Pros – How Would YOU Build?
This question goes out to the pros on this site; those who are builders, building science aficionados, or some mixture of the two.
Many folks, myself included, come here with some vague ideas of how they think they would like to build and then post their ideas asking for advice. Instead of starting somewhere and then working backwards, I’d like to know where the pros would start. So here we go:
QUESTION: Assuming a cold and humid climate (Zone 6A/7A) and a two story with basement design, how would YOU build a new home FOR YOURSELF to live long-term starting from a clean sheet of paper?
I’m hoping to hear details on slab insulation, foundation wall details, wall insulation, durability details and considerations, attic insulation, roof type and details, as well as mechanical, plumbing and HVAC system information. Let’s hear it!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Nice try ;)
Do you have a ballpark price per square foot? Or is this a purely theoretical exercise?
Lance,
In general, the best details are those that are used by builders in your area, as long as these details comply with the recommendations of building scientists. Construction details tend to be local.
The easiest way to get into trouble on a building site is when you try to convince a local builder to adopt a method that has never been tried in your area -- especially because "I read about it on a web site."
When it comes to walls, my recommendations are here: How to Design a Wall.
When it comes to ceilings and roofs, I prefer a simple roof shape. I like horizontal ceilings (rather than sloped ceilings) with a vented unconditioned attic above the ceiling. My preferred attic insulation is a deep layer of cellulose. This approach only works well if you have a relatively airtight ceiling connected to the air barrier on your walls.
Without knowing much about your climate, budget and preferences, its difficult to specify in detail.
Rectangular shape foundation, with longest sides north and south sides (up to 2:1 ratio) for south-facing solar exposure, minimize hot summer west-side exposure.
Colonial style two-story with basement?
Roof facing due south (or within 15 degrees), assuming views and solar access is equal in all directions.
No valleys in roof, no or minimize inside corners on the exterior (cheaper, easier, less maintenance problems likely).
Steel roof.
If cathedral ceiling, 4:12 to 5:12 max to avoid large interior height and heat stratification.
Unconditioned attic, ceiling insulation R-60 to R-90, depending upon the ease and cost of chosen installation, and analysis of wintertime heat loss/solar gains.
Wall insulation R-30 to R-50, depending on wall design and climate details. Double stud wall or 2x6 (prefer 24" o.c.) with exterior insulation polyiso or Roxul Comfortboard. Ply sheathing taped with Zip tape or Pro Clima tapes for ply joints and window flashing. Align windows/doors with existing studs. Careful attention to air-sealing and vapor management, specifics depend upon wall design.
Tilt-turn, casement, awning and/or fixed windows overall R-5/U=0.2 to R-8/U=0.12. Double or triple pane, argon-filled. South-facing windows double pane, higher SHGC, west and east triple pane lower SHGC. So you benefit from winter solar gain but avoid summertime solar gain. Majority of glazing on south side, minimize west side glazing area, assuming views and solar access.
Assuming plot plan and site design allows, decks/patios/porches on east and west sides to extend use from Spring through Fall, avoid shading south side windows, and shade west windows.
No central heating system except one mini-split per floor, and/or radiant or resistance electric heaters per each habitable space. No fossil fuel or woodburning anything to avoid pollution, maintenance work, complexity, and initial costs. Unnecessary with a really tight, well-insulated envelope, solar gains and electric heating. Put your money into insulation, air-sealing and an ERV, not complex heating systems, or gas stoves requiring venting lots of conditioned air.
Centralized plumbing layout with bathrooms, kitchen and laundry abutting each other or stacked above/below each other. First floor bath and doorways meet accessibility standards for wheelchair use.
If flat lot, I'd delete the basement, EPS Type IX below thickened raft slab edges, EPS or Roxul ComfortBoard along slab edge sides and below slab center. Polished, stained, sealed slab floor or tile floor throughout. Pangowrap termite/vapor barrier on slab edges and below slab.
Lance,
In case you missed them, here are three articles that address your question:
Ten Ways to Improve a New Home
Green Building for Beginners
Martin’s Pretty Good House Manifesto