Building Design

Combustible Exterior Insulation & Cladding

Something people don’t think about. New energy codes are pushing architects and contractors to build new buildings and retrofit existing buildings with exterior insulation. But despite building codes that require non-combustible materials, many of these insulations are combustible.

The problem seems to be particularly rampant in the United Arab Emirates – despite news articles reporting the authorities stating that all combustible exterior insulation & cladding would be restricted and banned in 2015 and yet again 2017. This obviously isn’t actually happening as another tower burned in May 2020 in Sharjah.

I’ve taken to spec’ing noncombustible exterior insulation – checking spec’s of the product from the manufacturer – but nobody seems to actually care. The NYC DOB doesn’t check or even look beyond verifying that you spec’d exterior insulation (you can literally spec nothing specific just state: “rigid exterior insulation 2″ thick R-10”) and it is the correct R-value. The building inspectors don’t bother to check if what you spec’d on the approved drawings is what is actually installed. On a project that got a violation for failing to install any insulation, the City was happy to approve the insulation that the contractor installed after getting busted. The product was not fire-rated, thus combustible. Hope that house never catches fire.

Mostly I’m working on small buildings – three story single-family homes, and three to four story apartment buildings, but the problem remains. New construction with combustible exterior insulation/cladding and any already installed is not removed. The code requires exterior walls that are two-hour fire-rated – built with non-combustible materials – yet nobody is bothering about the exterior insulation actually being non-combustible. Steel studs, 2 layers of gypsum board, R-10 – check. You’re approved.

I thought maybe after the Grenfell fire in London – a western city – things might change, but it has been many years now, and NYC has not made any changes.

Leave a Reply