Siporex Roof Panels

[woodman1967]

I am working on a project where there will be Air intake hood will be installed on the flat roof of an existing building. Everything was set and ready for installation when it was discovered the roof was built using 4" siporex roofing panels. The building is 40 years old. There was a concern that the panels may be brittle and may crumble around a hole cut in the panels to allow for the intake hood.

Problem is I am unfamiliar with the product. Does anyone have experience with this? The roof joists are spaced 10' oc and the opening will be 9' square.

Any help would be appreciated

 

[msquared48]

Why don't you avoid the problem by removing enough of the panels to create an opening larger than you need, then infill with supporting structure and other materials as needed.

Mike McCann
MMC Engineering

 

[Ron]

Are you sure the material is Siporex. I don't think it has been around 40 years. Are you sure it isn't Tectum?

 

[woodman1967]

Hey Mike, I think that is what they plan on doing.

Hey Ron, I have the original drawings from the late sixties and there is a detail specifying siporex.

 

[Ron]

woodman1967..thanks. I just couldn't find anything older than about 1980 for Siporex.

I wouldn't expect it to be more brittle with time. It's autoclaved aerated concrete (AAC). Most of the AAC I've encountered is relatively consistent.

I agree with Mike's approach. We would do that for most any type of decking material that we don't have specific properties for.

 

[SkiisAndBikes]

woodman1967,

Somewhere deeply buried in my library of information, I have a copy of an original Siporex manual. I will try to locate it if you still think it might have some useful information.

If memory serves me, the panels are usually in the 4 MPa or 5 MPa range for compressive strength. This may account for some of the reports that they may be brittle and crumble. They are quite easy to cut openings into. Years back I worked on a project where the Siporex panels were deteriorating due to rebar corrosion as a result of a long term leaky roof. We reinforced suspect areas with simple steel framing back to the post tensioned beams that supported the Siporex panels .... essentially a similar idea to what has been proposed above.

 

[woodman1967]

Thanks everyone for your advice

We have decided to clean everything back to the roof joists then infill, basically what Mike McCann suggested.

Thanks SkiisAndBikes, the info would be interesting but probably not necessary for now.

Thanks again

Malcolm