hello
the walls inside my home are plaster and they are in real good shape. but the “insulation” in the walls is not that good. when i added a closet to our bedroom i had to open an exterior wall and there was fiberglass batts but they were so old that they were only about 1″ thick. however the staples in the paper flages were still holding tight and the paper vapor barrier was in good shape.
like i said the walls are in good shape so i dont want to demo all the plaster , then insulate and rerock if i dont have to. now here comes the best way i can think of other than demo.
drill holes in every stud bay at the top big enough for the hose and blow cellulose into each cavity. if i use a hole saw the patch wont be so bad. and would the cellulose add any r value if the batts are still in place or will each bay be hit or miss?
thatnx in advance for any help you can give.
Replies
if you can open the holes enough so you can maneuver the hose and reduce the hose to a smaller diameter... you may be able to get the hose between the batt and the sheathing and get a fairly good blow
but i think it will take more than say a 3" hole...
i think say a 1.5" flex pipe wouldn't clog very often and would still be flexible enough to slide up & down and side to side to get good coverage
You don't say how thick your wall cavity is. I assume it's a good deal more than the 1" of fiberglass.
Have you considered blowing cellulose from the outside? Depending on what kind of siding you have, this might be preferable (it's how most cellulose retrofits are done).
If you get proper density (about 3.1 pcf), then the cellulose will give you R-3.8/inch, considerably reduce air infiltration, increase the fire-resistance of the structure, and help with soundproofing.
So many blow in jobs executed from the outside should have the insulation contractor executed. IMO it is far better to drill the plaster and blow from inside. Patching plaster is much more likely to be done well than exteriors.
Au contraire, mon ami.
Drilling plaster with a hole saw will destroy several hole saws in short order and may loosen the plaster surrounding the hole. There is no way to hide the plaster patches and it will require considerable feathering to make the patch disappear.
If the siding is clapboards, then its a simple matter to remove one course high and one course low on each floor, drill the sheathing, blow cellulose in the cavity between the sheathing and the existing fiberglass batts (stapled to the inside of the stud bays), and then re-install the clapboards.
A perfect job with no sign of "forced entry".
You must need a better hole saw (industrial diamond or corundum).I've done this and can get virtually flawless results in plaster.Around here there is no shortage of horrible exterior blow in botch jobs.
You did not give us much information about the house.
1" fiberglass and plaster tells me that your house was probably built in the 1950s or early 60s. Probably plaster over sheetrock. Good walls, but probably 2x4.
If you can insulate from the outside I would do it that way.
I would remove siding about 1 foot from the bottom. Drill 2 1/2" holes in each stud bay. Angle the holes up as much as possible. A hole saw is not going to cut it. You are going to need an auger type bit with a feed screw.
Get a flexible insulating hose about 1 1/2" in dia. by 10" long and connect that to the 3 " hose from the machine. I have one in my garage. Lot's of help.
Push the hose up the stud bay until you know you are near the top. The fiberglass is going to fight you on this. You might have to twist and rotate to get past points. Pull back 6"-12". Start filling the stud bay, when the insulation stops running pull down about a foot. It should take you a couple of minutes to fill the stud cavity.
If you have a 2 story house do the same with each story. The joist cavity will take alot of insulation and it is probably the key to getting the house tight.
Make sure the machine you get can regulate the air pressure and the volume of insulation with a gate. For sidewalls we usually blow with the air on full and the product gate closed to about 1/3. For attics we reverse the settings full open with the product but reduce the air. You want to pack the insulation in so you want alot of pressure and little product.
If you are plugging alot the close the gate some more.
Seal the hole with tar paper or Tyvek and tape. You may have gypsum sheathing. Reinstall siding.
I would look for a minumum of a Force 2 or a Krendal 500 machine. Might be a problem finding a good machine. Be prepared to spend some time getting the machine to run properly.
If you blow from the inside. Get a good wife first. Then a good shop vac.
Doesn't matter where you drill your hole but it is easier to put the tube up from below. Without the 1.5" tube inside the wall you're just fooling yourself if you think you are going to get any meaningful insulating done with the fiberglass in place. About the same is true even with open stud bays.
If you have hardwood floors the hose and clamps can wreck havoc. Good luck.
Rich
If you have wood X braces or fireblocking (or both like my house) you will need to drill lots of holes. Use a good studfinder, locate and mark everything or you will have cold/ hot spots (like my house).
Hole saws are a small price to pay for the comfort but I too am cheap and cut new teeth with a 4" grinder and a thin blade. Works fine in plaster with drywall lath.
Kurt
Use a carbide or diamond hole saw to drill your holes. If you have wood lath you may want a second drill with a standard wood saw to use on it.
Get a standard saw that the inside diameter is slightly larger then the holes you drilled.
Using 1.5" thick ridged foam board cut plugs with the above bigger holesaw. A drill press helps.
Tap the plugs into you holes 1/8-3/16" from the face of the plaster. Top over them with a compound that has some plaster in it USG Easy Sand. I think I used fixall as a base coat and dry wall compound on top of that. Sand paint.
Did this ten years ago in a clients house still can not find the plugs, plus it is warmer inside then doing it from the outside this time of year.
Wallyo