Nope; his cost. I'd prefer not to see HVAC (or plumbing) in outside walls in northern climates.

You sure this guy is a real GC/Builder?

Milwork - I am starting to wonder.. I did walkthroughs of a few houses he did and everything looked great.. Whole structure felt solid and I thought we were safe.. As each day goes on I start to wonder.. The sad thing is that they were even one of the higher priced builders.. We quoted about 6 builders and his estimate was I believed the 4th highest but after seeing the finished work we thought we were in safe hands.. This is just getting to be ridiculous..

Ichabod - I agree with the staying out of exterior walls.. Unfortunately I had no say in it and being an amateur when it came to home building I didn't know the difference nor did I do the proper thing which would have been to have a HVAC designer brought in when doing the house plans.. When I visited the site I found the ducts in the exterior walls and even voiced my concerns but was assured it was done all the time and would not be a problem.. Well here we are lol...

On a side note.. Anyone have any idea the cost to fill these cavities? They are 2x6 framing 16oc and 9ft high

He should have known better. He should be embarrassed it happened and no way try to pan it off on you as if it were a change YOU made.

His problem. He should never have tried that in the first place.

We don't put ducts in outside walls here in Southern California.

Seems like your builder has a lot of chutzpah. (for those who don't know Yiddish it means a lot of balls. Sorry I couldn't figure out a less course way to say that.)

He may be a real GC/Builder or he may not be but is sure doesn't sound like he is a good businessman and this needs to be a lesson he learns the hard way in other words on HIS DIME!!

What did your HVAC detail show for duct location? This should have been detailed in the drawings so locations of the duct work and the vent locations shouldn't have been a surprise to you. Which doesn't mean that he's off the hook. He should still have known what it would take to meet the energy codes, bid accordingly and done the work to meet the codes.

The building code requires a wall R rating of at least 20 and I am not aware of an exception for ducts in the wall. But even if the inspector would accept it there is a minimum insulation requirement for ducts which I think is R6.

Whatever the code requires should have been in the original contract price. You are not responsible for his design mistakes. An owner is not responsible for checking the contractor's design documents but if the design was provided by the owner's architect or consultant, the owner would have to pay for any corrections and then try to recover that cost from the architect or consultant. So it is important to know who designed the system.

Of bigger concern is how he can meet the code even with high-density closed-cell foam which might provide an R of 7 per inch. Reflective foil is not insulation, has no R rating and needs a 3/4"+ space next to it to work at all and if such space were available it should be filled with foam. Bubble wrap with foil offers little insulation.

As for doing it all the time, to my knowledge, it has always been considered a bad practice. When exposed to the exterior, because of the higher air temperature, a duct needs more insulation than a wall, not less.

Dlm2000 - this is where I messed up.. The architect we used only drew up the structural plans and no hvac design was included.. So when we brought the plans to the builder in essence he and his contractor were supposed to come up with the system.. Again, this is where I messed up in not having a pre designed hvac plan by a professional..

Jds - part of the problem is the design of the house and all structural points.. There are not enough interior walls that can support the hvac system so they were "forced" to use exterior walls.. The problem now being the insulation.. The part that gets me upset is I even offered to help with the issue by paying for rigid foam board to be installed all around the exterior.. I figured I would pay for materials and we could split install.. I was basically offering them the opportunity to make a little something extra over just having to fork over money for spray foam.. Their reply was to say I'm the one paying for spray foam because they didn't account for an inspector to do his job.. Amazing..

Also, the inspector spoke with the HVAC contractor and the HVAC contractor offered to double wrap the ducts with the insulation which the inspector quickly disregarded saying that the double wrap would take away from the insulation value due to some kind of needed spacing and went on to say that there would then be no room for standard wall insulation.. Below is a picture of the wrap that the contractor has on all the ducts in the exterior walls.. I want to say that I thought I heard him say it has an r6 value..I want to say the ducts are about 3.5 inches as they have them in the interior 2x4 walls on the second floor master and unwrapped they look like they barely fit.. I want to say that there is about a 1-1.5 inch max gap behind the ones in the 2x6 walls, however they are wrapped with the foil insulation..

foil bubble foil wrap is not insulation read the following article:

http://www.energyvanguard.com/blog-building-science-HERS-BPI/bid/29497/The-Foil-Faced-Bubble-Wrap-Sham-Understanding-Radiant-Barriers

It is possible those duct wrappings have an insulation value of R6 when surrounded by an air gap. So OK when used in an attic or basement, even an interior uninsulated wall, but not in an exterior wall where you also need to add insulation.

Sounds like the HVAC guys are clueless also.

Exterior rigid foam?

The air space between the duct and framing regardless of its size cannot be more than 1.0 so the foil can slow the movement of infra red energy but cannot be used to meet the building code. High density closed cell spray foam is the only possibility if the inspector will accept an R of 7 or 11. Of course, exterior foam board would help.

I've designed too many buildings to believe there is no way to keep the ducts out of the exterior walls. It's not something that has ever been suggested on one of my projects. Is there no basement or attic? Where is the HVAC system located?

I agree with the others, I don't think it's a good idea to run ducts in an exterior wall and then "insulate" it, whatever that means.

Although one way to maybe have it be ok from an energy code standpoint is look at it in the context of the whole building envelope. If you don't have an over abundance of windows, simply figure in the envelope energy calcs the areas with ducts as if they WERE windows with an R of like 5 and see if you still pass.

Just as an aside, we lived in an older house here before we tore it down and rebuilt on the same foundation and one duct ran up an exterior wall above the foyer. In the summer it rained in the foyer!

Bad idea.

Just got my update from the builder.. He informed me that "we did not design this house" and went on to say they are trying to do everything to conform with codes given the situation.. He went on to say that nowhere in the blueprints did it say they had to use spray foam and so it is not their problem.. He continued that my options are to go out and get a mechanical plan or pay for the added insulation.. He gave me a price of $600 to do 1inch thick spray foam in the bays with hvac ducts for an r6 value and stated that the wrap gives an r4 value for total of r10.. He then said they would use fiberglass batt for any left over cavities after spray foam and wrap..

What you're saying is he is saying that he didn't design the house. Tell him that may be true but who designed and put in the hvac system? And ask him how many times he's put an hvac system in exterior walls in NJ?

Yea, red flag when you said he was going to foil over the duct and spray foam to get the required insulation, this after talking to the architect (who wouldnt be the authority here, the GC should know already). Not possible to achieve the correct R value with the thickness of the duct. There is a reason they have to use 2x6 studs now on exterior, the entire cavity is to be insulation and a 2x4 wont pass insulation code. Take the ducts out of the walls and install as floor registers near the exterior, with returns near the center of the house. This will be easier/cheaper/more proper for the GC than trying to jimmy rig these wall ducts, basically buy register boots and cut a hole in the floor for the boot.

You live in NJ. I live in MD. Both states are virtually identical when it comes to condensation and hot, humid and moist summers.

I don't think ducts in exterior walls will work.

We also have too few interior walls, and our architect didn't plan out the HVAC. I thought we'd planned for places to run HVAC, and then the joist company put joists under Every. Single. Wall intended for HVAC runs. We ended up insulating the exterior wall, then building a stud wall in front of that for running pipes and ducts. Probably a lot cheaper than spray foam, and definitely more effective.

I think he's out to lunch trying to pull this and now expecting you to foot the whole cost.

I have never seen this done in my 35 years in const. You run in interior partitions, or you build bulkheads and chases to box them in, or you go loft-style with exposed ducts. Period.

ZOMG

Casey

Get your bank involved. Now. You're dealing with a jackleg, not a real builder here. You may need the assistance of some financial pressure to get him to do things correctly. And you may need to jettison him entirely. Sorry, but that's a deal breaker. No just NO, but HELLS NO! Ductwork is never run in exterior wall cavities.

Now, you may need some interior chases or soffits in an open plan, but that's when you make lemonade out of lemons with a ''tray ceiling'' that hides the ductwork, etc.

You want a house built to code. He chose to move forward with a HVAC design without your approval - you assume what he is doing is to code. If he had an issue with the design he should have run it by you before he put it into place. It was not your choice he chose to run ducts in exterior walls.

I have to agree with the others. Assuming the contract states he'll build to all applicable codes, and if you didn't specifically specify, either live or in writing somewhere that the HVAC should be run that way, you'd don't owe him a dime. I'd tell him he has two choices (and I've had a few argument with my builder that took a couple of rounds); move the HVAC, or pay whatever it takes to have it to code where his contractor put it. It's the builders job to build to code at a minimum, whether or not he messed up his budgets has no bearing on it.