Hardieboard and R-11 batt......... Moisture, code, reality, advice needed

[Armatron]

I live in Atlanta. I have a tudor style home that is (was) sided with 4x8 sheets of 70's compressed fiberboard garbage. Original install from late 70's was r-11 batt, r-4 foamboard, then the fiberboard for a total of r-15 to r-16. No plywood or sheathing or wrap. Just foam then fiberboard It was maintained well, but I was sick of maintaining and patching it.

I hired a very, very reputable (and expensive) company to replace it with hardie. The crew is meticulous and have done a fantastic job. However, I realized halfway through the job that they were removing the foamboard, replacing it with plywood sheathing, then hardie housewrap, then hardie 4x8 sheets. Plywood is 0.6, hardie is 0.3. So I am now at r-12.

Code is r-13 to r-15. Does this include drywall?

Efficiency is great but do I need to be concerned with dewpoint or condensation inside the wall cavity? The last side of the house they are pulling out the r-11 and replacing with r-13 after I pointed all of this out. I REALLY do not want to push them to rip off the 3 sides of hardie including soffits, complex tudor batten trim, that they've already finished to replace r-11 with r-13. Realistically we will be in this house another 10-12 years max.

Thoughts?

 

[acer66]

Code normally only refers to insulation for R values since everything else is hard to measure and/or is so little that is does not matter.

Doubt that you have worry about the dew point and I would not rip things out do get a bit higher R Value.

If it gets inspected just make sure all the inspector can see is at least R 13.

 

[Armatron]

They pulled a permit for other unrelated modifications but hard to inspect anything when it's behind hardie and wrap....... Thanks for the input. I'm going to (try) to not worry about it

 

[jack stand]

I'm curious if the hardi will be any different to the "70's" material in 50 years.
I'm doubtful of significant difference if any 50 years from today.

 

[Leaflessshadetree]

Does today's code legally apply to a structure built 40+ years ago or did you specify bringing the structure up to code?

 

[acer66]

Does today's code legally apply to a structure built 40+ years ago or did you specify bringing the structure up to code?

Normally they make you only update things you are working on anyway.

If they see something that is outright dangerous or something that was build that was never up to code.

One of my inspectors saw a deck build with more current materials not build to more current codes.

He was not looking for it but passed it many times to the job until it finally caught his attention.

But he told me what needed to be done which was easy peasy.

Your experience might differ of course.

 

[Armatron]

I'm curious if the hardi will be any different to the "70's" material in 50 years.
I'm doubtful of significant difference if any 50 years from today.

For sure hardi is better than this fiberboard ****. I've dealt with it on this and other homes. If you keep it perfectly painted, caulked, 100% mint it's fine. But one drop of water hits it and it expands and has to be replaced.

 

[jack stand]

I'm just impressed that you got 50 years out of this "fiberboard ****" and the painting requirements are the same for hardy product to expect similar results.
Hardy is just the "fiberboard ****" of the day. Just like the Masonite siding of the 80's.

 

[Nofries]

The house wrap and the rigid board are/were at the exterior that vapor barrier is in the same place no need to worry about moisture. Usually only problems arise when you have two moisture barriers at different point in the wall with then condensation occurs between the two and won't dry out. Rigid, insulation generally is also a continuous insulation where batt is not. Code enforcement probably won't say anything. May affect your heating and cooling though. If they are putting in r13 now, and they are reputable, no reason they shouldn't have put it in originally and should do so for the entire house. Depends on what was contracted.