Foam Home

[behappy]

I am posting this here and am looking for knowagable comments.

Our home is being built NOW. One of my customers just bought a foam insluation business. This is were you spray styrofoam insluation (3") in the walls, you block off the eve vents and spray the roof rafters all the way to the peek (5.5") with no ridge vents. The home is "sealed" with styrofoam insluation and NO ventalation in the attic (cold weather freezing is not an issue here). There is NO insluation over the ceiling sheetrock and the attic becomes another conditioned space. The other side benifit to the R-20?? for the walls and R-38 for the roof is a very tight house (this is great for reducing infiltration) and is a great sound reducer.

I really didn't consider this mostly because I have already decided on the higher R value glass and high eff. equipment. BUT, I had a "Good Cents" meeting with one of the power companies (not the one I will be on) and the head tech/troubleshooter and I had a two hour discussion on this (the marketing people rolled their eyes and left us alone). He opened my eyes on the proper way to run a load calc. on this and the advantages of this system. I am waiting on a price from my customer (who I trust).

Now this may end up being a budget buster and everything may be out the window, but I am looking for comments on this.

Thanks,

[behappy]

One thing I forgot to add. You have to condition the attic because it is part of the conditioned space. Usually not much because there is only roof load and volumn only.

I told the wife that when her sister visits her sister could sleep up there...

[danglerb]

Last time I played with a styrofoam cup and a match building a house out of it wasn't my first thought.

What climate is this house being built in?

Given how cheap it is to get R38 above the ceiling with conventional methods, I don't think I would be willing to try anything that radical. Whats the long term effect on the wood underneath, that kind of questions.

Squirting the stuff in to seal up some areas I could see, but between studs I would guess premade blocks would be much cheaper.

What about other super insulation tricks, like building the walls on 2x6 and staggering the 2x4 studs so inside and outside walls don't have a direct path through wood.

[cem-bsee]

and the R value of this is?
probably about 5/inch, so walls =~R15,
roof=5*5.5*0.8= 22 because wood rafters not covered.

w/o covering this with sheetrock, then nothing can be stored in that attic!
I would probably cover it with 0.375" tk sheetrock in attic for peace- of- mind. -- should not be that expensive during new hse construction & no taping --

how about shrinkage after 5y?

[dan sw fl]

Originally posted by behappy
Our home is being built NOW. One of my customers just bought a foam insluation business.

The home is "sealed" with styrofoam insluation and NO ventilation in the attic (cold weather freezing is not an issue here). There is NO insluation over the ceiling sheetrock and the attic becomes another conditioned space.

The other side benifit to the R-20?? for the walls and R-38 for the roof is a very tight house (this is great for reducing infiltration) and is a great sound reducer.

Now this may end up being a budget buster and everything may be out the window, but I am looking for comments on this.

Spend ~$2,000+ extra (< ~$1.50 /S.F.) on this spray foam insulation and select lesser (14 or 16 versus 19) SEER equipment and put in one less window to maintain your budget. You are likely to be pleased with decreased operating costs and better home comfort.

http://www.airtightinsulation.com/

See "Understanding Attic Ventilation" at
http://www.buildingscience.com/whatsnew.htm

[tom21769]

What is the insurance company's take on this?

As I recall from when we were considering SIPS (sandwiched foam panel) construction, there has been some "heated" discussion of fire safety and insurability related to the choice of foam core types. Most of the concern seemed to center on EPS (not PUR) cores. Smoke production as well as melting/flashover was discussed. The builder (who offerd both EPS and PUR panels) vigorously defended the fire safety of his company's products. I was satisfied with his explanation at the time (though we did not proceed for unrelated reasons).

[mjk_na]

How is summer condition at your area? Painting the roof with light colour will help in reducing heat gain through radiation, if summer is quite long and hot.

Why no ventilation at roof? It might help heat gain as well.

JMO.

[mark beiser]

The spray foam insulations used for this type of construction are NOT styrofoam! The products used generally tend to have low flamability and flame spread characteristics, some are less flamable than wood. Some are even soy bean based.

If you live in a hot humid area, sealed conditioned attic type construction is the recommended way to go by buildingscience.com

http://buildingscience.com/designsthatwork/default.htm

FYI, you don't actually need to have supply outlets in the conditioned attic, it will stay within a few degrees of the home due to heat transfere through the cieling.

If you are considdering going this rout, please research it some, as there is more involved than just foaming the bottom side of the roof decking.

Originally posted by mjk_na
Why no ventilation at roof? It might help heat gain as well.

For the same reason you don't ventalate any other conditioned space in the home with outdoor air...

[pstu]

>>If you are considdering going this rout, please research it some, as
>>there is more involved than just foaming the bottom side of the roof decking.

Mark, I wonder if you could point us to some of that research for the next level. My neighbor (an old fashioned HVAC guy) just did an add-on type of foam job on his house, at great expense. It seems obvious to me his house is better sealed because of it, and he reports much lower cooling bills. Part of me is very envious but I cannot help wondering what are *all* the things you need to do with this type of job.

Best wishes -- Pstu

[mark beiser]

http://buildingscience.com/

[behappy]

Mark has it right..

This is not a coffee cup type of styrofoam.. It is two part closed cell and has a flame retardant. The stuff will not burn (I have read the MDA sheets) but it will melt if heated enough.
Good side:
1)Very good R value R-38 onroof and R-22~24 I beleive in the walls (Will know for sure when the price comes in).

2)Makes a VERY tigh home, lessens the infiltration and lowers the H.P. equipment size.

3) Super sound absorber with insluated windows and doors keeps the outside noise way down.

3) qualifies for Energy Star (rebates).

Bad:
1) This is a super insluator and the product is not flamable
BUT, If a fire is started because of the insluation values the structure quickly heats up to a very high temp.
We are planning to install and intergrated fire/burglar alarm system (for the insurance 10% discount)so this may not be a big thing. Also insurance company is indifferent to this type of insluation.

2) Price is about (I will find out soon) twice as much as regular fiberglass insluation. I was going to use prodex foil/foam/foil as a house wrap (the help the outside wall r valus) and radient barrier in the attic. This was adding to the insluation cost already (which I will save with foam).

My two hour discussion with the "Southern Company Rep." verified everything that I researched. We live in So. MS. and have Florida weather conditions.. Hot and VERY humid.

I have already worked out a deal to install an Affinity 2 speed H.P. so in the summer it may hardly come out of low speed.....

[flick]

Happy, I'm assuming that you are doing this in Southern Miss., so may I suggest that you look into incorporating a fresh air exchanger, such as the Aprilaire, into the system. We have several styrofoam insulated homes in our area. The houses will get very stuffy if fresh air is not exchanged. Learned that the hard way.

[behappy]

Originally posted by flick
Happy, I'm assuming that you are doing this in Southern Miss., so may I suggest that you look into incorporating a fresh air exchanger, such as the Aprilaire, into the system. We have several styrofoam insulated homes in our area. The houses will get very stuffy if fresh air is not exchanged. Learned that the hard way.

Thanks!
Not sure we will do this.. but this is the imformation that I am looking for.

[wolf225]

The dirtiest air we breath is in our own homes. This is do to the amount of plastics, foams and vinyals used in construction and furniture. When a house is tightly sealed we don't exchanged these exhaust fumes with fresh air. If you are going to go this route, I'd strongly sugest an Exhuast heat recovery ventilator. Honney well makes a very nice one. Surf their residental web sight under ventilation.

[hackmaster]

Definitely have to bring in fresh air for these type houses. Carbon Monoxide becomes an issue in these houses especially if using ventless fireplaces ect.

[mark beiser]

As others have pointed out, you MUST bring in outside air into this type of home to get the proper air changes for good IAQ. Since it is so tight, you also have to provide for exhaust of indoor air.
The good news is that you get total control of the quality of the air you bring in, and can recover energy from the air you are exhausting from the home. There are a number of quality products for doing this.

Sealed conditioned attic construction is a lot more expensive than the typical construction, but it does allow you to cool and heat the home with much smaller HVAC equipment than would normally be needed. Be sure someone does the load calcls and system design that understands the needs of the type of construction you are using.

If you are on a budget, and this is busting the budget, considder downgrading something else that can be upgraded dlater. Like you could not put the wood floors in a couple of rooms, or go with vynal flooring in the kitchen or a bathroom or 2, so money is freed up for the foam. You can always upgrade floor coverings later with the money you save on energy.

[mark beiser]

Originally posted by hackmaster
Definitely have to bring in fresh air for these type houses. Carbon Monoxide becomes an issue in these houses especially if using ventless fireplaces ect.

You absolutely do not use ventless fireplaces with this type of construction. Gas furnaces and water heaters have to be 2 pipe sealed combustion type that bring in thier own combustion air supply from outside, or be located outside of the conditioned space.

[amickracing]

For what it's worth, if the price is feesible bringing in outside air (in a controlled mannor where you can temper it and clean it like you can with the ERV's and HRV's) isn't a bad idea even on a normal house.

Much better to be in control of the air coming in that letting it just leak where ever. Not to mention it should feel more comfortable with no drafts coming in by the leaking areas.

[uktra]

To design a energy efficient and comfortable home with good IAQ, you need to take a "systems approach" to the home. This will provide the largest improvement from the least amount of building cost. Spray foam is excellent insulation as well as an air sealing mechanism for frame construction. It is expensive and there are ways to arrive at the same benefits for less money. The other key is eliminate the HVAC equipment from the attic area, and you can use blown cellulose and the new tyvek attic system to air seal. With this products built in radiant barrier, this would be an excellent product for your area. When you air seal the home, one must be very carefull in selection of products installed, that cause poor IAQ and the need to mechanically ventilate is a must. When you can mechanically ventilate a home for $300.00 it is silly to do otherwise.

[teddy bear]

A tight home with a clothes drier, kitchen hood, and bath fans needs make-up air routinely everyday. Introducing 50-75 cfm of make-up air when the home is occupied provides enough air change to purge the pollutants, provide oxygen and make-up air for the exhaust appliances. Air to air heat exchanges do not provide make-up air because they also exhaust air. The other issue is controlling humidity during high humidity months in a green grass climate. Well insulated homes use much less cooling conserving energy. But like lesser homes, humidity builds during low/no cooling loads. A ventilating dehumidifier is a better solution all of these problems. Building Science research has proven this over and over. Using a ventilating dehumidifier provides fresh filtered air to home, while maintaining <50%RH with no/low cooling loads. This is an important comfort and indoor air quality issue. <50%RH assures no mold in the cool areas of the home and no dust mites in the apholstered surfaces of the home. We do thousands of ventilating dehu retrofits a year. People like Honeywell and others are now offering this equipment. I would suggest you include this in your new home. Nothing like being able to maintain <50%RH, clean fresh air ventilation without overcooling your home. How fast we forget. TB