Nailable Concrete Roof Channels - circa mid 1950's

[WEJ83]

Looking at a roof deck on a mid 1950's era building. The owner has limited structural plans. The roof is fairly steep pitched and is called out on the plans as asphalt shingles over roofing felt on 2 1/2" nailable concrete roof channels. The panels have the legs turned down and notched over steel joists at about 4 feet on center.

Apparently, a roofer in the past removed the asphalt shingles and installed a new composition shingle roof using standard roofing nails, or at least something not appropriate for the decking. Many of them are simply bent over and don't have any penetration into the deck itself.

Looking for any historical info on the deck span capacity and the appropriate fasteners to use for a new composition shingle roof.

 

[KootK]

Check out this thread: Link. The available capacities seem significant.

 

[JLNJ]

General Motors has millions of square feet of these roof panels. They had trouble with spalling of the concrete and the rebar corroding since the cover over the rebar is almost nothing. Their brittleness and lack of redundancy caused a few failures and fatalities. Be careful about using the advertised capacities.

 

[WEJ83]

Thanks for the input. From the bottom sides these particular panels look to be in excellent condition, but no idea how the top sides look as far as moisture damage, or possible damage from someone possibly using the wrong nails. I'll be sure to include plenty of cautions to the roofer and some field observation once the existing roofing starts to come off and the deck is exposed.