$8,500 does sound ridiculous however I live towards the east coast so I'm not familiar with pricing out on the west coast. Its always a good idea to seal up the attic, if not to safe energy, then to at least keep animals and insects out. This process should take very little cost for materials. I just sealed up our attic and here's what I needed:

- 1 can of spray foam ($4)
- 3 tubes of white silicone caulking ($9)
- a roll of aluminum screen material ($8)

So I spent about $20 and it took me a couple hours to do. I needed the spray foam because there were a couple spots with 1-2" openings where I could see birds had made nests before. Also while looking around I could see gaps where light came through, which is where I used the white silicone caulking. I chose white so it would block out light and I could see I covered it all, and I chose silicone because it is flexible and regular latex caulking isn't. The aluminum screen material was to cover both of our attic vents. One was missing a cover and the other was damaged. This means bees could freely come in and create a nest if they wanted to.

Personally I wouldn't bother removing the existing insulation and instead just add more on top. Also some white silicone might come in handy to seal up windows & doors both inside & outside your house.

I added R-38 worth of blown insulation over my existing 37 year old insulation. The cost was just at $1/Sq-Ft last year in the Maryland suburbs of DC. Down the center of my attic they put r-38 Batts over the walkway for future accessibility.

I'm suprised your auditor didn't give you more info.
there are other options,

if you hire a company to vac out old insulation then you
can put foam in the attic. not cans of foam but foam insulation.

roofline install would be one option. it will be more
costly depending on the roof pitch, and in my hot humid climate we use open cell which would allow moisture to pass through the foam. closed cell will trap the moisture at the leakage site and cause decking to rot.

another option would be to remove existing insulation and
install foam insulation between ceiling joists of attic floor. this would seal leakage sites into the living space.
and be less costly than the roofline install.
again..open cell. if you have recessed lights they would have to be made air tight..do you have recessed lights?
you could always do a combo of 4" open cell and blown insulation over the foam to bring the R-value up more affordably.

adding insulation won't help if you still have leakage sites
from the attic into the living space, and if you have allergy issues..it only makes it worse.
conventional insulation slows air movement, it doesn't stop it. foam stops air movement.

if your auditor made note of the leakage sites you could hire it out. but without a comprehensive list of leakage sites and options on how to properly seal..and another blower door test to determine if the whole of the leakage has been sealed..it will be difficult at best.
I do this type of sealing work..have for years and without
my pre and intermediate testing..the end result is not as good.

visit buildingscience.com and look for climate specific information on insulation options for your area.

best of luck.

Thanks everyone for your valuable feedback. Ideally we want the company to remove the existing insulation first. Once they remove the insulation we thought we'll go up and seal everything possible. Like you mentioned we have had rat issues in the past, so sealing up the attic would certainly help with insects/rodents not coming in. We do have recessed lights in all the rooms. They are IC rated and we do have CFL bulbs. Is it ok to put insulation right on top them? One company says they'll create baffle cones around the recessed lights and then blow in insulation even if it is IC rated and CFL while the other one says that it is ok for the insulation to be on top of the lights. Not sure which option to choose.

energy rater, The auditor doesn't have a list of all the holes that need to be sealed in the attic because many of them are still buried under insulation. That's the reason they recommended removing the insulation first. I'll look into the other options you suggested.

energy rater la - the OP lives in No California. That would appear to be a place where payback on foam would be >100 years (I exaggerate but most places in NoCa are pretty mild).

To properly seal the attic, you would probably have to remove the old insulation. It is pretty important to seal the leaks.

I'd expect your job here to cost about $2500 for removal, sealing and replacing with R-38. So I'd expect that to be about $5000 in No Ca.

I'd guess I'd start by asking how much you spend for heating per season and how much do your peers pay (ie similar size and age house). You could then get an idea of what you might save by sealing and insulating.

I do a lot of things myself. If I lived in NoCa - I'd do even more. The labor cost and regulatory cost are so prohibitive as to be unreasonable (in my mind). You could remover the insulation in a day, seal really well in a day, and pump the new insulation in another day for about $1000 in supplies. 3 days to save $7500 - not bad.

To seal my attic (new house - done during construction) took more like 10 cans of foam - I am shocked by the person who used 1 can of foam. I'd expect an older house to need more.

A handyman could probably seal about 90% as well as someone with better experience. Probably worth it if you could save a lot of money. Sealing a crawlspace can mean very different things and in my world $1800 is a pretty good price but it includes things you would never do in NoCa (b/c of humidity differences).

I've heard of homes in NoCa with zero insulation under the floor over a crawlspace. If that is the case, then that is a no brainer. Doing R-38 might be overkill in the attic in your climate - but I do realize that NoCa is a pretty diverse area in climate. You might help get a better answer by typing in your zip code and getting your HDD (and CDD is there are any).

I was quoted less than $8500 to remove all existing fiberglass insulation and install open cell spray foam in the rafters along the roofline on over 5000 sq ft of surface.

From my research, this is the best way to seal infiltration and is also a great help if you have attic HVAC equipment and or ducts.

My only hesitation right now is that I've seen reports of problems with fumes remaining in the house after foaming the attic like this.

Enery_rater_la, what is your experience with any of these types of problems?

Our home doesn't have insulation under the floor(above the crawlspace). So from what I get fixing the leaks in the crawlspace shouldn't be that difficult. BTW, We live in the SF Bay Area so the temp variations are less when compared to many other cities in Northern CA. Nevertheless, the insulation contractors recommend R-38. An advantage to doing that is because we get rebates from our local gas and electric company. If the insulation is removed, we can do the sealing ourselves before the insulation is blown in.

Sf bay area is still pretty broad. Berkeley is much cooler than palo alto. My dad lives in Berkeley. It never gets below 40 and he doesn't even have a/c. To foam in that climate is a crazy waste of resources. I know you weren't even considering foam but others have recommended it so had to throw that out there.

I don't think you need baffles over ic cans. I have a new house with no baffles over ic cans. Now you are not supposed to foam ic cans without baffles.

More specifics requested on locale. Also, don't forget that contractors love to rip off rich greens in the bay area and that $ might be better spent on a charity that seals and insulates homes of people in the northeast or Midwest.

sweet home
there are inserts to make IC recessed lights air tight.
IC is insulation contact..which means that insulation can be
installed next to and over cans. However..IC cans have holes in the housing, when insulation is piled next to and over these cans the insulation particles are drawn into the house. when insulation is not next to or on top of the hot dirty attic air is drawn into the house.
These inserts are installed from inside the house..by removing the trip piece and bulb. the insert is a sealed system that will aleviate the above mentioned issues.
get the name brand and model number of your recessed lights
and go online to the company. search the site for ICAT.
That is the easiest way to find the inserts.
Oh and if you want to find the leaks that are buried in the attic insulation..look for dirty insulation. as the air filters through the insulation it leaves dirt marks.
next to every hole is a dirt trail..
I just think they should have been able to identify the sites..I dig out recessed lights..one or two to show home owner..and other known leakage sites. Its not rocket science
and leaks are easily found when house is depersurized.
just my experience.

organic possum..I've had several chemically sensitive clients that had no problems with the smell of foam,
although one did move out for the day of the install and
came back the next evening. putting the ducts and mechanicals under the insulated rooflines is a great idea
for my climate.

best of luck to both of you.

David & energy_rater, Thanks for your feedback. We got a quote from another insulation company today and their quote seemed to be reasonable. So the first quote indeed looks like a rip off. We also found out that PG & E(our local electric company) requires baffle cones to be on top of IC cans for it's customers to be eligible for their rebates. So looks like we don't have a choice but to go that route.

David, We live in the South Bay(San Jose area). The temp is comparable to Palo Alto.

The decision making process never seems to end for us. One company wants to blow in cellulose whereas the other company wants to blow in fiberglass. We read the pros and cons of both but haven't been able to make up our mind yet. I am leaning towards cellulose because of how fiberglass is being publicized as a carcinogen. If you feel strongly about either one of them, pls share your thoughts with me. The info provided in this thread by all the folks has been VERY helpful for us. Thanks!!!

What a great thread! Just what I needed to read tonight, as we've been discussing this.

David Cary: We are self-building, new construction. The insulation sub is going to blow R-38 Cellulose in the attic. You mentioned going into your attic with 10 cans of foam. Can you tell me exactly what you used, and what we need to seal so we can be sure to have it sealed prior to the R-38 to avoid the OP's current issue? Do we just seal around the recessed lights and drywall seams?

Thank you!

wear_your_baby: you can use the Great Stuff foam in cans with straws from your local orange or blue big box store. They don't give you great control, but they'll do the job. Dow (Great Stuff) also sells foam guns that you thread the can into and have a lot of adjustability in how much you're squirting out. I'm on my 2nd one, IIRC they cost ~$40. There are several other brands out there. I buy EnerFoam from a local tool shop b/c it's in big cans and is a relatively good deal. You can also use their low-expanding window/door foam to seal between all your windows/doors and the adjacent framing.

Places to seal:
- penetrations into the attic for wiring, plumbing, ductwork, etc
- framing gaps into walls below (drywall to top plate)
- I would do ceiling boxes for light fixtures (wire penetration and at drywall)
- Others I'm sure I'm forgetting despite 2nd cup of coffee this AM

Backing up a couple steps, if you're building new you have a lot of opportunities to end up with a tight, well-insulated home. I'd spend a bunch of time looking at the Building Science and Southface sites to learn more. There are framing details, air sealing details (many opportunities besides attic), etc. Foam is great in a lot of places, but caulk is cheaper and works for a lot of the framing sealing.

Two other thoughts- get insulation-contact airtight (ICAT) recessed fixtures; these will have gaskets for the ceiling flanges, so no foam necessary (not to mention they'd get hotter than I'd be comfortable with next to foam if you use incandescents).

Second thought- some will say that with cellulose you don't need to do all that sealing. I would argue to do just what I've listed b/c the cells will seal but they're also a dusty mess that you don't want leaking down into the house.

If the insulation will be removed and it will meet code requirements I would buy styrofoam coolers and use canned foam to seal the recessed cans. Wal-mart has them for 1.77 each and a friend of mine that does hvac and home sealing did a commercial building with 1400 cans recently. He purchased the coolers with no tops for under .25 each and charged 15.00 each to seal.

The recessed light sealing trim units work good but are around 7.00 each. They still leak more air than a foamed up cooler light but it is tremendously better than nothing at all.

Sealing all of the hvac ductwork and keeping the air where it is supposed to be is huge. Return air that is pulled out of crawlspaces, attics and unfinished basements is hard on the equipment and kills efficiency.

Unless you go totally nuts... almost all effort used to keep air from moving from conditioned spaces to unconditioned or visa verse will pay for itself.

If it is sealed it up too tight and has no means to exchange air there can be problems but in home that is already built I think the chances are slim that would happen.

I did have my recessed IC cans flow tested at the time of my hvac upgrade and with very little wind mine ranged from 5-7cfm each with 14 lights. Leaking at 6 cfm all day that is 120,960 cubic feet per day. I did the air test with the a/c on so I do not know the accuracy for 24 hours.. but even on a hot day and 12hrs of run time.... wow 60k cubic feet of lost air and that is only on recessed lights.

As far as sealing air leaks during construction - I paid my installer $200 or so to foam all doors and windows. In the attic - my attic was pretty dark during the day and the light from the windows below really showed all the leaks. This should be done at a few phases of construction but before electrical final was the most helpful.

Every boxed light has leaks - the box has leaks and the drywall cut around them has leaks. Fluorescent lights around here are roughed in with just a wire hanging through the drywall - significant leak. The most surprising to me was all the fan leaks - bathroom fans. There are just big holes to the attic.

Either way - you go up there with Great Stuff and it is pretty easy to get the attic dark. I foamed around the ceiling registers for the HVAC as well but they were pretty tight.

Where the electrical service comes into the house can be a pretty big hole. They put like a 2 inch plastic tube through the wall - with a terrible cut - and fill with a 1 inch wire. This was the single worst leak but it depends on the individual house - basement/crawlspace etc whether this goes to conditioned space.

Ok - I am sort of shocked at the number of HDD in the South Bay - I think this is where the number is a bit off. There are 2900 and where I live is 3500. We have frosts from December to April and snow (not regularly). That is not my recollection of the South Bay. Now - they count some HDDs in July where you probably don't really run the heat. So much for HDD's as a good predictor. You don't really have that much heating need as who runs the heat (more than maybe a morning warmup) on a sunny 60 degree day. Or for that matter a 55 degree day. I should come up with a new number that gets rid of 2000 HDDs based on sunlight and then the South Bay would be 900 and my climate would be 1500 which gives a pretty good relative heating requirement.

For those that are building new - at least where I live ICAT cans are code so don't bother worrying about that much at all. I still foamed them but they had gaskets once they were trimmed out. They were pretty tight without the added foam but since you can't get at it later - it seemed like a no brainer.

I find that the trim is not the leakage..or not the worst of the leakage. the gap that the trim covers can be caulked
but to seal the holes in the housing..inserts.
I have used the ice chest method also..many times!
the rule of thumb is 4" clearance on all sides and
top of recessed can to ice chest. (ROT from La DNR)

intresting thread..good to hear everyone's pov.

best of luck

I would like to seal my cans with the ice chest method. Anyone have a picture of final product with ice cooler? Thanks.

If the OP is still reading this thread---what did you end up doing? We're also in the Bay Area and faced with a similar decision...quote of $6K for 1250 square foot home, which makes us eligible for $2K in rebates. We know our house is leaky, but wondering whether we should really invest this much in fixing it right now. What did you wind up doing, and how much did it cost? Does it seem to be effective thus far (knowing we haven't had much cold weather yet!)?