What is the best exterior wall insulation

[h-town humidity]

I was wondering if any of you had opinions on the best wall insulation. I am building a new home in Houston, Texas, and the standard wall insluation is R-13 unfaced batts in 2x4 walls and R-19 on exterior 2x6 walls. The standard insulation in the attic (two story home) is R-30.

I am going to upgrade to R-38 blown in for the attic, and have been given a quote for Ownes Pro-Pink blown in for the exterior walls. Have any of you had experience with this stuff and what are your thougts versus cost as it is 2-3 times the cost.

Also, they are using cellulose spray for sound control on some of the ceilings and R-11 owens-corning sound batts around some interior walls. Why not just use spray on substances or other?

Essentially, I am in need of help for the best reccomendation on insulation for the house. We went with three Trane 14 SEER, 80% variable furnace systems with Lennox media filters in the house and want to maintain as much energy efficency as is worth the cost. Thank you for your help.

[platchford]

I went with spray-in foam insulation for my home by an Icynene (http://www.icynene.com/) dealer. It deadens sound tremendously, seals out nearly all air infiltration through the walls (not that this should be a problem with new construction), it doesn't settle over time and it does not readily absorb water if you were to have some sort of leak. You'll pay more for it but in my opinion it is well worth it. One of the problems with fiberglass and many other insulations is if you have air infiltration through the wall then the R value of the insulation is almost completely negated. :(

[Daltex]

I agree with using the spray foam insulation. Increased R and air tight! If cost is too high then maybe just the south and west walls with fiberglass on north and east. Heat gain will be your biggest expense in Houston.

[brian in mass]

spray foam is the only insulation in my eyes if there is an option.

[firecontrol]

For lower air conditioning loads I put this product on my new home when I built it.

http://www.jm.com/insulation/building_insulation/products/bid0022_ap_foil-faced.pdf

I'm not sure what help it did in the heating months which are long here in wisconsin, but when we have 95° summer days I can cool 1600 sq ft with a 5000 btu window shaker to as low a temperature as the control will go down to.

[platchford]

For lower air conditioning loads I put this product on my new home when I built it.

http://www.jm.com/insulation/building_insulation/products/bid0022_ap_foil-faced.pdf

I'm not sure what help it did in the heating months which are long here in wisconsin, but when we have 95° summer days I can cool 1600 sq ft with a 5000 btu window shaker to as low a temperature as the control will go down to.

Which R value (thickness in this case) did you use? How much did it add to the cost of insulating your home (per sq ft)? I'm only asking because I looked into similar products when rehabbing my house and, honestly, it was basically the same cost to have someone else spray foam as it would have been to have ME insulate with fiberglass and exterior foam sheeting. To top it off, the spray foam will still fill gaps and eliminate more air infiltration than the foam sheeting. Regardless, it still seems foam of one type or another is the winner. ;)

[mlo1]

Generically commenting...cellulose dense fill or wet blown. Like most everything, a quality install is also key. You happen to live near Payless insulation. Larry is a great wealth of knowledge and knows your climate. Maybe give him a ring.

[rtucker]

I insulated a home last summer with B.I.B. insulation. It stands for Blown In Blanket. They cover the studs with a thin cloth, much like on the back of box springs. Then the blow in loose fill insulation. The product has a lifetime manufacturers warranty from settling. It can actually be packed it a little tighter and raise your R-value somewhat. That is still a big debate with all products. (packing x cost = not much gain in R-value) I have been happy with it and it is better than batts and cheaper than foam. They have a web site. Do a search.
RT

[Daltex]

Remember also that the wall heat loss is much less than the ceiling loss. I don't think I would pay for the wall foam in a new install unless the attic was also foamed (due to the main benifit of decreasing air infiltration).

[teddy bear]

Air tight is good but what about mechanical fresh air ventilation? Regards TB

[platchford]

I insulated a home last summer with B.I.B. insulation. It stands for Blown In Blanket. They cover the studs with a thin cloth, much like on the back of box springs. Then the blow in loose fill insulation. The product has a lifetime manufacturers warranty from settling. It can actually be packed it a little tighter and raise your R-value somewhat. That is still a big debate with all products. (packing x cost = not much gain in R-value) I have been happy with it and it is better than batts and cheaper than foam. They have a web site. Do a search.
RT

In general, how would you really ever know if the product settled in the wall or not? Also, packing it tighter to increase R value doesn't sound right... makes as much sense as packing fiberglass tighter which would decrease R value... how does this work?



Remember also that the wall heat loss is much less than the ceiling loss. I don't think I would pay for the wall foam in a new install unless the attic was also foamed (due to the main benefit of decreasing air infiltration).

Honestly, why would you not foam the attic if you are foaming the rest of the house? At a minimum do 4" of foam in the attic followed by several more inches of fiberglass in order to achieve the R value you need if you don't want to do all foam. Also, the foam I mentioned is open-cell... if you really want some R value choose a closed-cell and the R value per inch nearly doubles.



Air tight is good but what about mechanical fresh air ventilation? Regards TB

Very true. In my opinion I'd rather have a mechanical fresh air intake that I can filter rather than depending on the loose construction of my home. Also, mechanical fresh air ventilation gives you the opportunity to utilize any number of systems that recover some of the heat from the stale exhaust air and apply it to the incoming fresh air.

[Daltex]

Honestly, why would you not foam the attic if you are foaming the rest of the house? At a minimum do 4" of foam in the attic followed by several more inches of fiberglass in order to achieve the R value you need if you don't want to do all foam. Also, the foam I mentioned is open-cell... if you really want some R value choose a closed-cell and the R value per inch nearly doubles.

I already said I'd foam the attic. Most of the foam insulation in my area is closed cell. The attic foam is on the inside of the decking, not on the attic floor, so you don't add batting.

[platchford]

I already said I'd foam the attic. Most of the foam insulation in my area is closed cell. The attic foam is on the inside of the decking, not on the attic floor, so you don't add batting.

Sorry, my point was more directed as a "why wouldn't someone foam the attic" rather than a why wouldn't you foam the attic... my bad. :) As for foaming the decking, that is definitely the better way to go. I was speaking speaking from more of an installation cost standpoint being that there is less surface area on the floor than within the decking. ;)

[2old2rock]

Best isulation is 2x4 wall, 1" dead air space, another 2x4 wall. Called "Super Insulated" in these parts.
Also, I wonder why you would go with an 80% efficient furnace when you're so concerned about insulation value. I understand cooling is your main concern, but throwing 10 -15% of your heating out the chimney doesn't make much sense to me.

[Shophound]

Best isulation is 2x4 wall, 1" dead air space, another 2x4 wall. Called "Super Insulated" in these parts.
Also, I wonder why you would go with an 80% efficient furnace when you're so concerned about insulation value. I understand cooling is your main concern, but throwing 10 -15% of your heating out the chimney doesn't make much sense to me.

Houston has a minimal heating season. Going much above 80% is hard to justify for payback.

Houston also seldom goes above 100 in summer, but that's due to the high humidity levels. Which translates to high latent loads for the a/c system. Therefore I think the best bang for the buck is low infiltration strategies...if the spray-in foam accomplishes good insulation AND good sealing properties of the building envelope, it would be good. The main concern I'd have with any building envelope in a humid climate is proper drainage of water away from the exterior sheathing. Since Houston is hot AND humid, any water trapped behind the exterior siding that can't drain off naturally or dry out, will be driven into the wall sheathing and insulation via vapor pressure/diffusion, increasing the risk for mold.

I think the OP would be well advised to visit the Building Science website and read about building envelopes for hot/humid climates. Lots of good info there.

Oh...and be sure your HVAC installer seals the ceiling supply boots to the ceiling drywall. Most commonly overlooked thing there is...and leaving it neglected is asking for excessive infiltration.

Teddy Bear is also right on, as usual...if you build a tight house, you need to provide deliberate fresh air exchange via mechanical means. Whole house dehumidifier with fresh air intake is what he recommends, I believe. If you opt for fresh air intake on the return side of the HVAC system, the system must be sized adequately to handle the additional sensible and latent heat loads that will be imposed.

[h-town humidity]

Sorry about the delay in responding, I lost my log-in information. I think we have the fresh air covered with a whole-house mechanical system that is independent of the AC.

I am going to leave the walls with the r-13 unfaced batts in the hot walls, I dont see the energy savings based on what I am hearing for BIB versus batts, and I am afraid spray foam on the walls will be a moisutre problem with the stucco exterior.

We have a radient barrier and are going with R-38 blown in for the attic. I am contacting a few Icyene dealers as well to see about the attic, but I am not sure if it will be worth the cost.

[platchford]

I am going to leave the walls with the r-13 unfaced batts in the hot walls, I dont see the energy savings based on what I am hearing for BIB versus batts, and I am afraid spray foam on the walls will be a moisture problem with the stucco exterior.

I'm not sure why you think spray in place foam would be a moisture problem... it won't let moisture in from the inside so how will moisture get behind the stucco from the outside? In fact, IMO if moisture were somehow able to get behind the stucco then any other insulation would be a problem for sure because of dampness and mold. I'd still recommend you ask any Icynene dealers in your area about you moisture concern before settling on a particular insulation type.

[firecontrol]

Which R value (thickness in this case) did you use? How much did it add to the cost of insulating your home (per sq ft)? I'm only asking because I looked into similar products when rehabbing my house and, honestly, it was basically the same cost to have someone else spray foam as it would have been to have ME insulate with fiberglass and exterior foam sheeting. To top it off, the spray foam will still fill gaps and eliminate more air infiltration than the foam sheeting. Regardless, it still seems foam of one type or another is the winner. ;)

I'd have to do a lot of digging through invoices to figure out the added costs. If you want to do the math: 180' of exterior wall surface. I used 1" thick product.
An exterior wall is made up of approximately 80% cavity and 20% studs. I felt the 20% was an important quantity to insulate that extra amount.
I've read all the advertising and claims of the foam companies and it all seems great, but if the exterior envelope and interior envelope is sealed by what are standard building practices (and in some or most cases code requirements) then infiltration should be very minimal.
Now think about living the rest of your life in a balloon or a glass jar. No fresh air coming in and no interior polluted air leaving. So what happens? An air to air heat exchanger or other forms of powered ventilation is installed and guess what........ the infiltration that you spent hard earned money on to stop is now replaced with mechanical equipment that cost you more of your hard earned money.
Most infiltration in modern day homes is caused by improperly installed or sealed ductwork, poor quality doors and windows or a multitude of other means.
I do heating and cooling loads for a living and when I designed my own home I did some cost comparisons. Very little difference was gained in the walls in either heating or cooling loads when varying the R value. 1600 sq ft and about 12,000 btu's/hr @ -40°F to 95 in the summer. Put the best windows and doors in and all of a sudden it's 45,000 and I need an air conditioner.
What did I learn? Put your money into the best doors and windows, build longer overhangs and plant trees for shading. I added the exterior insulation for upping the 20% of the walls to a higher value, gave the exterior another layer of vapor and infiltration control.

[cem-bsee]

why not insulate on the outside of the exterior stud walls = 2" thick T&G Styrofoam?
super insulation = R60 in ceiling, R40 in wall, R10 under slabs.

adding some foam inside of wood framing will help seal the wall -- be sure to not use foam which may shrink, say after 5y. having foam between framing will not stop 'bridging'. foam should prevent having bridging across gaps common with batts.

using advanced wall framing techniques will help greatly. = at corners & interior wall intersections -- to allow the max insulation.

payback | ROI -- the price of fuel is unlikely to decrease in the future -- so, the question is what is it worth to you to save some now, lots more later? 'It only costs a little more to go first class.'

It is HARD to add insulation later in walls.

[teddy bear]

Sorry about the delay in responding, I lost my log-in information. I think we have the fresh air covered with a whole-house mechanical system that is independent of the AC.
am not sure if it will be worth the cost.
A little dicussion on "have the fresh air covered". You made a comment on ERV ventilation earlier. In the Houston climate which is a moderate climate regarding temperature, the critical issue is humidity verses heat reclaim. Your clothes drier, kitchen hood, and bath fans exhaust air to the outside. These devices need make-up air to function properly. Therefore your ventilation should be a make-up fresh air device to avoid depresurrization of your home. Also a well insulated home in a humid climate that is properly ventilated needs supplemental dehumidification during the cool humid weather. During hot weather, the a/c is capable of mantaining low humidity, Dehumidification that maintains <50%RH regardless of the cooling load, fresh air ventilation, or number occupants provides IAQ and ideal comfort. I hope that "fresh air covered" means a whole house ventilating dehumidifier. They only cost a little more than ERVS. This is new technology that most a/c contractors have not used. Ultra-Aire, Honeywell, and Aprilaire are among the mfgrs. The Ultra-Aire is the pioneer and the most efficient. Any a/c contractor can supply these. Regards TB

[h-town humidity]

Thanks. I believe that I have a honeywell whole house dehumidifier. I based it on your comments I think from an earlier post. We also dont keep our house that cold, so using the AC (unless perhaps we got a two stage) was not our best option. We have a 5,500 sq ft house, so I do need to confirm whether they tied it into the duct work for one of the 3 ac systems or if they ran new duct work.

[teddy bear]

Thanks. I believe that I have a honeywell whole house dehumidifier. I based it on your comments I think from an earlier post. We also dont keep our house that cold, so using the AC (unless perhaps we got a two stage) was not our best option. We have a 5,500 sq ft house, so I do need to confirm whether they tied it into the duct work for one of the 3 ac systems or if they ran new duct work.

Great! Best to have an independent return from the home to the dehumidifier and discharge the dry air into the a/c supply. Keep us posted on your results. Regards TB

[air311]

Foam isn't the best for exterior walls. It settles, leaving bare spots with no insulation. A neighbor sprayed foam in his walls 3 years ago, recently took some siding off, and noticed the setting problem.

[platchford]

Foam isn't the best for exterior walls. It settles, leaving bare spots with no insulation. A neighbor sprayed foam in his walls 3 years ago, recently took some siding off, and noticed the setting problem.

If applied properly it should not settle. Did he spray it himself using one of the products available over the web? If he hired a professional I'd have them come back because something wasn't done right. The stuff sticks to everything it touches when sprayed properly. It took force to pull it off the exterior sheeting and inside of the studs when I needed to make room for the vent of my range hood and it was installed about 3 years ago here... definitely no settling. As a matter of fact, if the wall cavity was properly sprayed and filled then how could it settle? There should be nowhere for the material to settle to. :confused:

[brian in mass]

guys....how can there even be a debate on this ?? There is no contest. I wish it were code...with all these tree hugging dirt worshipers out there you'd think it would be by now.
A closed cell spray foam is the only option for someone who is serious about it.
Honestly....r-7 per inch.....zero infultration, which means what air you do bring in is controled on all levels. And you guys are forgeting something very important....a sort of added bonus. Sprayed homes gain structual strengh. Ready ?....12,000 times !!!!! That's incredable in my eyes.
The way I feel is this.......and this is true for whatever type you go with that is much more efficient.......it costs ALOT more to do it the cheap way then to do it the expensive way. My grandmother could not wrap her mind around that statement. I had to break it down for her.....but basically, you pay more up front for something like spray foam, and then it quickly pays for itself. After, it's pure savings. If you live in your home for any length of time, you just keep adding up that kind of savings. You'll be amazed at the differece you saved over say ten years with something like foam compared to regular batts. And then factor in the difference in savings on smaller heating and cooling equipment. Think that all air in your home will now be acounted for and conditioned to your specs. Your home will be alot more quiet than other homes.....no traffic noises and barking dogs.
I just don't see any dowside at all. The only thing I see is narrow minded short sighted people who think on a whim rather than with their wallet.

[geodude]

When I built my shop, I had high density polyurethane sprayed on the walls and ceiling. It simply is the best bang for the buck. A customer of mine liked it so much he did his whole house with it. And the all sheet metal duct system we put in got sprayed with it too. Of course we installed an ERV system and a dual capacity geothermal unit. that was in june of 2000 and he still is happy. The main draw back is the exspense of the high density foam.

[brian in mass]

again....don't think short term. It's not expensive....it's a hell of a lot cheaper.

[geodude]

again....don't think short term. It's not expensive....it's a hell of a lot cheaper.

In that context, I agree!