Sometimes you come across an odd toilet rough-in size like 13.5 inches from the wall to the toilet flange drain hole. In such a situation it will be ideal if you can buy and install a 13 1/2 inch rough in toilet instead of going for a 12-inch rough-in toilet I see many people resort to as a last option. Fortunately for you, I was able to find a 14-inch rough-in toilet model that can be installed even on a 13.5-inch rough-in.
Here is that best toilet for 13.5 inch Rough in toilet replacement.
* Kohler K-3949-0 Highline Comfort Height Elongated Toilet (Amazon.com link)
Kohler K-3949-0 for 13.5 Rough in Toilet Replacement
This Kohler K-3949-0 toilet model is designed to be used as a 14 inch rough in toilet. However, when you install it on an exactly 14-inch toilet rough-in, it leaves a gap of 3/4″ (0.75″) inches between the tank back and the wall.
Below is the diagram from the Kohler K-3949-0 specification sheet that shows the gap of 3/4 inches between the tank back and the wall when installing on a 14″ rough-in. (See where pink arrow points)
This toilet model is bit expensive but is ideal for your non-standard 13.5 rough in size issue. The toilet comes from Kohler which is a very good toilet brand and the features are good. It has a taller Comfort Height seating position which is easy for adults and even people with disabilities. The elongated toilet bowl makes is more comfortable to sit on and provides better thigh support. It also offers more space to clean yourself than the old round bowl toilets. I checked its customer reviews and ratings online and they seem to recommend this as a good toilet to buy.
Another advantage of this Kohler model is it will leave a small 1/4 inch (0.25″) gap between the toilet tank back and the wall. Having this gap is good because it will prevent mold and mildew that form when toilet tanks touch the wall.
I hope this helps you. I see many people buy and install 12-inch rough-in toilets when they have a 13 1/2 inch rough-in. When you install a 12 inch rough-in on a 13.5″ rough-in, you get a large and very noticeable gap between the toilet tank and the wall. So your toilet placement will look odd. Also this gap increases the length of space taken up by the toilet. So, installing the above Kohler toilet will help you avoid these issues and save you space too.
Best Toilet for 13 inch Rough in Toilet Replacement?
Now, what do you do if you have a slightly smaller rough in size that needs like a 13 inch rough in toilet? Ideally, it would be great if we can find a 14-inch toilet model that fits even a 13 inch rough in. So I checked the specification sheets of all the 14 inch rough in toilet models for sale in the US market. Unfortunately, I couldn’t find any 14 inch toilet that will fit a 13 inch rough-in situation.
However don’t despair. I found several good 12 inch rough in toilet models that can be great for 13 inch rough in sizes. I recommend them, because when installed on a 12 inch rough in these below models hardly leave any gap between the tank and wall. So if they are installed on a 13 inch rough in they’ll only have a gap of 1-inch between the tank and wall.
One inch gap between tank and wall is normal. Many toilet models leave a one-inch size gap even on standard rough-in sizes like 10, 12 and 14 inches. Having a gap like this will also allow you to clean the back of the tank and avoid issues like, mold and mildew growth that happen when toilet tanks are too close and touching the wall.