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R13 vs R15

david001 | Posted in Energy, Heating & Insulation on October 13, 2009 04:43am

I’m insulating a 2X4 wall with fiberglass batts.  R-13 and R-15 will both fit in the 3-1/2″ cavity.  The R-13 would cost $35.92 and the R-15 would cost $127.29.  Is the added R-2 worth the extra $91.37?

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  1. Piffin | Oct 13, 2009 04:57am | #1

    something is wrong with those figures

     

     

    Welcome to the
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    1. DanH | Oct 13, 2009 05:02am | #2

      I'd agree.
      As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz

      1. user-201496 | Oct 13, 2009 07:02am | #3

        Ditto!

  2. Piffin | Oct 13, 2009 02:34pm | #4

    So, have you figured out your error yet?

    Some hints. Don't look at the total price of a bag of product. Look at how many Sq Ft it covers and break down to price per Sq Ft.

    Some bags contain more than others. For instance, the bag I get from local yards has more sq ft than one I might get from Lowes for same product. The marketing makes it look like it is cheaper to buy at Lowes at first, until you work the math.

    Another place you may have had error, is somebody might have quoted you for 16" oc with one and 24oc for the other.

    or you might have just hit the wrong key on your calculator.

     

     

    Welcome to the
    Taunton University of
    Knowledge FHB Campus at Breaktime.
     where ...
    Excellence is its own reward!

    1. frammer52 | Oct 13, 2009 04:25pm | #5

      Normally it is around the same price, at least here it is!

    2. david001 | Oct 13, 2009 04:45pm | #6

      Actually, the numbers are solid.  I'm insulating a 18ft length of wall with an 8ft high ceiling giving me 144 sq ft.

      The R-13 comes in 32ft rolls which cover 40 sq ft so I need 3.6 rolls.  At a cost of $8.98 a bag, 4 bags comes to $35.92.

      The R-15 comes in 93 inch lengths (cut for an 8 ft ceiling I guess) and covers 56.13 sq ft per bag so I need 2.6 bags.  It comes with 6 pieces per bag, and I have 14 wall cavities to fill.  Buying 2 bags at a cost of $42.43 a bag comes to $84.86 while leaving two cavities empty.  Getting 3 bags with alot of waste will fill all the cavities without stuffing the last 2 cavities with left over waste, but brings the cost up to $127.29.

      Since I'm doing the work myself, labor isn't an issue.

      Is it worth the extra $48.94 to $91.37 for the extra R-2?

      1. Piffin | Oct 13, 2009 05:05pm | #7

        something still sounds wrong there. I have never bought any with only six per bag. That seems like a small bag of the r-15. dbl chk that figure.I'd be figuring r13 at about .27/ft and r-15 about .30-.31/ft. You have .21 and .66 respectively.Maybe somebody is running a sale on th er-13 and is surcharging a speial order pricing for the r15 if your prices are indeed right
         

         

        Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

        1. Griffin12 | Oct 15, 2009 04:59pm | #12

           David is correct in his numbers. R-15 insulation costs about 50% more than R-13. At Lowes you can buy a "door buster" priced roll of R-13 that is 32' long for eight bucks and change. Their standard pricing for a bag of R-13 with 11 batts in it is around 42.00. Their standard pricing For R-15 is around probably 32.00-35.00 bucks a bag which has 6 batts. The dramatic difference in price is attributed to the "door buster" 32" roll.

           

           In my experience the difference in R-15 and R-13 is marginal. The quality of the installation is where the real difference will be.

          1. Pac NW | Dec 16, 2017 05:07am | #24

            R-13 costs $50.97 for 11 batts not $42 as claimed and R15 costs 37.98 for 7 batts.

          2. calvin | Dec 16, 2017 06:49am | #25

            Pac

            You are responding to an 8 year old thread.

            Not quite as drastic as asking your grandmother what the cost of a loaf of bread was when she was young.

      2. Pac NW | Dec 16, 2017 04:40am | #20

        Home Depot selss them at 7 pe bag so you would spend $75.96 for 2 bags of R-15.   R-13 comes 11 per bag so you would spend $101.94 or 1/3 MORE for R-13.  So it depend more on packaging then actual cost.  The R-15 cost per aquare foot is 56 cents and it is 48 cents per square foot for the R-13.  By either measurement 56 is not three times as much as 48 nor is 75.96 three times as much as 101.  Rolls cost either $19.13 at either Lowes or Home Depot NOT $8.98 as claimed.  You numbers are simply wrong.  One thing is right rolls will always be cheaper the batts but even 3 rolls would cost you $57 vs $76 for R-15 batts and if R15 were in batts the differences would be even less significant.  Again, 76 is not three times 57.

  3. PedroTheMule | Oct 13, 2009 08:25pm | #8

    Hi David,

    You are apparently shopping the big box stores....I've seen such wide swings on "off the shelf" pricing. You didn't mention how much you're insulating so it's hard to offer this next idea....we built every last bit of the house we're in now.....and I was planning to insulate it myself but thought I'd give the "specialty" companys a shot since I needed so much.......4600 sq ft house, cathedral ceilings, insulate interior walls and floors as well to assist in noise/buffering......lot of insulation.....it cost me $213 "more" to have them do it vs doing it myself.....that included "their labor"......they did such a quality job that I only found 2 nit picky areas that I touched up after they left.

    Secondly you don't mention any specifics of what your construction phase is, if the siding is not up, you need to get a thermal break up for the biggest savings......1 or 2" of foam sheathing will make a dramatic difference.

    Again, you need to provide details. Simply throwing up cost checking on numbers can be done over the phone with suppliers.

    On Edit: I read futher into the thread after responding......for a single 18' wall I probably wouldn't spend the difference you're relating unless this is some addition and you're not adding additional heating and cooling...still so many factors that could make it worth spending more, but all in all the difference you've been quoted is out of line. Be sure to post back with all the details if you'd like better informed advice. Respectfully stated: right now you're asking whether to buy a 4' trailer or a 20' trailer.....if we advise the 4' and you want to hall 12' hardie siding.....well you get the idea.

     

     

    View Image  



    Edited 10/13/2009 1:54 pm ET by PedroTheMule

    1. Piffin | Oct 13, 2009 08:32pm | #9

      assuming yo now see that he is only doing one wall. 

       

      Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

      1. PedroTheMule | Oct 13, 2009 08:49pm | #10

        assuming yo now see that he is only doing one wall.

        Hi Piffin,

        Yeah thanks......#7 after I answered #1......

        On a similar note I wonder if that's an interior, exterior and all the weather stuff he's dealing with.....I'd still rather use the cheapest sound deadening R11 with an inch of foam.

        Here in NC we have a milder climate than you but we were able to heat our 4600 sq ft with a 40k lp heater prior to the fiberglass insulation based completely on good windows, doors "and" the foam board providing top notch thermal break.

        I'm still mentally working through the Mooney Wall.....maybe that "with" foam panels......glutton for punishment <grin>

         

         View Image  

        1. david001 | Oct 15, 2009 04:31pm | #11

          I've gone with the R-15 because.... Well, if it's worth doing, it's worth over-doing, right?

          I'm still puzzled though.  Is the latest code change from R-13 to R-15 practically or politically driven?  Would you walk into a room and say "Oh yeah, it's allot warmer in here.  You must have used R-15 in those walls."

          Does an R increase of 2 make a statistically significant improvement???

          1. PedroTheMule | Oct 15, 2009 05:17pm | #13

            I'm still puzzled though.  Is the latest code change from R-13 to R-15 practically or politically driven?  Would you walk into a room and say "Oh yeah, it's allot warmer in here.  You must have used R-15 in those walls."

            Does an R increase of 2 make a statistically significant improvement???

            Hi David,

            Well there will definitely be the potential for savings but unlikely a difference in saving as much as it cost extra in material. This nature of insulating only makes a difference in the bays. You still have the thermal conductivity of the studs themselves. But even this is dependent on your general climate. You've not yet filled out your profile so I'm not certain the extremes you may experience.

            For mild climates, your payback is forever, if you're at the north pole, your payback may be a couple of years.

            We're working on our final designs for our retirement home in south west Virginia and although this is subject to change, we're currently planning to frame with 2x6 24" OC. The cost of lumber is nearly identical to the typical 2x4 16" OC. Our benefit is less surface for thermal conductivity and deeper areas for more insulation. We will also use a double layer of foam panel insulation overlapping the sheets on the outside of the wall providing a superior thermal break.

            IMHO a thermal break is the most cost effective insulating barrier you can invest in.

            Another cost effective solution is described here: http://www.builditsolar.com/Projects/Conservation/MooneyWall/MooneyWall.htm 

            This one has been discussed at length here at BT and I think it is a good option on a budget as well.

            Then you can get into radiant barriers which I'm a fan of as well but I prefer those on the outside of the wall.

            There are so many options but to answer your question in a different way, once you've spent the money and all is in place, I don't think you've wasted a thing and you will have some added benefit thus you can enjoy the pride of having given your particular installation the best that's offered between bays!

             

             

             View Image  

          2. Griffin12 | Oct 15, 2009 07:47pm | #16

            Abingdon area?

          3. PedroTheMule | Oct 15, 2009 08:09pm | #17

             

            Abingdon area?

             

            Hi Griffin,

            Absolutely love Abingdon....I currently have 3 pieces in Patrick and Floyd with offers on another in Pulaski & Tazwell. Going to look at two right up above Abingdon the first of December.....Saltville is the actual area....we've looked around Coeburn but quite hesitant as the areas we've been introduce to at this point were carlessly & intentionally trashy.....I'm not talking good 'ol country livin'....I'm talking personal garbage dumped in the rivers and such.....might have simply been the wrong end of town......

            So, still have a couple more years to the "big move" and still open to that "perfect" setting. If we don't find anything better than what we already have. Looking for seclusion, yet no more than 30 minutes to nice typical facilities, don't need big chain store access, simply access to the basics and good folks. Focusing in the 40-60 acre range with no restrictions and good water. Power is not an issue since we plan to be off grid but we'll connect as backup if it happens to be available.

            Bike riding is also nice up that way.

            So, I take it that's your neck of the woods?

             

             View Image  

          4. Griffin12 | Oct 15, 2009 09:45pm | #18

             Actually I live in Johnson City, TN in the corner of the state. I do alot of work around the Abington area which is about 45 minutes from my house. The Abington Area has seen great growth the last few years along with soaring land prices. I know what you mean about Coeburn. There are really some nice people around "coal country" but a bit strange also. Just try stopping at a convience market. The people instantly know you are "not from around here" and tend to look at you like you have a third eye.

             Saltville is a nice area along with Glade Spring and Damascus. You might also consider Shady Valley and Mountain City in TN. The prices are not as high and there is no state income tax in Tennessee. Also the area just above Abington going toward Lebanon is beautiful along the Holston River.

          5. PedroTheMule | Oct 16, 2009 01:31am | #19

            Hi Griffin,

            I sure appreciate the confirmation of what I'd experienced and the tips.

            The 3rd eye thing is funny and accurate.....it's the Scotts-Irish gene's and upbringing....I've been around it, experienced it, handle it jest fine.....it doesn't take much conversation before they figure I ain't there to chop up their liquid or crop income.....besides I got a nice Scottish last name.....those folks come by their cautiousness naturally by 300 years of history.

            More funny - don't ask the locals for local directions.....no telling where you'll end up....ask 'em for directions 50 miles from where they live and you'll get info that'll lead you precisely where you want to go and how many pebbles on the side of the road you'll pass.....anything to get you out of their territory <grin>.

            I really ought to look around Mountain City again.....I actually liked the area but had one nasty experience with a motel manager many years ago. She was so bad, I wrote the whole area off to some degree....I'm big enough to realize that "one" person doesn't represent the whole area but it was so distasteful that I skipped over real estate in the area to look in other areas. That lady was basically an excuse to narrow my targeted areas and nothing more. I'll check it out again as we otherwise had a wonderful visit and an incredible meal....all I can remember is it was a privately owned, italian eatery and on the left when headed south about a mile or two before the ....uhhh I think it was a holiday inn express on the right....been years.....

             

             

             View Image  

          6. Pac NW | Dec 16, 2017 05:01am | #23

            24 OC would not meet code here, if built now..  My house was built in the 60 so it has 24" OC in the roof area but uses wood up to 4 x 12 not just 2x4 everywhre like modern houses around here.  I had all it walls turn down a decade ago.  I assume to remove and toxic paint or insulation since it was the house the contract was living in while building the other houses and for several years afterward.  Yhey added in studs so I have uneven studs for the walls but the attic was left original. 

          7. DanH | Oct 15, 2009 06:20pm | #14

            Keep in mind that in non-DIY construction the cost to install the insulation (which is reasonably constant regardless of R value) is likely greater than the cost of the insulation itself.
            As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz

          8. Griffin12 | Oct 15, 2009 07:30pm | #15

            With "professionally installed" insulation, labor costs are only about 20% of the total cost. Insulation companies make their money by buying their insulation in large volume. That bag of insulation you are buying at lowes for 50.00 cost them no more than 30.00 and maybe just 25.00.

          9. Pac NW | Dec 16, 2017 04:59am | #21

            Insulation Costs

            Not if you want something like denim insulation.  I doubt they can get that for half price.  Only for stuff they can buy in the truckload.  Not sure if the can even get something like Safe N Sound for half.  I have tried to get quotes but they never call back.

    2. Pac NW | Dec 16, 2017 05:00am | #22

      Numbers

      His R-13 price must be for used since both Home Depot and Lowes sells that size roll for $19.13 not $9, I bet it is their claimed price after a 50% rebate (your house must be certain age also which mine is) but you only get those if you hire an approved contractor and that would cost more then the rebate is worth.

      1. florida | Dec 18, 2017 04:12pm | #26

        You're not paying attention. The thread you'd so so anxious to correct was posted in 2009, all the prices are 8 years old.

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