Abandoned skylight shaft in attic

[Bob R]

I found what appears to be an abandoned skylight shaft in an attic. The skylight has since been roofed over and the ceiling below drywalled as well.

My concerns about reporting is I can't determine if the ceiling is insulated where the shaft was in the ceiling and shouldn't a portion of the sides be removed for proper ventilation.

I would appreciate anyone's thoughts.30255

[Jack Feldmann]

Kind of strange. It would be pretty easy for someone to remove the drywall and stcik some insualtion in there, and open it up as well.

[Billy Stephens]

I found what appears to be an abandoned skylight shaft in an attic. The skylight has since been roofed over and the ceiling below drywalled as well.

My concerns about reporting is I can't determine if the ceiling is insulated where the shaft was in the ceiling and shouldn't a portion of the sides be removed for proper ventilation.

I would appreciate anyone's thoughts.

The shaft would have a higher R factor than the insulation shown in your photo.
*trapped air would be the insulator.

What is the device behind the plumbing vent that's plugged into the junction box?

[Raymond Wand]

Note the staining on the side drywall panel - condensation staining, drip marks.

As Jack suggested - open it up and add insulation.

[Billy Stephens]

Note the staining on the side drywall panel - condensation staining, drip marks.

As Jack suggested - open it up and add insulation.

I always noted skylights as a current or future source of water intrusion. Probably why this one was removed. Current condensation could be a stretch.
*still wouldn't do any harm to open it up.

[Garry Sorrells]

......The skylight has ....been roofed over and the ceiling below drywalled as well.

My concerns ........... is I can't determine if the ceiling is insulated where the shaft was in the ceiling and .......a portion of the sides [should]be removed for proper ventilation.

...........


I think you said it in your OP pretty well. Just had a few extra word in the OP.:)

[Jerry Peck]

My concerns about reporting is I can't determine if the ceiling is insulated where the shaft was in the ceiling ...

Maybe something simple like this: Skylight has been removed ... the skylight shaft in the attic remains and there is no evidence the ceiling area inside of the shaft has been insulated.?

After all, from your post it is fair to say that you did not see any evidence that it was insulated, correct? :)

[John Kogel]

Here is where the IR camera can sometimes give some helpful information.
Unless the air in the vacant space is a similar temperature as the insulated ceiling, which is often the case.
As usual, the best way to see what's behind the drywall is to put your fist through it. I learned that on TV. :D

[Raymond Wand]

You've been watching too many Mike Holmes shows! :D

[Phillip Norman]

I think the report should question roof integrity as well. I expect sheathing is plywood or OSB, capped over by a perhaps too-thin sheet on the roof. Look for signs of patch overlap on-roof. Sharp edges might cut through new roofing. That is no way to make a patch.

[Jack Foster]

What is the device behind the plumbing vent that's plugged into the junction box?

I didn't see any other response to this comment, so here's my two cents worth:
Looks like another JB with another wire running toward the top of the picture across the joists. You can see one of the white clips nailed to the joist holding the yellow wire. Looks like a DYI addition to the electrical system, likely without a permit.

[Larry Morrison]

Here is where the IR camera can sometimes give some helpful information.

Definatly agree, and this is why I use IR on every inspection. Altough determining if the area of the covered skylight has insulation is not open and visible for inspection it would be out of the SOP, But much of the SOPs are just minimums and technology can now eisily expand our eyes, ears and noses.

[Donal Hughes]

What is the device behind the plumbing vent that's plugged into the junction box?[/QUOTE]



Isn't that plumbing vent Tee
installed upside down?

[Bob R]

Here is where the IR camera can sometimes give some helpful information. :D
John
This is the DON'T "Show Me" State. If I whipped out an IR camera... Id have to give CPR to the Seller and or the Realtor.

[Bob R]

What is the device behind the plumbing vent that's plugged into the junction box?
Billy
Just a junction box with NMW connection. Does look different in this photo though.

[Rod Butler]

The shaft would have a higher R factor than the insulation shown in your photo.
*trapped air would be the insulator.



Your statement is incorrect. Unless of course you were being sarcastic.

[Billy Stephens]

Your statement is incorrect.

In what way Rod?

[Phillip Norman]

I think the nub of this thread is whether drywall about an abandoned skylight must be knocked out. A dead air space on an attic floor is just as needy of insulation, as an empty wall. The fact that surrounding loose fill is average R4 doesn't excuse taking out the drywall. The drywall is a barrier to general access, and hides crimes. I still think patches at ceiling below and at roof, are both suspect. Proper patches must be applied mainly in the attic.

[Jerry Peck]

Your statement is incorrect. Unless of course you were being sarcastic.

Rod,

Billy was, I am sure, referring to the exposed drywall ceiling areas visible in the photo - no more R-value for that than for the non-insulated ceiling (if uninsulated) in the skylight shaft.

[Billy Stephens]

Rod,

Billy was, I am sure, referring to the exposed drywall ceiling areas visible in the photo - no more R-value for that than for the non-insulated ceiling (if uninsulated) in the skylight shaft.

Air has a thermal conductivity (k) of 0.024 W/m K. "R-value" is, if I recall correctly, a square foot fahrenheit degree-hour per BTU; it's a resistivity value, not a conductivity value. It also includes surface area as it is mainly used for floors, walls, and ceilings. Smaller k and bigger R mean better insulators.

To calculate energy loss given conductivity, you multiply by area and temperature differential, and divide by the thickness of the insulating material.

R-value takes into account the thickness of the material, since home insulation is generally made to stuff into a limited amount of wall space. So assuming you had a given thickness of trapped air, you could convert k into R by taking the reciprocal and converting units.

0.024 W/m k comes out to 5.6 feet * F degree * hours / BTU if I did the conversions right. This would be for a foot of trapped air; multiply it by the thickness to get the R value (5.6 per foot of air).

However, remember that air is a free-flowing fluid, and will transport heat by convection as well as by conduction. It also provides no resistance to radiative heat loss. This makes the "true" R-value lower. Aerogels, which are basically a solid "froth" of immobilized air molecules, are some of the best insulators out there.

Air has a thermal conductivity (k) of 0.024 W/m K. "R-value" is, if I recall correctly, a square foot fahrenheit degree-hour per BTU; it's a resistivity value, not a conductivity value. It also includes surface area as it is mainly used for floors, walls, and ceilings. Smaller k and bigger R mean better insulators.

To calculate energy loss given conductivity, you multiply by area and temperature differential, and divide by the thickness of the insulating material.

R-value takes into account the thickness of the material, since home insulation is generally made to stuff into a limited amount of wall space. So assuming you had a given thickness of trapped air, you could convert k into R by taking the reciprocal and converting units.

0.024 W/m k comes out to 5.6 feet * F degree * hours / BTU if I did the conversions right. This would be for a foot of trapped air; multiply it by the thickness to get the R value (5.6 per foot of air).

However, remember that air is a free-flowing fluid, and will transport heat by convection as well as by conduction. It also provides no resistance to radiative heat loss. This makes the "true" R-value lower. Aerogels, which are basically a solid "froth" of immobilized air molecules, are some of the best insulators out there.

Air provides the R value, not the insulation itself.

[Vern Heiler]

The shaft would have a higher R factor than the insulation shown in your photo.
*trapped air would be the insulator.
At first blush you would assume that the large volume of trapped air would be a great insulator, but as Rod alluded to, it is not. Warm air at the inside surface will travel to the cold surface (heat always goes to cold), and air circulation will take place inside the cavity. The R value will be better than open to the attic but not as good as insulation that is directly in contact with the surface of the drywall.

[Billy Stephens]

The R value will be better than open to the attic but not as good as insulation that is directly in contact with the surface of the drywall.

Not as good as this ?;)

[Larry Morrison]

The sum total of Energy loss of a skylight with exposed walls like this, is greater than just the horizontal attic area it occupies.

Let us say the ceiling area of the light is 2'x6'=12sf or 12 Sq. Ft. of attic area (same as two insulated attic access hatches.
But (if) the height from ceiling to roof is 8ft. 8'x2'x6'=96 sq. ft. of exposed wall, and that wall is exposed to very much hotter attic temps than the other exterior walls of a house is exposed to.

Skylights such as these are very much an energy drain and a week point in any home that has them (even if they are insulated well, still a lot of exterior wall that adds nothing to the living space of a home) Throw in a couple of these types of skylights and it will easily equal 10% or more of the total exterior wall area of a 2,000sf. home.

[Phillip Norman]

I don't think the heat burden on that 12 sf ceiling area in summer is more because of the troublesome walls in the attic. The inspector should not address this as an unusual missing-insulation issue. It is that patching within is abnormal and questionable, especially at the roof.

[Rod Butler]

. . . . . .
However, remember that air is a free-flowing fluid, and will transport heat by convection as well as by conduction. It also provides no resistance to radiative heat loss. This makes the "true" R-value lower. Aerogels, which are basically a solid "froth" of immobilized air molecules, are some of the best insulators out there.

Air provides the R value, not the insulation itself.

Great reply Billy, you summed it up very well.

The key point is the movement of the air and the convective currents inside ofthe shaft enclosure and as Larry pointed out above, the larger exposed area toambient conditions. That is also apparent on windows that have too large of anair gap between panes. There is an optimum spacing that reduces the convectivecurrents and that increases the U value. If the shaft were less than 1/2"in width it would have proved to be a better insulator that just the exposed gyp.

Great comments and discussion.

- - - Updated - - -


I don't think the heat burden on that 12 sf ceiling area in summer is more because of the troublesome walls in the attic. The inspector should not address this as an unusual missing-insulation issue. It is that patching within is abnormal and questionable, especially at the roof.

:) Yes, to stay on point you are correct. But Bob did say he would appreciate anyone's thoughts. Kind of a dangerous statement around here!:confused:

[Jerry Peck]

The sum total of Energy loss of a skylight with exposed walls like this, is greater than just the horizontal attic area it occupies.

As I understand it, the skylight was abandoned and closed off - that tells me that the ceiling is closed off as well as the roof is closed off, which means that there is no more heat gain in the abandoned skylight shaft than is in the attic, and that there is no more heat transfer through the uninsulated drywall ceiling closing off the abandoned skylight shaft than there is through the same amount of exposed uninsulated drywall ceiling area shown in the photo.

[Larry Morrison]

As I understand it, the skylight was abandoned and closed off - that tells me that the ceiling is closed off as well as the roof is closed off, which means that there is no more heat gain in the abandoned skylight shaft than is in the attic, and that there is no more heat transfer through the uninsulated drywall ceiling closing off the abandoned skylight shaft than there is through the same amount of exposed uninsulated drywall ceiling area shown in the photo.
True, the OP situation here (closing off the skylight at ceiling) negates the extra wall area...I kind of "wondered off the reservation"... with regard to these types of skylights in general.:)