Welcome to our comprehensive guide on water heater code requirements!
In this article, you'll learn:
When inspecting homes, I sometimes come across water heaters that have missing TPR valves and other risky issues.
When the TPR valve and discharge piping isn't up to par, it can lead to burns. Or if the water heater isn't protected from cars, it can result in severe damage.
And if you are in an earthquake or seismic zone, straps need to be installed in case of disaster. Just imagine: water heaters sometimes enter zones of extreme temperature and pressure, and building code helps prevent costly mistakes.
Keep reading to learn our list of the top 11 water heater installation codes!
Jump To A SectionWater heater installation code requirements improve home safety and help prevent water damage.
A water heater is a compact tank full of pressurized hot water. Water heaters have even been known to explode on occasion. And of course, water heaters can cause significant water damage if it leaks in a finished area.
Water heater installation code is clearly laid out in the IRC or International Residential Code in Chapter 28 - Water Heaters.
The IRC is known as a model code, and many U.S. states and countries have adopted it. Your local state may have some variation to the IRC or exceptions.
And don't forget, your local county or state will likely require a permit for a water heater installation and for it to be installed by a licensed plumber.
This article covers the most important water heater install codes in the IRC, but always check your local state because it has priority.
A catch pan should be installed underneath the water heater where leakage will cause damage.
A catch pan will collect any leaking water and prevent drywall, subfloor, wood flooring, and any other finish materials from getting damaged.
If the water heater is installed in a finished area, there should be a pan installed. If the water heater is in a garage, unfinished basement, or outside, then a catch pan is not required.
Also, if the water heater is in the attic, the water heater needs a catch pan because it may leak onto the finished ceiling below.
The catch pan should be made out of No. 24 galvanized steel, plastic at least 0.9-mm thick, or other approved materials by the manufacturer.
If the catch pan is made out of plastic, and the water heater is gas-fired, then the plastic pan needs to have a flame spread index of 25 or less. Also, the smoke developed index should be 450 or less.
Water heaters are prohibited from being installed in any area if it is being used as a storage closet.
Water heaters are prohibited from being installed in bedrooms or bathrooms unless it is in a sealed enclosure. Also, combustion air cannot be taken from the adjacent bedroom or bathroom.
Water heaters need to be protected from getting hit by cars.
If the water heater is in a garage or some area where there is risk of car damage, then it needs to have a barrier.
Water heaters need to be raised above the floor on a platform if it has an ignition source.
If you have a gas or oil-fired water heater with an ignition source (open flame or spark), then the water heater needs to be raised at least 18-inches above the floor.
Sometimes flammable vapors get released by accident in homes (especially garages), and the vapors tend to stay near the floor. If the water heater creates a spark or flame, it may ignite the flammable vapor, which is why this code is required.
One exception to this code is if the water heater is flammable vapor ignition-resistant as stated by the manufacturer.
The water heater needs to be protected from earthquakes if it is in a seismic zone.
There should be at least two straps on the top 1/3 and the bottom 1/3 of the water heater.
Each strap should be able to handle horizontal forces of at least 1/3 the weight of the water heater. For this building code, it only applies to homes in Seismic Categories of D0, D1, D2, and townhomes in C.
A TPR valve (temperature pressure relief) is required on water heaters to prevent an explosion.
If the pressure becomes too great in the tank, or if the temperature rises too high, then the TPR valve will release water and steam.
It can be a single 'combo' TPR valve, or the water heater is allowed to have a separate temperature relief valve and pressure relief valve.
The TPR valve needs a discharge pipe.
Sometimes when I inspect homes, the water heater is missing a discharge pipe.
This is dangerous because if the TPR valve is released, and if someone is in the room, they can get severely burned.
The discharge pipe for the TPR valve should go outside, to a catch pan, or a floor drain.
If it terminates on the outside, the discharge pipe should be visible to homeowners.
The discharge pipe should also be adequately sloped so it will drain by gravity.
The discharge pipe needs to terminate a maximum of 6-inches above the floor, and a minimum of 2x the pipe diameter.
Here are a few other code requirements for discharge piping:
Check valves and shutoff valves are not allowed to be installed between the TPR valve and the termination.
If the water heater is installed in a garage and vulnerable to car impact, adequate protection such as bollards or a wheel stop must be installed.
Damage to a high pressure appliance such as a water heater that is filled with hot water is potentially catastrophic.
The only exception to this building code is if the water heater is installed in an alcove or if it is elevated above cars where it won't ever get impacted.
Water heater installation codes are essential guidance for safety.
Water heaters are pressurized tanks, and have the explosive potential to destroy an entire home. And if they leak, water heaters may cause significant flooding damage.
Probably the most important codes has to do with the requirements for the TPR valve and discharge piping. The TPR valve is an essential safety device, and the discharge piping will also prevent burns to a nearby person.
I hope you enjoyed our guide on water heater installation code.
Hey, I'm Arie and I created this site. I am a licensed home inspector in Virginia and Maryland. I'm here to help you maintain, inspect, and renovate your home! I have seen many house defects over the years and saved my clients hundreds of thousands of dollars. And that's why I am your guide on the intricacies of home maintenance, saving money, and avoiding costly mistakes.
Hi Arie,
What are the requirements for condensate drains for hybrid heat pump water heaters? Can they go to a floor drain and are their any visibility requirements like the TPR drain? Reply
Hey Marty… there are no visibility requirements for condensate drains unlike TPR valves, and yes, floor drains are an approved termination point. The drain just needs to be properly sloped and it also may need a trap to prevent sewer gases escaping from the drain. I recommend checking with your local building department. Reply
Isn’t a bollard required if the water heater is in a garage? ReplyYes, if it is in path of possible car damage and not installed in an alcove or elevated above possible car impact. It’s detailed in Section M1307.3.1. Reply
Susan TameleoIs an electrical disconnect required if the main electrical box is not within reach of the water heater? Reply
Yes, I believe that is correct. I think this is discussed in the NEC and not the IRC. Reply Keith ElwoodIs it required to have a drain line to the outside. Not the TPR drain but the one that drains the water heater? Reply
In the IRC, it is required, though you will have to verify with your local code. Reply
Lita JohannesI’m looking at a home to buy. We did the initial viewing (new build) and we noticed the water tank is under the house (crawl space) and half of it is underground! I’m not a professional but this seemed odd to me. Can you tell me why a builder would do this and is it safe? FYI, home is in TN. Thank you! Reply
I’ve been told by a contractor (state of Maryland) that our residential water heater flue cannot ‘by code’ exhaust alone up our ceramic chimney, and thus requires either a metal upgrade to our chimney or to have it replaced when we replace our boiler with a ‘combi-boiler’. I don’t see anything obvious in the code here or in the Maryland code. What am I missing? Reply
Though I am in Florida, have you ever heard of a Code requirement of using Flex lines? Reply RICHARD NORRISThanks for taking my questions.
Are there clearance requirements between the water heater and wall?
Is a 3/4 inch PVC line sufficient for the drain pan?
Is the use of shark bite fittings accepted most of the time?
Is it OK to put the water heater on a heavy wooden platform? Reply
Hey Richard, Yes, 3/4″ is the minimum required for the drain line and the pan itself should be at least 1.5″ deep. I don’t see anything specific to water heaters for clearance in the IRC but there are associated requirements in regards to easy access, general gas appliance clearances, and the vent pipe (if it is gas-fired). You can see those requirements in this IRC section here. In IRC M1306.1, it basically states to follow the appliance label and the manufacturer’s instructions in regards to clearances. I would look up your water heater manual and see what it says. As far as I’m aware, all SharkBite fittings are approved for electric/gas water heaters. In regards to the wood platform, I believe some U.S. states do not allow it such as CA. I recommend checking with local state code. I don’t see anything specific to wood platforms in the IRC. It’s probably not the best idea though if the water heater is gas-fired. Some cement board can at least be fastened on top of it. I hope this helped. Cheers,
Arie Reply
