Posts Tagged ‘wall insulation’

Cellulose Insulation

November 15, 2010

An excellent question from Patricia in Ohio on wall cavity insulation (BTW, folks, you can feel free to post your questions here rather than emailing them.  Chances are, other people have the same question, too.  We’ll do our best to post an answer.):

“Wouldn’t packing your walls with old newspapers [i.e. cellulose insulation] increase the fire risk in a wood-framed house?”

Counter-intuitive as it may be, the answer is a resounding NO! Use of cellulose insulation, which is made out of recycled newspapers, actually reduces fire risk, and addresses a host of other problems. Here’s why:

The recycled newspaper (or other paper fiber) is treated with a fire retardant called borate, which is a naturally occurring non-toxic mineral. This means that the insulation is effectively non-flammable, so when it comes into contact with a flame it forms a scorched crust, which actually slows the progression of fire. Additionally, correctly installed cellulose is packed so densely into the wall cavities that it inhibits the movement of air. We all know that fire needs oxygen to burn, so densely packed cellulose slows the progression of fire in two ways.

If you’re not convinced, or you just want to see some firemen burning some houses down, take a look at this great video that compares how quickly fire consumes otherwise identical un-insulated, fiberglass insulated and cellulose insulated houses. The cellulose insulated house took about 25 minutes longer to succumb to fire – that’s translates to a lot of extra time to save your house, and seconds count to get yourself and your loved ones to safety.

As if that wasn’t enough, the borates in the cellulose product can kill insects, and squirrels, rats and other rodents don’t like to nest in it, so by insulating with cellulose you are taking a step towards eradicating pests.

Insulation is good—and cellulose is a great choice for many applications.   Fiberglass and foam insulation each have their places, too–we use them both in addition to cellulose.  What is important is to understand the needs, abd the correct application of whatever you’re using.  And for goodness sake, remember that insulation doesn’t work properly without air-sealing.


Dense Packed Cellulose Insulation

August 17, 2009

In existing homes, where wall cavities are closed up with siding on the outside, and drywall, plaster, or some other finish on the inside, good insulation becomes problematic.  How do you fill the whole cavity when the cavitiy is already closed?

A great way is with “dense packed” cellulose insulation.  Cellulose insulation is essentially ground up paper (e.g., newspaper) with fire retardants added.  We like 100% borate retardant–low toxicity and critters don’t like it.  

Dense packed cellulose stays in place even if drywall is later pulled down (we don't recommend pulling the drywall down to check, though!)

Dense packed cellulose stays in place even if drywall is later pulled down (we don't recommend pulling the drywall down to check, though!)

In yesteryear, cellulose was essentially poured (loosely blow) into wall cavities.  The challange with this was that the cellulose settled over time, leaving a gap with no insulation at the top.  Dense packing overcomes this and is a great way to insulate walls in existing homes.  First, the loose fill insulation fill nooks and crannies and does a great job filling cavities, providing the type of coverage you need for insulation to be effective.  Second, dense packing actually pumps insulation into a cavity a higher density than it would settle to.  Thus, over time we don’t see additional settling.  In fact, the insulation is in there so tight, it generally doesn’t fall out even when you take the wall covering down.  In the picture, you see the wall I just removed this weekend as part of a major bathroom remodel.   And you see how the cellulose completely filled the wall cavity (less a few holes from my hammer as a pulled the plasterboard down).  And the insulation is packed so well, that is stays in place even without the plasterboard covering it.  [Good job, Tom, Joe, and Jason.]

Good stuff.  Works great!  A practical solution for those wanting to make their homes more efficient.  (I’m still amazed how many homes have little or no insulation in their walls.)  And this insulation qualifies for the $1,500 tax credit currently avaiable for energy-efficiency retrofits.


%d bloggers like this: