Transite – Bill Stone ACI

Transite is a a trade name for a product manufactured by Johns-Manville and was introduced to the building industry as early as the late 1920’s.  Johns Manville is not the only company that manufactured rigid panels and pipe using asbestos content.  The addition of Transite asbestos to Portland cement allowed the manufacture of strong and thin sheet products, typically the amount of asbestos content was somewhere between 12-50%.  Due to its fire retardant nature, Transite was widely used in residential construction and is often found in siding, flue pipes and in sheet form lining the areas around furnaces and hot water tanks but it was also widely used in siding. 

When used in siding it often mimicked cedar shingle siding but unlike cedar, which is a natural and imperfect product, Transite shingle siding will be uniform in nature.  When painted, the asbestos is contained, but when paint fails, weathering can release asbestos fibers to the air.  In addition, paint prep work such as scraping can release the fibers as can peeling paint itself.

Transite siding.

       

Transite is easily identified; it is very rigid and has a gray cement color to it.  Since one of its leading benefits was its fireproof nature, it will be often found lining utility rooms or in flues.    Leading producer Johns Manville’ materials typically have a cloth like pattern to it.  Remember that without lab testing, there is no way of knowing the asbestos content.  Asbestos in Transite was phased out by the 1980s, the asbestos content being replaced with crystalline silica which has its own list of health concerns.

Transite ductwork.

Due to its rigidity, the presence of Transite does not necessarily mean asbestos fibers are airborne.  Unlike boiler insulation wrapping, Transite boards require force to damage them, but crumbling or broken pieces of Transite board are a problem and if Transite is subject to continued moisture, it can delaminate.  Areas where this may occur are in slab ductwork and when used as appliance venting.  Sometimes the Transite extends above the roofline, in other cases it can be subject to high moisture in flue pipe from condensation etc.

What to do if you find Transite?  I recently inspected a slab home with Transite ductwork and followed the progress as the potential buyers attempted to determine the potential health risk.  My clients first contacted several duct cleaning services and asked if they ever clean ducts in these homes.  The answer was no, but I believe if they weren’t informed of the Transite first, they would have cleaned the ducts without any questions/concerns.  Several asbestos abatement contractors were called out.  All agreed that the product was Transite and it would most certainly contain asbestos based on the year of construction, which was the late 1960’s.  All advised against any lab work as they firmly believed it would have asbestos in it.  One contractor said he could apply a coating to the ductwork, but could not guarantee full coverage.  None of the contractors had camera snakes to determine existing condition or to inspect after duct coatings were applied.  It seems that it is difficult to get competent abatement contractors at the residential level as the leading companies are working in the more lucrative commercial arena.

As home inspectors, per the ASHI standards, we are not required to even identify items such as Transite, but I feel it is a disservice to not inform our clients about these risks.  Unfortunately, the list of solutions to the problem you’ve identified will be short and your clients may find it impossible to mitigate the risks to their satisfaction.