Attaching XPS To Concrete - Insulation - DIY Chatroom Home Improvement Forum
Advertisement


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

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

Like Tree2Likes
  • 1 Post By Abuc
  • 1 Post By Abuc
Reply
 
Thread Tools Search this Thread
Display Modes
Old 12-21-2019, 12:43 PM   #1
Member
 
Join Date: Aug 2018
Location: West Chester, PA
Posts: 265
Rewards Points: 530
Default

Attaching XPS to Concrete


Have read many thread and articles. Almost all say use a lot of adhesive (1 tube per 4’ x 8’ sheet) and use bracing until adhesive cures. Only one person said Loctite FuzeIt will hold immediately without bracing. No way I am going to install XPS if I have to use that much adhesive and temporary bracing. Watched one manufacturer video which used 4 plastic anchors per sheet. This would be ok if I get a hammer drill which I would like to have anyway.

So, what is the easiest most efficient way to secure 2” thick, 4 x 8 XPS boards to my poured concrete basement walls? Thanks.
Abuc is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 12-21-2019, 12:54 PM   #2
Exterior Construction
 
Windows on Wash's Avatar
 
Join Date: Aug 2011
Location: Washington DC Metro Area (VA, MD, DC)
Posts: 26,072
Rewards Points: 944
Blog Entries: 41
Default

Re: Attaching XPS to Concrete


Plates and concrete screws work and you can usually find a cheap sealant that is non reactive to the foam that will help maintain a physical bond with it. Just test out a few pieces and find something that is inert with the foam.
Windows on Wash is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 12-21-2019, 01:15 PM   #3
Member
 
Join Date: Nov 2015
Location: Maine
Posts: 10,720
Rewards Points: 242
Default

Re: Attaching XPS to Concrete


What are you going to cover that rigid with. Codes often require a layer of drywall or other thermal barrier over the insulation. In that case adding strapping provides a place for the drywall to be attached and it secures the foam while some dabs of adhesive cure.

Also provides a small gap for wiring, although I prefer more space.

Bud
__________________
I volunteer my help and opinions, but you are responsible for what YOU choose to do with that information.
Bud9051 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 12-21-2019, 01:20 PM   #4
retired framer
 
Join Date: Jun 2017
Location: Fraser Valley BC Canada
Posts: 38,125
Rewards Points: 860
Default

Re: Attaching XPS to Concrete


__________________
Do not use flat bottom gables with scissor trusses.
https://www.fema.gov/media-library-d...6/chapter7.pdf
figure 7-14
Nealtw is online now   Reply With Quote
Old 12-21-2019, 01:33 PM   #5
Member
 
Join Date: Aug 2018
Location: West Chester, PA
Posts: 265
Rewards Points: 530
Default

Re: Attaching XPS to Concrete


Quote:
Originally Posted by Nealtw View Post
This is what I plan to do. Looks much cleaner and easier than adhesive.
Nealtw likes this.
Abuc is offline   Reply With Quote
Old 12-21-2019, 01:40 PM   #6
Member
 
Join Date: Aug 2018
Location: West Chester, PA
Posts: 265
Rewards Points: 530
Default

Re: Attaching XPS to Concrete


Quote:
Originally Posted by Bud9051 View Post
What are you going to cover that rigid with. Codes often require a layer of drywall or other thermal barrier over the insulation. In that case adding strapping provides a place for the drywall to be attached and it secures the foam while some dabs of adhesive cure.

Also provides a small gap for wiring, although I prefer more space.

Bud
I just started reading about the fire hazard. I have read that the Dupont Dow blue board has been certified to use without covering. Don’t know about other brands. I was going to attach the XPS board directly to the concrete and then construct a 2x4 wall with Sheetrock. There would be a 1” or 2” gap between the XPS and the studs. Can’t find much info on fireproofing XPS. Articles say it has to be covered (except the blue board) but they don’t say if the sheetrock has to be tight against the XPS. I will have fireblocking at the top of the wall.
Abuc is offline   Reply With Quote
Old 12-21-2019, 01:43 PM   #7
retired framer
 
Join Date: Jun 2017
Location: Fraser Valley BC Canada
Posts: 38,125
Rewards Points: 860
Default

Re: Attaching XPS to Concrete


Quote:
Originally Posted by Abuc View Post
I just started reading about the fire hazard. I have read that the Dupont Dow blue board has been certified to use without covering. Don’t know about other brands. I was going to attach the XPS board directly to the concrete and then construct a 2x4 wall with Sheetrock. There would be a 1” or 2” gap between the XPS and the studs. Can’t find much info on fireproofing XPS. Articles say it has to be covered (except the blue board) but they don’t say if the sheetrock has to be tight against the XPS. I will have fireblocking at the top of the wall.
As long as there is drywall between the foam and the living space you are fine with that plan.
What he doesn't talk about it the top plate of the wall should be wider and go all the way in to the sill plate on top of the concrete and that can be plywood or OSB or 2x?. We do that first.
__________________
Do not use flat bottom gables with scissor trusses.
https://www.fema.gov/media-library-d...6/chapter7.pdf
figure 7-14

Last edited by Nealtw; 12-21-2019 at 01:46 PM.
Nealtw is online now   Reply With Quote
Old 12-21-2019, 01:58 PM   #8
Member
 
Join Date: Nov 2015
Location: Maine
Posts: 10,720
Rewards Points: 242
Default

Re: Attaching XPS to Concrete


I am aware that Dow Thermax has a foil facing that has been approved to be left exposed in some applications but have not heard of the blue board being approved. Can you post the link you are reading?

As Neal said the 2x4 wall with drywall will do the job, just use pressure treated at the bottom with approved fasteners at all points and no need for the gap. The studs can be installed directly against the rigid. Only need for a gap is to be sure wall is vertical if foundation isn't.

Bud
__________________
I volunteer my help and opinions, but you are responsible for what YOU choose to do with that information.
Bud9051 is offline   Reply With Quote
Old 12-21-2019, 02:14 PM   #9
retired framer
 
Join Date: Jun 2017
Location: Fraser Valley BC Canada
Posts: 38,125
Rewards Points: 860
Default

Re: Attaching XPS to Concrete


Quote:
Originally Posted by Bud9051 View Post
I am aware that Dow Thermax has a foil facing that has been approved to be left exposed in some applications but have not heard of the blue board being approved. Can you post the link you are reading?

As Neal said the 2x4 wall with drywall will do the job, just use pressure treated at the bottom with approved fasteners at all points and no need for the gap. The studs can be installed directly against the rigid. Only need for a gap is to be sure wall is vertical if foundation isn't.

Bud
I you use sill gasket, no need for treated wood and worry about rusting drywall screws
__________________
Do not use flat bottom gables with scissor trusses.
https://www.fema.gov/media-library-d...6/chapter7.pdf
figure 7-14
Nealtw is online now   Reply With Quote
Old 12-21-2019, 03:39 PM   #10
Member
 
Join Date: Nov 2015
Location: Maine
Posts: 10,720
Rewards Points: 242
Default

Re: Attaching XPS to Concrete


Sill gasket is a bit thin. I prefer the 1.5" PT bottom plate with my drywall set 1/2" up providing more protection from water. Nothing is perfect and the sill gasket is probably good in most cases.

Bud
__________________
I volunteer my help and opinions, but you are responsible for what YOU choose to do with that information.
Bud9051 is offline   Reply With Quote
Old 12-21-2019, 04:21 PM   #11
Member
 
Join Date: Aug 2018
Location: West Chester, PA
Posts: 265
Rewards Points: 530
Default

Re: Attaching XPS to Concrete


Quote:
Originally Posted by Bud9051 View Post
I am aware that Dow Thermax has a foil facing that has been approved to be left exposed in some applications but have not heard of the blue board being approved. Can you post the link you are reading?

As Neal said the 2x4 wall with drywall will do the job, just use pressure treated at the bottom with approved fasteners at all points and no need for the gap. The studs can be installed directly against the rigid. Only need for a gap is to be sure wall is vertical if foundation isn't.

Bud
The wall needs to come out far enough to clear waste plumbing. My contractor likes to use PT on the bottom plate so I will go with that. Will look for the link.
Bud9051 likes this.
Abuc is offline   Reply With Quote
Old 12-21-2019, 04:37 PM   #12
Member
 
Join Date: Aug 2018
Location: West Chester, PA
Posts: 265
Rewards Points: 530
Default

Re: Attaching XPS to Concrete


https://www.buildsite.com/pdf/dowche...tes-400113.pdf

https://www.dupont.com/industry-upda...echnology.html

Last edited by Abuc; 12-21-2019 at 04:41 PM.
Abuc is offline   Reply With Quote
Old 12-21-2019, 04:39 PM   #13
Member
 
Join Date: Nov 2015
Location: Maine
Posts: 10,720
Rewards Points: 242
Default

Re: Attaching XPS to Concrete


The gap is more of a problem when the foundation is not insulated. Moisture entering through the concrete as vapor at the bottom is pushed upward to where it finds the cold foundation at the top exposed to the outside. There it deposits its moisture and a ice begins to accumulate.

you will have the nice layer of rigid so minimal moisture and nothing should be below freezing.

Bud
__________________
I volunteer my help and opinions, but you are responsible for what YOU choose to do with that information.
Bud9051 is offline   Reply With Quote
Old 12-21-2019, 04:52 PM   #14
retired framer
 
Join Date: Jun 2017
Location: Fraser Valley BC Canada
Posts: 38,125
Rewards Points: 860
Default

Re: Attaching XPS to Concrete


Sill gasket is cheap and stops water from wicking up the wall

https://www.homedepot.com/p/Owens-Co...-1FS/202084452
__________________
Do not use flat bottom gables with scissor trusses.
https://www.fema.gov/media-library-d...6/chapter7.pdf
figure 7-14
Nealtw is online now   Reply With Quote
Sponsored Links
Advertisement
 
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