I am looking to build a natural gas line in the back of the house for an outdoor grill. There is a line already running to the rear of the house for a gas fireplace, as depicted in the picture.

enter image description here

The plan is to direct gas to a grill with 61000 BTU and a burner with 30000 BTU - there may be times when both are used simultaneously - unlikely that I'll be running the fireplace at the same as these 2 cooking appliances. The existing run is about 50 ft. from the main line - and the outdoor grill will likely extend/divert/add another 10 ft.

My questions are:

  • Can I use a CSST pipe to tap into one of the 2 available capped ports with a provision for a shutoff valve?
  • Can I run the pipe under a deck, or will it have to be buried?

Of course, a licensed professional will handle the installation and pressure test, but before seeking quotes, I wanted to understand the scope of work. CSST pipes appear to be moldable and easier to run compared to metal pipes - at least to me :)

  • You still haven't mentioned length. That's critical for any decision relating to gas piping.
    – isherwood
    Feb 28, 2022 at 21:09
  • 1
    I added a large gas grill to a 1/2" line that supplied a water heater and a dryer with no problem ( 30 ft to the grill). Mar 1, 2022 at 1:20
  • 3
    The regulator in the picture reduces gas pressure -- you can't just use either of the pipe stubs; you need to use the right one. Which is the right one depends: if the existing regulator has capacity to serve the new load you'd want to attach on its output side. If it does not, you could attach an additional regulator to the stub on the supply side.
    – Greg Hill
    Mar 1, 2022 at 3:00

1 Answer 1


By some charts you'd be exceeding capacity of 1/2" pipe at 20 feet already with 91,000 BTU/h. Code doesn't allow you to state that you'll only use one appliance at a time. You have to pipe for simultaneous full capacity use.

IFGS 402.1:

Gas piping systems shall be of such size and so installed as to provide a supply of gas to meet the maximum demand and supply gas to each appliance inlet at not less than the minimum supply pressure required by the appliance.

So, this may work, but only if the 1/2" run is less than around 20' total. This may mean upgrading the portion of pipe inside the structure, or running new 3/4" line from the last tee at larger pipe.

For more detailed and confident answers you'll need to provide a complete diagram of the gas network in your home, and information about the meter.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.