Sunday, March 24, 2013

Insulation Upgraded

The last post mentioned deficiencies in the insulation in this house.  When we first got the place, we weren't sure what it had for insulation at all.  As work was beginning, I found a couple of spots where holes from old toggle bolts or other fasteners allowed a peek into to the wall, and didn't see any.  Inspection of the attic showed about 2" of cellulose, and about 2" of fiberglass batts that had been originally stapled into the rafters but had mostly fallen down.  A few electrical boxes turned out to have some shreds of cellulose in them.  Finally I decided to settle the matter, so I chucked a 1/2" masonry bit into my cordless drill and started going around drilling holes in the walls.  (We were already planning a lot of drywall over the plaster because of the age and condition of the plaster, and if not, holes that small aren't hard to patch.)

What I found:  Sometime, the owners did blow cellulose insulation into the walls, but they didn't do a very good job.  There were areas they had skipped, especially above the windows.  In most places they did not get enough in the wall cavity and it settled, leaving gaps (some of them only 2" high, some of them close to a foot high!)  And of course the channels for the sash weights on each side of the windows (3" wide by 4-5 feet high) had no insulation at all.  There were also places where they guessed wrong about where blocking was between joists and half of the height of a stud bay had no insulation at all.  There was a section of the kitchen wall that was not insulated at all, on the side toward the laundry room that sits between the kitchen and the garage.

The house is now much better insulated.  The attic has been topped up.  On the sloped ceilings above the second floor knee walls I cut out the drywall, pulled out the old 2" fiberglass batting and put in 6", then covered it with new drywall.  We had decided to eliminate the storage areas behind the knee walls (a closet you have to crawl into is a bit of a pain when you're past 60), so I put fiberglass batts in the walls from the back side, then covered the floors with blown cellulose.  On the gable end walls I used a stud finder to locate the blocking and drilled to check for gaps. 

I ended up drilling a lot of holes on this project.  Drywall can be hard on drill bits; plaster is really hard on drill bits.  So I bought a carbide-tipped hole saw to make 1-1/4" holes to blow in the cellulose.  We now have holes all over the outside walls of the house, but they have insulation in them.  You make two holes for each stud bay, one up high and one halfway up.  Even if you don't have blocking in the walls, it's best to fill the bay halfway up first, then finish it from the top.

A few thoughts on fiberglass vs. cellulose:  They each have advantages and disadvantages.  Fiberglass can make your skin itch (washing with vinegar afterwards takes care of it), but it is easy to cut, doesn't take much in the way of tools, and goes up quickly if the walls are open.  You need to wear a dust mask to keep the fiber bits out of your lungs.  It's more recently been found that fiberglass loses its effectiveness at very low temperatures, and air will flow through it.  Cellulose is dusty, requires the use of a machine to shred the bales and blow it in, but does not cause health problems.  They have come up with a wet-spray form of it that can be used in open walls, but it is not a DIY process, and the equipment is not available to the homeowner.  It does NOT lose effectiveness like fiberglass does when it gets colder, which is an advantage for attics.

The biggest hassle on doing the walls was fighting with the blower.  Most of the big-box lumber/building material outfits will sell you the cellulose, and if you buy enough they provide the machine at no cost (you do have to leave a deposit, refundable when you return the machine).  The machines work well enough on attics, where you are blowing it through a 3" hose.  That's probably what most of the customers are doing.  But to do walls, you have to add a restrictor plate to the hopper (design varies according to the manufacturer) and a tapered nozzle that ends up less than a 1" opening.  I spent a lot of the time clearing a clogged nozzle.  As the day went on, my son, who was feeding the machine, worked out a partial solution; when starting a new bale, we took off the nozzle, blew the insulation into an empty garbage can (held about half of the hopper's capacity, shredded), dumped it back into the machine and ran the rest into the can.  Shredding it twice greatly reduced the amount of clogs we had to deal with.

Anyway, it was a long day on the walls, (a house has more wall space than attic floor, plus the smaller nozzle takes longer to move the stuff), but we got it done.  We ran out of material with about 3' of space above the top of one window to finish; I'll break out the plaster in that spot and stuff fiberglass above that window.  But this house should be a lot easier to heat now.

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