Buiding a conditioned attic in a hot & humid climate the right way!

[SprayFoamInspections]

Foam looks like it was sprayed "COLD", Dripping all over the ducts also looks terrible, and the duct work looks like it had a few Kinks restricting the airflow. The depth of the foam looks correct.....

[amusingisthedawn]

Im my opinion, adding a radiant barrier like a foil - with a small air gap between the foil and the roof deck - and THEN spraying the foam would be much more efficient. The foam has better air sealing abilities...but it isn't much different than laying batt insulation.

[MattRisinger]

@amusingisthedawn Good point about the radiant barrier. This house has a very reflective Galvalume metal roof so the radiant barrier is on the top side of the roof. Also, you could not effectively insulate this particular attic at the roof line with batt insulation. The foam forms a total seal and insulation barrier over ALL the framing which batts couldn't accomplish. Thanks for commenting. Matt Risinger

[HomeEnergyNow]

@MattRisinger I don't know if you have tried it, but we sealed a house so tight I had to use the small ring on my duct blaster to test the whole home. We would have never gotten near that tight with spray foam, it is actaully much easier to tighten a house to .5ach 50 w/out spray foam. Passivehause design is superior to GBCorporations designs, just out of curiousity why not use them? They have software that leaves ol Joe lookin simple. Spray foam is kind of a big sloppy/rough method of sealing.

[MattRisinger]

@aaronoftexass This was not a pretty install. This particular crew was fairly new at spraying foam. I highly recommend using a coat hanger to do a depth poke test. Just wrap a piece of tape around the 5.5" mark on a coat hanger and you can ensure that it's meeting that min depth. That's one of the beauties of using foam in that a rookie crew can still do very well performing install even if it's not pretty. Using traditional insulation requires expert crews and even then it's not as good.

[HomeEnergyNow]

@MattRisinger I've put a lot of blown in, in a lot of new houses, your assumption that spray install is even close to as easy as loosefill to install is just plain bonkers. Loosefills are much faster and much, much easier to install. There actaully is a value to "consistancy" in insulation, and no batting or any other insulatin could possibly be installed as inconsistantly as that foam. It literally seems to go from R-30+ to less than R-10 w/in inches due to the bubbling.

[tappakeggaday1]

I have a question about this myself,I live in North west Florida and when I was younger and doing roofing I was inside a roof and had asked why dont they put insulation up here as well? The answer I got back was the shingles get hot enough on top of the roof and if the insulation was under them they would bake off of the roof so i never thought anymore about it.in this video are you under a metal roof or a shingled one?I can see metal holding up with the foam but not sure about shingles.

[MattRisinger]

@tappakeggaday1 GREAT QUESTION> Conventional wisdom has been that shingles need to be vented underneith or they will cook. In this house we used a metal roof so that issue doesn't translate to metal. However, the latest building science talk is that shingle temp only rises by 2-3 degrees without venting underneith. Building Science expert Joe Lstiburek talked about that issue in the latest issue of Fine Homebuilding. I wouldn't hesitate to foam under a shingle roof and have done it before.

[tappakeggaday1]

@MattRisinger There have been a few applications when I was hanging fiberglass insulation and in some of them we had to use card board batting for an airspace,I have watched quiet a few foam spraying videos learning about this and thought if they had an inch of space stapling up cardboard between the rafters and then spraying the foam it would seem the singled roof would then get its airflow that way without overheating the shingles and still have the insulation?

[HomeEnergyNow]

@MattRisinger Don't forget the osb roof sheeting if you used it, they have always needed ventilation to maintain their warranty. That explains it!!!! This whole time! Dude, Joe Lstiburek is a HACK! Find out how many houses he has built himself...........you have probably built more! He treats houses as if every occupant is "standard". That really takes some major genious there. He acts 140point IQ smarter than he actually is, he's from mobile home capital of the world. Get your tips form a pro!

[HomeEnergyNow]

@HomeEnergyNow It's like getting tips on how to play football, buy talking to the sports writers.......lol.

[MattRisinger]

@HomeEnergyNow Sorry buddy but I can't agree with your opinion of Lstiburek. I'm a disciple of his teaching and I'm a big fan of his work. There are very few Building Science experts of his caliber. Matt Risinger

[HomeEnergyNow]

@MattRisinger I don't think he went to college for "residential building science" I think he took a different degree and wanted to capitalize so he made "building science corporation" and sold a bunch of books and has convinced people somehow that there is a "building science" standard and he teaches it. He is more of an "analyst", all you can do with occupancies is sit back and watch, the occupant is factor number one, and no science can even figure them out. "building science" sells books

[Artoconnell]

Would LOVE to work in that attic...the equipment life is basically doubled from being more serviceable, and also not being in such an extremely hot environment. NIce JOB

[HomeEnergyNow]

@Artoconnell Are you saying you would do a worse job of serviceing a hard to get to a/c to the point it would only last half as long? And they are designed for that "extreme" envionment arent they? I just saw an a/c from 1960 still working in an attic...................please tell us a/c pro how this stuff makes a/c's last longer and why, but come up with something better than saying a/c guys do crap work until they get into an attic that the homeowner cools all year. extra btu load=more a/c run

[MattRisinger]

@Artoconnell I can tell you from experience that a conditioned attic with temps in the low 80's on a 100 degree Austin TX day are much more manageable to be in compared to a typical Austin attic that's 130 degrees when it's 100 outside. Think about how much more efficiently this equipment will run when the environment around it is 50 degrees cooler than a neighbor's house. Seems to me that anyone working in a hot attic would be tempted to hurry with their job at hand. -Matt Risinger

[HomeEnergyNow]

@MattRisinger You must remember, the 50 degree cooler environment that the a/c is in, is an environment the neighbor does not cool. It is easier on the a/c to be in the 50 degree hotter attic, than it is to semi-condition the attic down 50dgrees w/out re-sizing tonnage. Basically, it is easier to cool just the HVAC system, than the entire space it is w/in. Required R-38 ceilings, but R-8 duct? The city, HVAC industry and builders need to stop being idiots and quit the attic HVAC completely.

[HomeEnergyNow]

I have been trying to use my thermal camera to come up with real world heat gain comparisons. This may seem crazy, but it looks like a thin layer of radiant barrier foil will emit less heat than the underside of a foamed roof deck. Your dislike of the r-value system comes straight from our climate where conductive heat is only important in our smaller heating season. But your like for foam is odd, it does as little for radiant and conductive heat as installing r-19 batts on the roof deck.

[clintsmith96]

Matt,

What R value do you get with 1 inch of open cell foam? Do you ever use the closed cell foam?

[MattRisinger]

@clintsmith96 Good question. I believe it's just shy of R-4 per inch. This assembly is technically R-19 in total but don't be fooled by R value totals. I'll take R-19 at the Roof Deck over R-42 blown any day. We've totally sealed out any air leaks from penetrations (ie Ceiling Cans), we've run our ducts through a hospitable environment, and we've lowered the tonage of our AC system. Perfect for a hot/humid climate. Since this video I've gone to adding rigid foam on the roof deck too. -Matt

[HomeEnergyNow]

@MattRisinger Why not be fooled by r-value, is that what ashrae would say? As energy professionals do we calculate loads with hearsay?

[Dutchy1965]

fire hazard?

[MattRisinger]

@Dutchy1965 It's a gas burning unit but the sealed combustion chamber makes it completely safe. I've been building homes with gas furnaces for 15 years and never heard of any fire issues. The foamed/sealed attic does mean that you can't use a traditional flue pipe nor rely on the combustion air coming from the attic however. Not using a sealed combustion unit with air from the outside would be VERY unsafe. Houses are complex and we need to use good Building Science judgement when building.

[HomeEnergyNow]

@MattRisinger Like adding up the extra cost of insulation, then the extra cost of and air exchanger, then the extra cost of a high efficiency furnace, than applying an 8% mortgage to those costs, then realizing that annually you lose money by using that system. Send 5$/month to the bank in interest to send 1 less dollar/month to austin energy? I though I also heard that if you figure in manufacturing waste, petro used, biodegradeability and intallation waste that foam was on of the least "green

[WindPowerKits]

Nice video, Check out my videos about Home Wind and Solar system intalling on the Rooftop. On Earth Day I won a green design contest for my home energy system the RoofMill. Have a look at my home wind turbine videos of installing and running Hybrid Energy Systems. Friends and Subscribers Wanted. Have a good day , Thanks, Sam

[Artsee77]

Matt, have you ever used a HRV/ERV in any of your projects. I'm not familiar enough with your climate down there, but it seems like an ERV would prosper within the humid weather areas. However, doesn't the ERV require an additional dehumidifier to be set up since it is not considered a dehumidifier itself?

[MattRisinger]

@Artsee77 I've not done an ERV yet. I think it's a great idea but I've just paid the energy penalty for bringing in unconditioned air. I think a better option would be a dehumidifier that had a fresh air input so it would be mechanically dehumidified. I read Martin Holiday's post this month on ERV's and he think they move very little moisture. It's really HOT in Texas but we're never more than +-25 degrees from 75 (inside temp). I think HRV's are more impt for cold climates with 50+ deltas

[Artsee77]

@MattRisinger Thanks Matt for the opinion as well as mentioning Mr. Holladay. I had not come across his blog before now and I'm glad you brought it to my attention. Thanks again.

[HomeEnergyNow]

Say you were a HERS rater, and you are filling out your audit forms. Would it not be better to have r-60 loose-fill on the ceiling, a flat ceiling so that the enveolope is smaller and less conditioned space. I have plugged sample numbers into both REMrate, and DOE's NEAT program, and they both show the loose-fill, flat ceiling method as using less energy to heat an cool, it also happens to cost less. I have even played around with the manual j, and can't figure out how spray foam is better?

[MattRisinger]

@HomeEnergyNow So, remember we're talking about Texas in this video. Mostly slab on grade construction with HVAC systems inside of a very HOT attic. By moving that insulation up to the roofline our HVAC ducts that are typically r-8 are now inside the thermal envelope. Attics in Austin can have daytime temps above 130 degrees so with this system my attics are maybe 7 degrees hotter than the indoor temp. Also, the foam is an air barrier that seals out leakage. Tough to beat in the real world.

[HomeEnergyNow]

@MattRisinger I too live in TX and see alot of HVAC's in closets, so I still don't understand from a RESdesign perspective, even if you fill in the duct system as being w/in the envelope, it still doens't seem to trump the increased conditioned space, the increased evelope sqft., and the r-30 ish foam setup, compared with the up to r-60 loose fill. Those three items seem to increase the btu gain beyond the saved btu gains of bringing the ducts into the envelope.

[01mustang05]

5 or 8 degrees higher then the rest of the house? Wow, really?, thats cool. Thanks for the info, I would have thought higher as radiant heat waves travel through this insulation.

I would REALY like to know how THICK that closed cell spray foam insulation is. It is closed cell isn't it?

[MattRisinger]

It's really amazing how cool the attic is in these foamed attic's. This house doesn't have a radiant barrier on the inside, but we used a silver metal roof (galvalume) so the radiant barrier is on the top! Best roof for this climate in my opinion. The spray foam is open cell and is 5.5" thick. Closed cell would be even better to use but jumps up the cost quite a bit. I didn't do it in this house, but my new best practice is to lay rigid foam on the roof deck then spray foam under.

[HomeEnergyNow]

@01mustang05 As long as it doesn't bother you knowing you are paying to remove btu's from your attic space. 

[kylemlm]

IBC code req. ventilation in the attics & basements. Are you using ac equip. for ventilation of the attic?

[MattRisinger]

IRC allows for unvented attic spaces. HVAC equipment is all power vented so it brings combustion air in through a PVC pipe, has a sealed combustion chamber, then vents the combustion gases through a pvc pipe. Fresh air is brought in through a dedicated pipe with an AprilAir controller and damper system.

[kylemlm]

@MattRisinger @MattRisinger ; I do not have IRC book & do not do sticks & bricks construction. I read the AprilAir PDF on line .

You are closing up attic air tight & you have natural gas for heat & AprilAir stops working below 0 or above 100 degrees, sounds like formula for mold & natural gas explosion in your attic. Commercial side 2003 IBC req. mech. ventilation system. Thank you for your time.

[MattRisinger]

With this system there is no possibility of a natural gas explosion in the attic. All the combustion is sealed inside the unit. It's a 95% efficient gas furnace with sealed combusion inside the combustion chamber. All the air needed for combustion comes from an input pipe to the unit so no attic air is being burned inside the unit. I hope this clarifies. For more information see the book "The Builders Guide for Hot-Humid Climates" by Dr Joseph Lstiburek published by Building Science Press

[kylemlm]

@MattRisinger Thanks, I guess I had concern about gas water heaters and gas furnace. I under stand the concept & I think its good direction but can not agree with stopping mech. vent system. I have friend on the IBC board & going to ask more info & my MEP guys also. Thank you for your professional responce & hope your business is great in 2010.

[HomeEnergyNow]

@MattRisinger Is there a warning if the fresh air sytem stops bringing fresh air?

[MattRisinger]

@HomeEnergyNow The gas furnace has it's own combustion air system so the fresh air system in the house is strictly for occupant air quality. There is no warning system as installed. Is there a concern you have?

[HomeEnergyNow]

@MattRisinger I meant the fresh air system for the occupants.....if it stops working, the house is now dangerous for the occupants, I was wondering if there is any way for the homeowner to know if the fresh air system has stopped working? And what about covering the ducts with insulation, 10{" over the duct with fiberglass would make R-34 or so on top of the duct and R-60 for the sides and bottom. And if the btu's are being removed from the attic, aren't you paying to do so?

[benpie12]

@MattRisinger death

[MattRisinger]

@benpie12 What? Are you referring to the fresh air system not functioning? We don't have a single combustion appliance in this house. All furnaces are power vented and sealed combustion, tankless water heaters are mounted on the exterior. The fresh air system is purely for indoor air quality issues. It's meant to remove general pollutants from the indoor air and replace that stale air with outdoor air at a prescribed rate. We follow ASHRAE 62.2 standards for how much fresh air is needed.

[HomeEnergyNow]

@MattRisinger Can you guarantee 100% that the house will always get .35ach? I take it you do the pop a hole run a duct from the outside to the return plenum and pressurize the house? How can you use that system to guarantee proper fresh air. What if they don't run the hvac much? I guess my question is, how exactly can you guarantee .35 ach without an erv, or tested natural airflow of .35?

[Axel2989]

Die Mäuse werden sich sehr wohl fühlen :)

[d1incharge]

One of the first jobs that I bid in TX was an older home overhaul downtown Atx. I look up to see an almost flat ceiling/roof with 2x6 rafters, and asked the framer about how they expected to get R-38. He said "inspector says we only need R-19" So as I am biting my tongue I look up to see no way to ventilate the top or bottom of this ceiling/roof, and within one of my first bids here I learned really quick, the inspectors here are f-ing morons.......at least this one was.

[d1incharge]

Actually it is r-38 for ceilings, maybe they are allowing those to be considered as vaulted/cathedral ceilings, which are r-19(minimum). For the same price of your r-19 foam, you could install R-60 fiberglass, so why foam? It is also the Austin Energy minimum for rebates, but they do not rebate for foam. I read at the DOE, that the air inside of your house is far worse for you than the air outside, if your hvac doesnt run, say during the nice times of year, then you are getting 0 fresh air?

[MattRisinger]

The gold standard for air quality is outdoor air not indoor air which is typically terrible. ASHRAE standard 62.2 gives us a standard for how much outside fresh air should be brought into a home. My BUILT TIGHT VENTILATE RIGHT philosophy means that I want a tight envelope so I can decide when & how to bring in fresh air rather than relying on uncontrolled leakage. The fresh air system exhausts stale air and brings fresh air through the HVAC system.

[d1incharge]

But you use energy to do it.....My main concern is not your fresh air system, it is the foam system here is inferior and more expensive. Why... 2009 IRC requires no more than 20% or 500sqft of cathedral ceiling, the DOE recommends even within a cathedral for this climate at least R-38, a 10/12 roof pitch can add 60% more air to condition, and 23% more ceiling surface to the envelope. People think attic air is hot, now your envelope is the roof+23% more of it!

[d1incharge]

I mean no disrespect, your heart is definately in the right place, and you are obviously well qualified to build. It is your foam guy, maybe even your HVAC guy I dont trust. If your ducts are sealed and insulated properly, your HVAC load would actually be GREATER with your R-19 cathedralized setup.....because of the numbers stated earlier. 99% of green is in design, there is not that much to lose by bringing more of the system within normal envelopes. Cost of foam IS a lot to lose + the likely %

[MattRisinger]

Build Tight and Ventilate Right is our motto. You can't build too tight BUT a tight house need a fresh air source. This house has a fresh air input that brings in fresh air through the HVAC system, filters it then sends it throughout the house. The galvalume roof is silver and acts as a radiant barrier. R-19 is the code for attic insulation for Austin, TX and 5.5" of open cell foam meets that code. In the past year I've also been adding 1.5" of rigid foam on top of the roof for R-27 total.

[d1incharge]

Do you test to make sure the home is not too tight? If they are, which they should be if foamed, what is your solution? Does your metal roof have a radiant barrier rating? How deep is the foam? I cannot figure out, at R-3.6/inch, how anybody gets the minimum R-38 in Austin, or the recommended r-49, which would be almost 14", am I missing something? Thnks for the vid.

[MattRisinger]

We test all our homes for both duct leakage and air infiltration (blower door test). Our duct leakage needs to be less than 5% loss for the Green Building Program 5 star rating and air infiltration needs to be less than .40 ACHN. Most of my foamed houses are closer to .2 ACHN. That means the house air is exchanged once every 5 hours if the house is closed up. We want a VERY Tight house so we can ventilate through our system that filters the incoming air rather than uncontrolled leakage.

[loganl1995]

Matt, I thought you did a great job of conveying information to potential customers. However, who does your foam work? I've been in the business for 6 years, and that application really looks bad. Too bad I'm in Louisiana, or I'd help you out. Again, you did a great job. Hoyt

[MattRisinger]

Hoyt, Yes indeed it's not the prettiest foam job. My crew has gotten better at making it look less lumpy but the performance is the same. That's one of the best things about foam, you don't have to get a perfect install to get great performance. If you are installing fiberglass batts you need a perfect install or your performance suffers big time (and a perfect batting job still can't touch foam's properties). -Matt

[MattRisinger]

It's tough to tell from the video, but we're in the attic of a house that's framed with conventional 2x8 rafters and OSB roof decking on top. The foam is sprayed directly onto the OSB to created a conditioned (and unvented) attic. On top of the OSB is two layers of 30 lb roofing felt then a 24 ga metal roof. That roof should last for 75+ years, but a re-roof is easy since the foam is adhered to the OSB and not the metal roof. Did I answer your question fully? -Matt Risinger

[DrZarkloff]

I like that. Is there some sore of barrier between the foam and the roof. I'm just wondering how you've solved reroofing.

[MattRisinger]

We foamed the underside of the attic decking so the foam is adhered to the 1/2" plywood roof deck. Re-roofing will not affect the foam underneath. Also, this house has a galvalume (silver) metal roof that should easily last 50-75 years so it will take a hail storm no problem unlike an asphalt roof.