Attic insulation shield, really? For class A and cellulose


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Old 12-13-15, 07:05 PM
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Attic insulation shield, really? For class A and cellulose

I am finishing off my garage, sheet metal ceiling, 24" of cellulose insulation and 6" class A for wood stove. I bought most of class A system, SuperVent is the brand. SuperVent calls for a Insulation shield which holds the insulation away from the class A flue. But if I do that it will be a cold spot, air leak and possible spot for condensation. I can't have that. I was thinking about wrapping the class A with fiberglass, but in check the cellulose might be more fire resistant, or rock wool.
Solutions? Suggestions?
SuperVent: SuperVent USA
 
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Old 12-14-15, 02:44 PM
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Follow the manufacturer's directions for installing their product.

Wood stoves are a leading cause of house fires. Take NO chances.
 
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Old 12-14-15, 04:59 PM
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following the manufactures directions won't work. I will have 24" of insulation in the attic and the insulation is only 12' tall. Also that will create a cold spot and problems.
 
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Old 12-15-15, 03:35 AM
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You are not following. You MUST follow the manufactures directions end of story.

Any air leaks can be sealed high temp silicone or fire caulk. Any condensation will dry out every time you light a fire. I have a pellet stove with similar instructions and have had zero issues.
 
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Old 12-15-15, 05:25 AM
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I am following and saying I don't does not strengthen your argument. I thought I could get some advice from people that knew better. But to say the manufacturer always knows best is naive.

To create a non-insulated air-gap is a poor design when some fireproof insulation could be used.
 
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Old 12-15-15, 06:05 AM
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Since you know more about insulation and materials than the manufacturer, you should do as you want and not have anyone to blame.

It is strange how people get myopic on a subject. When there is a disaster (fire, moisture, etc.), insurance companies protect themselves from people that know everything based on seat of the pants limited opinions. If you go out in "left field", you may have no insurance coverage.

Dick
 
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Old 12-15-15, 06:14 AM
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Easy bk,
Are you saying we should have advice that is not recommended by the mfg. That would really be irresponsible. Here's what you are missing. That section of chimney needs to be installed as tested for that application. Surrounding it with insulation would trap the heat in that area allowing the temperature to rise above its design. This isn't just you, but all similar chimneys.

When there is an air gap around the chimney a metal flange can be installed and sealed with the appropriate caulking to the metal and sealed to the ceiling. I can't see your installation, but that should stop the air leakage from below. Your post said "I will have 24" of insulation in the attic and the insulation is only 12' tall." If that is 12" of a designed sleeve meant to protect any insulation, then 12" of surrounding insulation would not be an extreme cold spot. A better description of that might help me.

Bud
 
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Old 12-15-15, 06:23 AM
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Of course we still have insurance coverage, it does not matter if we follow directions or are all out negligent. I investigated fires and other claims for insurance companies full time for 15 years. Now I have a construction company. A couple things I learned was manufacturers and building inspectors are not always right, and there is usually a better way of doing things. Be open minded.

Of course I will do it the way I want, what should I do it the way someone else wants?
 
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Old 12-15-15, 06:37 AM
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Bud, thanks for the response and trying to help.

I will seldom have a fire, and I want all of the ceiling insulated well. The cellulose will be 24" deep the "insulation shield" is 12" tall. I installed this same system in the house, what I think I did was I used the shield, but wrapped the class a pipe above the shield with fiberglass so I could get the insulation deeper. Now that I am doing another I was wondering why use the shield? And I took a torch to the fiberglass and it melted. A class A pipe should never get that hot to melt fiberglass, but if there is a insulation that doesn't melt.
 
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Old 12-15-15, 07:01 AM
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It's hard to believe you've worked with insurance companies for 15 years and still believe you'll be covered if you DON'T follow the instructions.

Woodstoves make insurance companies nervous. I had to switch insurers when mine flat out refused to insure my detached workshop because I had a woodstove installed.
Knowing that IF I ever had a claim they would be looking for ANY excuse not to write a check, I followed the manufacturer's directions.
 
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Old 12-15-15, 07:29 AM
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If you create another insulation dam 24" high with the required clearance around the insulation shield and keep the insulation inside that dam at 12" and then the rest at 24" the loss of insulation value will not be measurable. Let's say you build a 2'x2' dam 2' high, just as an example, and your ceiling in just that room is 200 ft². That would give you 196 ft² @ R=84 (using 3.5 per foot). And 4 ft² @ R=42. That's 2% at R=42 and 98% at R=84. There would still be joists, recessed lights, fans, entrance, and possibly other adjustments, but with just this your net ceiling R-value would be R=82.35 instead of R=84. On a yearly basis that would cost you 16 cents extra. The minimal savings is due to the reduced benefits of that extra foot of insulation. I can provide my rough numbers, but basically, any risk associated with bundling insulation up against that extra foot of chimney isn't worth trying to save a few pennies.

Bud
 
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Old 12-15-15, 10:23 AM
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If you don't lie on your insurance application you have insurance no mater what stupid (negligent) thing you do. I investigated many fires from hot ashes put in the garbage, both from smoking, stoves and fire pits. If someone else does something negligent that damages your home, you are still covered but the insurance company may pursue subrogation.

Bud, thanks for the help. I want to use the most non combustible insulation near the heat shield or chimney pipe.
 
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Old 12-15-15, 10:38 AM
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Check out Roxul. It is mineral based, from slag, and has a good r-value plus very dense.

Bud
 
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Old 12-16-15, 01:10 PM
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Inspectors commonly aren't liable for their mistakes. But YOU as a contractor, ARE.

Frankly, your attitude is scary.


Once I was an expert witness for a person who just moved in to a new home. They lit up their unvented fireplace, and the next thing they new they were in the hospital being treated for carbon monoxide poisoning.

The contractor had installed an unvented fireplace and hadn't followed the complicated directions provided by the manufacturer on how to arrange the gas logs. That caused quite a bit of carbon monoxide to be produced.

Needless to say, the home owner sued the contractor for his negligence. The only real issue was how much the contractor's insurance company would pay.
 
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Old 12-16-15, 03:10 PM
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This is on my own house. I don't do HVAC for hire. I would have insurance coverage no matter how I managed to burn my concrete house to the ground.

Code and apparently the SuperVent directions are "minimum standards". I am looking to improve on that.

Those that blindly follow code or in this case a manufacturer, are what I call "Sheeple". I can think for myself and form my own opinion.
 

Last edited by bkvanbek; 12-16-15 at 03:55 PM.
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Old 12-16-15, 04:53 PM
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Your thinking of minimum code is backwards. The minimum distance is 2". Your welcome to improve on it and have an air gap of 6". That would be above and beyond code.

BTW - Did you ever look into the Universal Shielding Insulation? (JUSI/SUSI) Universal Shielding Insulation (SUSI/JUSI)

From the link: "The JUSI/SUSI Insulation is used to reduce cold air infiltration into the
dwelling and to provide additional protection against radiant heat
from the chimney or venting system."

"A MAJOR CAUSE OF CHIMNEY-RELATED FIRES IS FAILURE
TO MAINTAIN REQUIRED CLEARANCES
(AIR SPACES) TO COMBUSTIBLE MATERIALS."


Your friendly Sheeple
 
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Old 12-16-15, 06:40 PM
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Tolyn, you are getting there. Now if I could just buy a roll of the universal shielding insulation and skip the $45 metal shield. That's what I am looking for to have non combustible insulation.

My thinking is not backwards, just optimistic. Air space is not the only way to insulated from heat and possible fire. To have an uninsulated air space isn't going to happen. I have an existing wood stove, same SuperVent setup, wrapped in fiberglass. Going on fire years.
 
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Old 12-17-15, 07:07 AM
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I have an existing wood stove, same SuperVent setup, wrapped in fiberglass. Going on fire years.





.
 
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Old 12-17-15, 01:02 PM
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Actually they are standards that have been proven to provide safe operation of the appliance if they are followed.

You are simply substituting your guesses for what has been derived experimentally by engineers.


When I was employed as a repairman for a gas utility, and later in my own repair business, I encountered people who were guessing that they could determine what was safe to do. Not infrequently, they were creating real and sometimes substantial and imminent risks for building occupants.

In my opinion, such people are best characterized as being fools.
 
 

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