Wednesday, June 14, 2017

Architectural Foam - a Fire Hazard?

It may look like stone, but its basically Styrofoam.

The recent fire in London has everyone scratching their heads.  How can a high-rise building catch fire like that?  After all, it's made of steel, glass, brick and stone, right?

Maybe.  Maybe not.  We'll find out in the coming days what it was sheathed in.

I can tell you from experience that a lot of high-rise condos in Florida were sheathed in Architectural Foam, which is either expanded polystyrene (Styrofoam) or urethane materials, both of which can be highly flammable.   This foam may then be skim-coated with a thin layer of synthetic stucco to give it a stone or stucco-like appearance.

After the hurricanes in 2004, we saw huge chunks of this stuff blown off the new high-rises on A1A.  A big piece of "stone" cornice was in the middle of the road and I was sure it would have destroyed my car if I hit it, until I realized it was blowing down the street like a paper plate.   It was foam, not stone.   But it looked like stone.

The appeal of this process is obvious.  It weighs a lot less and is easy to install.   One condo high-rise in Alexandria's Crystal City was supposed to be sheathed in brick.  The contractor got a zoning variance to use synthetic stucco.  They put foam sheathing on the outside of the building (which is good insulation) and then stucco'ed over it.   It looked good, particularly with the fancy trim pieces on the corners and such.

But after a few years, it started falling off in sheets.   If not prepared properly, this synthetic stucco will peel off, and on a 20-story building, sheets of stucco can crush or severely damage a parked car or even kill a resident, if they are hit.   A lawsuit ensued and it took years to settle it and make repairs.

Fire, well, that might be another issue.

It is too soon to tell what they used on the outside of this high-rise in London.   But I am guessing it was some sort of architectural foam, from the way it lit up like a torch.  One witness stated they saw something like foam "snow" falling from the siding as it burned ("Witnesses described a white, polystyrene-type material falling like snow from the building as it burned.").  Other sites claim the refit last year was to add cladding to "improve thermal insulation" which sure sounds a lot like insulating foam to me.

The question is, how many other buildings in the world have similar foam cladding?  It is a popular form of re-fit, and makes an old building like like new - and look expensive, for a fraction of the cost of real stone.  And it provides better insulation as well.

And how many people with these stucco mini-mansions are basically living in unlit candles?

I guess we'll find out shortly.

UPDATE:  The BBC claims the cladding panels were insulated with polyethylene.   Ouch.