Insulating outside walls?

Question

I'm going to redrywall some rooms in my house that all have outside walls, so I figured that while I'm in there, I might as well replace the insulation.. now, I have a few questions.. what is the best insulation to use on an outside wall? Standard pink/fiberglass inulation, blown insulation.. or is there something else that's better.. also, do you always have to have a vapor barrier on an outside wall, or is that only in the bathroom and kitchen.. where there's lots of moisture? Right now, there isn't a vapor barrier, so should I put one in since I'm going to do the insulation and drywall or is it uneccessary?

Answer 1

I work for an architectural frim as a drafter and all the architects put vapor barrier on their projects. They call for batt insulation in the walls. Blown-in insulation is usually for situations of existing stuctures were you would not be replacing the drywall like you are doing. Good Luck! :)

Answer 2

I suggest using rigid styrofoam insulation. It has a higher R-value per inch of thickness than fiberglas or blown cellulose insulation.

The reason for a vapor barrier it to keep any condensation from forming on the insulation, and degrading it over time. If you are not planning to rip out and replace your wall studs, then there is little benefit to using a vapor barrier because any VB you would install would have gaps where the existing studs touch your exterior wall.

Another good reason to consider rigid foam insulation - it doesn't matter if condensation forms on it - water will not degrade it's insulation performance.

One other option is to have a contractor spray a foam insulation on your open walls. As it is applied, the foam quickly expands to fill all the space between the studs and any electrical or plumbing utlities. The only downside is you have to rough-cut the excess foam flush with the studs, using a hand saw, and remove all the excess debris, before you can install your new drywall.

Good luck.

Answer 3

Don't know what kind of exterior walls you have. Code required
insulation barrier (vapor) if you home is less than 30 years old or so. If wall is brick or such you might not see any barrier but it should be there.

I use blown (liquid) insulation (by blow rite) It is liquied that sets up and hardens in the perfect insulation. Since its liquid it settles into all the space.

It's cheaper and so much faster for me.

I don't care much for the rolled out insulation r30 ect since it still leaves gaps. The blown fuffy insulations settles down inside walls
as time goes by leaving exposure. (great for attic/ceilings.

If you tore off the old sheetrock and can see exterior walls then you don't have vapor barrier. Then liquid would surely be your best bet.

Truck coming up-hoses out-1 hour later done.
You can install sheetrock or better yet masonry siding interior wall.
Blow rite drill about 1/2 inch holes to pour insulation.

If using 2x4 for studs don't use cross studs (horz support) just vertical studs. This way every 16 inch or 24 inch they can plan
pouring to competely fill standing wall.

If you use rolled insulation of blown fuffy insulation and you can see exterior wall has no vapor barrier I would use 6mil thick clear or black plastic to line walls first then put in insulation.

Liquid is fast and simple and hardens to make a perfect insulated
wall.

Check with you local companies before you decide.
My walls are 4" brick 4"poured insulation 4"brick. 12 " thick walls.
Temp stays at about 72* year round. Cold or Hot I am saving money. I only need overhead ceiling fans,
My central air takes a break most all year on heat and cooling.

I credit that to the liquid insulation.
Don't forget overhead (blown fuffy-ceiling and attic area) and floor if your foundation has a crawl space (rolled out Insulation).
I used r23 and r30. and also 6mil thick plastic on ground to prevent moisture from rising up.

Good luck on your reno job.

Answer 4

Best insulating properties will be obtained by using a foam product. These are generally more compact and pretty easy to use/install. A vapor barrier is crucial if you use a fiberglass or blown in product, otherwise the moisture will wet the insulation and you'll loose the insulating properties. It is less important on a foam insulation because it is a closed cell insulator.

Answer 5

I would look into reflective insulation....it is basically bubble wrap with an aluminum coating. It reflects radiant heat...that's what I'm using on my re-model. From what I have read and heard from a few builders, it's the way to go. Other than that, I would use the foam board insulation. Definitely go with a vapor barrier. It generally goes on the outside of the walls, though. Unless you are taking the siding off of the exterior to put up the vapor barrier, you are going to have too many uncovered areas like the outside of your wall studs. I wouldn't spend the money to do it, unless you are going to do it that way...but it would be money well spent.

Answer 6

Vapor barrier should be done on all outside walls....

as far as insulation goes...if you are going to replace all the drywall I would just use the paperbacked fiberglass R19 or better. very easy since they wall will be stripped anyways

If you were not going to replace the drywall you would have to use blown in which will settle over time and need redone...

Answer 7

put on vapor barrier for any outside wall.
you can use blown in insulation BUT it settles after a while and needs to be redone
standard pink is the best way to go just make sure it's rated R-20 or better.

Answer 8

You can either lay 2x4 flat and get insulation board to put between them (they make different grades so check into them), or you can build a stud wall 3 1/2" and use fiberglass insulation.

Answer 9

You should always use vapor barrier for air leakage,so far fibreglass insulation is still the one .Use highest R value you can afford. Why are you replacing the fibreglass insulation, did it get wet(it would lose R value)?