Can CSST Gas Piping Be Run Through Concrete?

I ran into this the other day on a 1950’s era house that was fairly meticulously updated by a builder. The renovation work was not done as a flip or to sell. This builder had lived in the house for about 5 years and was now selling. he clearly took great pride in his work and much of it was well above-average. However, these are the kinds of jobs I am always on guard. Even the best builders don’t always read all the directions.

One of the critical element to this find and call in your home inspection report is to try and identify the brand of CSST.

The product I am most familiar with is Gastight and FlashShield. I see this product the most and they have a nice installation manual, attached here. Gastite

On page 55 they have clear instructions 4.3.8 Routing Through masonry Material

“Masonry material” includes but is not limited to brick, concrete, mortar, and stucco. The term “through masonry construction” refers to any enclosed/concealed construction spaces where CSST is routed in close proximity to masonry but does not apply to exposed CSST mounted to a set masonry surface. When it is necessary to install Gastite/FlashShield+ through masonry materials the tubing shall be routed through a conduit that is 1/2″ larger in diameter (to ease routing) than the OD of the CSST and appropriate for the application. The sleeve must maintain a continuous watertight barrier between the masonry material and the CSST, up to or past the edge of the masonry hole. Masonry encasement refers to any enclosed/concealed construction within “masonry material” that produces distributed loads. For masonry encasement see Underground Installations (Section 4.9).

Interestingly, TracPipe seems to be less clear. See their illustration below – found on page 44 of their TracPipe installation manual. The illustration says to sleeve if required. It is not clear to me who is going to require this if not the manufacturer but I suppose this must vary by jurisdiction.

In this case, the repair seemed to be an easy call for my home inspection report and in general, it seems logical to me to protect this piping as it passes through masonry, so I generally recommend a sleeve for protection when I find this condition. If you run into TracPipe, you may want to be more careful in your recommendation.

When it comes to burial or running the piping into the slab, the manufacturers seem more clear. Here is TracPipe

4. TracPipe®CounterStrike® SHALL NOT BE
The conduit shall be sealed at any exposed end to
prevent water from entering. See instructions for
underground installations Section 4.9.

This is from Page 70 in the Gastight manual

a) Gastite/FlashShield+ CSST shall not be buried directly in the ground or directly embedded in concrete (e.g. slab on
grade construction, patio slabs, foundations and walkways). When it is necessary to bury or embed Gastite/FlashShield+
CSST, the tubing shall be routed inside a non-metallic, watertight conduit that has an inside diameter at least 1/2 inch
larger than the O.D. of the tubing (Fig. 4-87). For ends of the conduit installed outdoors, the conduit shall be sealed at
any exposed end to prevent water from entering

I hope this helps and please find the attached manuals if you have additional questions. This blog is not intended to be comprehensive but specific to CSST and concrete.