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bcool
Premium
join:2000-08-25
The Ozarks

4 edits

R-30 to R-38 in attic

New construction. Southeastern Missouri.

Builder blew in "ample" R-30 value into my attic. The outfit that did the original job quoted me about $500 to come in and bring that up to R-38 estimating another 5 inches of insulation in attic to bring it to R-38. 1365 sq.ft living space. Cathedral ceiling in living room/dining room/kitchen. R-13 batt in 2 x 4 walls. HVAC: 2.5 ton HP + 60000 BTU gas furnace backup.

I don't know much about insulation. Please forgive dumb question. Is it worth it for me to pay some $500 to go to R-38 in attic considering everything else especially the R-13 in walls and uninsulated floor?



mityfowl
Premium
join:2000-11-06
Dallas, TX

You'll have to figure out your ROI.

What do you hope to accomplish?

How long will you live there?

Type and cost of fuel?



pende_tim
Premium
join:2004-01-04
Andover, NJ
kudos:1
Reviews:
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1 recommendation

reply to bcool

If you do decide to increase R value, ask how much to take it to R 50 or so, bet would not be that much more. R 30 looks like minimum for most areas below the Mason-Dixon line.

Here is the EPA energy star guide: »www.energystar.gov/index.cfm?c=h···on_table
--
The difference between genius and stupidity is that genius has its limits.



cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to bcool

Quick answer: save your money for something else - like insulating your floor. You'd only reduce the losses through ceiling by 25%.



StillLearn
Premium
join:2002-03-21
Streamwood, IL
reply to bcool

If adding 5 inches brings you to R-38, you probably did not have R-30 to begin with.



pende_tim
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Andover, NJ
kudos:1
Reviews:
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reply to cowboyro

said by cowboyro:

Quick answer: save your money for something else - like insulating your floor. You'd only reduce the losses through ceiling by 25%.

Without seeing the Manual J for the house and $/BTUH for the OP, it is hard to put an exact $ number on the savings.

Generally, in a tight house, the conduction losses through the ceiling can be 30% of the energy budget for the house. So If he took the ceiling from an R 30 to R 45, he would save 10% of his total heating AND cooling cost for the house.

This could be worth $200/year. I would take a 40% return on my investment any day.

These are just typical/assumed numbers, your results will depend on the construction, energy costs and climate.
--
The difference between genius and stupidity is that genius has its limits.


chamberc
Premium
join:2008-08-05
Irving, TX
reply to cowboyro

said by cowboyro:

Quick answer: save your money for something else - like insulating your floor. You'd only reduce the losses through ceiling by 25%.



aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1
reply to bcool

Given the R-13 walls and uninsulated floors, it is probably not worth to beef up the insulation over the ceiling.

However, if you plan to do something about the walls and the floors, then it's a whole different ballgame. Adding extra insulation in the attic is usually reasonably cheap and easy, so you may just do it, even if you don't get much immediate benefits. However, if you do so, you probably want more than just R-8 extra since I think labor is a significant portion of the cost, and getting R-16 shouldn't be a whole lot more. Of course if you add extra insulation there, eventually you may also want to insulate the floor, and preferably add some extra insulation to the walls. Insulating the floors shouldn't be too difficult either. The walls, on the other hand, can be tricky and expensive.
--
Wacky Races 2012!



cowboyro
Premium
join:2000-10-11
Shelton, CT
Reviews:
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reply to pende_tim

said by pende_tim:

Without seeing the Manual J for the house and $/BTUH for the OP, it is hard to put an exact $ number on the savings.

Most favorable (for savings) scenario: 8ft walls assume a 30x45ft house (1350sqft), that gives 1200sqft of R-13 walls and 1365sqft of ceiling with R-30.
Disregarding the higher losses of doors, windows, air leaks and even floor, the ceiling would represent 33% of losses. Increasing from R-30 to R-38 would save 7%.
However OP has stated the presence of cathedral ceilings and uninsulated floors - which means the actual savings would be significantly lower -> waste of money (at least for now). No need to patch a pinhole leak in a strainer...

robbin
Premium,MVM
join:2000-09-21
Leander, TX
kudos:1
reply to aurgathor

said by aurgathor:

Given the R-13 walls and uninsulated floors, it is probably not worth to beef up the insulation over the ceiling.

Sounds like you are saying that if I am wearing shorts and sandals then there is no reason to put a cap on my head.

Attic is easy to add insulation to and I would do it but take it up to R50 while they are there.


Cho Baka
Premium,MVM
join:2000-11-23
there
kudos:2

Maybe it is because I am not from a warm place (Texas), but yeah, I'd tell you to put jeans and a jacket on before a cap.
--
The talented hawk speaks French.


robbin
Premium,MVM
join:2000-09-21
Leander, TX
kudos:1

Cap is easier and makes a difference. Point being, the attic is easy to add insulation to. Walls are very hard. Where it is easy, add it.



pende_tim
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join:2004-01-04
Andover, NJ
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Reviews:
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reply to bcool

You say floors are uninsulated. What is the nature of the space below the uninsulated floors? Is it conditioned, finished space, insulated walls, etc? What is temperature in the basement area? In other words does it need insulation in the floors?

Can the area over the cathereral ceilings also be insulated?
--
The difference between genius and stupidity is that genius has its limits.



bcool
Premium
join:2000-08-25
The Ozarks

1 edit
reply to bcool

House is 1365 sq.ft.
957 sq.ft. sits on top of unconditioned crawl space
408 sq.ft. sits over (partially finished) basement.

Basement has some batt along top of basement walls. Temp in basement around 66 degrees F. +/- Windows and door not well insulated.

Isn't there cellulose a top the cathedral ceilings when they originally blew in insulation into attic?

And by the way, I have recessed halogen lighting in kitchen and living room (cathedral ceiling). House was built July 2012. How do I determine that they used lights that pose no fire hazard in attic if in contact with insulation (I don't even know if light fixtures would come in contact with insulation in the attic?).



bcool
Premium
join:2000-08-25
The Ozarks

4 edits
reply to bcool

So that I get this straight in my head....

For argument sake, after their touched up in the attic a few days ago, let's just say I have solid R-30 in attic. Builder always boasted that they tend to add extra but let's discount that for now.

Fiber-lite cellulose insulation:

I have R-30 value in attic. If the minimum job this outfit does is 5" blown insulation, what in fact would another 5" on top of real R-30 ACTUALLY give me then? I could end up closer to R-45 (at least more than R-38) if I let them blow in minimum job @ $500. Cha-ching, yes? No?



35245635

join:2013-03-04
North Reading, MA

1 edit
reply to bcool

Blown cellulose is around R3.5 per inch so adding 5 inches would be R17.5 roughly. If you have R30 now you'd be looking at like ~R48 after this work. You should have around 8 1/2 inches of insulation now if you are really at R30. You might want to check that first.
--
"Everyone has his day and some days last longer than others." - Winston Churchill



bcool
Premium
join:2000-08-25
The Ozarks

~R-48 wouldn't be too much cellulose in my attic, do you think? I have three gables (exterior sheathing up next to gable is not house wrapped) and I have ridge vents.



pende_tim
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Andover, NJ
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reply to bcool

Ok, this is confusing at best. The Spec Sheet claims an R value of 3.7/inch before settling. They do not state the reduction in fluff for long term settling however.

So lets assume it looses 10%.
For an R 30 attic, you should have about 8.5" down now. If you look in the attic, there should be "tape measures" stapled to the roof trusses/joists that show how much is put down. These are like a dip stick. If they are below 9" get the builder back and have him fix it on HIS dime.

Now it gets interesting. If they will be adding 5" to the area, that will be adding 5*3.7*90%= R16. ( After losing 10% for long term settling). This means that the final R of the attic will be in the range of R45. not R38. (R30 +R16)

For a better idea of the savings, what have your heating and cooling bills been since you moved in? Can you separate from the general energy use? Adding R15 value to the ceiling will save 30% of the heat loss/heat gain through the ceiling. If we assume the ceiling is 1/3 of the total energy budget for the house, this additional R15 will be a savings of around 9%.

Don't forget there are tax savings for adding insulation!

As far as the comments about not bothering with spending the money on attic insulation when you have uninsulated floors, keep in mind that heat loss is a parallel process. You are loosing energy everywhere and it ALL adds up at the end of the month whne you pay the gas/electric bill. Just because you insulate the floors, does not mean that you will stop loosing heat/cooling through the ceilings. Take all the savings you can get now, the cost of energy will not be going down.

If your crawl is staying at 66*, there is not much of a temperature difference between the living area and the crawl so there is not a whole lot of heat loss there. If you want to insulate this area, it could be a DIY project. Use R19 bats and metal stays to hold them in place. It will be messy but fairly inexpensive project.
--
The difference between genius and stupidity is that genius has its limits.



bcool
Premium
join:2000-08-25
The Ozarks
reply to bcool

I'm assuming added insulation in attic will also reduce A/C (cooling) cost even if by small percentage? Or are we talking heating only here?



35245635

join:2013-03-04
North Reading, MA

said by bcool:

I'm assuming added insulation in attic will also reduce A/C (cooling) cost even if by small percentage? Or are we talking heating only here?

It helps both. Look at it this way. If it costs you $100 a month for heat or A/C per month so say $1,200 a year. If this insulation saves you say 4% it would take you 10 years to pay for it. After that it is pure profit. If it saves you 8% now it only takes 5 years to pay for itself. If your bills average more then $1,200 a year you save faster. If you plan to be in the house more then 5-7 years it a no brainer to add the insulation. Don't forget it will also be a selling point if you ever want to sell. You can say the house has upgraded insulation. It may or may not help but it can't hurt.
--
"Everyone has his day and some days last longer than others." - Winston Churchill


cowboyro
Premium
join:2000-10-11
Shelton, CT
Reviews:
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reply to bcool

said by bcool:

House is 1365 sq.ft.
957 sq.ft. sits on top of unconditioned crawl space
408 sq.ft. sits over (partially finished) basement.

If there is no insulation in the floor and you're only spending $500 then do the ~1000 sqft of uninsulated floor first - that will give you the best bang for the buck. You're likely to lose 2-3 times more heat through the floor than through the ceiling. Increasing the amount of insulation in the ceiling will eventually pay off, but not as fast as fixing the biggest losses.
BTW are your floors cold to the touch in winter?


bcool
Premium
join:2000-08-25
The Ozarks

Yes, the floors are cold to the touch during winter. I have a hunch, though, that doing 1000 sq.ft of floor is going to cost me way more than $500?



bcool
Premium
join:2000-08-25
The Ozarks
reply to 35245635

said by 35245635:

said by bcool:

I'm assuming added insulation in attic will also reduce A/C (cooling) cost even if by small percentage? Or are we talking heating only here?

It helps both. Look at it this way. If it costs you $100 a month for heat or A/C per month so say $1,200 a year. If this insulation saves you say 4% it would take you 10 years to pay for it. After that it is pure profit. If it saves you 8% now it only takes 5 years to pay for itself. If your bills average more then $1,200 a year you save faster. If you plan to be in the house more then 5-7 years it a no brainer to add the insulation. Don't forget it will also be a selling point if you ever want to sell. You can say the house has upgraded insulation. It may or may not help but it can't hurt.



One thing I did not bring up in this discussion. We've concentrated on the finite math and savings to energy bill. The topic is comfort.
This winter (which have been moderate for last few years here) there's been a slight chill in the living room and hall way just enough to make sitting on couch uncomfortable without a small "blanket" of some sort. Thermostat set at 71 F for winter.
I understand that insulating floor would go long way but that is likely to be more than my budget could stand here and now.


35245635

join:2013-03-04
North Reading, MA
reply to bcool

said by bcool:

Yes, the floors are cold to the touch during winter. I have a hunch, though, that doing 1000 sq.ft of floor is going to cost me way more than $500?

I'd guess $1,000 to $1,300 for the floors. You get a tax credit of 10% off up to $500 also to help. It sounds like doing both would pay for themselves in a few years.

Another option is get in someone to do an energy audit with thermal imaging. They'll tell you where you are losing heat then you'll know where to throw your money.
--
"Everyone has his day and some days last longer than others." - Winston Churchill


bcool
Premium
join:2000-08-25
The Ozarks
reply to bcool

I'm sorry to belabor this issue....

but maybe it would be smarter to leave attic alone for the time being and put money toward doing floor @ R-25 batt or something like that, right?



35245635

join:2013-03-04
North Reading, MA

said by bcool:

I'm sorry to belabor this issue....

but maybe it would be smarter to leave attic alone for the time being and put money toward doing floor @ R-25 batt or something like that, right?

Normally you'd use R-30 for the floor. A roll covers about 30 sq. ft. so you'd be looking at $525 plus tax for a DIY install on the floor. After the 10% rebate you should be around $500 in just materials. Normally they charge about the same price in labor as materials so I'd guess $600 for installation. Honestly you could install the floor insulation yourself in a day. If you DIY the floor and pay them to do the ceiling you should be around $1,000 for both.
--
"Everyone has his day and some days last longer than others." - Winston Churchill


bcool
Premium
join:2000-08-25
The Ozarks

Ok. Good. thanks all.



pende_tim
Premium
join:2004-01-04
Andover, NJ
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Reviews:
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reply to bcool

What is the floor covering? If it is carpet, that is worth an R3 0r R4

R25 in the basement is overkill with such a small temperature difference between the basement (66*) and the living space (71*).

Nice thing about the basement is it can be a DIY project and you can chip away at it. Get a roll or two of R19 (or R13 ) insulation each month. You can get a 50ft^2 roll for about $18.00. So if you do 2 rolls a month, most of the house will be done by next winter.

If it were me, I would do the attic first as it will give you the most savings due to the temperature differential between the attic and the ceiling. In the winter and summer there is a 50* difference between the attic and the living space. That is a lot of load. Attic will also benefit you for heating and cooling.

Basement insulation will only benefit you for the heating season and will not really save that much as there is only a 5* difference between the areas.
--
The difference between genius and stupidity is that genius has its limits.



35245635

join:2013-03-04
North Reading, MA

1 edit
reply to bcool

Click for full size
Our basement ceiling isn't insulated. Our's is almost exactly what pende_tim said. We keep the living space at 71 and the basement stays around 67. I've had 2 energy audits by different companies over the last 2 1/2 years and both recommended against insulating the basement ceiling. Not sure why but I had them do the attic space last year. It was around R-19 to R-22 and they took it up to R-50 to R-52. That was the most they could install. It cost about $1,000 after utility and tax rebates. So far I've calculated we saved about 300 gallons of heating oil. That's about $1,100 in heating oil so for us insulating the attic was a 1 year return on investment.

Edit: Attached my job from last year. The cellulose quantities are the square feet they installed. You can see it's about $1.38 per sq. ft. for 9 inches of cellulose before rebates and incentives.
--
"Everyone has his day and some days last longer than others." - Winston Churchill


cowboyro
Premium
join:2000-10-11
Shelton, CT
Reviews:
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reply to bcool

said by bcool:

I have a hunch, though, that doing 1000 sq.ft of floor is going to cost me way more than $500?

Not quite...
»www.lowes.com/pd_177781-1722-B39···rating|1
$15.65 for 31.25 sqft
You do the math
And then you can get some federal tax credits on top of it.
Sure you'll have to add some staples and a couple of plastic sheet rolls to that but still...