Wednesday, August 14, 2024

The (More or Less) Final Design

Following many productive email discussions with the architect regarding technical details including HVAC routing, truss design, garage door size, window and door locations, and wall thicknesses to accommodate mechanical systems, I recently gave approval to begin developing the construction drawings.

Roughly six months after we began the design process, we arrived at what I think is the final design. The overall design concept was created to mirror this structure:

That image was in my design concept archive for some time and I found myself coming back to it again and again before I ultimately realized that the external appearance is very close what I wanted to achieve.

Here's the floor plan:

I dabbled some time ago with the idea of a staggered stud exterior wall assembly. That eventually migrated into a double-framed wall, meaning, a 2x6 exterior wall finished with sheetrock on the inside, followed by an independently framed 2x4 wall meant primarily for mechanicals. The architect quickly opined that would be almost impossible to achieve, mostly because the sheetrockers want to be one-and-done, and not come back to finish the job at a later date. She also pointed out even if we did manage to convince them to come back a second time it would be at considerable cost. So we compromised with a 2x8 exterior wall assembly that will receive 2x6 mineral wool bats. The gap left between the sheetrock forming the interior wall and the bats will allow me to snake wires or other mechanicals down the walls as needed.

Why is this so important? Because unlike most residences, this structure will have to grow with my personal and business needs and there is no way for me to know all of my requirements right now. This means I have to build the structure to be adaptable and easily modified, long after the initial construction is complete, and while mineral wool insulation is probably the best solution from a performance perspective, its density is so high that it is essentially impossible to snake anything through it. Had I decided to fill each cavity with a full 2x8 bat I would have to pull sheetrock down to modify the structure.

And if you're wondering why I'm not considering fiberglass insulation, it's for two reasons:

1. Years ago I spent a lot of time in attics as an electrician and saw what happens to fiberglass over time. Simply put, it compresses under its own weight and this compromises its R-value significantly. I remember seeing one particularly bad case in which the insulation, originally specified to fill the cavity of a 2x8 ceiling joist, had compressed to approximately 1/3 of the original height.

2. Fibreglass bats do not maintain their dimensions during installation to the same degree as mineral wool bats, and the fibreglass would likely expand (particularly at the base of the wall assemblies) to the point that it would hinder the installation of mechanicals down the road.

Of course, not every wall will be 2x8. Most uninsulated walls used simply for internal partitions have been specified as 2x4 to save cost, while all walls that incorporate mechanicals -- in particular, plumbing -- are 2x6. Why did I do this? Have you ever seen what plumbers do to route a 4" DWV pipe through a 2x4 wall? They cut the plates and that's crazy. We did that for decades of course, but that doesn't make it right.

My architect proposed a simple slab-on-grade construction method for the foundation but I quickly dispensed with that idea and instead said that all structural members would be placed atop a poured stem wall with roughly 3 feet above and 3 feet below grade. The goal being, of course, to minimize any possibility of termite / pest infiltration. If termites attempt to crawl up the stem walls I'll see their mud-tubes and be able to take action before they reach the wooden structure. For interior walls that are secured to the slab I plan wrap the plates with metal flashing material beneath the standard sill sealer material so as to prevent termites from finding their way through inevitable cracks in the concrete slabs.

There are a couple secondary benefits of a stem-wall foundation including the ability to pour three slabs independently rather than create a single monolithic pour, and that will be simpler, logistically speaking. Additionally, each slab will be fully independent and thus easier to insulate and ultimately heat. Additionally, a failure in any single hydronic heating system will not impact the remaining remaining systems.

The first thing car-enthusiasts will likely notice is the two 12x12 foot garage doors. I originally considered doors 10 feet wide but my brother said that if he had the chance to build his garage over again he would have incorporated wider doors. I didn't take the opportunity to rub salt in his wound and remind him that I proposed a 20-24' wide door on the left side of his building back in 2008 rather than two 10 foot wide doors, but instead took his advice and increased the width to 12 feet. This is wide enough to accommodate larger pieces of equipment, modern trucks with towing mirrors, and large tour-bus style RVs. I have two long-time friends with RVs that I knew would love to have a place to stay and park their RV securely while visiting the area, so I'm comfortable with that decision, in spite of the doors dominating that side of the building.

Some time ago I started talking to banks about financing the project and the first bank I spoke to told me that due to the small residential space, confined to the right side of the building at that phase of the design process, they would only write a note with a maximum of a 65% loan-to-value. This would have required me to put more cash into the deal above and beyond the land value. I found that ludicrous but telling as to what other bankers might say so I elected to change the names of the rooms on the left side and add a second bathroom.

As a consequence of this change, I now have both a primary suite and a guest suite, separated by a high bay garage, and both suites can be converted into usable office / lab space when I ultimately build the formal home at some point. I also have two bathrooms, which in retrospect I should have included from day one, since I told myself long ago I'd never own another property with a single bathroom. The kitchen space can be used by friends / family / guests or anyone I might employ to assist me in my business or it can serve as a backup in case the appliances in my home kitchen fail. Of course, modern appliances for which we pay thousands of dollars are totally reliable and last forever so this probably equates to needless redundancy.

In keeping with the barn aesthetic I elected to add two cupolas on the top of the structure. These are functional but not in the traditional sense. Cupolas were historically designed to aid in ventilation but in this case, however, because the attic will be part of the conditioned space, the cupolas will instead be framed in as skylights. They will provide natural light in the garage during the day, be illuminated at night for a nice effect when viewed from the outside, and mirror the design concepts I have planned for the formal home.

The only thing up in the air at the moment is whether I'll do anything with the space above the garage doors. I'm leaning toward windows above the garage doors and a hay-loft style door in the attic space, but that will be sorted out later.

The gable end illustration shows a 8:12 pitch for the garage roof, which will provide additional headroom in the attic, as well as contribute to the design looking more like a barn and less like a warehouse -- an aesthetic quality I deemed critical to both passers-by, as well as the banks.

The side elevations show symmetry of window and door placement -- something important to me and the architect. The only potential asymmetry has to do with the window in the utility room. I have yet to do the detailed design of that space but I will need as much wall space as possible in that area to hang electrical equipment, including disconnects, meters, inverters and batteries. I'm also concerned about keeping that room as secure and cool as possible, since it will be the nerve center of the entire property, and a window will represent a possible intrusion vector as well as present a thermal load that I'd just as soon avoid.

Construction Documentation Begins

Up to this point we've been working with high level design drawings. The next phase of the design process will involve the creation of construction drawings, including a site plan. During this phase I'm going back to my requirements document to update it to reflect the scope of this structure and identify specific requirements in each room, including defining the routing of various mechanical systems, particularly those that will be in or under the slab, since that will be the first thing the builder tackles.

Speaking of the builder, I got some news perhaps reflective of an impending recession. My architect said the builder she thinks will be a good match for the project has time in their schedule, so as soon as we have drawings the builder should be able to quote the job, and as soon as I have a realistic quote I should have what I need to get financing in place. Once that's ready we should be able to get a shovel in the ground. And although the architect told me that the builder was able to complete a similar project in about 7 months, I'm expecting the build to take a full year. Ideally, I should be able to move in about 18-24 months, which will put my total time in Florida at around 2-3years -- about what I expected.

I will miss the convenience of being in Florida, and being closer to my sister, but she's planning to move out of Florida soon as well, possibly to the Carolinas or Maine, so leaving Florida won't mean much to me. After all, I'm more of a mountain-guy than a beach-guy.