20# vs 24# bond, vellum, and mylar: which paper for which job
Most architects, engineers, and contractors order blueprints on autopilot — same paper as last time, because the choice is invisible until something goes wrong. Usually that’s fine. But the choice between 20# bond, 24# bright white, vellum, or mylar can change a permit set’s longevity by months and a bid set’s cost by 30%. Here’s how to pick, with no marketing fluff.
The four substrates you’ll see in AEC printing
20# bond, white. The standard. About 75 gsm. Light, fairly opaque, takes plot ink cleanly. What 90% of permit submissions are on.
24# bright white. Heavier, brighter, slightly stiffer. About 90 gsm. Costs a few cents more per sheet, but you feel the difference the moment you pick up a set. Brighter paper also makes black-and-white linework look crisper.
Vellum. Translucent, smooth, archival. Historically used for original drawings because you could overlay it for tracing. Today mostly archival storage and the occasional jurisdiction that still requires it. Specialty order — email us.
Mylar. Polyester film, dimensionally stable, waterproof. For prints that have to survive weather, repeated rolling, or long-term archival. Expensive. Specialty order.
When to use which
Permit set: 20# bond, B&W, ARCH D or ARCH E depending on jurisdiction. The set lives at the building department for a few weeks, gets stamped, comes back. Paying for 24# is paying for durability you don’t use.
Bid set: 20# bond, B&W, usually ARCH D. Bid sets get handled, marked, photocopied, and discarded after the bid closes. A 12-set distribution at 24# costs about 30% more without giving subs anything they’ll notice.
Construction set / field copy: 24# bright white. This is the set in the GC’s trailer that gets unfolded a hundred times with notes scrawled across it. 24# stands up to the abuse. The brightness helps in a dim trailer at 6 a.m. Pay the extra for the field set.
Owner / client presentation set: 24# bright white, often with full-color title sheets. The one set the firm wants to look like a firm produced it.
Archive copy: Vellum or mylar for 30+ years (institutional, hospitals, public works). 24# bond is fine for 5–15 years in a flat file.
The cost difference, with real numbers
Industry-typical pricing, B&W, no shipping. 24# generally runs 15–25% over 20#:
| Sheet size | 20# bond (our price) | 24# bright white (typical market) | Difference |
|---|---|---|---|
| ARCH C (18×24) | $1.25 | ~$1.50 | +$0.25 |
| ARCH D (24×36) | $2.00 | ~$2.40 | +$0.40 |
| ARCH E (36×48) | $3.50 | ~$4.20 | +$0.70 |
A 25-sheet ARCH D permit set: $50 on 20#, roughly $60 on 24# — a $10 upgrade. A 12-set bid distribution of the same 25 sheets: $600 vs about $720. Worth it for a presentation set. Generally not for permit or bid sets.
What we stock: 20# bond, online, at the prices above. Heavier bond, vellum, and mylar are quote-based specialty runs — request a quote with size and count. For field sets specifically, we’d argue the cheaper play is a 20# set plus a one-click reprint from your saved file when it gets wrecked, rather than paying a premium up front for paper that’ll get rained on anyway.
Color: when it earns its cost
Full color costs roughly 3x more per sheet. It earns the cost in three situations and not elsewhere: rendered drawings where the color is the point; color-coded coordination drawings (MEP where duct is one color, plumbing another); and owner-facing presentation sheets like cover pages and zoning analysis. For permit and bid sets, color almost never earns its cost — most reviewers and contractors prefer B&W.
A practical rule of thumb
Building department, subcontractor, or anywhere it’ll be discarded in a few weeks: 20# bond. Jobsite trailer: 20# plus a saved file so reprints are one click. Owner presentation or anything that’ll live for months in a binder: 24# or coated stock — ask for a quote. 30-year archive or weather exposure: vellum or mylar — email us for a quote.
The vast majority of AEC printing is 20#. Default to it and step up only when the use case genuinely earns it.
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