question for the contractors out there, R11 vs R13 insulation
 

how much real difference is there between R11 and R13 insulation.

I have a chance to get a bundle of R11 insulation at half price and wanted to know could you really tell the difference or would it be such a small difference as to not be noticeable?

guy was told he bought the wrong kind so he went buy R13 and now is trying to sell the R11 for half what he paid for it.

they are both 3 1/2" thick x 15" bats so im thinking I might use it in my house unless its going to make a lot of difference just for those 2 digits of R value.

from what I have been able to tell, R11 is mainly used in basements

house exterior has 5/8" plywood on top of house wrap, then 1/2" sheetrock will be going on after the insulation

should I buy it and not think twice about it or pass and get R13 because it makes enough of a difference

Use it on the wall where the sun shines the lesser amount.

well this would be 5 bags of bundles of 93"x15" bats (5 bags x 155 sq ft per bag = 775 sq ft) so its pretty much going to be enough to do the whole house (30x30) if I get it, and its not worth getting if I don't use it all

I'd do the 13

Whatever you put in the walls, make sure you also adequately insulate the attic, and seal the home properly!

I wouldn't consider 11. 13 is good but I used 15 in my walls and would recommend it.

I might just get it to add in the attic on top of the R19 as an extra layer in the attic, its only 3 1/2 more inches but the price makes it hard to pass up and im thinking that should bring the attic up to R30. just have to peel the facing off it first.

thanks for the advice guys and I wasn't aware they had R15 so i'll look into finding some of that. after all, if your going to do it, do it once and do it the right way.

so is there something the same thickness as r19 but with a higher r value?

I have a decked attic space so I am limited to 6" thick ceiling insulation but I do want the get the best r value there is for it. is there an r21 or something like that?

If you want the best R go with spray foam, there are do it your self kits out there. Ill be doing my own.

Spray foam?

Not true
Open cell spray foam @ 3.5" ( 2x4) wall is r-13 . You can achieve r15 with blown fiberglass product called "assure-r" @ 3.5" thick

But

You will get a better seal with the spray foam than you will with the blown fiberglass


Another thing with spray foam is the majority of installers and the majority of Hvac contractors don't know how to properly install / mix product or properly design a Hvac system that works with a sealed envelope

You should consider some powered attic vents . I don't use 2x6 ceiling joists over decked attics for that reason , ideally you want r38 in your attic

You are correct on the open cell, I should have specified closed cell. Closed Cell at 1" offers an R14 value, you have to be careful with closed cell if you are doing an attic, you have to calculate your air flow envelop and have proper ventilation. Closed cell will SEAL you roof to a point that it can be a bad thing and cause a mold situation, thus the Air flow envelop calculation, I assumed K was asking about walls.

guess I should have paid attention better

And adds structural value ... It's some pretty cool stuff

as well the new stuff is a fire retardant, Ill spray foam my home AFTER I run all the wiring for this factor, if I happen to have a short HOPFULLY the the foam will keep it from taking off

Isn't it an additional coating you have to apply to make it fire retardant .

Even when using open cell with a roofline that is shot with foam you run risks of mold / house sweating .

I'm not a fan for a sealed attic. Imo wood natural moves / needs to breathe .

In researching this, for doing it my self, the small do it your self kits, yes, its an additional coating you have to put on. Now the guys that come out to your house with a 20ft trailer and have the entire set up, they can mix it in as it being processed in the trailer. Been trying to figure out a cost effective way I can buy the large 55gal drums of the two main components and all the gear for spraying for this reason as well trying to cut my cost if I do all the work. Cheapest I have found was a complete ready to spray trailer set for 20K. BUT I have 2 quotes to do my house, one was 12K the other 14K.

SO do I buy the RTG trailer set up do all the work my self and then try to sell the unit, or just spend the 12K

Back to K

The EASIEST is going to be just get the rolls, anything ADDITION you add to your current insulation will help be it r11 r13, if your ADDING it to your current, and you can get that R11 for 1/2 price Id go that route, but thats my opinion, just like belly buttons, everyone has one

Pay the man , that is some nasty stuff to work with . There is a lot more to just mixing and spraying . You have to pay attention to the temps of the wall you are applying it to . IF you go the open cell route n fill the wall cavity make sure all of your low voltage is secured tightly because when that foam expands it pushes the wires out and the guy trimming the excess off can easily nick that thin LV wire for alarms , av etc . And you wouldn't know until you try to get it working after you move in

its a complete gut so its just like new construction, nothing is being "added" because nothing at all is there now


yes, I even heard that stuff sticks to you like tar and sticks to your skin.

there is a lot of good to say in spray foam but there is bad too, I see all the stories of air conditioning and ventilation issues with moisture and mold problems concerns me a lot.

the way I understand how to properly condition the air in a foam sealed house is, you have to pump in or draw in, outside air and exhaust an equal amount outside, so it exchanges and this is done at a certain rate using a heat exchanger to conserve the condition airs temperature. something like 25% of the air in your house is replaced every hour.

I know that something sealed too tightly can be a very bad thing, so I would like to find a way to get the benefits of foam but not seal the house up so air tight. maybe its better with high r value fiberglass and letting the house be able to breathe better and be better air to breathe. or maybe its better with a combination of both with foam walls and fiberglass matt in the ceilings :confused: