Hot Topics: Correcting Poor Contractor Insulation Installation

A bad insulation job.

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In the nick of time, this DIYer realized there was something wrong with the "professional" installation of insulation in their home addition. Turning to the forum for advice, they decide to correct the mistakes on their own.

Original Post: New Addition - Insulation

TamiS Member

I have hired a contractor to build a large addition to my home (about 1500 sf plus a double car garage). I am concerned about the insulation that was installed. I want to share pics and get advice. Please let me know your thoughts. Thanks in advance.

Insulation installed incorrectly.

Incorrect insulation installation.

Incorrect insulation installation.

Chandler Forum Topic Member

Welcome to the forums! Sloppy at best. Inefficient at worst. Sloppy I could let slide, but you can't compress fiberglas insulation. The vapor barrier must remain intact and across the wall. Stacking insulation offers little insulative qualities and no vapor barrier. It looks as if he is trying to poke R-21 insulation in a 2x6 wall. 2x6 walls generally take R-19 at a max.

Ask him what he plans to do for a vapor barrier on the bare fiberglass.

joecaption Member

That is all just so wrong (too many things to even list). There's not even enough insulation in the attic, and he's trying to fit a quart of Jell-o in a pint jar in the walls. I would flat out refuse to pay for that part of the job until it is done right.

Bud9051 Member

As Chandler and Joe have said, there isn't any good news from those pictures. If you brought in your own building inspector at this point before the drywall goes up they would probably have a long list of concerns, including the insulation you have questioned. There is no excuse for this and had you not seen it and taken pictures, it would all have been buried. What does that say about your builder?

Stop the project and get someone in there to make sure it gets built correctly.

There are now energy codes in effect in most states and I see no effort to air seal and tape, let alone install the insulation correctly. If you have no other source for an second opinion, your local building inspector should be able to help, unless he is personal friends with the builder.

TamiS Member

Thank you all for responding. I watched about a dozen videos on how to install insulation and I'm working on replacing all of it. I've been careful to not compress the insulation and split it around all of the wiring and plumbing. I'm getting the entire cavity filled with any compression—everything cut to fit.

I'm concerned that some of the insulation has been compromised by being flattened. Can I reuse any of it? Also, because of all of the tears, I'm wondering if I can cover all of it with 3 mil poly when I'm done. In other words, can I cover the paper backing with poly or is that overkill?

Also, there are no blockers (I think that is the word) in the eaves. Some of the R-30 isn't even close to the eaves (huge gaps). Is that OK? Do I need a better R-value in the attic?

Bud9051 Member

First, the compression concerns:

R-19 is intended to fit into 5.5" wall cavities. It is rated at about r=3.45 per inch. If you were to compress that into a 3.5" wall, it still performs as insulation, but you just end up with 3.5" times 3.45 per inch, or R-12, or 13. If you compress it to the point where there are no longer air spaces between the fibers, it stops functioning as insulation. So, avoid compressing it too much, but don't go paranoid about a little stuffing. A good friction fit helps keep it in place.

If any is totally flat, replace it. If any is still fluffy, it's
OK to reuse.

Yes, you can add a layer of plastic over the kraft paper—not a problem.

If you are going to add blown-in insulation, you need to prevent it from filling the soffit cavities. If using batts, the concern is less, but those batts do need to cover the top of the walls. I believe your current code requires R-38, but check your local code office.

TamiS Member

I only reused the insulation that was still fluffy. I have 2x6s in the outside walls and my R-21 is made for 2x6s, so that's good. All of the insulation that I have installed myself looks good and fluffy right now. Actually, it will take the drywall to make it perfectly flat against the wall. I didn't caulk or foam around the holes where the plumbing comes in because I didn't think to do that. Otherwise, I hope it's good.

With your advice, I plan to add 3 mil poly to all of it.

I'm concerned about the R-30 vs R-38 in the ceiling.

calvert Member

Did your contractor have his own workers do the job or was it done by an insulation subcontractor?

There is a numerical rating system for fibrous insulation installations that takes into account compression, gaps, and other defects.

Congratulations to you for recognizing the shortcomings of the job and taking the time to correct issues before drywall covered it all. I'd be looking for an apology and a credit from the contractor. I've supervised over 13,000 insulation jobs and would be embarrassed to hand someone a bill for work like that.

TamiS Member

Thanks for the feedback. I can use all the help I can get. My contractor is using his own guys.

I am slowly replacing all of it, as I said. I'm finding that some of my R-21 insulation has been split in half, removing 1/2 of the pink stuff and then stapling it down so that it's not easy to find. I have been removing the staples and examining/fixing/replacing each batt until it is done correctly.

I think I have another issue: the insulation in the ceiling doesn't meet the eaves. I can see daylight by lifting up any of the batts along the ceiling edge. They installed baffles, but there's no point really since the entire eaves are basically open to the attic. I've been searching for a solution and it appears that I need soffit dams or blockers or something that blocks off the air and allows ventilation only through the baffles. I see where some baffles are bent so that they block the area, but mine are not. Any advice on this?

This is a daunting job if you're doing it by yourself and learning as you go.

calvert Member

It becomes difficult to assess without seeing firsthand. I would probably remove the piece that they started with at the outside wall/ceiling junction and make sure vents are placed so they extend far enough into eaves to keep open an air path. Fit the ceiling insulation carefully under the vent to cover the top plate of the wall. We usually pull back the paper and fold it down over the face of the top plate, lining up the edge of the paper with the joint between the double top plates of the wall, and staple it in place on the face of the plate. This can become somewhat tedious if there are tie down plates nailed to the ceiling joists and top plate. You have to cut the paper to fit around those metal plates while still trying to keep the fiberglass to insulate and seal as well as possible so that you don't see daylight when looking up at that juncture.

If, after placing that first piece properly in place, you have a gap between it and the next piece, I would fill that space with a newly cut piece of the same material to fill the gap. If there is access to the attic above, I would try to get in there and maneuver carefully to make sure that at the top side of the job the batts come together and form a continuous blanket across the space.

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