How do I get R19

[mdshunk]

I got ahold of a property to rehab when the weather gets a little warmer. Since it will be a gut job, the building department wants pretty much everything to be up to modern code. I have no problem with that, but I'm wondering how to get the R19 outside walls I need. I'm in zone 12. The house is studded out with modern 2x4's (3-1/2") and has 7/16 plywood and vinyl siding. The windows and doors will all need changed to meet code. Would it be better to fur out the inside walls to get r19 fiberglass in or just insulate the walls with 3-1/2" thick batts add some thickness of Celotex on the outside of the house before installing the new windows, doors and siding? How is this typically handled? What's the most cost effective way to do this? Is there any insulating product that will provide r19 in a 3-1/2" bay?

[Jacksnap]

Try this link
http://www.owenscorning.com/around/insulation/project/extrapower.asp

[suemarkp]

Good info. I wish the codes didn't go this far when doing a retrofit to a 2x4 structure. I doubt you will see much benefit changing a wall from R-13/14 to R-19 when it is full of windows and doors that are R-4 at best and have some air infiltration. The styrofoam is nice, but expensive. Also creates a potential problem for making the windows look nice when there's this extra inch of stuff that won't hold nails on top of the sheathing.

[Wgoodrich]

This is where the term existing comes in giving the inspector the final ruling what is existing and what can be adapted in the best interest of the home owner to allow best we can do condition. It is commonly not logical to double the effort, cost, creating a major change in cost and original integrity to make existing homes meet new construction standards. There are some Codes out there now that address working in existing homes making remodling rules different than new construction rules due to the conditions found in old style homes.

Check with your inspector to make a ruling of existing and what he will accept as an alternative to a total reconstrution tear the house down and start over condition utilizing best what is now existing. Most inspectors are aware of the problems with remodling. Communication with those in authority is best way to find out what you can and can not do with existing conditions.

Let us know what you find I am curious

Wg

[mdshunk]

Check with your inspector to make a ruling of existing and what he will accept as an alternative to a total reconstrution tear the house down and start over condition utilizing best what is now existing. Most inspectors are aware of the problems with remodling. Communication with those in authority is best way to find out what you can and can not do with existing conditions.

Let us know what you find I am curious

Wg

In my case, they are unwilling to bend the R19 exterior wall requirement, since I an tearing out the heat pump and installing electric baseboard heat. If I left the heat pump stay, then they would permit the existing insulation under the BOCA Property Maintenance Code and not enforce the IRC. This will be another rental, and I put electric baseboard in all of them to keep the maintenance costs down. Couple this with the fact that I am basically gutting the whole thing and removing what bits of siding are left, so I'm really only reusing the rough framing and the basement walls. This was a slight fire burnt house, but the firemen went a little hog wild tearing the place up.

[Wgoodrich]

Check with your inspector to see if the R19 has been ammended in your state to a lower number. If not then sounds like you will need to scab onto the face of the studs making the wall thicker making room for the R19. If this is the case you will need some imagination to address the extension on the windows. I would still scab on but using better quality lumber around the windows and doors.

Just an idea

Wg

[Shroomer]

What about spray foam such as Icynene Perhaps they would bend a little for the benefits of less air infiltration.

[BobMeans]

Icynene won't get you to R19, but some of the high density closed-cell foam has an R-7. That would get you to R-19 in a 3.5" space. Maybe a little pricey.