Historic Resources Committee

This message has been cross posted to the following Discussion Forums: Residential Knowledge Community and Historic Resources Committee .
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Regarding the use of Snow Grip on historic structures, such as a slate or metal roof, the product is available in a clear coating.  It would not only enhance the snow retention capability of the roof with or without mechanical devices; but snow grip may also increase the service life of the roof.  The clear coating will likely change the appearance of the roof but I would encourage a sample / test application to see if the aesthetic change in sheen or chroma is acceptable.  Again the website www.snowgripit.com offers a way to contact the manufacturer.  Or send me a message at dennis.garde@gmail.com and I will put you in direct contact.......

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Dennis Garde Assoc. AIA
Principal
Energy Veritas Ltd
Mt Prospect IL
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I have been working on a National Historic Landmark with a slate roof, that dates to 1860. This roof was in wonderful condition for 140 years, and since 2000 a salesman came along and sold a coating that would do some of the same things that Dennis is claiming below for this new product. 10 years later, it looks like the best option for this slate is now a full replacement. The coating was so "plastic-like" that it sealed the slate so that it could not move, breathe, expand, or do anything that the natural material had been successfully doing for 140 years. Most of the slates have cracked in half, the coating has started to wash into the copper gutters, and we have a documented a series of problems.

This is not to say that this new "snowgripit" is anything like the product that we are dealing with. I wrote this post to remind all of the discussion readers that every new product deserves a chance, but the proper lab testing and investigation by conservationists is key when dealing with historic buildings and historic materials. And in this case for a coating on metal (or any other) roofing, I would check with a structural engineer - particularly due to the number of recent roof collapses from snow in New England.

(For legal reasons, I will not publicly share the name of the coating we are dealing with.)

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Robyn Chrabascz AIA, NCARB
Historic Project Architect
Kann Partners
Baltimore MD

I couldn't agree more. I am restoring an 1894 library in Maine. It has a beautiful Monson slate roof that is being dis-assembled to replace felt, some flashing, install ice shield, then re-installed. About 200 SF will be replaced from slate salvage source. As we all know, slate is a wonderful material that needs to stand on its own (pun). As is the case in with sealing masonry, it may not be the right thing to do to "preserve". Many products out there have yet to withstand such tests of time as slate on its own. 

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M. Curt Sachs AIA
Portland ME
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Original Message:
Sent: 03-21-2011 10:29
From: Robyn Chrabascz
Subject: Snow Grip - A New Product

I have been working on a National Historic Landmark with a slate roof, that dates to 1860. This roof was in wonderful condition for 140 years, and since 2000 a salesman came along and sold a coating that would do some of the same things that Dennis is claiming below for this new product. 10 years later, it looks like the best option for this slate is now a full replacement. The coating was so "plastic-like" that it sealed the slate so that it could not move, breathe, expand, or do anything that the natural material had been successfully doing for 140 years. Most of the slates have cracked in half, the coating has started to wash into the copper gutters, and we have a documented a series of problems.

This is not to say that this new "snowgripit" is anything like the product that we are dealing with. I wrote this post to remind all of the discussion readers that every new product deserves a chance, but the proper lab testing and investigation by conservationists is key when dealing with historic buildings and historic materials. And in this case for a coating on metal (or any other) roofing, I would check with a structural engineer - particularly due to the number of recent roof collapses from snow in New England.

(For legal reasons, I will not publicly share the name of the coating we are dealing with.)

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Robyn Chrabascz AIA, NCARB
Historic Project Architect
Kann Partners
Baltimore MD

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Edward Cazayoux FAIA
Principal/architect
EnvironMental Design
Breaux Bridge LA
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Very interesting Robyn.  As a consultant to a historic renovation, I recommended that the architect not spray the underside of the slate roof deck with the closed cell foam he had speced to seal the attic from the exterior.  He did it anyway.  Does anyone have any information on this type of application?






Original Message:
Sent: 03-21-2011 10:29
From: Robyn Chrabascz
Subject: Snow Grip - A New Product

I have been working on a National Historic Landmark with a slate roof, that dates to 1860. This roof was in wonderful condition for 140 years, and since 2000 a salesman came along and sold a coating that would do some of the same things that Dennis is claiming below for this new product. 10 years later, it looks like the best option for this slate is now a full replacement. The coating was so "plastic-like" that it sealed the slate so that it could not move, breathe, expand, or do anything that the natural material had been successfully doing for 140 years. Most of the slates have cracked in half, the coating has started to wash into the copper gutters, and we have a documented a series of problems.

This is not to say that this new "snowgripit" is anything like the product that we are dealing with. I wrote this post to remind all of the discussion readers that every new product deserves a chance, but the proper lab testing and investigation by conservationists is key when dealing with historic buildings and historic materials. And in this case for a coating on metal (or any other) roofing, I would check with a structural engineer - particularly due to the number of recent roof collapses from snow in New England.

(For legal reasons, I will not publicly share the name of the coating we are dealing with.)

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Robyn Chrabascz AIA, NCARB
Historic Project Architect
Kann Partners
Baltimore MD

Eddie,
When faced with a dilemma such as the one you describe in a similar situation - we were installing closed-cell foam insulation in a stud space - we achieved reversibility by first installing a layer of felt to isolate the historic fabric. I'm sure there's no panacea, but we regarded this as the best solution in that circumstance.

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Thomas Howorth FAIA
Principal Architect
Howorth & Associates Architects
Oxford MS
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Original Message:
Sent: 03-22-2011 07:22
From: Edward Cazayoux
Subject: Snow Grip - A New Product



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Edward Cazayoux FAIA
Principal/architect
EnvironMental Design
Breaux Bridge LA
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Very interesting Robyn.  As a consultant to a historic renovation, I recommended that the architect not spray the underside of the slate roof deck with the closed cell foam he had speced to seal the attic from the exterior.  He did it anyway.  Does anyone have any information on this type of application?