Seal it or Vent it?

[Gary Burnett]

Just did a 1 year warranty inspection on a big home and it had a really nice 8 to 10 inch closed foam insulation job. The attic was sort of warm though and I thought it may have something to do with the fact the builder left two large gable vents open to the attic. Couldn't believe it! If that wasn't enough there was an extra pvc vent (must have moved the tankless water heater) through the roof that also let in a little air and moisture. Upstairs took a little longer to cool when I ran the AC. I think I would want a rebate on my electric and gas bill from the builder. I don't know how they are going to get to the vents to seal and insulate since the HVAC is blocking one of them and the other is through a pretty tight space.

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[tkaiser1]

What a deal! Build a boat and punch two large holes in the hull, then sell it.

After the fact: As you correctly surmised, the gables need to be sealed and insulated. It doesn't look to be impossible to get to the second one, hire a skinny guy.

The tankless water heater venting (both supply and exhaust) needs to be directly connected to the exterior and all associated penetrations need to be properly sealed against the entry of both air and water.

The original builder should be held to account.

Just did a 1 year warranty inspection on a big home and it had a really nice 8 to 10 inch closed foam insulation job. The attic was sort of warm though and I thought it may have something to do with the fact the builder left two large gable vents open to the attic. Couldn't believe it! If that wasn't enough there was an extra pvc vent (must have moved the tankless water heater) through the roof that also let in a little air and moisture. Upstairs took a little longer to cool when I ran the AC. I think I would want a rebate on my electric and gas bill from the builder. I don't know how they are going to get to the vents to seal and insulate since the HVAC is blocking one of them and the other is through a pretty tight space.

[Jim Luttrall]

Just did a 1 year warranty inspection on a big home and it had a really nice 8 to 10 inch closed foam insulation job. The attic was sort of warm though and I thought it may have something to do with the fact the builder left two large gable vents open to the attic. Couldn't believe it! If that wasn't enough there was an extra pvc vent (must have moved the tankless water heater) through the roof that also let in a little air and moisture. Upstairs took a little longer to cool when I ran the AC. I think I would want a rebate on my electric and gas bill from the builder. I don't know how they are going to get to the vents to seal and insulate since the HVAC is blocking one of them and the other is through a pretty tight space.

That is one of the problems around our area, lack of knowledge. They try to do a hybrid since they are not really sure about the science or execution of the newer method. I see it all the time with natural draft gas appliances. Kind of like getting into a boat while you hang onto the dock, either get in or out but don't keep one foot in and one foot out!

[Jon Denz]

I agree. The original builder should really be held accountable.

[Jeff Zehnder]

The builder and the local code official both should be held accountable

[Jerry Peck]

The builder and the local code official both should be held accountable

The local code official is not liable - the contractor is ... completely, no questions asked ... the contractor is the one who constructed what was constructed and is required to construct to code as minimum requirements for their work, and according to the approved construction documents for anything and everything which exceeds the code ... even if the contractor had not pulled a permit and no inspections were made.

It is the contractor who is solely liable and responsible for the construction as it is their work.

[ROBERT YOUNG]

The builder and the local code official both should be held accountable

Unfortunately AHJ can not be held accountable
The builders accountability makes cents, and as you well know, take care of the cents and dollars take care of themselves.

[Jeff Zehnder]

I don't need to pick a fight but...

While the builder takes most of the blame and it is difficult to sanction any government body or employee they still share blame and can be sanctioned. Each of the states differs on how that may work but that was such an obvious issue that any prudent person would and should questions it.

[Jerry Peck]

While the builder takes most of the blame ...
.
.
... but that was such an obvious issue that any prudent person would and should questions it.

The contractor (The "builder" is a contractor) is the responsible party because, as you said, "that was such an obvious issue that any prudent person would and should questions it", and the contractor, being the knowledgeable party and being the party performing the work, should not have created the condition without questioning it.

The contractor may ... may ... may have an out - if they have the paperwork trail from: a) an architect stating that it must be done that way regardless that it is wrong, against the code, and won't work; or b) the owner stating the same.

No such conversation from the AHJ should be accepted other than on official letter stating that it "shall be done" that way, at which time the contractor should give that official letter from the AHJ to their attorneys to address with the attorney for the AHJ (city or county attorney). Such a letter from the AHJ is not, and should not be taken as, permission to do something so stupid.

End result - the contractor is the responsible party*.

The AHJ?

One must keep in mind that all the AHJ really does is say: 'So, that is what you want to construct and how you want to construct it?' ... then either ... 'Okay.' ... or 'There are some things we noticed which don't meet code, change these things, then okay'.

All the AHJ does is give their okay.

*See exceptions for paper trail from architect or owner demanding that it be done that way, with a notice of assignment of responsibility for that item to that party and notification of a yet undetermined cost to correct/change/alter when someone comes to their senses and acknowledge that it needs to be changed.

[ROBERT YOUNG]

Sorry to go off thread but, this type of insulation under the sheathing and rafters is poor practice. Inconcunable in my opinion.
Why the hell would someone want to condition the attic space? Waste of energy.

Spray Foam Problems.
Mike Holmes started this fad in Canada. I have little use for Mike Holmes.

If the sheathing saturates, how does that trapped moisture escape?
If a rafter or upper truss chord saturates, how does that trapped moisture escape?
Rot is highly likely.
No replacement will be costly.

The ceiling should be blanketed, the attic allowed circulation and the roof vented.

[Jerry Peck]

Why the hell would someone want to condition the attic space? Waste of energy.

Because one is not conditioning the attic space.

One is sealing the attic space.

The attic now 'becomes' conditioned (versus 'conditioning' it).

And why? How does this sound for a reason why:
- In our house, I measured 138 F in the attic before having the attic sealed and spray foam insulation sprayed on the underside of the roof sheathing.
- In out house, I measured 80 F after sealing the attic - and no supplies or returns "condition" the attic.
- On a month to month comparison basis from year to year, our electric USE has gone down about 25% during the summer months, and about 15% during the other months (when it is not hot outside, and not cold either, even during the winter when the attic used to be very cold and required more heat in the house, with the attic temperature stable, that extra heat is not required).

Mike Holmes started this fad in Canada. I have little use for Mike Holmes.

I agree on Mike Holmes, but he was likely laughing all the way to the bank ... and very likely made many, many trips to the bank depositing all those checks he received.

The ceiling should be blanketed, the attic allowed circulation and the roof vented.

Only if you want a ventilated attic, and then there are inefficiencies with that insulation, starting with poor installation by contractors and their workers who don't care (sounds better than "don't know") how it is put in.

[ROBERT YOUNG]

I did not see any insulation on the ceiling joists or ceiling drywall. Only on the roof sheathing.
Jerry, if that is the case, no insulation above the rooms below, they are indirectly heating/cooling conditioning the attic if they use HVAC.

[Jerry Peck]

Jerry, if that is the case, no insulation above the rooms below, they are indirectly heating/cooling conditioning the attic if they use HVAC.

"indirectly heating/cooling conditioning the attic"

BINGO!

Think about the insulation value of drywall ... it's not much ... thus the temperature on the attic side of the drywall is not much different than the temperature on the living space side of the drywall - and it takes NO MORE COOLING/HEATING capacity/energy to do that, and, in fact, the cooling/heating load is less because the heat is moved from the attic to outside the attic.

During 'not summer months' when it is not "hot outside", the attic is typically within a few degrees of the living space, and during the hot summer months, the most that I have seen the attic temperature greater than the living space temperature is 8 degrees. Right now, the temperature in our attic is 2 F warmer than the living space temperature ... you get more than 2 F variation between rooms in a house.

Oh, by the way ... ... we do not have a small attic either ... the attic above our 8 foot ceiling areas is 12 FEET from the attic floor to the ridge, and I can walk over our 14 foot cathedral ceiling (I used to just stoop over a little bit, but now that the insulation is on the roof sheathing I have to stoop over a bit more ... but I am still upright and walking - not crawling - over that high ceiling.

[ROBERT YOUNG]

"indirectly heating/cooling conditioning the attic"

BINGO!

Think about the insulation value of drywall ... it's not much ... thus the temperature on the attic side of the drywall is not much different than the temperature on the living space side of the drywall - and it takes NO MORE COOLING/HEATING capacity/energy to do that, and, in fact, the cooling/heating load is less because the heat is moved from the attic to outside the attic.

During 'not summer months' when it is not "hot outside", the attic is typically within a few degrees of the living space, and during the hot summer months, the most that I have seen the attic temperature greater than the living space temperature is 8 degrees. Right now, the temperature in our attic is 2 F warmer than the living space temperature ... you get more than 2 F variation between rooms in a house.

Oh, by the way ... ... we do not have a small attic either ... the attic above our 8 foot ceiling areas is 12 FEET from the attic floor to the ridge, and I can walk over our 14 foot cathedral ceiling (I used to just stoop over a little bit, but now that the insulation is on the roof sheathing I have to stoop over a bit more ... but I am still upright and walking - not crawling - over that high ceiling.

I get your point. Nonetheless, those few degrees in more space will consume more energy to directly/indirectly condition.

[Jerry Peck]

I get your point. Nonetheless, those few degrees in more space will consume more energy to directly/indirectly condition.

The last sentence indicates that the first sentence is not understood.

Instead of trying to overcome 138 degrees radiating from the attic through questionably installed, and possibly inadequate insulation (the attic being 60F hotter than the living space) ... The difference may only be 20F - certainly that 40F DROP in delta T is going to take LESS heating/cooling Btus/gravitational.

How did the delta T 60F drop to 20F?

- Living space 78 to attic 138 through insulation = 60F which has to be overcome
- Living space 78 to attic 88 (through drywall) to outside 98 through insulation = 20F which has to be overcome

However, the attic basically serves as a buffer zone between the living space and the insulation, like the drywall ceiling and voids under the imperfectly installed insulation on the ceiling, so the delta T actually needing to be overcome is 10F between the living space and the attic.

Either way you like the math ... 10F or 20F ... it still is much better than 60F delta T.

[ROBERT YOUNG]

The last sentence indicates that the first sentence is not understood.

Instead of trying to overcome 138 degrees radiating from the attic through questionably installed, and possibly inadequate insulation (the attic being 60F hotter than the living space) ... The difference may only be 20F - certainly that 40F DROP in delta T is going to take LESS heating/cooling Btus/gravitational.

How did the delta T 60F drop to 20F?

- Living space 78 to attic 138 through insulation = 60F which has to be overcome
- Living space 78 to attic 88 (through drywall) to outside 98 through insulation = 20F which has to be overcome

However, the attic basically serves as a buffer zone between the living space and the insulation, like the drywall ceiling and voids under the imperfectly installed insulation on the ceiling, so the delta T actually needing to be overcome is 10F between the living space and the attic.

Either way you like the math ... 10F or 20F ... it still is much better than 60F delta T.

I concur. Good differences between the 2 numbers..