How Architects Select Building Materials in Practice

The order is the method

This is an editorial decision sequence, not a universal scoring formula. Record why each candidate remains, is excluded or needs evidence.

Assumed example: an exposed upper-storey wall needs a project-approved fire assembly, confirmed support capacity and reachable maintenance. These fictional candidates have no product performance claims.

Takeaway: An assumed pass on one constraint does not clear the remaining unknowns.

Step 1: Define the application precisely

“Exterior wall” is not an application. A usable definition names:

• Which elevation, and its exposure — driving rain, prevailing wind, sun path.
• What height, because fire and access requirements change with it.
• What substrate the material fixes to, and what that substrate can carry.
• What the building is used for, because occupancy drives regulatory requirements.
• What performance is required — acoustic, thermal, impact, water.

Takeaway: Write the exposure, substrate and required performance before shortlisting.

Step 2: Apply the hard constraints

These are pass or fail. A candidate either satisfies them or leaves the list.

• Fire performance for the building’s height, occupancy and jurisdiction. For facades particularly, this is frequently the constraint that decides the answer, and it must be confirmed against local regulations and the tested assembly rather than the material family.
• Structural capacity — can the wall or frame carry the material and its support system, and can the fixings reach something that will hold them.
• Code and approval — some materials require specific approvals for specific applications, and those vary by jurisdiction.
• Planning or conservation constraints on appearance, where they apply.

Takeaway: Resolve the applicable fire, load and approval constraints before appearance.

Step 3: Filter on durability in the real exposure

Not durability in general — durability under the conditions this building will actually experience:

• UV intensity and orientation
• Moisture load and drying opportunity
• Freeze-thaw cycling
• Salt, in coastal or de-iced environments
• Impact and abrasion at ground level
• Chemical exposure, in industrial contexts

Fixings and support systems belong in this step too.

Takeaway: Check fixing corrosion, attachment and support compatibility separately; a panel result does not establish fixing performance.

Step 4: Filter on maintenance and installation reality

Two questions that get skipped:

Who maintains this, how, and how often? Not what is theoretically possible — what will actually happen. In a hypothetical example, assume recoating every five years at fifth-floor level above a public footpath. If the agreed budget cannot fund that access and work, reject that assumed maintenance plan. Use the product’s actual guidance for a real decision. See durability and maintenance comparison.

What happens when part of it is damaged? Check whether individual panels can be removed, how a continuous finish is repaired and how replacement pieces will match weathered work.

Takeaway: Review access and repair instructions with the maintenance budget.

Step 5: Then choose on appearance

From the surviving candidates, compare appearance now and at the project’s intended review horizon.

Use samples and mockups at the intended size and in the building’s light. See natural vs engineered building materials for how variation behaves differently across those two families, and interior vs exterior wall materials for what changes when a material crosses the envelope. The building materials and finishes guide covers the wider context.

What this process protects against

• Late elimination. Discovering at technical design that the chosen material fails a fire or weight requirement, after it has been rendered, presented and approved.
• Unqualified comparison. Tables of adjectives instead of tested figures with their conditions.
• Cost illusion. A cheap material with an expensive maintenance regime, chosen on supply price alone.
• Sample bias. Approving a whole elevation from a small swatch.

Where the process legitimately bends

Occasionally appearance is a hard constraint — a conservation requirement, a planning condition, a client commitment that will not move. Then it moves up into step 2 and is treated as pass-or-fail like the rest.

Takeaway: Record an appearance requirement as a hard constraint when it is genuinely binding.