Hey there! In this first blog post I’d like to get everyone up to speed on the steps taken so far in terms of the design of the house. Firstly, hat’s off to Laurel for taking the initiative to learn some drafting software months ago and building out her vision for a ranch style house. It’s an amazing layout featuring a spacious master bedroom with easily accessible laundry and master bath, double opposing offices, a gym that overlooks nature, garage and dream kitchen.
Secondly, about Vectorworks Design Suite: it’s a tool that delivers powerful 2D, 3D, and BIM tools for seamless architectural and landscape design. It unifies all these things into a platform that streamlines workflows, ensuring accurate plans, realistic visualizations, and efficient documentation. Since we’re collaborating with a home builder that is *probably using* Vectorworks, we can transfer design data without compatibility issues, which will reduce errors and saving time. Additionally, I learned that it has planting tools and terrain analysis which will give allow us to fully understand / design on the contours of our land.
My purpose here is to outline the thought process behind the decisions I’ll make as I implement her design in the context of a net zero home (a sustainable home is one of our big goals). Here are the major design decisions I’ll dive into:
- Exterior Wall thickness
- Sound dampening within the house
- Beanman’s litter box area
1. Exterior Wall Thickness
In order to determine exterior wall thickness, I used ChatGPT 5 to give me an idea of what materials are used in net-zero houses for insulation. The goal apparently is to reach an R-Value (which is a measure of how well a material resists heat-flow) of R-40. Here’s a table it generated for the common materials used and their corresponding R-values.
| Insulation Type | Approx. R-Value per inch | Thickness for R-40 |
|---|---|---|
| Closed-cell spray foam | R-6.0 to R-6.5 | 6–6.7 in |
| Rigid polyisocyanurate board | R-6.0 | 6.7 in |
| Mineral wool (rigid batts) | R-4.2 to R-4.5 | 8.9–9.5 in |
| Dense-pack cellulose | R-3.6 to R-3.8 | 10.5–11.1 in |
| Fiberglass batts (high density) | R-3.7 | 10.8 in |
We’ll need to do more research in terms of cost, but succinctly, the thicker the wall, the higher the cost for wall materials. However, the higher the quality and cost of the insulation type, the thinner the wall needs to be. For now, I’m going to go with the closed-cell spray foam, which is polyurethane. Here’s another table which estimates the thickness of the wall based on this choice. This assumes we’re modeling the full wall assembly thickness (structural + insulation + cladding), not just the insulation layer.
| Layer | Thickness (in) |
|---|---|
| Interior drywall | 0.5 |
| Stud wall (2×6, 5.5″ cavity) | 5.5 |
| Exterior rigid foam | 2.5 |
| Sheathing | 0.5 |
| Air gap + siding | 1.0 |
| Total Wall Thickness | 10.0 in |
For interior walls, there’s no difference in thickness between a net-zero home and a conventional home, unless it also serves a special function such as separating a conditioned and unconditioned space, soundproofing, or plumbing chases.
- Load-bearing walls: Still often 2×4, but sometimes 2×6 for extra strength or to align with exterior wall framing depth.
- Non-load-bearing walls: 2×4 studs (3.5″) + ½” drywall on each side → 4.5″ total.
So I’ll model all interior walls at 4.5″ thickness.