RES CHECK FOR HOME CONSTRUCTION

GMcD

And it was called INSANITY and IGNORANCE, if this is in a cold climate. The vapour barrier and the high insulation value in the attic must be installed, full stop, period, in a cold heating dominated climate. There are no laws of physics or building science that would allow otherwise, unless you are in a warm, tropical climate.

GLENN_14

RES CHECK FOR RESIDENTIAL CONSTRUCTION

Have I been asleep here..... I have a insulation contractor telling a homeowner that they only need to put in r-21 insulation in the attic areas of a home because the rest of the home is foam block poured concrete design with a very hight r-value. So according to the res check system, he is just fine using r-21 according to the contractor. Oh and by the way this same contractor is stating that he plans no vapor barrier on the insulation for the attic because he has "learned" that we now want the moisture to be able to escape from the attic..... Has anyone heard this before???????

Tim P._2

REScheck

REScheck is an acceptable alternative in most states. You can d/l it from the DOE.

Rather than using the prescriptive method of energy compliance, you can use rescheck which will give you credit for different construction techniques (raised-heel rafters, soffit sizes, HE equipment etc). Consequently, you could be told by the program that you need less insulation in the attic.

No comment on the vapor barrier.

Tim

GLENN_14

res check

I just don't know why anyone would want to eliminate r value from the attic insulation... And YES this is a coldclimate...Upstate New York.... ASHRAE 98% 2 degrees F. I feel that to eliminate any insulation is crazy. Cost to install is the same only the material has a cost difference. As for the vapor barrier Why no comment tim?????

singh

ResCheck

Glenn,

I'm upstate NY also, and I run into rescheck issues all the time. Especially when I require insulation under tubing for radiant, I had one issue with builder he wanted no isulation because he was ok with rescheck.
It is true you can swap cetain building methods, materials, and lack in other areas. (i.e. 90+ boiler vs poor insulation or poor windows = ok from rescheck.) Rescheck is a requirement for the NYS energy conservation code.

I would insist on the R-38 insulation in attic or get it writing it was not put in.

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Weezbo

here is a definite reason to regard ones own thinking abilities

at least on a standard above and beyond some BS printed in a prescriptive code or standard.
listen , the Oil company will be happy if you follow blindly along doing things wrong ....i have R71 in my lid...someday my broken down shanty will have to be removed, when that day comes i intend to change the walls that have a mere r 20+ to a structure that uses this century best products and design. 28 years ago i thought 'well, i would Like to increase the walls to R 40+ ... just don't have the shekels...'

it can go way below zero here. insulation is a very good investment as is a waterproof sealed vapor barrier.

insulation ventilation and heatilation.

how many frozen pipes on heating systems are required before someone "Gets It".
.

jp_2

reschek=ice dams!!!

improper roof insulation will result in ice dam problems, no matter how well the walls are insulated, going to melt snow on roof and cause BIG problems anyway.

doesn't CODE specify Rxx for ceiling insulation? we have r40 minimum.

Chris S

res check & ICFs

ICfs perform really well- but why let all of that energy out through the ceilings/ roof.
I have built with Icfs, they claim energy performance = to R50 ( I read the article about underslab products claiming to perform like R-11) no comment on that
Thermal mass is the answer there, but we still would install minimum R-38 I like R-19 Batts and a blown layer to fill all of the voids.
While you're at it don't forget the air to air heat exchanger, that's going to be a very tight house!

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GLENN_14

GOOD POINT

I already got the customer to put in a hrv for air exchange. So now it's just the ceiling issue we need to solve. I am getting the customer to sign off on not using the proper ceiling insulation.. At least I covered the bases....

GW

batts

C,

I'm not an insulation person, I'm just currious why you like batts first then blown on top, instead of just going with all blown-in.

Gary

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GW

ice dams = heat leakage


I've done a little thermal envelope training, but my main role in life is heating. Is it just me, or does the whole world have no clue why 90% of all ice dams come from?

When I had by building built (new shop), I paid more for the foam guy to spray the ceiling (of the shop below) to the roof line (with the vent thingies in place).

Fiberglass is useless when it comes to air barrier, but somehow the fiberglass people have done a good job brainwashing the entire population on how great fiberglass is. How many times have you heard a non-informed person say "it's really insulated well" and make no comment on the air tightness?

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GLENN_14

I agree

Infultration of air is a definite problem. We also recently saw a problem with a spray foam job in which the foam was applied to cold moist walls. The end result was mold growth and ended up having to be totally removed and redone. What a mess that turned out to be....

Brad White_185

RES Check Function

If I may:

The purpose of RES-Check (and the companion "Com-Check" for commercial compliance) is just that- code compliance. It does not dictate "what you should do" any more than your Horoscope is your Daily Planner.

It merely dictates at what point a building's envelope performs compared to a minimum overall standard (u-overall) mandated by that state's energy code. (The output is stated as "exceeds code by X%" or the inverse, that it falls short by a given percent.)

It does allow trade-offs: Better glass or less of it will increase the compliance margin. Adding R value to the wall will "buy" minimal glass area increases. Exceptional wall R-value (such as SIP construction) can allow lesser roof R-values.

No one is suggesting that one not insulate the roof to the maximum or that RES-Check is a license to do that. It is just a code-compliance verification tool.

If you do not have the sense to do the right thing and allow what is a useful but rudimentary software program to dictate your practice, you might as well take up playing piano in a house if ill repute

That said, ice dams aside, the reason insulation is piled on in roofs and attics is "because it can be".

The actual savings in heat loss between different R values can be expressed as follows for 1,000 SF of roof area and a 70 degree delta-T:

No insulation, R-2.5 roof materials only: 28,000 BTUH

R-14 (like a wall): 4,900 BTUH (82.5% decrease from uninsulated.)

R-25 (Attic Blanket): 2,800 BTUH (90% decrease)

R-50 (double Attic Blanket): 1,400 BTUH (95% decrease)

R-75 (no room for Christmas ornaments): 934 BTUH (96.6% decrease)

The integrity of these R values is as important as the presumed label R value of course. That all important air sealing and a cross-layer to mitigate framing interruptions cannot be over-stated. But those first few added layers do the bulk of the work.

Just keep it in perspective. You all know to do the right thing of course.

Chris S

blown in

Even the best insulators- when insulating from below will miss places that insulation should be. Go into an attic after a house is finished and there will almost always be gaps in certain areas. In a house with a lot of recessed lighting for instance this can be a large area for heat loss. We generally spec IC ( insulation contact) housings, and the the insulation can be blown right over them making a continuous blanket.
Other areas of concern include walls running parallel to the roof framing ( usually a gap ) and any odd cut outs.
I've seen R38 ( 12") installed in attics where the gaps for the ceiling joists ( 2x material) were the biggest uninsulated area.
Details are important, I believe air infiltration in a well insulated building cancels out the extra benefit many think they are gaining with extra R value
Just my opinon though

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kpc_10

that's what ...

he is saying...why bother w/ the blanket? why not just seal up the gaps w/ caulk and foam, use poly on the ceiling then blow in fiberglass....

GW

i just didn't know if there was some sort of cost savings... just wondering.

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Larry Weingarten

In theory...

... people consider putting less insulation in to save money. But nice things are possible when you "over-insulate". Heating/cooling equipment can be greatly downsized or eliminated. Savings in equipment can more than offset higher insulation cost. (Yes I know this is harder in residential. It's proven already in commercial.) It's been called "tunneling through the price barrier", when overall price per square foot falls because of good energy detailing.

Then there is the ongoing cost of energy to consider and also the longevity of the work being done and how energy prices could affect expenses over the life of the work. Fun stuff to ponder ;~)

Yours, Larry

[Deleted User]

Question for Brad

Thanks for the info. on attic insulation. Do you have similar charts showing the diminishing returns on insulation
thicknesses for walls & floors (above crawl spaces)?

jp_2

not necessary

use the same numbers brad gave for ceiling and apply to walls and such. keep in mind the sq footage of those areas.

Chris S

fiberglass

We usually put in R-19 beacuse it satisfies the vapor barrier ( I'm not a fan of plastic stapled to the beams) and the R-19 gives us some insulation so we can continue to work. Our jobs are usually 6-9 month builds so it extends into cold weather & the insulator isn't always available to do the blown in right after the Sheetrock is installed.
The way I described is just another way to get to the end product we all want
Now... Ice dams that's a whole nother thread If you want to start one. I was on a job last winter- mechanical equipment in the attic, uninsulated heat pipes, insulation missing and 6" of ice on the roof. It goes on & on

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Chris S

fiberglass

We usually put in R-19 beacuse it satisfies the vapor barrier ( I'm not a fan of plastic stapled to the beams) and the R-19 gives us some insulation so we can continue to work. Our jobs are usually 6-9 month builds so it extends into cold weather & the insulator isn't always available to do the blown in right after the Sheetrock is installed.
The way I described is just another way to get to the end product we all want
Now... Ice dams that's a whole nother thread If you want to start one. I was on a job last winter- mechanical equipment in the attic, uninsulated heat pipes, insulation missing and 6" of ice on the roof. It goes on & on

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