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Blown-in Cellulose Through Top Plate vs Through Siding

Blown-in Cellulose Through Top Plate vs Through Siding

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  #1  
Old 07-30-14, 03:01 PM
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Blown-in Cellulose Through Top Plate vs Through Siding

I plan on adding a lot of cellulose to the attic of a ~100yr old house soon. I'd like to get as much of the exterior walls as possible too. In the attic I have some access to the top plates of my balloon-framed walls, so I could potentially get a lot done from there.

I'd have to drill holes (1.125 or 1.25", I think) down through what is probably a double top plate. I'd also need to check carefully that my exterior sheathing actually runs up to the top of the walls rather than cutting off above the soffits.

I've blown in cellulose from the inside of a wall (cutting and repairing plaster after) and from the exterior (removing bevel siding, drilling holes, and then replacing the siding over the holes). I've never drilled through top-plates and worry a bit about weakening the structure. I figure I'd be drilling 2 holes per wall-bay.

If it turns out that there's no exterior sheathing on the top ~2ft of the wall, the top plate option will be impossible. Should I try to blow-in lower from the exterior or will it be impossible to stop insulation from blowing up into the soffits?

This house also has fairly old cedar shingle siding, and I'm not confident that we can remove and replace shingles without damaging them if we blow from the exterior. At best it would be very tedious and time-consuming.

Anyways, I would value some suggestions on a best plan of attack from anyone who has done such work.

Thanks!
 
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  #2  
Old 07-30-14, 05:02 PM
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Do you know what insulation blower you would be using?
 
  #3  
Old 07-30-14, 08:02 PM
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Probably a Krendl 425 from Menards. $35 for the first 4 hours and $5/hour after that.

...unless I should be looking at something else.
 
  #4  
Old 07-31-14, 03:10 AM
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You may want to check with either big orange, or blue. Their blowers are free if you buy the insulation from them. I wouldn't rent one.

I have insulated walls from the interior by drilling the appropriate sized hole in the top of each stud bay below the plate and one at mid wall to evacuate air. Once the insulation reaches the mid wall hole, you plug it temporarily until the bay is full. Repair the holes and paint.
 
  #5  
Old 07-31-14, 04:12 AM
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I have not used the machine you mentioned but I will say that in general the free machines at big box stores are not capable of producing the best results in the situation you are describing.

I am not saying you won't get insulation into the wall, just saying that insulation performance is a function of the density of the material and it is unlikely you will get the most desirable results with this approach.

There are other factors to consider as well such as the fact that if your house is balloon framed then your floor joists run into the exterior walls on an inset ledger board. This means your floor joists bays are open to the exterior wall cavities and as you blow material, you will have the floor cavity to deal with that is going to make doing an long term acceptable job more of a complication.

You might entertain approaching the job by doing all of the prep work as detailed by a responsible insulation contractor familiar with doing blown in insulation in sidewalls. Let them do the installation with a more professional grade machine for the application you have.
 
  #6  
Old 07-31-14, 03:18 PM
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Dasco 640 24-Inch Shingle Ripper - Roofing Tools - Amazon.com

Get one of those to remove the nails holding the shingles in. Buy yourself a new pack for replace ments. That will be your best bet.
 
  #7  
Old 08-01-14, 12:04 PM
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The Home Depot in my area stopped doing any rentals, period.

Last I checked (a few years ago), Lowes had a $250 minimum purchase. To get the machine free I had to buy more than I needed and return the rest.

Menards used to be free with any purchase and they quit that. The machines they have now also look a lot more awesome than the old ones.

$5/bag for cellulose at Menards and $6 everywhere else. Maybe $75 savings for me.

A better/more powerful machine would easily be worth the $35-50 rental cost.
 
  #8  
Old 08-01-14, 12:10 PM
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I have that exact tool. It's not foolproof, especially with old shingles.

You really can't match aged cedar shingles with new ones.
 
  #9  
Old 08-01-14, 12:13 PM
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calvert,

I'm familiar with the floor bay issue. In the past I've just let it fill part of the bay as the wall fills. I don't see a problem with this and if anything it'll add to the soundproofing and further insulate a spot that is otherwise very thermally weak.
 
  #10  
Old 08-01-14, 04:01 PM
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I'm not trying to discourage you, just saying that I have done that approach with one of my machines that is much larger and got good results but again, much more powerful machine and still took a long time to do.

If you try is, I might suggest an approach whereby you drill a few cavities, blow them to what you think is acceptable and do a bag check to find what density you are getting for the area involved before you start doing the whole place.
 
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Old 08-01-14, 05:50 PM
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calvert,

Did you read my original post? I've done this work before with success - you're not going to discourage me. The main purpose for my post was to ask about drilling/blowing through the top plate, which I have not done.

When I've done balloon framing before I did a few checks at the bottom of the wall cavities by removing outlets. I also watch how much goes into each bay. What really gets you in older homes is when the wood lathe for the 1st floor ceiling was haphazardly installed so that some pieces extend into the wall bay. If I get 85% coverage I'll be happy.

I looked at blowers today. The Menards tool looks far superior to anything that Lowes has. It has double the power draw (two 120vac plugs, which I assume means ~twice as powerful), a wired remote control, and a nice crank-adjustment for the intake. It's also about 2-3 times as heavy (it's built like a real machine). The other ones (that I've used before) are basically glorified shop-vacs. The lady at Menards said contractors are frequently renting their blowers for jobs and it is common to have all 3 rented out at once. The Lowes people didn't seem to know what the machines were for. For $35 I'll try the heavy duty version.
 
  #12  
Old 08-02-14, 04:28 AM
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One more thought for you.... are your stud cavities open to the basement and if so can you use what is known as the insert tube method to blow upward and get the lower wall area done this way.
 
  #13  
Old 08-02-14, 12:16 PM
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No, they're not. Standard bottom plate on top of subfloor construction. I've never seen walls built the way you describe.

I've determined that any inside approach is worse than removing shingles and drilling the sheathing. I'll try prepping a few bays this way today and see how it goes.
 
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