So my house was built late-70s. The insulation is original and has that funk smell when the weather here in San Diego gets hot and more humid. As a result,we're looking into getting the stuff replaced and my nature is to research all possibilities.

The options appear to be; roll-in insulation like the original build or blow-in type. In either instance, the old insulation will be fully removed.

So to you in the know (maybe Arc?), what are the advantages of each with regards to both cost and thickness for the same R-factor?

What, in the long run, are advantages or disadvantages of each?

And, when hiring a company to do this, what shuold the buyer look for to ensure the seller is able to do what they are describing they do?

Tell me more about the home. So you have batts in the attic? What other conditions are there? How is the attic vented? HVAC units up there?

If the home was built in the 70's, what do you know of the walls, and how are the windows?

Is this a typical one story or split level?

Getting rid of the existing insulation in an attic, gives you the opportunity to address any penetrations or imperfections in wall top plates , recessed lights, and other outright holes.

How the roof/attic is vented will be a factor. Any "cathedral" ceilings?"

If I'm hiring an insulation company, I want them to know what a blower door is, and I want to see them use infrared cameras, among other tools.

Two story home with a rectangular footprint.

If length of house were orientated N/S, main room and small bedroom are on the east side, kitchen and one master bedroom on west side. Second master bedroom above lwr master bedroom and second small bedroom above kitchen (loft between these two room).

Living room is open (vaulted?) to loft, landing of stairs and other upstairs area (ie, living room ceiling is angled up from 8' to approx 20' for the loft).

Attic area (where insulation in question is) is horizontal over upstairs bedroom and loft. Current insulation might be R-15 batts.

Windows are still the super, high-tech, aluminum framed single panes of glass where the sealant is allowing for 1/16" gaps in the corners (one step at a time, right now is some new insulation).

Two standard (for the area and time of build) soffit (is that's the correct nomenclature) "holes" on the N and S ends of the attic. No ridge vents nor (yet) whirley balls (plan is for two to go in).

Disclaimer: I am not a professional. (But I am fairly well-read on this subject.)

quote:

Originally posted by LS1 GTO:
Two standard (for the area and time of build) soffit (is that's the correct nomenclature) "holes" on the N and S ends of the attic.

That sounds like gable vents. Soffits are an area under where the roof overhangs the walls. That's where soffit vents would be.

quote:

Originally posted by LS1 GTO:
No ridge vents nor (yet) whirley balls (plan is for two to go in).

Whose idea was it to install those? I ask because you may be about to make a common homeowner mistake: Installing additional exhaust vents w/o regard for how the attic ventilation was designed to work.

The idea behind gable vents is wind blowing more from one end of the house will create a breeze across the attic, resulting in air exchange.

Problem is: No breeze = little to no air exchange.

Adding vents at or near the ridge line to an attic designed to use gable vents does little in the absence of the wind blowing, because the gable vents are only at the ends of the roof and are too high up on the gables to effect air movement from the lower portions of the attic.

When gable vents were designed-in, installing additional vents at or near the ridge of the roof can even make things worse, because, when there is a breeze, the additional vents near the ridge line short-circuit the breeze that would otherwise flow from one end to the other, resulting in less total air exchange in the attic, rather than more.

Exhaust vents at or near the ridge of the roof are meant to work in conjunction with intake vents located low on the roof or, as in the case of soffit vents, under the roof. Warm air rises out the top, drawing cooler air from the bottom.

Ensigmatic,

Thank you for the clarification on the gable vents. Based on how you are describing, pretty sure there are also soffit vents (they look like 2.5" to 3.0" holes along that edge you describe. Pretty much even along the whole E and W side.

Regarding the whirly balls, the attic space just cooks during the summer (think 150 to 160 degrees measured when I first moved in and was curios bout the temps up there) and very little, if any, noticeable airflow. If/when the balls go in, they will to be in support of a whole house fan.

quote:

Originally posted by LS1 GTO:
Two story home with a rectangular footprint.

If length of house were orientated N/S, main room and small bedroom are on the east side, kitchen and one master bedroom on west side. Second master bedroom above lwr master bedroom and second small bedroom above kitchen (loft between these two room).

Living room is open (vaulted?) to loft, landing of stairs and other upstairs area (ie, living room ceiling is angled up from 8' to approx 20' for the loft).

Attic area (where insulation in question is) is horizontal over upstairs bedroom and loft. Current insulation might be R-15 batts.

Windows are still the super, high-tech, aluminum framed single panes of glass where the sealant is allowing for 1/16" gaps in the corners (one step at a time, right now is some new insulation).

Two standard (for the area and time of build) soffit (is that's the correct nomenclature) "holes" on the N and S ends of the attic. No ridge vents nor (yet) whirley balls (plan is for two to go in).

What you describe is no soffits, gable end vents. This is OK. It's ridge/soffit, OR gable vents, or any combination that gets the volume of air needed. If you have soffit vents, attic insulation needs to not block them. Gable end vents of sufficient size do the job.

If you do have single pane windows, then a modern double pane with Argon and a U factor of .30 or less will literally pay for itself. The energy leaving, and the solar gain of single pane is killing your ass.

quote:

Originally posted by arcwelder:

quote:

Originally posted by LS1 GTO:
Two story home with a rectangular footprint.

If length of house were orientated N/S, main room and small bedroom are on the east side, kitchen and one master bedroom on west side. Second master bedroom above lwr master bedroom and second small bedroom above kitchen (loft between these two room).

Living room is open (vaulted?) to loft, landing of stairs and other upstairs area (ie, living room ceiling is angled up from 8' to approx 20' for the loft).

Attic area (where insulation in question is) is horizontal over upstairs bedroom and loft. Current insulation might be R-15 batts.

Windows are still the super, high-tech, aluminum framed single panes of glass where the sealant is allowing for 1/16" gaps in the corners (one step at a time, right now is some new insulation).

Two standard (for the area and time of build) soffit (is that's the correct nomenclature) "holes" on the N and S ends of the attic. No ridge vents nor (yet) whirley balls (plan is for two to go in).

What you describe is no soffits, gable end vents. This is OK. It's ridge/soffit, OR gable vents, or any combination that gets the volume of air needed. If you have soffit vents, attic insulation needs to not block them. Gable end vents of sufficient size do the job.

If you do have single pane windows, then a modern double pane with Argon and a U factor of .30 or less will literally pay for itself. The energy leaving, and the solar gain of single pane is killing your ass.

Windows are next.

The reality of the temperature here is, is the swings are not that extreme. (Think maybe an AC for 7, maybe 14 days a year. Intent here is to maintain keep the internal from swinging too much. The goal of the attic is to address the low-hanging fruit first. There is still some discussion between retrofit and new-construction and, maybe some tweaking of the windows' design (maybe a bay window in the kitchen and/or windows in the living room, larger installs where asthetically possible., etc.

quote:

Originally posted by LS1 GTO:
Ensigmatic,

Thank you for the clarification on the gable vents. Based on how you are describing, pretty sure there are also soffit vents (they look like 2.5" to 3.0" holes along that edge you describe. Pretty much even along the whole E and W side.

You have soffit vents and gable vents? Ok, again: Not a professional, but that sounds wrong.

quote:

Originally posted by LS1 GTO:
Regarding the whirly balls, the attic space just cooks during the summer (think 150 to 160 degrees measured when I first moved in and was curios bout the temps up there) and very little, if any, noticeable airflow.

If your attic ventilation was properly designed you'd feel air movement up there pretty much all the time. I do in our attic. Particularly if there's any sun load on the roof at all. (We have soffit and ridge vents with a hip roof.)

quote:

Originally posted by LS1 GTO:
If/when the balls go in, they will to be in support of a whole house fan.

Again: Whose idea was it to do this as a solution? Because if it was your's, based upon the common homeowner belief that "more is better," you could be making a big mistake.

This article is pretty good and not too terribly long: Five Attic Ventilation Traps to Avoid

I wonder if the house wasn't originally designed with gable vents and somebody tried to "upgrade" it with soffit vents, but failed to ensure the soffits were actually clear in the attic?

Do you know if those soffit vents are even breathing?

The first thing I noticed is that you said that the attic had a bad smell in humid and hot weather.
That means that the vapor barrier (the water repellent material) on one side of the insulation was installed facing the wrong direction.
What most folks don't understand is that moisture from the living space will travel through the walls and ceilings and enter the attic (eventually). In which case (in any case, really) the vapor barrier should be installed facing the living space. IF the vapor barrier is installed correctly and you have a large number of long roofing nails protruding into the attic that can cause the insulation to get wet as well. (wait for it...) you see that in freezing weather, moisture will collect and freeze on the nails. As it thaws it drips on the insulation. Sounds crazy I know, but it is a possibility,especially when you consider the length of time involved (installed in the seventies).
Another problem exists where attic insulation can get wet and musty from a dampbasement. If there are no firestops in the walls around the house, moisture from the basement will travel through the wall insulation and end up into the attic. Of course, this make the insulation in the walls musty as well.
The afore mentioned problems are generally due to old building methods. Good luck with your upgrade. It can be a real pain, but if done correctly it will be worth it.

Furthermore, stopping "air movement" in and out of the living space (we are talking about winter time here) will cut your heating bill literally in half in an old drafty house.
I know you said that you have good windows installed, but there may be other areas that need to be addressed. I believe that is why someone posted to "have the contractor use infra red". There is a little machine/camera device that will show different temperature along your walls and windows. Cold shows up a dark blue. That is where you need to holes or cracks.

Phew!!!
Aren't you glad you asked???

edited to add...

If your insulation is getting wet/damp you just lost some R-value there. The cold is being conducted toward the living space.

This guy has some good videos on what Arc mentioned, sealing holes prior to replacing insulation.
https://m.youtube.com/user/MattRisinger

quote:

Originally posted by USMCE4retired:
The first thing I noticed is that you said that the attic had a bad smell in humid and hot weather.

I noticed that, too. His attic "... has that funk smell when the weather ... gets hot and more humid." We get hot, humid weather here in S.E. Michigan. Late July through early September often consist of nothing but hot, humid weather.

Despite the fact the original owner had actually plugged the soffits with insulation and there was moisture damage to the underside of the roof sheathing, the attic of our late-60's-built home never had any "funk smell." Not that I could smell, anyway.

When I added an additional 6-1/2 in. of fiberglass batt a couple autumns ago there were times my facemask was literally buried in the old insulation. (Hip roof. Very low out near the edges, and especially corners.) Merely smelled "dusty."

My wife has a very sensitive nose--often detecting smells I cannot. I've had the attic access open for hours-upon-hours at a time when working up there. She never mentioned anything other than dustiness. Even had she not noticed it because airflow would've tended up, she surely would have smelled it on my clothes when I came back down.

quote:

Originally posted by LS1 GTO:
So my house was built late-70s. The insulation is original and has that funk smell when the weather here in San Diego gets hot and more humid.

Others have keyed in on this statement. I'll add that you should also verify that you do not have any bathroom vents, or any other vents that are discharging into the attic space!

quote:

Originally posted by nhracecraft:
Others have keyed in on this statement. I'll add that you should also verify that you do not have any bathroom vents, or any other vents that are discharging into the attic space!

Ha! Forgot about that. In addition to stuffing the soffits full of insulation, thus nearly eliminating nearly all free airflow through the attic, the idiot original owner, after adding an addition to the back of the house, left the existing bathroom to vent into the attic crawl space and had the clothes dryer venting into the addition's ground crawl space.

Never mind the fact there were only three box vents on the roof, and they were all on the addition's roof. Since the idiot also left the old roof in place, sheathing, shingles and all, save for a narrow opening between the two areas, there was little way for air to exhaust under the roof of the original part of the house.

The original owner did a lot of stupid stuff like that. Going on 28 years of possession, and I still find new & wonderful surprises.