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Accidental Painter
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Discussion Starter · #1 ·
Next month I plan on reinsulating my house. In the attic I can see down all walls.

The plan is to blow in and stuff the walls & go batxhit crazy in the attic afterwards with about 3 feet of insulation.

I have heard though thats not a good idea. After a certain thickness it does no good.

true?
 

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Next month I plan on reinsulating my house. In the attic I can see down all walls.

The plan is to blow in and stuff the walls & go batxhit crazy in the attic afterwards with about 3 feet of insulation.

I have heard though thats not a good idea. After a certain thickness it does no good.

true?
There are diminishing returns.... but I know of no detrimental effects.
 

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You can go as much as you want, but as MTN says there are diminishing returns. But you can fill the attic as high as you want so long as you don't block the vents. Blown insulation is relatively cheap since you're doing it yourself, have at it. But even if you blow 6 feet in the center, you'll still only have 1 foot or so at the eaves.

Also, while it's still empty you would be well served to address some air sealing.
 

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I'm not sure what the weight of all that insulation would do to the drywall in the long term. I've had a couple ceilings on older houses fall down in a place or two after insulating, but they didn't use glue to hold the drywall up. I see a lot of drywall "sag" after a number of years. Don't know why it does that, perhaps it was from before they used 5/8's on the ceiling.
 

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Next month I plan on reinsulating my house. In the attic I can see down all walls.

The plan is to blow in and stuff the walls & go batxhit crazy in the attic afterwards with about 3 feet of insulation.

I have heard though thats not a good idea. After a certain thickness it does no good.

true?
Loose fill in the walls doesn't provide that much insulation, so blowing 3 feet in the attic would be like installing super insulated triple pane windows and leaving one open.
 

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Loose fill in the walls doesn't provide that much insulation, so blowing 3 feet in the attic would be like installing super insulated triple pane windows and leaving one open.
Very true. There are retro wall insulation methods.

Be sure to check and make sure all your junction boxes are properly covered in the attic and to cover any non-insulated can lighting.

As mentioned already, be sure that the eaves are clear so that sum biatch can breath otherwise you may find yourself a mushroom farmer.
 

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Go as thick as you want, as long as you still have ventilation and the ceiling doesn't cave. Before you do it, go through the attic and air seal all penetrations into the attic. SLStech had a good tutorial on his website of how to do this.

That's also my recommendation for walls - air seal first, then insulate.
 

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Livin the dream...
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That's also my recommendation for walls - air seal first, then insulate.
+1

I just insulated my house. Gutted the hole thing. 1" spray foam and 5" of wet cellulose in walls. I think they put in about 15" of dry cellulose in my attic.

I was continuing to finish the house but hadn't got around to taking care of my attic access holes. I had a piece of drywall in my two opening but no insulation and no air seal around the edges. I COULD NOT BELIEVE how much hot air was getting through there this summer and how much of a difference it made after I got 2" foam and a couple pieces of R-19 insulation over my drywall that finished the opening. I noticed an immediate difference in how often my geo was running.

Seal everything you can.
 

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Really good advice by everyone above... get rid of those airleaks....put in IC air tight cans where you can....

Also, I'm not sure about this one as to any increase in efficiency, but after my joist bays are full, I've laid extra roll insulation perpendicular (and tight) to the bays and primary insulation.

I suppose blow in does the same thing....

but Johns Manville in Denver for some reason often gives Habitat all this extra roll insulation.... so it's very inexpensive.... but sorta back breaking work to lay in there in a tight attic.
 

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diplomat
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For 5/8 drywall on 24 oc joists keep insulation under 2.2 PSF Weight. Might be the same for ceiling stamped 1/2".

In most situations the 30 year cost of over r60 is higher, in other words diminishing returns.
 

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Blow in 3 feet now ans you will kick your own ass later when you have to run wires and install can lights.
 

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Sean
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first lets start with the walls - any water issues, electric wiring - is it copper or...
Make sure you deal with those issues first or you will be dealing with some major issues later (peeling paint, rot, fire issues, etc...)

Going to R60 or even R100 - generally not an issue, but you have to deal with air sealing issues first, baffles, etc... & there is some good points above

Many thanks for the shout out HDavis on the piece(s)
Air Sealing: Attic – Insulated attic hatch
Air Sealing: Attic – Storage & Walkway Options
Air Sealing: Attic – Sealing those Pesky Air Leaks
Air Sealing: Attic – Baffles
Air Sealing: Insulating Your Attic

As for blown versus batt - both will work fine, it is just easier to get things done right with blown in as compared to batts - it just depends on how much you want to spend on labor (whether paid or your own) versus materials - personally I will go with blown in

One other item to keep in mind, in most cases a professional installer can install the blown in cheaper than you can buy it or blown in due to discounts given to them
 

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Accidental Painter
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Discussion Starter · #14 ·
You know SLS you do make a good point. While initially I thought it would be a great project for me & my son, after reading your blogs I've come to realize theres alot more to it.

You just dont know what you don't know. You do raise a good poibt on materials. Heck I was surprised I could get it for $500.

The house has recently been replumbed/wired so that should not be much of an issue. although the electrician left behind the old knob & tube setup. Dunno, guess he was lazy...

It's all original plaster, no drywall anywhere. That may ease the process. But the real story will be seen after cleanup.

I will call a specialist, & depending on how labor intensive it is, outsource it.
 

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It's all original plaster, no drywall anywhere. That may ease the process. But the real story will be seen after cleanup.
Typically, interior plaster walls can have huge air leaks into the attic.

Drill and fill on plaster from the inside is worse than drywall - get it done from the outside.
 

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What about shoving the hose in from above? It's all visible.
If it would fit, you could (where there are no obstructions). I don't imagine this is practical - you'd probably have to neck it down to a smaller hose after the control, and having 15-20 feet of smaller hose is a clog waiting to happen, IMHO. You'd still need to drill for places like below windows, areas with cross bracing, etc. Then there are the electrical wires, plus places where the plaster keys are really large. Personally, I wouldn't count on it, but maybe someone here has actually tried it - I haven't.
 

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Sean
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I got to agree with HDavis though I have seen it done successfully from above & sometimes you have no choice but to go from the inside.

A few big caveats - make sure you have no water issues with your walls, be careful with the plaster as you can blow it off the wall if the pressure is set to high / it has issues & the stuff listed in the articles - most insulators don't do that normally as "no one would pay for all that" - make sure it is listed in the scope & in the immortal words of Reagan, trust but verify
 
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