This won't help you now, but it might give other readers some ideas to consider before they approve a plan.

1) You could have excavated the basement another 2-3 feet, allowing space for ducting and still ending up with 9 ft ceilings.

2) You could have used a Unico HVAC system that takes up less space than typical systems : https://www.unicosystem.com/

If you have an architect and spec'd a 9' ceiling in the basement I'd suggest you call your architect and ask him/her how they are going to fix it. Did the architect not plan for the ductwork, or did the contractor not follow the plan? Is your architect not visiting the construction site to tend to such things? I'd agree that you should be able to say you want a 9' finished ceiling and have the guys designing and building it figure that out.

I will say that when we learned the price of a full 9' ceiling in the basement we pretty quickly compromised on some pretty big soffits to accommodate the ductwork that had to run perpendicular to the joists. Fortunately I caught the HVAC guys in time-- they were going to hang everything below the joists "after all, there's so much room down here".

We built a 10 foot deep basement to try to avoid the issues you're having. With a crappy architect that provided no HVAC plan, it was up to us to talk to the HVAC installers to get them to run the main trunks in less obtrusive paths. Despite splitting the supply/return trunks so they run along the front and back walls of the house, we still have to deal with large soffts and some plumbing drops. In the main area of our basement, our ceiling will be reduced from 10' to 9' and even 8.5' for the HVAC soffits. Unless you're using a steel or engineered truss with some kind of large pass throughs, boxed in mechanicals in the basement are a necessary evil. You just need to try to be creative in hiding them.

Hope you can find a compromise you are happy with. In the south they put everything in the attic. Hvac not being planned in advance was an issue for us too.

I am sorry that others are having problems with the same thing. I am not having the architect do site visits mainly because the project ended after 10 plus months of designing(this was not on us we could have moved so much faster) with 2 construction bids that were double and triple our original budget, it was the most frustrating situation ever. A lot of changes were made quickly and I just think he was done with our project, I assumed that the HVAC would have plenty of room, until the trusses were run---its to late, I hope someone learns from my post.

The only positive note is that the ceiling in the bathroom is actually 7'6" not 7' like I thought yesterday so there is that....

Planning for the location of HVAC and other necessary services is an integral part of professional architectural services for a custom designed and built home. I always included drawings for mechanical schematics, lighting and electrical, and plumbing schematics. To get this level of design, however, one must pay appropriate architectural fees, including bidding assistance and construction observation. There are many ways to avoid the OP's situation.

That said, I'm very sorry and frustrated that there is probably little to be done at this point to improve the OP's situation without substantial costs, if even that is possible.

This is a lesson learned which should be a permanent "sticky" for every consumer considering a custom home. This didn't have to happen...

I have an acquaintance who is a HVAC contractor and his constant gripe is "architects" like the OP's who don't plan for the HVAC ducting ... they stick in a little spot for the equipment that may or may not be in a good spot but forget that air has to be pushed out from and return to the unit.

Or they suddenly (like AFTER the framing and sheetrock) realize they didn't figure out how the air exchange was going to work.

I am so sorry Mig for what you are going through. We had issues with drop downs on our main living space (main floor). The HVAC contractor could not understand why we were bothered by a main trunk going down our great room. Our ceiling height is only 8 foot, so the drop down brought it to 7 feet under his ducting. We decided to stop the ducting progress the HVAC guy was making. We hired an HVAC designer, who suggested we move to a high velocity heating and cooling unit. The ducting for this unit is mainly 4 inch duct runs, although there is one 6 inch run (maybe that one is 5). We were able to run all of those ducts inside the i-joist, and in some case we made 4 inch holes in the i-joists (within framing guidelines). We have virtually no drop downs now.

So, how much of the ducting has been done in your home? Has the equipment been purchased? Is there an HVAC designer in your area (HVAC expert that does mechanical designs)?

If it is too late to make changes, I hope in time you will be okay with 8 foot ceiling height in some of the basement (and close to 8 in the bathroom). Maybe it would not bother you forever? Our whole house is 8 foot ceiling height (our house was a rebuild so we had to work with the existing ceiling height which was 8 foot).

Good luck.

BTW, we too had an architect too. He did do a basic mechanical design. However, the original HVAC contractor did not like the design, and made up his own design that involved the long drop down on our main floor. So thankful we found the specialized HVAC designer!

Carol

My planned HVAC contractor is in touch with my architect so they design together. I'm hoping this avoids all issues!

My soffits are significantly larger than I wanted them to be in the basement but we had a 9' basement so soffits still allow for 8'1" ceiling. We did not have mechanicals predefined with my design build firm builder.

You could pay a designer/architect to produce plumbing/mechanical/electrical plans, but not too many have expertise in all the various specialty trades required to build a custom home and not too many plans will get built that way by the trades. That's why the best projects are ones that involve the team of trade partners who will actually perform the work early in the design process (they are partners in the process not adversaries.)

Based on your current situation, I suggest either of two potential solutions: 1. Use a high velocity system which utilizes small diameter ductwork (work great, but more expensive than conventional forced-air systems) or 2. Install ductless mini-split heat pumps that eliminate ductwork altogether.

We have installed ductless mini-splits for a number of years in remodeling projects. They are well suited to new construction, too, particularly if the homeowners have allergies or sensitivities to stuff that can accumulate in ductwork.

Best wishes.

We found that the HVAC contractor was not skilled in taking aesthetics into consideration when planning the duct runs. The HVAC designer specialized in the design component, freeing up the contract to concentrate on the install now that he had an well thought out design that the owners had approved of.

I agree with Charles that many architects can do mechanical plans, but that is not their area of specialization. After we found our HVAC designer, our architect took note of his name so he could work him into projects where required.

Carol

We had a similar situation where the stairs spilled out in the basement. The soffit for the HVAC was going to bring the 9' ceiling down to 7'6" for the last couple of steps. Definitely not ideal. We were still in the design stage so changes could be made. We decided to show the plans to a HVAC contractor we know that does commercial work. He had some great ideas and suggestions that made everything work. No HVAC soffit at the bottom of the stairs or anywhere else. It just took someone thinking outside the box and using techniques and a design that wasn't common in residential to come up with a fix to our problem.