Carpentry, Roofing, and Building Envelope
Framing and carpentry
Platform framing dominates light construction: floor joists, subfloor, walls, then the next floor or roof. Know stud spacing, header sizing, king and jack studs at openings, fire blocking, and the difference between bearing and non-bearing walls. Sheathing provides racking resistance and a nailing base; fastening schedules are specified and inspected.
Roofing
Slope dictates the system. Asphalt shingles generally require a minimum slope, with a double underlayment layer in low-slope applications; below that, a membrane roof applies. In cold climates an ice-dam protection membrane is installed along eaves before underlayment. Flashing - at valleys, penetrations, walls, and drip edges - is where leaks actually occur. Roof ventilation follows the balance rule and code ratios relating net free vent area to attic floor area, with intake low and exhaust high.
Building envelope
The envelope controls water, air, vapor, and heat in that order of priority. Water-resistive barriers shed bulk water; flashings direct it out and down; the air barrier controls infiltration; the vapor retarder belongs on the warm side of the assembly for the climate, and misplacing it traps moisture. Windows must be integrated into the WRB with sill pans and proper shingle-lap sequencing so upper layers shed over lower ones. Sealants are a maintainable backup, never the primary defense.
Trap
A question asks why condensation or rot appeared in a wall and offers 'use more sealant.' The correct answer nearly always involves a discontinuous air barrier, misplaced vapor retarder, or reversed flashing lap.
Rule of thumb
Water goes down and out. Every flashing detail should shed water onto the material below, never behind it.