I agree with Mike on the "masking of variations (due to inconsistency in
firing) in the lighter glaze colors."
On the quality of the brick "it depends". We just did a project where the
original white glazed brick was failing from poor detailing of the 1950's
cornice stripping of a 1920's building on the Upper West Side. A previous
project (by another architect and contractor) rebuilt one of 2 street facing
parapets with matching brick in 2002. We were working on the other parapet
last summer and the project extended thru this past winter. Over the course
of the winter the glaze began to spall - the parapet was just 5 years old.
First in little pin-holes then larger as the winter progressed. We probed
the wall and noticed the same faulty details used in the 1950's had been
incorporated in the parapet which was rebuilt in 2002. The faulty detail
allowed terra cotta belt courses to be back-pitched towards the wall (this
terra cotta was reused from the original 1920's construction). The water
saturated the wall and the modern brick below failed. However, later in the
year rebuilt building corners also began to spall too where there was no
influence from the back pitched terra cotta. So, we identified the white
glazed brick that was used, got test data from the manufacturer and
discovered that the brick did not comply with Severe Weathering Criteria
which is typically required in NYC. Admittedly the back pitching was not
good but less than adequate bricks were also a big problem. Ultimately we
added flashing over the terra cotta and replaced the spalling brick with
better material. Hopefully this will not reoccur.
Eric Hammarberg, Assoc. AIA
Vice President
Thornton Tomasetti
51 Madison Avenue
New York, NY 10010
T 917.661.7800 F 917.661.7801
D 917.661.8160
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Sent: Friday, July 06, 2007 3:58 PM
To: [log in to unmask]
Subject: Re: [BP] white brick
-----Original Message-----
From: [log in to unmask]
To: [log in to unmask]
Sent: Fri, 6 Jul 2007 2:41 pm
Subject: [BP] white brick
Co-op at 71st and Fifth Avenue, ca. 1960, is replacing its white glazed
brick facade, due to the usual failures. In this case they have chosen ...
white glazed brick.
question 1: why are there little raised black specks on the glaze? To make
it look interesting, But not very.
question 2: is currently produced white glazed brick better than the 1960
version? It MAY be. Glazed brick wasn't well understood back then and is
GENERALLY better understood now. The question is whether the current a/e
specified and the manufacturer provided a GOOD brick which will not be
overly water-absorbent and will therefore be frost resistant or were the
failures due to maintenance? Not a maint issue. The old brick absorbed too
much water, which got stuck behind the glaze, froze and spalled.
c Ralph
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