Following.

Sounds high to me, and you generally don't need to remove the old insulation if you're just adding blown-in. There is no reason you can't do this yourself more cheaply. However, you may also want to contact your local utility: many of them have energy conservation departments that will do a free assessment and an estimate of what this should cost. In addition, they can also give you tips on other cost effective conservation measures to take.

Blown-in insulation is definitely a DIY job. Read up on the process and watch some videos. You’ll need another person to help you - one feeds the machine, the other runs the hose. Most home centers will give you a “free” rental on the machine if you buy x bags of insulation. You will also need a van or truck to get the machine and insulation home.

Typically you don’t need to remove the old insulation.

There's a whole bunch of youtube videos on this. I plan to do 16" of cellulose - R-value is about 3.5 per inch so that will net R-50. If you buy 10 bundles of insulation the blower rental is free and then return unused at HD. For me cellulose is superior than fiberglass (doesn't mold, animals won't nest, better insulation factor, nicer to work with - though dusty so use a mask). Just blow it in on top of fiberglass. You need to seal any leaks first and build a small casing around lighting if not rated. Also add the plastic vents around the soffit vents (less than $2/ea at HD) so you don't block them. Haven't done this myself yet but can't imagine it'll be more than $500 for your small area. The videos will show all. Here's a start... owens corning cellulose insulation videos

@Seabornman - There may be some air sealing to do, but I don't imagine much. The house is so old there's really nothing in the attic - no plumbing (aside from one venting pipe), no electrical, and we have gable vents (not soffits). Ceiling and walls are lathe and plaster (no drywall). Should be a pretty straight forward job.

@badabing2 - The cellulose definitely sounds like the way to go. we've had some rodents up in the attic, so hopefully this will deter them. (also gotta find out how they are getting up there and seal it). Checking out the videos on YouTube. Thx!

Are you including radiant barrier, that makes a huge difference in insulating value?

Use a good dust mask. One that seals well to your face. Put plastic down where you plan to put the blowing machine. The cellulose goes everywhere. I gave up cleaning it out of my lawn. It'll decay eventually.

@Raye Smith - Would you do both radiant barrier & insulation or is this "belts and suspenders"? I use Reflectix on my RV windows and it's amazing how it blocks heat.

It depends on your climate and building codes. Although this shouldn't require a permit it would be best to follow code so you don't get dinged by the inspector when the time comes to sell.

I'm not an energy conservation expert, just a homeowner, but I'm not a fan of cellulose. I prefer fiberglass batts. To me that's easier than messing with a blower, but what do I know?

Cellulose insulation settles and packs down over the years, and its R-value falls off as a result. I guess you could stir it up again, but what a nuisance. I never have.

Cellulose is also really unpleasant to have to work in later, especially as it gathers dust and dirt over the years. I've had to do electrical wiring work around cellulose insulation, and I really hated it.

But it is cheap.

I had blown-in cellulose done for a poorly insulated attic years ago. In the following 20 years I owned it, there was no noticeable settling. I think it’s the easiest, least expensive, and most practical approach for the OP.

@kudzu9 Did you notice an immediate change after getting this done? Did your house noticeably retain heat better? Right now. our propane costs are kind of insane (typically $400/mo) and the house is really only occupied on weekends. Im hopeful if I get this done we'll see that cost drop.

Personally I would go with fiberglass batts. They have changed so that the glass is less "sticky" and causes less itching. Technology is pretty easy, cut it with a utility knife and no expensive machinery to rent.

@User I dont think I could make a radiant barrier work as the framing and roof is so old (1850s) so the underside of the roof is a bit of a mess.

Typical installation of radiant barrier is under the roof for warm climates and over the floor joists for cold climates. I had it installed several years ago, my home is older than yours and I see a big difference in energy usage.

Stephen- The effect will be immediate: you should have a noticeable decrease in your bills and your house should feel less chilly. It’s also important, however, to make sure the house is well caulked around windows and that your doors have good weather-stripping.

@kudzu9 good to know. we've sealed a lot of the old windows, but they are all still single pane and not all that great.

@User interesting. ill dig into this a bit.

One other benefit I've heard is noise reduction from the outside.

Don't forget to check to see if you have a properly vented attic.

Definately not a pro, just had to research ‘lathe’ ceiling as mentioned in first post? The only reason i’m chiming in is bc my parents house is log cabin ie wood ceiling (like slats?) very well made and close fitted, BUT they claim that dust comes from the ceiling constantly from the old insulation in the attic? Idk but the insulation that is batted may prevent that problem. I know that makes your project more ‘intense’ but maybe in long run better. Take blown in out, replace with batting. Probably not know what i’m talking about, just occurred to me to mention?

Given the 'slats' I think removal & foam as opposed to faced fiberglass. Any gaps need to be sealed. Of course, the assumption is this is the cause not duct leakage or HVAC bringing it in.

Absolutely

badabing and Alice-

The OP referred to the ceiling as lath and plaster, which has nothing to do with “slats” or gaps. The lath is the wooden support system hidden under the plaster. Don’t confuse this with a wooden ceiling.

I've seen cellulose settled and packed at 30-35 years.

I also have some in my present house that probably dates back to the 1950s. I'd estimate that it's settled 20-25%. It's also filthy, and deeply unpleasant to have to dig through.

The walls also have blown-in cellulose, which has packed down at least as much.

I have Alice's dust problem here. A neighbor thinks it's because this house was once heated by coal and wood. All the dirt that's accumulated in the insulation somehow filters down through the plaster ceilings, making this the dustiest, dirtiest house I've ever lived in.

Your decision, of course, but I'll never put cellulose insulation in any house I own.

Kudzu9, thank you for that, i was confused with that term.

Like Mike said, if you buy certain amount of bags the blower machine rent is free, I did all my attic with recycled cellulose, I did the top and another person was feeding the machine outside, just remember to also buy a breathing mask and googles, it can get very dusty and you'll definitely need a shower after it.

PS. Make sure to cover the attic access as best as possible because the dust will find its way to the room where the attic access door is.

Thanks everyone for all the great comments here. I ended up getting (most of) the job done. I will say, depending on the size and type of attic you have, it could be a bit of a challenging weekend job, and probably best to not do this alone (like I did).

My attic is pretty small, and there isn't an easy way in, so this involved a lot of climbing up and down from, and crawling through, a fairly small space. I wouldn't call this a fun project by any means. And yes, there were lots of spiders, and even some old markings on the trusses from when the house was built in 1850. This was definitely hard work, super messy, and something that I really would have rather had someone else do for me. But... I saved a heap of money, so thats the upside.

That said, in terms of the work itself, it is probably best to do this work with someone else, but this is definitely a job you can do yourself if you're up for a good challenge. I did have to run up and down the stairs and up into the attic many times to unclog and refill the machine. The way I controlled it was to set it to "on" and connect it to an extension cord that I was able to bring up into the attic with me, so I could easily turn on/off the system as needed (I found this tip on YouTube).

I bought 30 bags of cellulose and ended up getting just over 3/4 of the attic done with about 18 bags. I still need to finish above the master bedroom. I ended up leaving the existing insulation in, and just sprayed right over it leaving about 12-14" throughput the entire space. I opted to not pull out the old insulation and look for gaps to seal, mainly because it would have been an incredible amount of work, and getting rid of the waste would have been difficult without a large garbage bin, and I figured the 12-14" layer of cellulose was in a way sealing the space up already. At very least, it will keep the rodents out, as apparently they don't like digging through cellulose (and I cant blame them, its dusty and kinda gross).

I'm hoping to get the last area above the master bedroom done in the next month or so, and then we should see some real improvement in our heating and a reduction in propane costs.

Next up - new storm windows!

Thanks for the feedback! The half lap and peg at the ridge without a ridge board predates 1850 around here, but you never know.

All of the connections in my pre-1840's attic are done with massive pegs similar to that.

@Seabornman we are told our house was originally built in 1763, with the main structure built around 1850. Its unclear what part is from the earlier period. Tho we do have a large fireplace in the basement that is definitely 1700's era. What region are you in? We are in Hudson Valley, NY.

I'm in upstate area southeast of Syracuse. It's interesting following the progression from hand-hewn to all stick-built in houses around here. My current house is probably ca.1840 and has quite a mixture of sawn and hewn pieces. But it didn't seem to ever have a major chimney.

@Seabornman - for reference, this is our house...