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Old 06-27-2010, 09:28 PM   #1
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Installing insulation under addition.


My wife and I bought a house in Sept 08 that had a heated enclosed porch addition. During our home inspection prior to closing the inspector noted that the insulation under the porch had been installed upside down(vapor shield facing away from the building). He said that instead of replacing it we could puncture holes in it to allow the moisture to escape. I did what he said but I have been wondering lately if this is a realistic solution.The inspector comes from a company with an excellent reputation but I'm still concerned. The insulation was installed around 2004 and I have noticed some mold on the inside of the vapor shield. The room is empty and cold through most of the winter and is only used for holidays. Can I get away with just the whole punctures for the time being. What are the risks if I leave the insulation installed as is even with the hole punctures in it. Any advice that anyone could give would be greatly appreciated.

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Old 06-27-2010, 09:34 PM   #2
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Installing insulation under addition.


Were it mine, esp w/ mold visible, that vapor retarder would be toast in a minute. I would replace it with an AIR barrier that lets vapor out, yet keeps the air from moving through the insulation and reducing its R value to nil. If it is fiberglass, I'd also replace that w/ cellulose or cotton. I used fiberglass in my house, too, but will never use it again. Not in my large addition, and not in either of my boys' houses. My opinion. GL. j

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Old 06-27-2010, 09:36 PM   #3
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Installing insulation under addition.


Where are you located ?
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Old 06-27-2010, 09:38 PM   #4
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Installing insulation under addition.


South of Boston MA
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Old 06-27-2010, 09:41 PM   #5
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Installing insulation under addition.


Is the insulation exposed underneath and/Or in the room ? - no sheathing/drywall ?

Is the area under the porch enclosed ?
Pics ?
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Old 06-27-2010, 09:45 PM   #6
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Installing insulation under addition.


The insulation is on the outside of the porch(underneath) with the pink insulation facing towards the interior of the porch. The porch is elevated about 4-5 feet off of the ground and is completely open underneath. I can take pictures tomorrow once its daylight.
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Old 06-27-2010, 09:50 PM   #7
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Installing insulation under addition.


I'd take it down, reverse it & re-install if it is the proper R rating
Then put some sort of sheathing over it
The paper backing is flammable & should not be left exposed
The fiberglass will become a home to bugs & varmits & must be covered
I'd also consider closing in underneath
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Old 06-27-2010, 09:52 PM   #8
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Installing insulation under addition.


I'm sure this is a dum question ..but how can I tell if it is the proper r rating?
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Old 06-27-2010, 09:55 PM   #9
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Installing insulation under addition.


Well...the more the better...as long as it fits in the joist space without compression
2x6 = R19-21
2x8 = R22+
2x10 = R30
2x12 = R38
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Old 06-27-2010, 09:56 PM   #10
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Installing insulation under addition.


Thanks for your help!

BTW... What kind of sheathing would you suggest to cover the insulation once I reverse it? Plastic?
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Old 06-27-2010, 10:45 PM   #11
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Installing insulation under addition.


Plastic would be another vapor barrier...so I think that is out
...and it could be ripped by mice etc
I've never had a raised area exposed to the elements
I would think plywood or something like that would be your best bet

I'd prefer to simply wall in & enclose underneath
Sometimes its very hard to work in an area only 4' off the ground
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Old 06-28-2010, 10:57 AM   #12
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Installing insulation under addition.


Here are some photos of the addition. I over estimated the amount of space between the ground and the insulation. It is little more than 2 ft. I'm thinking of replaceing the insulation since there is already signs of mold. I spoke to someone at lowes today and he suggested placing sheets of polystrene foam over the insulation in order to keep the varmints out.

Anyone know what the law is regarding disposal of insulation?
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Installing insulation under addition.-101_0407.jpg   Installing insulation under addition.-101_0408.jpg   Installing insulation under addition.-101_0409.jpg  
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Old 06-28-2010, 11:17 PM   #13
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Installing insulation under addition.


I have a heated 4 season porch addition that has insulation exposed underneath. The previous owners installed the insulation upside down so mold has started to grow against the paper backing of the insulation. I plan to replace the insulation correctly but I have been told that leaving the insulation exposed can lead to varmint infestation. My plan is cover up the insulation under the porch, possibly with plywood. Can anyone tell me if this will present any problems in terms of additional mold growth or any other problems if I seal it?

I spoke to someone at Lowes and he suggested nailing sheets of polystyrene foam over the insulation to keep varmints out and provide some extra insulation. I am wary of this since I have heard that the foam can be a fire hazard.(Not that I plan to start a fire under my porch.) Any advice would be appreciated.

-2 threads on same issue merged-
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Old 06-29-2010, 12:08 AM   #14
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Installing insulation under addition.


Use it above the foam, tight to the floor: http://www.buildingscience.com/docum...n-crawlspaces/
Curious as to the joist size and span..........

Be safe, Gary
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Old 06-29-2010, 01:34 PM   #15
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Installing insulation under addition.


Insulation like that is just glass fiber. Reg garbage is just fine.

Instead of putting in new fiberglass, you might just want to put in two layers of 2" foam panel

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