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seton.prefab•2mo

Transport-induced microcracks in GRC façade modules — acceptability thresholds?

We’re shipping GRC (glass reinforced concrete) façade modules cross-country to a modular hospital project. On arrival, several panels showed hairline cracks near the embedded anchors — no full section breaks, but visible under magnification. The structural engineer signed off most of them as aesthetic-only, but our insurer flagged long-term liability concerns, especially due to seismic bracing exposure. We’ve reinforced edges for the next batch, but we’re unsure if these microcracks should trigger rejection or repair. Is there a performance-based standard or past precedent that supports field acceptance of non-penetrating GRC microcracking?

Comments (10)

concrete_conor2 months ago

lol our prefab crew just said 'if the crack don’t leak, it don’t matter'. Not helpful, I know, but point is this’ll keep happening unless transport gets reworked. Treat the root cause, not the crack.

imani.amlo2 months ago

Try referencing ISO 14692 from composite piping — it defines non-propagating matrix cracks as acceptable if localized. Not a façade code, but worked for us in a modular exterior review.

joe.bridges2 months ago

Cracking during transport usually points to lifting point misalignment or insufficient cradling. We had to add accelerometers to confirm — just visual QA won’t prove causation or prevent recurrence.

sarah.devops2 months ago

We had one case where the field crew patched hairline cracks with UV-cured epoxy filler. It met visual QA, but moisture trapped behind it later caused efflorescence. Don’t patch unless you’re sealing the rear face too.

tasha.qs2 months ago

Keep in mind — if you accept microcracked panels now and they fail post-handover, you’ll have to absorb replacement under DLP. I’d cost out that risk explicitly and include it in your commercial discussion.

angie_structural2 months ago

We ran DIC scans across cracked zones and showed sub-threshold strain under design loads. That gave the AHJ enough confidence to accept cracks without full repair. You need lab test correlation, though.

hp.consulting2 months ago

Insurers will always default to worst-case. We had to submit finite element modeling of crack propagation under lateral seismic load before they’d agree to leave the panels in place. Took a week, but saved 60 replacements.

tm_facades2 months ago

We added strain gauges to GRC modules in-transit once and discovered shock loading from crane sway during lift-off did most damage. Might be worth retrofitting rubber isolators in cradle slots to avoid repeat on next delivery.

francesca.struct2 months ago

Check the crack direction relative to load paths. Radial cracks around anchor inserts may not be visual only — they could signal delamination or shear cone initiation. We once failed a panel with <0.3 mm cracking due to pattern geometry, not size.

fatima.cities2 months ago

You might cite EN 1170-7, which allows visible surface cracks under 0.2 mm width as non-structural — but it depends on environmental exposure class. If exposed to freeze-thaw, even microcracks can propagate.

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