Existing Gypsum Deck

[jike]

Can anyone suggest some ways of evaluating the integrity of an existing gypsum roof deck from the 50's for updated gravity and uplift loads. I am sure the roof has had leaks over the years. No shop drawings are available.

 

[youngstructural]

Existing system analysis is becomming quite big down here in NZ... get a copy of the New Zealand Society for Earthquake Engineering's "Assessment and Improvement of the Structural Performance of Buildings in Earthquakes", Recommendation of a NZSEE Study Group on Earthquake Risk Buildings, June 2006. It's available as a free download from NZSEE's website, and has alot of valuable tips, tricks, etc for evaluating existing conditions. Also, there is CBD 230 "Applying Building Codes to Existing Buildings" from the IRC in Canada (That's Construction Building Digest # 130, Institute for Research in Construction). Also available as a free download, and discussed evaluating existing structures (basically outlines conditions where you can say a structure has been field tested).

Hope that helps,

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[Ron]

jike...I would load test it. About 10 years ago we had to evaluate a series of roof systems, including gypsum decks. We decided to go with a point load test to check the overall integrity of the gypsum deck as well as gain an indication of its load capacity (the premise being that with such small panels as you find with gypsum decking, a distributed load only tests the supports, not the gypsum).

The point load clearly checks the shear capacity and can be used to back-calculate a distributed load capacity.

 

[jike]

A couple of clarifications:

This is not in an earthquake zone.

The gyp deck is part of a dome structure.

 

[Lutfi]

I have old load tables for Buffalo bulb tees and gypsum deck.

I evaluated some of these in the past. Water is a big enemy of theirs. They are also placed on top of drywall type board. They also use chicken wire type steel mesh.

SlideRule, let me know how I can get you the scans so you can add them to your web site.


Regards,
Lutfi