Best R Value Batt Insulation for 4" Stud Wall?

harringtondav

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I'm furring out our river house's basement concrete block walls with 2x4 studs. Goal is to make this a year round house in cold winter Iowa. I put up 1/4" R1 fanfold behind the stud panels. What is the best R value batt insulation to stuff in the stud spaces?

I know I could triple up three layers of rigid foam board @ a total of R 15 + the R1 underlayment. But that's a lot of table saw work and mess.

...also would I gain anything by squeezing 6" R19 behind the drywall?

Thanks, Dave.
 

gm280

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DON'T try to "squeeze" R19 6" fiberglass insulation into a 4 inch space. It won't give you R19 value because you squeezed it into a tighter space then it was designed to fit and that defeats that design. It has to be installed in the proper space for the R19 value to work. Could check into the expanded foam type insulation. They blow it in and then cut it off even with the stud. That's about it, as far as I can think of.
 

sphelps

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I believe mineral wool insulation has a better r value and sound rating .. Or you can have open or closed cell insulation sprayed in . There are diy kits available also ...
Also agree with GM ..dont stuff the 6" in the 3.5 cavity .. It wont help ..
 

KJM

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Don't "squeeze" any insulation into a space, it s the trapped air that does the insulating. The more its squeezed the less air trapped. Cutting ridged foam with a utility knife shouldn't be too messy?
 

harringtondav

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Don't "squeeze" any insulation into a space, it s the trapped air that does the insulating. The more its squeezed the less air trapped. Cutting ridged foam with a utility knife shouldn't be too messy?

I found out ripping rigid foam on a table saw isn't so bad. ....will be better when I get the dust bag. I used it to build out a header cavity.

I could get R17.5 in that 3.5" joist space stacking two 1" layers and one 1.5" layer of the rigid. But the rigid is 3X the cost of R15 roll per cu. ft. In my basement that totals over $2400 more than the roll, and a lot more work on the install.

..looks like I'm going with the R15 roll.
 

KJM

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R15 VS R17, I doubt you would even notice the difference.
 

gm280

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Also remember, those labeled R values are in absolute perfect conditions and installation fittings. And we all know about labeled predictions... You could install the typical 3.5" fiberglass insulation and then cover over that with foam board on that. But unless you can adjust the circuit boxes out to compensate, you will have troubles fitting the receptacles, switches and plates. Also you would need longer drywall screws or nails as well. JMHO.
 

harringtondav

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Bob_VT

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How much of the block wall is exposed to above ground? You could also put foam insulation on the outside and cover it with stucco....... if the majority of the wall in underground you could add insulation underground to prevent the freezing from getting too deep.

I have a laid up stone foundation in my basement and I covered the walls in 6 mil plastic, added studs and 2" of foam which made quite a difference - it is not an occupied area.

Just a FYI when I created my garage floor slab - I installed 2" of foam below that too ;)
 

Mark ofs

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Just an FYI...coming from a building construction background, including high "R" walls (i.e., passive house, super insulated homes, etc.), ALL foam insulation products are rated on a 15yr life expectancy (originally derived from "flat" roof systems). They begin loosing their "R" value as soon as the off gassing starts.
 

harringtondav

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How much of the block wall is exposed to above ground? You could also put foam insulation on the outside and cover it with stucco....... if the majority of the wall in underground you could add insulation underground to prevent the freezing from getting too deep.

I have a laid up stone foundation in my basement and I covered the walls in 6 mil plastic, added studs and 2" of foam which made quite a difference - it is not an occupied area.

Just a FYI when I created my garage floor slab - I installed 2" of foam below that too ;)

The river side is walk out, fully exposed, and vulnerable. Large picture window and door. The best I plan is to replace the window with a pricey Anderson E Series (as in Eagle Windows), as well as the rest of the basement windows. ...already replaced the door with a good metal insulated core replacement.

The rest of the basement averages six feet under grade. So heat loss isn't too bad. Cored concrete block adds R1 to the total. 1/2" drywall is another R.5. So if I lie to myself I'll have R17.5 with the R1 fan fold and R15 batt fiberglass. 4 (or six if I can find it) mil poly to help with the infiltration. Heavy curtains over the big picture window.

We're 100% electric at the river house. Our REC gives a 40% discount on six month winter heat....if the whole house is insulated to "code" which is R19 for new construction. The REC rep has given me a pass since the place is 40 yrs old, and I'll have a better insulated basement than the original upstairs 2x4 construction. Plus they will give me up to $600 rebate on insulation materials.
 

sphelps

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Just an FYI...coming from a building construction background, including high "R" walls (i.e., passive house, super insulated homes, etc.), ALL foam insulation products are rated on a 15yr life expectancy (originally derived from "flat" roof systems). They begin loosing their "R" value as soon as the off gassing starts.

So your saying my house ICF foam block constructed 2-1/2” foam both sides with 4” concrete core . And closed cell spray foam on the underside of the plywood roof will loose R value after 15 years ? I won’t say it couldn’t but seems unlikely to me . I’m currently cooling 2600 sq ft with a 3 ton ac unit ..
 

Mark ofs

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I really debated saying anything about this for a few days as I didn't want to step on anyone's toes.

This was brought to my attention a few years ago (i.e. about 7yrs now), and at that time was/is referenced from engineer's/expert's participating in a world wide passive house design gathering. The conclusion is, at some point in time the "R" value will be basically zero in all foam products. As foam insulation was originally used under ballusted/EPDM or rubber roofs, and these had a 15yr life expectancy, that is all the product was ever needed to last too, as it would be replaced when the roofing was replaced, and at least to that time (7yrs ago) that was still how the industry was rating foam products.The company I worked for at the time, also sold SIP panels made from an outside vendor, but never shared this information with their Clients, even though they also built their own high performance panels that did not use foam.

Like anything, hopefully time has expand the knowledge and duration's, as an example, take when SIP panels first came out, the manufacturers, didn't know ants liked the foam so much, and the ants decimated the foam inside the panels. They found they needed to add a chemical to the foam to keep the ants from infesting and eating it. They also found that "mix" of chemicals was extremely important, as a bad mix lowered the "R", caused the foam to shrink, could also cause shrinking and twisting of panels which required replacement, etc.

I am not saying not to use it, but be aware of it's plus's and minus's. I would definitely use it under concrete floors, against earth, under ballusted/EPDM/TPO/rubber roofs and areas like that. I also am not saying you might not get a long life from the insulation, but only saying the product has been tested at that "R" value for a 15yr life expectancy. Take the "old" asphalt shingles (before fiberglass reinforced) they had an expected life of 10yrs or so, but, I have seen them get upwards of 25yrs to 30yrs. As an fyi, Googling the subject yesterday, I see manufactures claiming everything from 20yrs to 50yrs for their foam products.

However, personally, especially after the information I received, I am skeptical of it's use in wall, floor and roof systems being a very (relatively speaking) new product to the market. I will wait for some years to see how real life testing of systems that have been in place for 20+ years are performing before recommending them to anyone, especially with the problems a foamed system will create when needing to renovate or chase future plumbing/wiring problems within these systems.
 

harringtondav

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You should have it done by an expert. Have your basement checked by someone with knowledge in home improvement. You thought you are saving money for your DIY project, but in the long run you'll have to spend more if your work is not strong and sturdy enough to hold the wall. Have it done by the experts

This is a DIY forum, and most boat DIYers are DIY elsewhere, like me. I'd rather eat a bar of soap than pay someone for something I can do myself, or learn. This is my second full basement finish job. The first was 25 yrs ago. 1300 sq ft. Two BRs, full bath, family room with kitchenette. I did it all: Framing, insulation, plumbing, electrical, drywall, countertops.

I did hire the original HVAC outfit to put in the heat ducting then. Now I'll be doing that myself on this project. I learned enough from watching the "experts" on the first job. For 41 yrs I've been a DIYer, learning from the pros or from friends who had the skills. Back then there weren't forums or You Tube. I've always consulted licensed electrician pals to keep me code compliant and safe.

I haven't added the receipts, but I figure I'll have around $1500 in so far. That is everything roughed in, ready for HVAC and drywall., including a roughed in basement bathroom. This work would have cost at least $7500 in "expert" labor. The finished job will have the same resale value. The sweat equity will go into my pocket.
 

gm280

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I have to honestly admit that I too am a DIYer and will absolutely try things myself before hiring anyone. And even if I screw up, which is a learning curve for me, the redo doesn't even come close to "expert" cost.

When I was still young and really dumb, I thought "experts" were superior magical type beings that were above everyone else. As I grow older and saw what was considered an expert, I noticed they were the same iffy kids I went to school with, nothing else. And some of them as dumb as a rock too. So "expert" doesn't really mean anything to me these days. AN over-used word that really doesn't offer me any comfort when knowing who those experts are/were.

Knowledge is everywhere and there for the person that wants to read and learn how to do most anything... JMHO
 

harringtondav

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gm280 . I ended my windy sermon short. Every tool I own has payed for itself. Some many times over. I'll buy a special tool for a project and it pays for itself normally w/in two or three hours of use. The bummer is what to do when these tools when I pass. My son is a well paid structural engineer, and solves his problems with his check book. I've tried to give him some learning. Most of the time he falls asleep on his feet. ....hope my daughter marries a handy man.
 

gm280

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My typical take on such things is this, most of the time when something is broken and needs to be fixed, I look at it this way, it is already broken so what else can I do but fix it. And if I can't, it was already broken and it will cost the same to have it fixed.

And thus far, I have been able to repair everything I tried to repair. I mean what am I going to do...break it? It already is broken so what's to loose... And even if I need a "special tool" the cost of the tool to fix it doesn't even come close to the"fix it expert's" bill would be. And I still have the tool(s) too!

I sadly have to admit, I really don't see that mentality in the younger generation growing up these days. They wrongly think everything is either a throw-away item, or for the "experts" to repair. Sad isn't it!

One such item I had to "fix" was an automatic transmission for a chevy truck. I knew absolutely nothing about transmissions and made the decision to try to fix it myself. Well after buying the rebuild kit and a manual and video how to repair it, I tackled that job and amazingly rebuilt that transmission like new. And it is still running after over 130,000 miles on it since rebuilding it too. Same with rebuilding engines and electrical projects.

The information is out there. All you have to do is look for it! If you are a "I can't do that" type person, you defeated yourself before giving it a try! Knowledge is power that can't be taken from you by anyone...
 
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