Has anyone sealed their sill plates and rim joists themselves?

[Pullstart 62,783]

Since most of the basement walls are accessible right now, I’m thinking it might be a good time to insulate.  
 

I’m looking at cans, kits, etc.  though possibly wasteful, I am appalled at the price difference of small 12 or 24 oz cans, vs a big kit.

 

I BELIEVE that insulating with a spray foam over just batting can help with air leaks, mold, moisture, etc.  Thoughts?  Experience?

 

The 200 board feet at 1” thick kit is $.71/oz.  12. oz. cans are $.36/oz.  What gives?

[Pullstart 62,783]

Also, our rim joists are 2x10 lumber, not plywood or OSB.  Thoughts on foam board installation then spraying, vs spraying then adding batting?

 

 

[Jeff-C175 7,199]

25 minutes ago, Pullstart said:

What gives?

 

Ease of application and the ability to cover larger areas quickly.  

 

My crawlspace is 'sealed'.  Spray foam on all the rim and sill, 2" foam insulation on the walls, and the whole thing, walls and floor, completely covered with vapor barrier.

[Handy Don 12,141]

I used 6" fiberglass batts with vapor barrier painstakingly cut for each joist spacing before framing and insulating an interior wall (gapped and vapor barriered) on the entire basement wall. I had no money to hire a pro at that time, Today, I'd be very sure I'd planned properly for penetrations (existing and anticipated future) and get a pro to foam them.

 

I would NOT count on the insulating foam to "heal" any defects. Better to find and secure it all with the proper sealing foam (low or no expansion, depending...) or other repair before going ahead with insulation. Biggest challenge with foam insulation is making D A M N sure that no moist heated air can get through to the cold wood where it'll condense and lead to mold in one season and then rot or insect infestation soon after.

Edited December 8, 2022 by Handy Don

[WHX?? 48,762]

2 hours ago, Pullstart said:

insulating with a spray foam over just batting

Nety ney Jose... never foam over batting . foam first then batting if needed.  You foam over batting yer done you can't get at moldy batts without ripping out foam. 

Your construction you want to foam right in the box sills right up against the rim board.  Don't matter what the floor joists or rim board are. Lap the foam right down over the sill plate and onto the foundation wall.  This seals all air gaps in the sill plate to foundation connection. Continue right down the foundation wall you got the coin. Any wall studs & wiring should be in first. Typically this is the last thing that gets done in say a basement finish off just before drywall goes on.  You can stop just a couple inches down and batt the rest. I would do the whole wall... seals micro cracks that might be in the foundation & no vapor barrier needed. 

At least 3 inches in the box sills and nothing further needed.  1" foam = R-5 you know that. 

 

You think yer gonna do any kinda square footage with the big box stuff yer on crack. Needs to come out a 55 gallon drum which means a professional insulator. Prolly cheaper too.  

That froth pak is just for a small exterior wall project and its a getting it out of the can and a even coat.  Don't ask me how I know. 

Yer paying for the cans not what's inside the cans and the gun to get it out that yer gonna throw away when done. 

 

Edited December 8, 2022 by WHX??

[stevasaurus 22,706]

My problem with foam products, they do not let you ever do any work if some things need it.  I subscribe to the theory that when building anything, ALWAYS make it so you can get back in it and work with it.  Foam sucks for that.  Just insulate with the Pink batts.  You really need to have a certain amount of air circulation or you will have mold and rot.  

[Pullstart 62,783]

2 hours ago, Pullstart said:

 

I BELIEVE that insulating with a spray foam over just batting can help with air leaks, mold, moisture, etc.

Using spray form COMPARED TO just batting @WHX??   that’s what I meant, I wasn’t talking about spraying the wool in place 

[WHX?? 48,762]

Ahhh ... well ok yer still off yer rocker tho..  foam INSTEAD of batting... 

I agree Steve to a certain extent, but I come from the school of energy efficiency.  

I just like spray foam because it air seals.  Peel back a piece of older batting and it's dirty... because it was trying to act as an air filter. 

25 minutes ago, stevasaurus said:

ALWAYS make it so you can get back in it and work with it. 

Like needing to add that extra circuit in a flush mounted load center. 

 

Edited December 8, 2022 by WHX??

[stevasaurus 22,706]

You are better off sealing from the outside and insulating from the inside.  

[Jeff-C175 7,199]

I had 'glas insulation in the joist pockets.  Rodents love that stuff.  They hate foam.

 

 

Edited December 8, 2022 by Jeff-C175

[Lane Ranger 10,945]

We used battes in addition floor joists and bought the metal staves that made it a quick and easy task.  We had another house that had chicken wire under the floor joists holding up all the insulation batting! 
 

 

I agree the spray foam is not a friendly worker /workaround stuff once applied. 
 

But either one will make a big difference in warmth and heating!  

[Horse Newbie 7,052]

4 hours ago, Pullstart said:

Also, our rim joists are 2x10 lumber, not plywood or OSB.  Thoughts on foam board installation then spraying, vs spraying then adding batting?

 

 

You talking about sealing between the top of concrete wall and the bottom of the rim joists ?

[Rob J. 1,941]

I’d use 2” solid foam, cut to fit and glue them in. Then foam around where needed. 

Edited December 8, 2022 by Rob J.

[Pullstart 62,783]

25 minutes ago, Horse Newbie said:

You talking about sealing between the top of concrete wall and the bottom of the rim joists ?

The entire vertical part… it’s really no R value to the great outdoors.

[Horse Newbie 7,052]

Seal cracks with the foam- if between a rough opening and the door/window frame use low expansion, that way it won’t expand to the point of pushing on the frame enough to cause a door or window to not open or close properly.

If you are sealing a crack between say the top of foundation wall and rim joist you can use the high expanding foam… it will not expand strong enough to move structural stuff.

Then use batts with a vapor barrier with the vapor barrier facing the interior side. If you are adding insulation in an already insulated wall, take out batts that have a vapor barrier, put in the unfaced insulation, then put back the faced insulation with the vapor barrier facing the interior.

You can add insulation in the attic using unfaced insulation… this is assuming that the insulation has either faced insulation with the vapor barrier facing down towards the interior. If the existing attic insulation has no vapor barrier, you can just add batts on top or spray in attic insulation.

What ever you do just make sure you have the vapor barrier closest to the interior, and never go insulation-vapor barrier-insulation, and by the way, vapor barrier on insulation DOES NOT prevent vapor from passing through it… it does however only let the vapor pass through one way only. This is why some faced insulation actually says “ This side towards interior “

You want the vapor barrier to allow vapor to pass through to the outside 

[Horse Newbie 7,052]

Maybe you could watch a YouTube on insulating a concrete basement wall… you are talking basement and not crawl space, right ?

[Horse Newbie 7,052]

Maybe build a 2x4 frame wall, wire in receptacles, insulate with faced batts, Sheetrock, baseboards, and paint…

[Pullstart 62,783]

3 minutes ago, Horse Newbie said:

Maybe build a 2x4 frame wall, wire in receptacles, insulate with faced batts, Sheetrock, baseboards, and paint…

Baby steps Tim, let’s not rush our “moving in” process!  

[Zeek 2,286]

I stuffed paper backed insulation bats in each one on my old house. Cheap, easy, fast, effective. 

 

[Jeff-C175 7,199]

1 hour ago, Zeek said:

my old house

 

How old?  Looks like new construction!

[953 nut 55,062]

8 hours ago, Jeff-C175 said:

 

How old?  Looks like new construction!

Going by the date on the photo I guess it was in 2007.

[Racinbob 11,040]

 I'm a big advocate of spray foam. Efficiency wise it beats the snot out of the other types of insulation. But I'm talking about the good stuff professionally applied with the proper equipment. Definitely not the stuff out of the spray can. It might have it's place and I just finished using some of it but for the most part it's junk. I don't know about the bigger kits from the big box stores. I do know that one of the biggest foam contractors in the country based in Florida had 'portable' that they would use for tiny jobs and to go do a touch up on a finisher larger project so they didn't have to mobilize a fully equipped truck. I don't recall the cost of these units but they provided a finished result as close as possible to a truck project. These weren't routinely sold to the public but if you were an employee or a friend.............. 

 There are so many factors to consider. First, as Steve said, a house should he sealed for water and air from the roof down and the walls from the outside in. But most of us are dealing with existing conditions and there's just so much we can do short of the things they do on some of those HGTV shows. Kevin, if you're feeling air infiltration you need to seal it. If you know that water isn't getting to it go ahead and seal away. The moisture in the air trying to come in will be blocked and it won't condensate as long as you add the proper R-value to the inside after sealing it. All factors need to be considered with each situation. There is no pat answer. 

 Another consideration that Steve mentioned is access for future work. No, you didn't plan it out so well that you'll never have to add or change something. That just doesn't happen for any of us. Professional spray foam is still superior but only you can decide what you want to do there. 

 One of the most important considerations is fire. Some foams can be almost explosive. The fumes will kill you with a few breaths. Make sure you've researched the type you're considering and the need for a fire barrier. Example. This house we're in right now has Ice Block basement walls. That's a steel structure encapsulated in polystyrene. Per code there MUST be a fire barrier. There was none. The sellers were having trouble selling the house and it didn't make sense with the market. All they would say was that potential buyers wanted a finished basement which also didn't make sense. This house was built in 1998 and how they got a final certificate of occupancy is a mystery.......well, not really. Somebody knew somebody and the inspectors here don't care. Even the home inspectors caught it and that's where the previous deals fell through. I did my own inspection and saw the issue but I knew it was fixable. Within two months after moving in and 70+ sheets of drywall later and we were code compliant. Even if it's a small foam project be very aware of this. No matter what the can says take a cured piece of the foam and light it. You'll find out real quick just how flammable it could be. 

 

[Jeff-C175 7,199]

1 hour ago, 953 nut said:

Going by the date on the photo I guess it was in 2007.

 

Just an infant! 

[WHX?? 48,762]

5 hours ago, Jeff-C175 said:

 

Just an infant! 

Just 'cause you live in the Munster Mansion Jeff...