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Insulate a Basement Ceiling in an Old House :: How to Estimate & Install for Where You Live

Insulated Basement Ceiling

Disclosure: Owens Corning provided the materials for this project, but these my opinions alone, herein.


As I stood in my basement, looking up at the floor joists of the dining room, I thought to myself, “I guess I do know a few things about insulation.”

I mean — I know that snowy days are perfect for jobs like insulating a basement ceiling, of course.

Ha! And OK . . . . What I really mean is:


And this is the “look” that we should be going for (roughly):

image via


I do not know why we (OK, I) usually don’t think about insulating our home(s) till the winter.  It’s not like insulation doesn’t help, say — keep the warm out (hence the cool in) during other months of the year.  But it. just. is.  So . . .

Why Insulate Now? 

Well . . . personally . . .

Because it was on my todo list, though in not so many words – Insulate. Insulate at least portions of my basement as well as add to the insulation in the “crawlspace” area up under our back rooms (built out in a porch conversion).

And anyways, and in the winter months, there is almost always a slight (but very noticeable) temperature difference between our kitchen and our dining room.  (You must pass through the landing of a stairwell to go from one room to the other.)  And it is one spot, I think, where the original house was added onto, an addition — where things were not built quite so tightly.

A cool blast of air right there.  And with the help of Owens Corning . . . it was time to get it fixed.

How to Insulate . . . ? (Short Version)

* Before I started I had to first figure out two very important things:

1.) What product should I use?  I mean – I already knew I would be using Owens Corning‘s EcoTouch Insulation, but what (or which) R-value?  And Faced or Unfaced?


2.) How much of it would I need?

* Taking that, I started by measuring the space underneath my dining room. I measured the ceiling’s total length and width (adding a little to accommodate both for “old house foundation walls” and “the band”).

* I then measured the joist spacing, width and height, as well as the joist member thickness.

What I found here, as with most “old houses” (and built using a framing technique called balloon framing), the joist spacing was quite irregular, varying between a 16” oc in some places to, get this, a 20” oc spacing in others.

Beyond that I found that the interior spacing (inside of joist to inside of next joist) varied too.  On a joist space of 16” on center, I pulled measurements from just a little over 13” to sometimes nearly 16”.  (Uhhhh . . . old house!  And SURELY this would make for a little added time.  Oh well!)  I would need insulation for both 16-inch and  24-inch framing,  and . . . I would have to do some cutting.

Joist depth was, phew, easy enough at 10” and the joist thickness was actually 2” exact, making for a true 2×10 throughout.

* To determine which insulation thickness (read: R-value) I needed, I turned to the DOE’s “Insulation Facts.” (Maybe you’ll enjoy these easy to read graphics, and hey, there is also some fantastic info on insulation usage back there.)

I chose R-30 . . . batts.

* To determine how much I needed I used Owens Corning‘s handy insulation center.(I checked myself too with some simple math.)

* I took a quick trip to my local HD.

* Back at home, I cleaned my joist bays of all visible obstructions. I cleared out as much space as possible (in the room) to make working easier.

(And really there it is, in those few steps above, the hardest parts of this job.  Oh! and then, there is the installation too.)

* While cross cutting of insulation is easy enough, rip cuts are, well, something I knew I wanted to take a little extra time with.

* Using a scrap piece of ¾” plywood as a cutting station, a (drywallers) T-square, and both scissors and knifes (one utility & one folding) … I got jiggy.  Here is a little bit of my work(ing) below:

* And that’s basically how it went.  Measure, Cut, Hang, Repeat.

Taking special measures at the ceiling’s cross braces, I suspended the snugly fitted R-30 (kraft paper face up, of course) using Simpson Strong Tie’s Insulation SupportsNote: In most cases, these flexible metal “pins” needed to be cut down. (They are made, I know, for both 16″ oc & 24″ oc.)  I did all cutting here using a pair of end cutters and a little bit of ummph.


While I am not quite finished with the entire room (about 70%), I wanted to get it up before the end of “insulation” season.  (Hope you don’t blame me and I hope it helps.)


Something of a Review

I know that fiberglass insulation has historically be known to irritate the skin, eyes and throat.  And I guarantee that I have had more than my fair share of “itchies” after a day of insulation.  But, here, I have to give a nod to what the original DIY Guy (and his work) suggested.  The Pink, while much like other insulations I’ve used, had the surprising characteristic of being, well, a little . . . gentler for baby’s touch for these manly, and sometimes chainsaw-wielding, hands.

For the few hours that I have worked this project thus far, yep — sans gloves, sans sleeves (in some cases), no dust mask (though I probably would recommend it for dirty, dusty basements or attics), and, yes, sometimes sans eye protection … I only felt minor eye irritation one evening.

Call me guinea pig, and maybe I am building a tolerance. dk. And I can’t say I wasn’t advised. Here is recommended material handling.


Final Tip and Full Disclosure

I know you know you need insulation, and it’s good if you’ve got it, but not enough, or worse, not understanding the why and the how can seriously diminish its usefulness (just sayin’).

Thanks out to Owens Corning for including me in this fantastic program.

Thanks for reading and enjoy your weekend.  ~jb


But Wait! Even More Moxie

Now I’m out, back maybe with update on my drafty dining room or maybe *fingers crossed* home energy savings.

Update :: Here is a fantastic article on developing a “Basement Insulation System” (esp. important with finished basements) via Todd Fratzel.  (It made me re-think how I addressed the rim joists or “band” for this article.)

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