put some fiberglass on top of it.

With 1" of xps on the outside of the rim joist and 2" on the inside, I figure I have r-15, then I put 13 of fiberglass on top of that and call it good.
cleveman is offline   Reply With Quote
The Following User Says Thank You to cleveman For This Useful Post:
concretemasonry (11-14-2013)
Old 11-14-2013, 10:47 PM   #6
Registered User
 
Join Date: Mar 2009
Posts: 9,986
Rewards Points: 2,038
Default

How to insulate rim joists simply


Quote:
Originally Posted by french_guy View Post
How should I insulate my rim joists?
But I don’t want to use the 2 bottles foam kit though
I was planning to use Roxull or rigid foam-------

---------- Roxul alone will not stop the exterior air infiltrating or basement moisture from condensing on the rim. Requires foil-faced and thick enough to prevent condensation. The more fibrous insulation behind it, the thicker fb required because it will be insulated from the heat source and run colder--- exterior fb doesn't matter; last paragraph-- http://www.buildingfoundation.umn.ed...oistphenom.htm


But I’ve read so many different opinions…..that I’m lost

I’ve heard that in some areas, you cannot put the rigid foam---

-- many locales require an ignition barrier or thermal barrier= additional fiberglass batt or mineral wool batt---- or drywall, check locally with AHJ. Many accept foil-faced polyiso (PIC) as it doesn't require either. Google Thermax. Caulk the rim joints to sheathing/mudsill/joists - then add the PIC/canned foam.


But it seems to be one of the most used method (using 2” foam)
I was thinking about using 2” foam + Great Stuff to seal all around, or 1” foam + GF and additional layer of Roxull
I was also planning to “fix” the foam on the rim joist with some caulk, just to keep it in place with a gap of ½” all around to seal with Great Stuff

What do you think is best?
That should work.... 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.

Last edited by Gary in WA; 11-14-2013 at 10:54 PM.
Gary in WA is offline   Reply With Quote
Old 11-24-2013, 07:29 AM   #7
Member
 
Join Date: Dec 2010
Location: New Castle, DE
Posts: 156
Rewards Points: 87
Default

How to insulate rim joists simply


Did the 2" foamboard + GreatStuf on the rim joists here, this morning is below freezing with goddawful winds (my winter standard apparently) and I can already see a marked difference. Quick + cheap + (relatively) easy for an improvement I can feel? I'll take it every time, all that swearing in the crawlspace was worth it.
ThatDaveGuy is offline   Reply With Quote
The Following User Says Thank You to ThatDaveGuy For This Useful Post:
Dave Sal (11-24-2013)
Old 11-24-2013, 09:07 PM   #8
Member
 
Join Date: Sep 2012
Location: Greater Detroit area
Posts: 466
Rewards Points: 346
Default

How to insulate rim joists simply


So how did you do it exactly (step by step)?
french_guy is offline   Reply With Quote
Old 11-25-2013, 07:05 PM   #9
Registered User
 
Join Date: Mar 2009
Posts: 9,986
Rewards Points: 2,038
Default

How to insulate rim joists simply


If asking Dave, ignore the rest of this post....lol.



Caulk all joints in the cavity on the rim joist. This is your first-line of defense against air infiltration- no point in letting it get to the inside of rim to condense. Cut foil-faced foam board (2") min. 1/2" smaller than width/length dimensions of cavity. It HAS to be foil-faced to stop condensation/moisture passage; " Thus in these cases, the alternative is to install rigid insulation (such as foil-faced polyisocyanurate) flush against the interior side of the sheathing. This still allows air drying of the rim joist cavity but reduces the potential for interior summer condensation by decreasing the condensation surface to the bare minimum of the interstices of the insulation/ sheathing interface. In the winter, the insulation is protected from interior-sourced water vapor by the foil-facing." From; http://www.buildingfoundation.umn.ed...oistphenom.htm

Add foam compatible adhesive on the back around the perimeter and a center bead vertically to make two sections (in case you missed a 1/32" gap to the outside with the caulking) - this is second-line of defense that will limit air/moisture movement by 1/2 surface area. Press it against rim after adding glob of hot-melt glue or two for temp. holding power, centering it in space. When adhesive is dry (per label), add low-expanding "Window-n-door" canned foam around perimeter, not "Great stuff"(high-expanding). More on reusing foam can; http://netcrafting.com/homemx/greatstuff.html

Reason for caulking rim joist first; http://www.buildingscience.com/docum...d-but-strange/

And, page 51; http://books.google.com/books?id=iwS...joists&f=false

Remember; the more fibrous cavity insulation you add in front of the foamed rim, the thicker the fb required to keep the dew-point down.

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
Old 11-25-2013, 07:51 PM   #10
Member
 
Join Date: Oct 2011
Location: Ohio
Posts: 2,611
Rewards Points: 2,130
Default

How to insulate rim joists simply


spray foam
Attached Thumbnails
How to insulate rim joists simply-att-20b4.jpg   How to insulate rim joists simply-att-20after.jpg   How to insulate rim joists simply-100_5512.jpg   How to insulate rim joists simply-100_9672.jpg  
hammerlane is offline   Reply With Quote
Old 11-25-2013, 07:51 PM   #11
Member
 
Join Date: Sep 2012
Location: Greater Detroit area
Posts: 466
Rewards Points: 346
Default

How to insulate rim joists simply


Cool, thanks
Very well explained
I went to my local HD, and I didn't see the 2" foil faced foam though.....!!!!
french_guy is offline   Reply With Quote
Old 11-25-2013, 10:37 PM   #12
Member
 
Dave Sal's Avatar
 
Join Date: Dec 2012
Location: Chicago, Illinois
Posts: 299
Rewards Points: 266
Default

How to insulate rim joists simply


Quote:
Originally Posted by french_guy View Post
Cool, thanks
Very well explained
I went to my local HD, and I didn't see the 2" foil faced foam though.....!!!!
I bought my 2" foamboard from Menards and it also wasn't foil faced. To my knowledge, they don't carry it, but they might be able to special order it. I have no issues with moisture though. I used PL Premium as the adhesive to stick the foam board to the rim joist and then used silicone caulk to fill in the gaps around the edges. As soon as a piece of foam board was glued in place and sealed up around the edges I could feel the air movement suddenly stop when I was doing the west side, as there was a strong westerly wind that day. This job alone probably made the house more comfortable than anything else that I've done. The crawl space no longer gets ice cold during the winter. I was just down there the other day getting holiday stuff out of there and I was in a T-shirt and pants and wasn't cold at all, as it now stays around 63 degrees all year.
Dave Sal is offline   Reply With Quote
Old 11-25-2013, 11:10 PM   #13
Registered User
 
Join Date: Mar 2009
Posts: 9,986
Rewards Points: 2,038
Default

How to insulate rim joists simply


Tried this store for your location/zip, they carry 1", just double it up; http://www.homedepot.com/p/Unbranded...x#.UpQYmicbHAU

Hammer, you really need to replace the missing places of X-bracing for the floor to act as a unit rather than sections of smaller units. Flat 2x4 under the ducting works, in-line with the x-bracing, a 1x4 flat, nailed to the joist bottoms will improve the structure immensely; http://www.ewpa.com/Archive/2004/jun/Paper_278.pdf House wrap on the fibrous insulation will stop the attic inherent convective loops from degrading the top few inches of insulation of R-value; http://digitalcommons.unl.edu/cgi/vi...ventilation%22

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
Old 12-01-2013, 11:01 AM   #14
Newbie
 
Join Date: Feb 2013
Location: North GA
Posts: 12
Rewards Points: 10
Default

How to insulate rim joists simply


Hammer, Do you feel a big difference with adding more insulation in your attic. Heating/cooling wise and HVAC not running as much?

I was debating to add more, but on the fence.
princevlad is offline   Reply With Quote
Old 12-01-2013, 11:20 AM   #15
Member
 
Join Date: Oct 2011
Location: Ohio
Posts: 2,611
Rewards Points: 2,130
Default

How to insulate rim joists simply


Quote:
Originally Posted by princevlad View Post
Hammer, Do you feel a big difference with adding more insulation in your attic. Heating/cooling wise and HVAC not running as much?

I was debating to add more, but on the fence.
The attic area I refer to in the photo is above my family room and garage. IT actually extends back into the picture another 25 feet or so.

The doubled up batt insulation did help I think in warmth in the family room. On the other side of the wall that is spray foamed in the attic is a walk in closet and the sprayf foam did help in there.

The spray foam in the basement in the rim joist cavities not only helped with air infiltration, but also I have not noticed as many dead bugs in the basement. Previous to the rim joists being spray foamed, the cats we have would hunt at night in the basement killing bugs.

Advertisement

hammerlane is offline   Reply With Quote
Reply


Thread Tools
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
Move joists for higher ceiling jgrohol Building & Construction 11 10-03-2012 05:24 PM
Best way to frame in a lateral bracing between joists miamicuse Building & Construction 2 03-19-2012 11:08 PM
Strengthening Joists Before Basement Finish braverichard Building & Construction 16 06-20-2010 08:28 PM
Cut Joists - How to Repair? stubits Building & Construction 13 03-16-2010 06:12 PM
help with 2nd floor joists g heil Building & Construction 5 09-12-2008 07:41 PM




Top of Page | View New Posts