My house is now 30 years old. My builder just did a re-roof a couple of years ago and said the old insulation is settling, so we need more insulation. We currently have the blown in stuff that is like ground up paper. So the question is, which way to go. Do I put in more of the same, get some gloves and equipment and put in the pink roll stuff, or get some spray in foam. Which is better, which is cheepest? Thank you.

I don't know if it's the cheapest way but, soon I am going to rent an insulation blower machine from Lowes and blow my own. House is 11 years old and it looks pretty thin up there. See link

https://www.lowes.com/n/how-to...-in-attic-insulation

I paid someone to do it at our last house, same situation as yours. 30 yr old house insulation had settled and become thin. Big difference after with heating and cooling costs

Blow in fiberglass. Not very expensive and you can pile it up on top of the paper stuff. Actually easier to use in my opinion. Kinda comes in bales. The blower I used split the bags when you shoved them in. I've been very happy with the results in both summer and winter.
The best is foam if it's done correctly but it is also the most expensive. I have a friend in the business and if I ever have a bare interior wall it gets foam. Great R value and creeps into the voids.

Measure what you have now first.
Then compare that to the current recommended R values for your area.

I have gone the lowes route a couple times with their free use of machine.

Having the roof plane foamed is superior to any other method. Do this especially if you have any HVAC equipment or ducting in the attic.

If you add more blown in yourself, make sure you understand how the roof is vented. If you have soffit vents and a ridge vent, you should see propavents or a similar product in each bay keeping the insulation clear of the vents. You need to extend these up past the level you plan to add insulation to. Or you have sufficient gable end venting.

Make sure you don't cover the venting, it will encourage wind washing through the insulation and make it considerably less effective. It can also build moisture into the insulation, and that causes a host of problems.

Done right, propavents are sealed to the top plate with foam blocking, so that insulation doesn't simply get down past the vent, or wind come up behind it inside the insulation.

quote:

Originally posted by arcwelder:
Having the roof plane foamed is superior to any other method.

Not debating this recommendation, but wouldn't this pose a nightmarish situation if you ever had to remove say rotten sheathing from the roof?

Rotten sheathing or roof leaks are non thrilling any way you slice it. Open cell is easy, closed is more of a challenge, but I wouldn't call either "nightmarish." Dense pack cellulose sucks the most with leaks.

I’m sorry to have to disagree with Arc but foaming an existing home (unless your HVAC system is in the attic is a massive waste of money.

Open cell foam has the same R value as blown in insulation but is triple the cost.... It is also highly flammable while blown in insulation has a flame retardant in it...

In Michigan you should blow enough to have at least an R-50 value or more if it doesn’t interfere with your soffit venting.

Cellulose is garbage, it compacts and etc. Spray foam is very good but very expensive. I would have a professional blow in fiberglass insulation to a very good R value for your area (more than the basic recommendation). You should be able to blow it right on top of the cellulose and it's cheaper to have a professional company do it (if you shop around) than renting the machine and doing it yourself.

If your electric company does a free home energy survey, go that route as they generally will give you a rebate towards it and have people that are vetted to do it. Attic insulation is the best bang for the buck and repayment is usually 6 months or less.

Spray foam insulation is superior because of its air sealing qualities. Cellulose doesn't air seal. Also, you don't just spray foam and walk away. In an attic or similar space, an intumescent paint would be applied. Spray foam will perform better, it's not just about R value. Typically, someone spraying foam is planning on being in the home a while.

The downside of blown in cellulose, is the big pile of blown in cellulose, and lack of air sealing.

Very happy with my done wrong insulation. Blew a bunch of cellulose on top of existing 3" thick batts. Huge improvement. Had to fish in a new HDMI line for a failed one as well as microwave and bath GFI circuit. Disturbed it a bit. Will be blowing in more to fill in places I disturbed and add 2-3" more overall to compensate for settling. Can't complain one bit about the effect it's made.

Whats wrong with that? You can blow cellulose over batts. No reason to take them out.

quote:

Originally posted by arcwelder:
Spray foam insulation is superior because of its air sealing qualities. Cellulose doesn't air seal. Also, you don't just spray foam and walk away. In an attic or similar space, an intumescent paint would be applied. Spray foam will perform better, it's not just about R value. Typically, someone spraying foam is planning on being in the home a while.

The downside of blown in cellulose, is the big pile of blown in cellulose, and lack of air sealing.

Open cell foam which you were referring to earlier does not have any sealing qualities. It is just like your kitchen sponge. Closed cell foam is used for sealing purposes and is fantastic for that purpose but is typically used in thin layers. It is once again even more expensive than open cell foam.

My firm has been routinely recognized as one of the top ten most energy efficient builders in the state of VA over the past 10 - 12 years or so and we have over 35 years experience as a Class A contractor.

There is always a fine line between what is “best” and what provides the best ROI.

I know open cell doesn't on paper, but for years when we did open cell by itself, the blower door said it seals. Since then we've moved to flashing with closed then filling with open, or all closed. Personally I like closed cell for 3", then another 3" of mineral wool with the utilities in it. Entombing utilities in closed never thrills me.

The others have hit on the air sealing aspects of spray foam, but this should also be done when using blown in insulation.

Every wall inside your home acts like a chimney, and every light fixture penetration is an open avenue for heat to escape into your attic. You should seal all of the top plates of the walls and any other penetration to prevent this loss.

quote:

Originally posted by arcwelder:
I know open cell doesn't on paper, but for years when we did open cell by itself, the blower door said it seals. Since then we've moved to flashing with closed then filling with open, or all closed. Personally I like closed cell for 3", then another 3" of mineral wool with the utilities in it. Entombing utilities in closed never thrills me.

You could not be more correct about utilities in closed foam. I’m guilty myself and I’ve had crews cut right through water and power lines dealing with the stuff. Eventually we got smart enough to turn the water off to the structure prior to demo, if we could (occupied commercial buildings being a big exception).

So glad I’m not in the field/that side of the industry anymore.

quote:

Originally posted by arcwelder:
I know open cell doesn't on paper, but for years when we did open cell by itself, the blower door said it seals. Since then we've moved to flashing with closed then filling with open, or all closed. Personally I like closed cell for 3", then another 3" of mineral wool with the utilities in it. Entombing utilities in closed never thrills me.

We have found, through a series of real world tests that the most efficient wall construction is what we call a flash and batt. We spray 1/2” of closed cell foam against the exterior sheathing which provides an R value of about 3 then used fiberglass batts in either 3 1/2” or 5 1/2” depending on the stud size.
This should ideally be done after the siding has been installed so all the miscellaneous nail holes will be covered.

Sealing of the ceiling is also necessary as mentioned above. This starts by caulking the joint between the ceiling drywall and the wallboard BEFORE the joint is mudded. Can lights etc. also present a major source for air leaks. They make a cover that goes over the recessed can in the attic that is sealed with expanding foam to completely seal the opening.

I could go on....

quote:

Originally posted by a1abdj:
The others have hit on the air sealing aspects of spray foam, but this should also be done when using blown in insulation.

Every wall inside your home acts like a chimney, and every light fixture penetration is an open avenue for heat to escape into your attic. You should seal all of the top plates of the walls and any other penetration to prevent this loss .

Required to be fire stopped or have flashing installed around here for fire safety.

quote:

Originally posted by arcwelder:
Whats wrong with that? You can blow cellulose over batts. No reason to take them out.

Every insulation company around here wants to remove the old before adding new. I assumed that meant it was the right way to do it? Maybe they are just trying to pad their pockets?

quote:

Originally posted by Skins2881:

quote:

Originally posted by arcwelder:
Whats wrong with that? You can blow cellulose over batts. No reason to take them out.

Every insulation company around here wants to remove the old before adding new. I assumed that meant it was the right way to do it? Maybe they are just trying to pad their pockets?

I found that here in San Diego. From what I gather, and maybe it's a money grubbing thing, by removing the old stuff the company can certify the R-rating they're selling. Otherwise they're just spraying a bunch of insulating atop an unknown rated insulation.