'splain somethin to me

[Chad Fabry]

I inspected a mini McMansion today with a large (multiple hip roof thing)

attic.

2x8 ceiling joists and 2x12 rafters in the attic. R19 kraft faced between the ceiling joists and R19 kraft faced between the rafters.

Why didn't they just put the rafter insulation on the ceiling?

I can't believe that in this case R19 + R19 =R38. I think it'd be more like R19+R19=R19 as there is continuous soffit vent around the perimeter of the home.

Since about half of the rafter insulation is falling or has fallen, I think I should toss the suggestion of pulling the rest down, de-facing it and lying it on top of the ceiling insulation.

Whadda you guysfolks think?

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[hausdok]

Hi Chad,

If the soffit vents are allowing cold air into that attic beneath the stuff that's on the underside of the roof and there is continuous airflow through there, you've got an R19 ceiling with a roof that will reduce solar gain but won't help with winter heating costs.

If there are full-length air chutes above the insulation, which are sealed around their edges at the soffit ends and the discharge end at the ridge, or if there weren't any vents at all, one might consider it to be semi-conditioned space, since you'll get a certain amount of conditioned air leaking into the attic. That would probably give them better heat loss resistance than an R38 ceiling. However, I'd guess that only some before and after testing would prove that one way or the other.

Their choice is to airseal the house-to-attic ceiling/wall plane and eliminate all attic vents or remove the insulation from the underside of the roof and increase the depth of the insulation on the ceiling.

ONE TEAM - ONE FIGHT!!!

Mike

[Jim Morrison]

I think that whomever installed the insulation between the rafters doesn't understand how building envelopes work.

I also think that someone in WA should look in on Mike to see if he's OK. I can't remember for sure, but I don't think he's ever posted anything in 10,000 words or fewer before...

[Les]

Pull the rafter stuff, de-face it and place it on the ceiling joists perpendicular to existing. Insert baffles and call me in the morning.

[hausdok]

Originally posted by Jim Morrison

I also think that someone in WA should look in on Mike to see if he's OK. I can't remember for sure, but I don't think he's ever posted anything in 10,000 words or fewer before...

[%|]

[Les]

Chew can't do that for a couple weeks.

[Scottpat]

It is wrong. For starters it is a fire hazard to have the Kraft paper facing out like that. Second, I'm willing to bet that you will find some damp spots on the decking once the insulation is removed.

[sepefrio]

so would that make this wrong too? [:-dunce]

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Um, BTW, I'm just kidding......

[kurt]

Originally posted by Chad Fabry

Whadda you guysfolks think?

I think it would still be a piece of crap.

[Brandon Chew]

Originally posted by Les

Chew can't do that for a couple weeks.

Ha, ha, ha, ow ... ha, ha, ha, ow!

I haven't laughed that hard since my accident!

Chad - agree with the others. Can't see how that could be right. If the attic is vented, the insulation below the vented space is what counts toward meeting the required (or recommended) R value.

[Brandon Whitmore]

Regarding the exposed paper being a fire hazard.... I am curious as to how it poses more of a fire hazard than any other combustibles in the house? Once fire has hit that material, there are other problems. The only way I can see that being a problem is if the paper is acting as the tinder to start the fire, but I can't figure out what would lead to the paper catching fire.

What is the reasoning behind the fire hazard concern?

[hausdok]

Well,

Though I agree with your reasoning, it violates the listing and labeling on the insulation.

OT - OF!!!

M.

[Brandon Whitmore]

t violates the listing and labeling on the insulation.

Agreed.

[kurt]

Originally posted by Brandon Whitmore

I can't figure out what would lead to the paper catching fire.

What is the reasoning behind the fire hazard concern?

The mfg. covering their butts.

Simple cooking procedures in a kitchen are hundreds of times more dangerous than exposed paper in an attic.

[randynavarro]

There's also concerns with smoke spread, toxic smoke, and all kinds of nasty stuff that the firefighters don't want to contend with. Burning paper might be the least of their worries-- I don't know.

[Brandon Whitmore]

I've got a degree in Structural Fire Science....

Paper on insulation in a home would be my last concern.

[kurt]

No kidding.....[:-eyebrow

Explain Structural Fire Science in a few words. Can you?

Sounds fascinating. I attended an accelerated Fire Science class several years ago, and I still think about it as possibly the standout educational experience in my career.

Did you ever do arson investigation?

[randynavarro]

The predisposition of the male gender's fascination with fire continues . . .

[Brandon Whitmore]

Explain Structural Fire Science in a few words. Can you?

It was an associate of applied science degree. You go to college full time and work full time when not in classes. It has been quite a while. I can tell you some of the courses that were taken. Fire Investigation, Fixed Systems and extinguishers(sprinkler systems),Fire Physics, Fire Hydraulics, Building Construction for Fire Protection, Anatomy & Physiology (for the EMT stuff), Fire Law, Weather courses ,etc.

It was a pretty cool gig for a while, but I got burned out with all the medical work and politics, so I said screw it.... and here I am. (anyone want some books?)

Did you ever do arson investigation?

I assisted in some arson investigations on the structure side, but there were arson investigation teams from the state fire marshal's office that did most of that---- some of those guy's are sharp.

I performed more arson investigation work in the years I did wildland fires while working for the state... I mostly just put the stuff out. (I actually got paid to cut burning trees down... pretty cool job).