[MassHistPres] Question about use of "Azak" or other synthetic polymer based products
Sullivan, Charles M.
csullivan at cambridgema.gov
Wed Jun 6 19:15:42 EDT 2018
The Cambridge Historical Commission has adopted the practice of allowing synthetic replacements for trim details that are in ground contact (like porch skirt boards and step risers) or exposed to the weather (like rooftop balustrades or deck railings with no roof over them). We took this step after a property owner in the historic district was facing replacement of a balustrade in wood for the third time in 35 years.
Cellular PVC (as produced by Azek and other manufacturers) comes in many traditional profiles and common lumber sizes. It has a matte finish that can (and should) be painted, and when finished is indistinguishable from wood. Domestic lumber today bears no resemblance to the old-growth materials that were available until the 1940s and ’50s. Exotic hardwoods may be the answer for the time being, but they are getting more expensive to source and may not be environmentally (or ethically) sustainable in the long term.
The Commission has also allowed wood gutters to be replaced with copper or fiberglass as long as the profile matches the existing (or original) profile. We allow this because wood gutters are inherently undersized for all but the smallest roof surfaces. This mismatch of capacity vs. demand, combined with the propensity of narrow outlets to clog with the slightest obstruction, leads to destructive overflows and consequent deterioration of fascia, soffits, and siding. The same exterior dimension in a 4” x 5” (nominal) thin-walled metal or fiberglass gutter will have over three times the capacity of an equivalent wood gutter. High-end frame houses in the late 19th century were sometimes built with copper gutters formed to traditional profiles and painted to match the trim.
The Commission does not permit K-style gutters (the familiar flat-bottomed aluminum gutter profile) as replacements unless they were original to the building, but copper or fiberglass gutters in an appropriate profile preserve or recapture the traditional appearance of a cornice while offering measurable benefits in efficient capture of rainwater. While not cheap, they offer homeowners greater longevity and lower demands for maintenance.
Owners of designated properties in Cambridge may utilize these materials with staff review to ensure that replacements match existing or original details; more complicated cases are referred to the full commission for a public hearing.
The Commission has also approved synthetics for fence replacements in the Old Cambridge Historic District. One corner property had almost 500’ of frontage; the previous wooden fence, lasted less than 15 years before the Commission allowed it to be replaced with painted PVC. The result is functionally and visually indistinguishable from wood. Shiny plastic fences would not be allowed under any circumstances.
Charles Sullivan
_____________________________________________
Charles Sullivan, Executive Director
Cambridge Historical Commission
831 Massachusetts Ave., 2nd Fl.
Cambridge, Mass. 02139
ph 617-349-4684; fax 617-349-6165; TTY 617-349-6112
http://www.cambridgema.gov/Historic
[cid:image001.png at 01D2F0B7.974468D0]<https://www.facebook.com/cambridgehistcomm> [cid:image002.png at 01D2F0B7.974468D0] <https://www.flickr.com/photos/cambridgehistoricalcommission/> [cid:image003.png at 01D2F0B7.974468D0] <https://www.instagram.com/chcat831/> [cid:image004.png at 01D2F0B7.974468D0] <https://cambridgehistoricalcommission.wordpress.com/>
From: MassHistPres [mailto:masshistpres-bounces at cs.umb.edu] On Behalf Of Judy Neiswander
Sent: Monday, June 4, 2018 7:22 PM
To: MHC Preservation listserv <masshistpres at cs.umb.edu>
Subject: [MassHistPres] Question about use of "Azak" or other synthetic polymer based products
Fellow Historic District Commissioners;
Our Commission is often asked to allow the use of "Azak" or other synthetic polymer based products in moist areas in lieu of lumber. Most often requested are applications at the base water table adjacent to the grade, and for fascias and soffit material backing up gutters at the roof eave. When painted this material is indistinguishable from wood of similar dimensions.
Neither the Park Service nor MHC prohibit use and we are interested how other Historic Commissions have handled these requests. We would like to set a policy for our 'Guidelines'.
Thank you for your advice.
Judy Neiswander,
Commissioner,
Town of Dedham Historic Districts Commission and Historical Commission.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.cs.umb.edu/pipermail/masshistpres/attachments/20180606/0b0fbedb/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 777 bytes
Desc: image001.jpg
URL: <http://mailman.cs.umb.edu/pipermail/masshistpres/attachments/20180606/0b0fbedb/attachment-0003.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.jpg
Type: image/jpeg
Size: 778 bytes
Desc: image002.jpg
URL: <http://mailman.cs.umb.edu/pipermail/masshistpres/attachments/20180606/0b0fbedb/attachment-0004.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image003.png
Type: image/png
Size: 1220 bytes
Desc: image003.png
URL: <http://mailman.cs.umb.edu/pipermail/masshistpres/attachments/20180606/0b0fbedb/attachment-0001.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image004.jpg
Type: image/jpeg
Size: 809 bytes
Desc: image004.jpg
URL: <http://mailman.cs.umb.edu/pipermail/masshistpres/attachments/20180606/0b0fbedb/attachment-0005.jpg>
More information about the MassHistPres
mailing list