Let me try this again. I received no response in “Energy, Heating, & Insulation”.
Maybe I should change deodorant!
I have an old farmhouse built in the 1870’s. Balloon framed. I’d like to seal up the attic before the cold Chicago winds start to blow. All the stud bays (exterior and interior walls) open up into the attic. Approx size being 4″ x 16″ each. I already have rolled FG, but I know it’s incomplete. Any suggestions on what to fill these gaps. I don’t want to drop the “fix” down into the wall. I plan to seal any small gaps with foam. It’s the big holes I need help with.
Thanks in advance.
Replies
Get some foam sheet, beadboard or extruded. Cut to the approximate size and glue in place with spray foam.
Joe H
I like this idea. It seems clean and fast.
My only concern is air movement through the foam board. Will it be tight enough?
Absolutely as air tight as you need for this.
Cut the foam to fit in the opening with a couple places tight to hold it in place and foam thoroughly around it.
Yes, those bays are little chimmneys in a fire. Have you thought about blowing them full of cellulose all the way to the top? It will certainly help the heating bills & might even make your house confortable too.
Joe H
I definitely want to insulate the walls and I believe dense packed cells to be the correct application. It's just things are a bit tight ($$) right now. What would I expect to pay per linear foot? Any ideas?
Go to Big Box, buy cells & get free machine rental.
Joe H
I would recommend having Icynene poured or sprayed in the walls. I would never use fibergalss ever again since I used Icynene when I built my house. There is an even better product out called Insul-crete. Icynene has near zero flame spread but it is not flame retardant. Insul-crete is a magnesia-silica foam that can withstand a blow torch! It is poured into a cavity and ills up all voids as it congels. The cost is about the same as Icynene and both will pay for themselves in a few short years. Especially in the frozen north or sweltering south.
Blowing insulation in the walls might not be as expensive as you think.
We did it on my Brother's house a couple of years ago. Bought the insulation frrom a lumberyard, as someone already mentioned. And they et us use their blower for free. We spent an entire weekend doing it, but it only cost something like $90 in insulation.To all you virgins, thanks for nothing.
I'm quite sure these openings between floors should be sealed, not just to keep the cold North Wind out, but to rtetard the spread of fire as well. I suggest solid blocking, perhaps 2x6 ripped to the proper width, or 2x4 plus a plywood shim.
Al Mollitor, Sharon MA
I'm with Al - you've got ballon framing, and a whole bunch of small 2x4x16 (or so) chimneys which will do an amazingly efficient job of spreading any fire that might get started in the house.
Ballon framing now requires substantial fireblocking in the few cases where it is still used today.
I suspect they also do a great job of sucking heat out of the walls and transporting it to the attic. Bet your roof is one of the first to be clear of snow!
I would consider dense pack cellulose, kill 3 birds with 1 stone.
But foam? Will stop air movement, but not provide much, if any safety.
_______________________
Albert Einstein said it best:
“Problems,” he said, “cannot be solved at the same level of consciousness that created them.”
Your mileage may vary ....
"Bet your roof is one of the first to be clear of snow!"
Yes, everywhere but the eves! Ice dams were a problem a couple years ago until I vented the sofits. That helped a bit. Closing up the bays will be even better.
Assuming I go ahead with the blown cells, how do I access the top of the walls near the eves? The roof is pitched 4/12, so it's pretty tight inside. Although the gable end will be no problem. If I remember right, I could hardly fit my hand down into the wall cavity when I did some rewiring. Will I be able to snake down the hose 16 ft (2 story house)?
Just to clarify: The blown cell is not a replacement for sealing the open stud bays, particularly the interior ones.
No better for firestopping, but;
Stuffing the bays tight with heavy plastic bags filled with fiberglass batts is faster, easier, and really just as good as foam blocks for stopping air movement.
About the only thing fiberglass batts are good for...
Sealing up attics;
ZSmitty:
When blowing insulation into walls, be be sure you don't have the old knob & tube wiring in the cavities. K&T wiring uses the air to dispense heat and insulation near or around it might reduce the effectiveness of cooling.
Rookie
When blowing insulation into walls, be be sure you don't have the old knob & tube wiring in the cavities.
Good point!
_______________________
Albert Einstein said it best:
“Problems,” he said, “cannot be solved at the same level of consciousness that created them.”
Your mileage may vary ....