Perlite Precast Plank

[craigory28]

I am working on an existing building (1960s) that the roof is composed of precast perlite panels (about 1.5 feet wide) spanning between the roof joists. The company that made this product is no longer in business.

The roof has a lot of water damage and with the recent thaw it is raining in the building. Some of the perlite panels are saturated with water and the piece of the panel that had fallen off crumbles in my hands. I tracked down someone who used to work for the company who supplied the panels, and he told me water wrecks them.

I have the area closed off to the public, since the panel’s capacity has been compromised. I also said the panels need to be replaced with steel roof deck.

Does any know of any documentation or information on this product or the fact that water destroys it? I have a building owner who just accrued a large cost. I would like to provide him some supplementary technical information besides word of mouth from a former employee. Thanks

 

[dhengr]

Craigory28:
What do you expect people to say, since you didn’t have the forethought to name the product, or give any other meaningful info. on it. Read your own OP. There were hundreds (dozens?) of those light weight roofing products, each slightly different in their makeup, strength, resistance to moisture, etc., etc. That employee might be one of your best sources, and I would certainly not doubt his word. You already have your own evidence that he is right. Look around at college or technical libraries for catalogs, product info. and load tables on the product. A good source is an old Sweets Catalog from that era. This may be available over the internet, or on their own web site. It was a compilation of catalogs of products used in construction.

You didn’t make the roof leak. You didn’t buy the product in the first place. If it turns to crap when it gets wet, and you have evidence of that, what more do you need to say...., ‘it got wet, you let it get wet (maybe rephrase that to keep the client from hitting you), it’s crap, it has to be replaced.’ What good does investigating the makeup of the perlite in the product do at this point. You’ve got to just use some good engineering judgement, which it seems you have done so far, keeping people safe and about the prospect of saving this decking. And, unless the client is willing to pay for some long term investigation, I wouldn’t waste much time on it.

 

[CELinOttawa]

I agree with dhengr... We all want to tell a client "yes"; This time you just get to say "no".

 

[Sawbux]

I had a lot of experience with panels similar to the ones you described used in paper mills. However the ones I've seen appear to be a lot more durable, lasting 30 years in a wet environment.
The problems we saw were corrosion on the #3 rebars in the down-turned flanges or mechanical damage from maintenance dropping or wheeling heavy stuff on the roof. Temporary repairs were made with 2x12 wood planks wedged up under the panels. The flanges created a void where these could be fitted over the supporting steel roof purlins. You might get by using this method as a temporary measure to make it safe to occupy until replacement is done.

Steel decking would be an appropriate fix. It has similar span properties. We used heavy wood decking or fiberglass panels for corrosion considerations. Paper mill roofs are very bad environments!

Might there be a way to build a temporary "sub-roof" for safety of the occupants and to serve as protection during roof deck replacement? Plywood panels supported on wood joists?

When replacing roof, consider the lateral support of the roof beams and diaphragm shear provided by the roof deck. The concrete panels were probably lacking in both as they were either just set on top of the framing or tack welded in place.