One _____ at a Time: Saving the Planet by Saving Cincinnati's Obsolete Real Estate (AKA Troublesome Architectural Features)

Dormer on second story

If you have a dormer on your home, then you're likely to have a room with strange walls that look something like this:

Kneewall

...and you have energy problems. Behind the short walls, called kneewalls, folks like to store stuff like Christmas decorations and old Legos. They sometimes call it a “crawlspace”, but it would be more appropriately called an “icicle maker” in most of the homes I visit.

Why are these rooms so problematic? And what can you do about it?

Rooms that have this feature are normally the least comfortable room in the house, and reserved for in-laws or teenagers. It’s often called a “bonus” room when it sits above the garage. But in actuality, it acts more like “penalty box” in an ice skating rink than any kind of bonus. These rooms are a major source of energy loss because of how they are constructed and connected to other parts of the home. They can also end up causing a lot of ice/water damage to the roof and walls below, too.

If we were to add up all the square footage of rooms like this in the city of Cincinnati, we’d get an enormous real estate footprint. Of course, I don’t have the statistics on this, but for the sake of argument, let’s make something up--

Assume the following:

150,000 (homes in Cincinnati) x 10% (have a bonus room) x 150 sq ft (average bonus room size) x $50/sf (real estate value in this market) = $112,500,000.00

That’s a LOT of obsolete real estate that was bought but is not being enjoyed. On the contrary, there is a hefty monthly utility expense to keep it only quasi-comfortable, and on top of that there is the environmental impact of the pollution and CO2 and the degradation caused to the roof and gutters from ice dams.

How would you like it if you bought a home new home that was advertised as “3 bedroom 2 bath, in nice school district, granite countertops”, but the first cold day started acting like a “2 bedroom, 2 bath, with a frozen pond on the roof”? It would have to be a really nice school district to compensate, where the students learn all about DIY home energy retrofits.

I have an idea—give these rooms to me. Actually, you can’t even give them away—they belong more to Mother Nature that to you. They also belong more to the utility company than they do to you.

The issue is here, behind the walls and under the floor.

Here's where your energy saving opportunities lie

There are two types of kneewall cavities—ones above conditioned living spaces vs. ones above unconditioned spaces (i.e. garage). Whichever kind of kneewall you have, the problem is usually a combination of the following:

1) cold floors

2) drafts in other parts of the house

3) lots of spiders or other critters running amok

4) freezing pipes

5) ice dams

6) icicles

7) condensation beneath roof or water marks on inside walls

8) high energy bills

The solution is simple but not always easy.

Solution1—For the situation where the room is above conditioned space(s):

Prerequisite: (if there are floor boards like the pic above, stop storing so much stuff you don’t need, give it to the Salvation Army, take out the floorboards and then build a compost or Adirondak chair out of the wood).

1) Jam a tightly rolled-up encapsulated fiberglass insulation batt in each of the floor joist cavities directly beneath the kneewall,

2) Then spray the floor with a ½” of closed cell foam insulation from an kit you can buy online.

3) Then install a sheet of housewrap (like Tyvek) on the backside of the kneewall, tacking it up with special “wrap cap nails” (not staples). This will act like a net to hold back blown cellulose insulation.

4) Rent the insulation machine and blow cellulose behind the housewrap “net” and then all over the floor. The Department of Energy recommends R13-R15 in the walls, which is about all you’ll be able to fit in a 2x4 wall. DOE recommends R49 above conditioned space ceilings.

If the room is above an unconditioned space (typically a garage), then whatever insulation might have once been installed in the garage ceiling beneath the room, is susceptible to gravity—aka sagging. It might as well be rolled up on the garage floor.

Solution 2- For the situation where the room is above a garage (or another unconditioned space)

1) Fill the entire floor joist cavities beneath the bonus room with insulation. (Densely packed cellulose blown with a long hose works well. Fiberglass batts work terribly here).

2) Follow steps 1), 3), and 4) just like above.

When the project is finished, it should look something like this, where not only is the kneewall and kneewall cavity's floor insulated and air sealed, but the sloped ceiling(s) and walls below are also insulated: