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Old 09-18-2011, 09:27 AM   #1
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Insulating rim joist in odd balloon frame like construction


My house is a Cape built in the 1950s. The vertical studs for the second floor continue down past the floor and into the basement where they rest directly on the sill plate. There is no bottom plate under the wall at the first floor level.

The builders filled the wall cavity in the basement, and about 2-4" up into the first floor with a mix of rocks, bricks and cement. Some of the bays also have 1x10 or 2x10's over the rock, typically these are the ones that got rocks/cement as opposed to stacked brick--it seems like the wood was placed there as a form to keep the slurry in place while it setup.

My questions--

What is the purpose of these bricks? Are they just intended to act as fire stop, or do they also anchor the studs to keep them from twisting/moving?

What is the proper way to insulate this area? I was thinking of a few possibilities, of course the first step is to remove the bricks/rocks/etc, then I figure I could take two paths:

- Toe-nail in some bottom plates, seal with fire-block caulk and cans of fire-block spray foam. This would to difficult to do anywhere there are pipes/wires headed up, I'd have to be very careful on the removal and the bottom plates would need to notched in a lot of places.

- Use a DIY spray foam kit to fill those spaces.

In both cases my concern is the heating pipes, I'd need to be sure that whatever material is used is suitable to sit against the heating pipes which might be up to 190* when the heat is running (that's the temp of my boiler). I'm most worried about that when it comes to the spray foams.

Here are some images to illustrate, these are looking up from in the basement:

This is one of the bays that I cleared rocks/stones from so I could run coax/cat5 to the living room (BTW, I have no idea why that tilted framing member is there, it's angled such that it hit the stud to it's right about 24" above the first floor (I have a single gang low voltage box just below it, hopefully there is another vertical stud next to it, otherwise that's a big distance to go between studs)


Here's an example of one that is closed up w/ a form. I believe this is a 2x10, they span the entire length of the gable walls, but behind them they are filled with rocks/brick and the studs extend to the sill plate, I know because I gutted a bathroom on the other gable wall so I was able to easily see the construction and reach down into the cavities. The electrician who cut the holes was cursing about it, he tried his usual boring bit which jammed into rocks, so he had to break out a hole saw to be able to remove hunks of rocks to get the cable run, he had hoped the gable wall was different from the other... guess not!


This last one is a typical sight, it's stacked brick with mortar/cement, there is a heating pipe running up to a convector in this one, in many others I have old BX cable.


Last edited by bubbler; 09-18-2011 at 09:41 AM.
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Old 09-21-2011, 10:20 AM   #2
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Insulating rim joist in odd balloon frame like construction


The masonry was typically used as a fire stop at the base of the walls. I've dealt with a few other balloon frame structures recently that had the same condition.

If you are looking to insulate, you can remove the brick and replace with blocking for fire stopping. Then spray foam or caulk and place batt. insulation. note that if you spray foam code only allows for a rim joist application without a thermal and ignition covering.

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Old 09-21-2011, 10:42 AM   #3
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Insulating rim joist in odd balloon frame like construction


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Originally Posted by AGWhitehouse View Post
The masonry was typically used as a fire stop at the base of the walls. I've dealt with a few other balloon frame structures recently that had the same condition.

If you are looking to insulate, you can remove the brick and replace with blocking for fire stopping. Then spray foam or caulk and place batt. insulation. note that if you spray foam code only allows for a rim joist application without a thermal and ignition covering.
+1

Balloon framed homes leak a ton of air and this is a great place to start.

Check with you local code to make sure that the foam is suitable without an ignition/thermal barrier. Worst case scenario, you will have to put in some fire blocking.
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Old 09-21-2011, 03:41 PM   #4
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Insulating rim joist in odd balloon frame like construction


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+1

Balloon framed homes leak a ton of air and this is a great place to start.

Check with you local code to make sure that the foam is suitable without an ignition/thermal barrier. Worst case scenario, you will have to put in some fire blocking.
I have a few local companies coming to give me quotes on insulation, I'm hoping to do a split between them and some DIY, where I can knock out some of the straight forward, but time consuming, labor and they can come in to do the blown in, foaming, etc, the stuff that takes practice, equipment and manpower.

I'll look into the fire-blocking requirement, unfortunately our town hall sometimes has one of those attitudes where you're better off NOT asking the question because if they're forced to come up with an answer it will be the expensive/difficult one. The foam-it-green and other DIY kits, many of those seem to have fire block rating, or similar phrases, on them is that sufficient?

Any ideas as to why I have some tilted/angled framing members like shown in the pic? I noticed a few others elsewhere, always only about 3-4' long and I'm trying to figure out why that would have been done? Maybe it was scrap and they wanted to reduce waste so they'd cut a few angles and nail them in? I can't imagine it was a form of fire-block because I've pulled the interior walls in the kitchen and bath and found typical horizontal blocking there in a few spots.

Last question ... My exterior sheathing is 1x12 (or maybe 1x10) boards attached horizontally to the studs, there are 1/4" to 1/2" gaps between most boards. My siding apparently consists of those boards, followed by builders paper, followed by original wood siding, then covered by styrofoam (1/2" or less) and then vinyl siding. The vinyl siding looks horrible, it's cracked in several places (approx. 20 years old) and ideally I'd like to strip down to the sheathing and re-build from there. My question is whether doing blown in now would be worth it vs. waiting for when I do the siding, which might easily be ~5 years based on my unfortunate budget situation and the other work I have to get done. And, would doing the blown in now cause headaches for the siding replacement? I'm imagining the cellulose squishing out of all those gaps and making a huge mess...
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Old 09-22-2011, 05:00 AM   #5
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Insulating rim joist in odd balloon frame like construction


Stopping the air movement into the home (i.e. ribbon boards, top plates, bypasses, etc) will be more impact-full in the short term. I would combine the insulation and siding efforts into one project and just try to move up the time line.

You will be duplicating efforts otherwise.
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Old 09-24-2011, 09:34 AM   #6
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Insulating rim joist in odd balloon frame like construction


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Stopping the air movement into the home (i.e. ribbon boards, top plates, bypasses, etc) will be more impact-full in the short term. I would combine the insulation and siding efforts into one project and just try to move up the time line.

You will be duplicating efforts otherwise.
I've got a quote from a local contractor do to blown-in "R-15, Class-I dense-pack cellulose" into the exterior walls ($1550).

He included a proposal to foam the perimeter of each bay in the basement, then add rolled batts of R-19--leaving the bricks/cement/etc in place. What he described was that effectively I'd have a 4" pile of foam/FG batt sticking out from the wall at each bay, the foam will air seal and the batt will keep in the heat in the basement. I'm not 100% on that one to be honest, however I'm not sure how he can effectively blow insulation into the wall cavities without first sealing the basement areas where the cavities are open (after looking I'd say I have at least a dozen or more where there is nothing, you can just stick you hand in and reach up into the first floor wall cavity). His proposal for the basement was a small cost vs. the rest of the work, so I may just have him do it to facilitate the exterior wall work)

He also gave me a proposal for the attic/knee wall spaces. There is only so much I believe he can do given what I have, but his plan is to fill the joist bays between first/second floors within the knee wall attics, he says that the cavity is 10" deep so he will blow in R-38 (I'm fairly sure they are only 2x8, so I will have the double check). He had no proposal for adding air blocks under the knee wall, he said that the blown in insulation will extend several inches beyond the knee wall and act as a sufficient air barrier (My BS meter went up on that one because I know it does restrict air, but isn't an air barrier, but the real issue there is that I don't believe that he can create a sufficient block with blown in alone, I think I need something to act as a wall to hold the blown insulation back. To that end, I may just install some rigid foam pieces in there and spray foam, or in a pinch I think stuff a roll of FG batt under there might also help out.

For the knee walls he's proposing R-13 FG batt stapled up--my knee walls are 2x3 construction. He said that R-19 FG was also do-able for not much more money. My thought here is that that is probably about the best I can do. My interior wall surface is that cheap paneling stuff from the 60s, so I'll caulk and spray foam as best I can before they get in there. When they are done I'll put up tyvek on top of the batts, stapled to the studs (being careful to avoid compressing) to act as a wind blocker.

For the upper attic, there is some FG batt up there now. The joists are either 2x6 or 2x4, I'd say there is no more than R-15 because I see the top 1/2-3/4" of the joist. Anyway, he is going to blow in R-38 on top of what is there. That will get me into the high 40s or low 50s for the top roof area.

For the slope that connects the knee wall and upper attics he is proposing installing the vent chutes and then dense-packing w/ cellulose. It's 2x6 rafters, there is already some FG batt in there, but it's quite thin. I'm thinking between the original FG and the vent chute, he might only be able to get 3-1/2 to 4" in there which would be better than what is there now.

I've got a gable vent as well in one of the knee wall attics, I guess I will leave that open to help vent the attic now that the thermal envelope is being moved to skin the interior wall surfaces.

All said and done his proposals totaled just over $4K, but given that last year I was using something like 150-170G every 4-5 weeks of heating oil in a vacant house set to 60* and not HW usage, I figure this year if I don't do anything I'm looking at 150-170G every 3-4 weeks or worse. Combined w/ the 10-15% higher cost for oil it will be brutal, I could easily be looking at upwards of $4000 for my fuel bills, if I can save 15-20% of that with this insulation effort it will probably pay me back in just over 5 years.

I got a good vibe from this first guy, but I have a 2nd contractor coming this Tue to give me another opinion, I'm guessing it will be about the same, so it may come down to reviews for each company and price.

Last edited by bubbler; 09-24-2011 at 09:44 AM.
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Old 09-25-2011, 01:24 AM   #7
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Insulating rim joist in odd balloon frame like construction


That workscope seems pretty comprehensive and cellulose blown in under dense pack pressures is an effective air barrier.

I am super tired right now so I am having a hard time visualizing everything but I would ask for test in and test out blower door numbers to see what the net improvement in the repairs are.
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Old 09-28-2011, 08:39 PM   #8
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Insulating rim joist in odd balloon frame like construction


I'm doing sort of the same thing in my pre-1930's home. Will be ripping out all the old lathe and plaster this winter. With open walls, I'll run new electrical, the old stuff isn't knob and tube, but two wire no ground stuff. After the wires are run, I'm going to insulate with fiberglass rolls.

My similar issue is that I've got to close up all the open balloon framing under the house. Not just for insulation issues, but also to keep vermin and bugs from climing up thru the walls.

I am thinking about pressure treated 2x6's toe-nailed in with spray foam around the edges from the top. Seal it up!!!
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Old 09-29-2011, 07:22 AM   #9
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Insulating rim joist in odd balloon frame like construction


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Originally Posted by Captain Dan View Post
I'm doing sort of the same thing in my pre-1930's home. Will be ripping out all the old lathe and plaster this winter. With open walls, I'll run new electrical, the old stuff isn't knob and tube, but two wire no ground stuff. After the wires are run, I'm going to insulate with fiberglass rolls.

My similar issue is that I've got to close up all the open balloon framing under the house. Not just for insulation issues, but also to keep vermin and bugs from climing up thru the walls.

I am thinking about pressure treated 2x6's toe-nailed in with spray foam around the edges from the top. Seal it up!!!
PT is only required if it is touching concrete/masonry but you are 100% correct. Get it sealed up.

You have a unique opportunity to really tighten your home up. Get some spray foam, a bunch of caulk, and make that home tight. Your bills will thank you in the future.
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Old 09-29-2011, 08:45 AM   #10
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Insulating rim joist in odd balloon frame like construction


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Originally Posted by Captain Dan View Post
I'm doing sort of the same thing in my pre-1930's home. Will be ripping out all the old lathe and plaster this winter. With open walls, I'll run new electrical, the old stuff isn't knob and tube, but two wire no ground stuff. After the wires are run, I'm going to insulate with fiberglass rolls.

My similar issue is that I've got to close up all the open balloon framing under the house. Not just for insulation issues, but also to keep vermin and bugs from climing up thru the walls.

I am thinking about pressure treated 2x6's toe-nailed in with spray foam around the edges from the top. Seal it up!!!
I assume you're on a crawlspace? Have you considered laying down plastic and adding screening to any vents/openings? Seems like that should keep down the wildlife activity down there...

2x6... do you have 2x6 walls? Mine are 2x4...

After talking to a 2nd insulation contractor, I think I'm going to handle the basement myself. My plan is to pull the bricks/rocks--they only get in the way of doing things and they serve no real value--then I'm either going to fill the space w/ one of the DIY foam kits that is fire-block rated, or I'll toe nail in a 2x4 at the subfloor of the first floor to act as a fireblock (sealed w/ the fireblock caulking) then spray foam behind it. Since I have to do so much area I think buying the ~$600 foam kit may actually not be a bad deal vs. having to cut and fit rigid foam and then seal with smaller cans (which aren't cheap).

I also need air blocking in my attic under the knee walls, so my thought is that I can plan to buy a large enough DIY kit to also let me spray an inch of two of foam to insulate and air seal against a 1x8 that I nail in the joist cavity to act as an air block.

Based on the prices I've been seeing I think I will also be adding my own FG batts to the knee walls, followed by tyvek.

I may also try to install vent chutes myself to save on labor--BTW, both professional companies I called recommended not installing vent chutes, their claim was that in a 2x6 rafter space, the 1-2" of cellulose depth lost to the chutes is worse than not having the chutes at all... so basically the R4-8 that I lose is worse than not venting the attic... does that make sense to anyone? I should mention that the back knee wall attic has a wide open run to the upper attic, so even if the chutes are closed off the knee wall and upper attic are directly connected. The front knee wall attic does not have a similar connection, but it at least has a gable vent over my front door.

I'm more concerned about moving air for the purpose of controlling moisture than about preventing overheated shingles, this is relatively short length of slope (~4' maybe), so perhaps they are correct that it's not a big deal to not vent them, or that the extra insulating value is more important.

BTW, I don't have soffit vents in the knee wall attic space, but I do plan to consider adding a fascia-board based soffit venting setup when the roof is replaced which will be within 5 years based on its current age (20 years).

...it doesn't seem like it should be that complicated, but it seems like by solving one problem you potentially create another... I feel like the insulation guys are really only concerned w/ maximizing insulation value, while the roof guys are interested in maximizing roof life... it's tough to know who is right, wrong, etc...


Last edited by bubbler; 09-29-2011 at 08:53 AM.
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