by Jerry Peck - Codeman on Tue Oct 27, 2009 7:49 am
Hi Eddie,
The code you are under is likely the 2006 IRC (International Residential Code) which has the necessary sections of the IFGC incorporated into it.
Because you are running energy sources to an island, there really are only two ways to get from Point A outside the island to Point B inside the island: 1) from underneath; 2) from overhead.
This is from the 2006 IRC, it describes just what you described if you were to choose running the gas piping underneath the slab.
- G2415.6 (404.6) Piping in solid floors. Piping in solid floors shall be laid in channels in the floor and covered in a manner that will allow access to the piping with a minimum amount of damage to the building. Where such piping is subject to exposure to excessive moisture or corrosive substances, the piping shall be protected in an approved manner. As an alternative to installation in channels, the piping shall be installed in a conduit of Schedule 40 steel, wrought iron, PVC or ABS pipe with tightly sealed ends and joints. Both ends of such conduit shall extend not less than 2 inches (51 mm) beyond the point where the pipe emerges from the floor. The conduit shall be vented above grade to the outdoors and shall be installed so as to prevent the entry of water and insects.
If you elect to go overhead, the decorative covering would allowed to be decorative in nature on its finish, but would need to be structurally sound to serve as a chase for the gas line to provide both protection and support for the gas line. It is not something you would be 'covering the gas line with to make it look acceptable', it would need to be constructed from the island up as a hollow chase in which the gas line was then run. You could make this chase look like a column or even make it look like a support for decorative items mounted from it. You may even elect to install a matching one on another corner of the island to complete a certain look and add functionality to them.
One decision to make is what would be most practical in the long run? Spending the extra money and not having to work around one or two columns? Or, not spending the extra money and incorporating the column(s) into your design, knowing that you will not be able to remove that column in the future?
Also consider this: how are you running electrical to the island? In a separate raceway underneath or down from above in the same (or separate) chase you could then use for the gas line? The electrical would not just be allowed to have a slot cut out down into the concrete slab for the conduit, the conduit would need to go down through the slab, under the slab, and back up through the slab.
Another thing to consider is termite treatments. The slab was likely pretreated for termites, depending on the age of the house and the termite pretreatment used at the time of construction, you will likely be destroying that pretreatment in the areas in which the under-slab soil is disturbed, requiring new pretreatment.
If you elect to go with the vertical chase, keep in mind that the chase will need to be fireblocked at the ceiling level with all penetrations through it sealed around.
This sounds to me as though you have basically covered your two choices, underneath or overhead.
While each has its own peculiarities, underneath gives more island design freedom by not having to provide a vertical chase to the ceiling, while overhead gives more and easier flexibility for future changes as you will not easily add or relocated the gas or electrical from underneath.
Will the island require removal of areas of the slab for plumbing (a sink in the island) regardless of your gas or electrical choices? if not, that may be a helpful deciding factor in going overhead. If yes, then going underneath is already being part way done.
Jerry Peck - CodeMan
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Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired