Engineering calcs by text

The problem in one sentence

Your foreman is in a switchgear room asking what size copper feeder for a 60A circuit. Your HVAC PM needs CFM for a 24,000 BTU/h zone at a 20°F Δt. Your concrete super wants yardage for a 24′ × 38′ × 6″ slab. Today they call the engineer, or they guess, or they wait. Forward turns each of those into a four-second SMS round trip.

What you can actually ask

Each of the following is a real tool the orchestrator can invoke. Inputs match the descriptions; outputs always include the caveats and the formula used.

Electrical

• what size wire for a 60A copper feeder → NEC Table 310.16 lookup, copper vs aluminum, THHN / THWN-2 / XHHW temperature column applied when the insulation is known.
• voltage drop on #10 awg, 120ft, 30A, 240V single-phase → estimated drop with a flag for the NEC-recommended 3% branch-circuit threshold.
• what's the NEC section for GFCI in a bathroom → code-section pointer with the standing reminder that the EOR and the codebook are the source of truth, not the bot.

HVAC

• quick AC load for 1,800 sf sun-heavy in climate zone 3 → rule-of-thumb cooling + heating BTU/h with the “run a real Manual J before ordering equipment” caveat.
• CFM for 24,000 BTU at 20 delta-T → standard 1.08 × ΔT formula, returned in seconds, ready to size the branch duct.
• round duct size for 800 CFM at 0.08 friction → ASHRAE Fundamentals Ch. 21 sizing for a target friction-loss rate.
• OA CFM for a 30-person classroom → ASHRAE 62.1 combined per-person + per-area rate for the occupancy.

Plumbing

• GPM from 280 WSFU → Hunter’s-curve estimate of supply demand, used to size the building main.
• copper pipe size for 18 GPM at 8 fps cap → recommended nominal size for copper, PEX, or CPVC at the velocity cap you set.
• water heater for a 14-fixture office → rough storage + recovery sizing by occupancy and fixture count, with the “use ASHRAE Applications Ch. 50 for the actual spec” caveat.

Concrete & structural

• yards for a 24 by 38 by 6 inch slab → cubic yards with a 10% waste factor, rounded up. Concrete plants don’t take partial-truck returns.
• rebar LF for a 24 by 38 slab on 12-inch grid → linear feet of rebar at the bar spacing you specify, both directions counted.
• weight of 40ft of W12x26 → total steel weight for any AISC rolled section by length, useful for crane picks and hauling.
• allowable shear on a 3/4 A325 bolt → AISC single-shear allowable with the connection-design caveat.

Finishes & takeoff

• drywall sheets for 4,200 sf walls + 1,800 sf ceiling → 4′ × 8′ and 4′ × 12′ counts with waste factor.
• gallons of paint for 4,200 sf, two coats → gallon count at standard coverage.
• tile count for 240 sf of 12x12 with 10% waste → tiles needed at the waste factor you set.
• CMU block count for an 18 by 9 foot wall → standard 8″ × 8″ × 16″ block count with waste.
• flooring quantity for a 24 by 38 room in LVP → square footage with the waste-factor adjustment baked in.

Why this matters in the field

Every one of these questions is the kind that today routes through a phone call, a text to the PM, or a guess. The phone call interrupts the engineer. The text to the PM goes unanswered until lunch. The guess shows up in next week’s rework backlog.

The marginal cost of a wrong answer in commercial construction is enormous: a wrong wire size is rework + an inspection failure; a wrong duct size is a comfort callback; a wrong concrete order is a $1,800 short pour or an $800 partial-truck disposal. The marginal cost of a Forward answer is four seconds and an SMS round trip.

Caveats are not optional

Every calc the bot returns includes the formula or table it used, the assumptions baked in (default Δt, default friction loss, default waste factor), and the standing caveat that engineered loads, code applicability, and final connection design belong to the EOR, the codebook, and the published engineering standard — not to the bot. The bot exists to save the engineer’s time on the 80% of questions that are rule-of-thumb anyway, not to replace stamped engineering.

How the orchestrator decides what to do

Forward’s orchestrator (Claude Sonnet 4.6 with tool use) parses the text, picks the right tool, and fills the input schema from what you actually said. If a required field is missing — you asked for wire size but didn’t say copper or aluminum — the bot texts back one clarifying question rather than guessing. Forward’s ground rule is that a wrong answer in this domain costs more than an extra turn.

Try one from your phone

Text +1 (682) 300-6750 with what size wire for a 60A copper feeder. The demo project replies in under five seconds with the NEC table result, the temperature-column note, and the standing caveat.