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jimmiejames 01-14-2012 08:45 AM

Adding insulation to a finished wall w/some existing insulation
I'm wondering if its possible to add insulation to a finished wall that already has R-11 in those walls?

We live in GA and the home was built in 1990 and has R-11 in the existing walls and we'd like to add more insulation if possible without having to rip out the current wall.

Now with the walls already being finished with insulation I would figure trying to use blow-in from the inside walls would almost be impossible as I believe it would get caught up and clogged with the current insulation causing a mess and not working. However I was thinking if I did it from the outside wall the paper would allow the new insulation to more easily slide down and fill the wall??

Am I on the right track here or am I just stuck with the R-11 until I do a complete remodel and rip out the current wall(s)? Or is there a better way do do this that I'm just not thinking of?

Thanks in advance,

joecaption 01-14-2012 08:56 AM

Not going to happen.
Any added insulation would just compress what you have now and make it useless.
You have two choises, stip the walls of sheetrock and build the walls out and reinsulate from the inside. You also would have to make up some jamb extentions for all the windows and doors.
#2 Insulation can be added on the outside if you have siding not block or brick. A lot of work and money but it can be done.
How much insulation do you have in the attic and under the house?
Do you have replacement windows.

jimmiejames 01-14-2012 09:23 AM

The house has vinyl siding.

We replaced the old drafty wood windows with vinyl replacements last year.

The attic is 85% finished, in the unfinished side we added 1" rigid foam board over the existing R-30 in the roof and replaced the R-11 in the knee walls with more R-30 and then put the fom board over that was well.

Oh well I was hoping to add a little more but I guess it sounds like it'll just have to wait until we decide to remodel a room and then add it if/when we decide to do so.

oldognewtrick 01-14-2012 11:13 AM

I would take a siding zip tool and seperate one section of vinyl siding and look at the structure underneath. See if they installed house wrap and if the seams are sealed. What you want to do is stop moving air. Weather sealing is as important as insulation. A seam can be snapped back together rather easily.

joecaption 01-15-2012 07:31 AM

Not sure what your thinking by adding 1" foam over insulation. That will give very little R value and it will form a vaper barrier on the wrong side and may cause a mold problum.
If you really want to use it then it should have gone againt the ceiling, seal any gaps with spray foam then insulate over that.
As far as those knee walls how wide are the wall studs? If you installed R-30 then compressed it with foam you just lowered the R- value and once again added a vaper barrier on the wrong side of the wall. If you wanted to block the cold air you could have used Tyvex in the knee wall area.

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