installing sprayfoam roof and can't disturb existing | Ask Mason Knowles - SPF Consultant | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

Q&A Forums

installing sprayfoam roof and can't disturb existing Post New Topic | Post Reply

Author	Comments
daniel kempton Posted: Aug 26, 2013 10:52 PM	installing sprayfoam roof and can't disturb existing Here is an interesting problem, I have a metal roof to spray foam on, in a food processing plant type setting. Aside from the fact that the roof is enormous, extremely steep (11/12), there are remnants of an old asphalt coating that are starting to plister an peel in places. The roof can not be pressure washed or any type of mechanical sanding for fear of contaminating the food stores below. One theory of thought was to encase the entire roof with a type of wire mesh/chicken wire, run metal furring strip/bars continuously horizontally, not only to provide a continous contact securing the mesh , but also creating toe holds to traverse up an down on a safety line. Then spray 3" of closed cell roofing foam, and a urethane roof coating. The thought was that the old asphalt would basically be encapsalated, the furring strips would be screwed to the structural framing, anchoring the mesh, thus anchoring the foam roof. Have you heard of any situations similar to this? Do you have any suggestions or recomendations? Type of mesh? Any input would be greatly appreciated.
mason Posted: Aug 29, 2013 08:45 AM	Some years ago an enterprising foam contractor developed a system for installing a polyester roofing mesh to a provide a smooth surface to spray foam to a metal deck (non corrugated). The mesh was mechanically attached at 2 ft intervals and the foam was able to be sprayed onto the mesh. Much of the foam went into the mesh and bonded to the metal and also went part way through the mesh into the flutes. The system was tested by UL and showed exceptional wind uplift resistance. I inspected more than a million sq ft of this type of roofing after Hurricane Katrina in Pascagoula, MS. It held up fine. The mesh comes in rolls that are 2 foot wide. You stretch it out first, then fasten it to the top flutes of the metal. Then spray foam directly through the mesh. You might have to work with it a bit to get the process down. The metal furring strips would help keep the mesh in place as well as provide additional wind uplift resistance. Be sure to CYA. I would get the system reviewed by a engineer who is familiar with SPF and wind uplift calculations. Roger Morrison or Tom Smith come to mind. Also, make sure the system is approved by your local building code inspector and foam/coating manufacturer.

Author

Comments

daniel kempton

Posted: Aug 26, 2013 10:52 PM

installing sprayfoam roof and can't disturb existing

Here is an interesting problem, I have a metal roof to spray foam on, in a food processing plant type setting. Aside from the fact that the roof is enormous, extremely steep (11/12), there are remnants of an old asphalt coating that are starting to plister an peel in places. The roof can not be pressure washed or any type of mechanical sanding for fear of contaminating the food stores below. One theory of thought was to encase the entire roof with a type of wire mesh/chicken wire, run metal furring strip/bars continuously horizontally, not only to provide a continous contact securing the mesh , but also creating toe holds to traverse up an down on a safety line. Then spray 3" of closed cell roofing foam, and a urethane roof coating. The thought was that the old asphalt would basically be encapsalated, the furring strips would be screwed to the structural framing, anchoring the mesh, thus anchoring the foam roof.
Have you heard of any situations similar to this? Do you have any suggestions or recomendations? Type of mesh? Any input would be greatly appreciated.

mason

Posted: Aug 29, 2013 08:45 AM

Some years ago an enterprising foam contractor developed a system for installing a polyester roofing mesh to a provide a smooth surface to spray foam to a metal deck (non corrugated). The mesh was mechanically attached at 2 ft intervals and the foam was able to be sprayed onto the mesh. Much of the foam went into the mesh and bonded to the metal and also went part way through the mesh into the flutes. The system was tested by UL and showed exceptional wind uplift resistance.

I inspected more than a million sq ft of this type of roofing after Hurricane Katrina in Pascagoula, MS. It held up fine.

The mesh comes in rolls that are 2 foot wide. You stretch it out first, then fasten it to the top flutes of the metal. Then spray foam directly through the mesh. You might have to work with it a bit to get the process down.

The metal furring strips would help keep the mesh in place as well as provide additional wind uplift resistance.

Be sure to CYA. I would get the system reviewed by a engineer who is familiar with SPF and wind uplift calculations. Roger Morrison or Tom Smith come to mind. Also, make sure the system is approved by your local building code inspector and foam/coating manufacturer.

You need to login to reply to this topic. Please click here to login.