Adding hydro floor heat -Does staircase need to be redone because of height increase on bottom step?

Jimmyzee

We were just told by our contractor that after we add floor heating to our main floor (then put new tiles on top), it will increase the height of the floor and then take away from the height of the bottom step of our stairs, creating the need to redo the whole bottom of the staircase to make all the steps even (otherwise tripping hazard). I'm assuming this will also cause an issue for the top step of the stairs leading to the basement as well. Does anyone have any advice or experience in the matter which can help? I don't want to have to pay for staircase fixing if theres way to do it = save unnecessary spending

As well, if you have any expert advice on the general topic of how we should go about adding the hydro floor heating

Thanks so much in advance!

STEVEusaPA

Yes by code, all risers need to be the same height. There's a video showing a staircase at a subway entrance that was (I think) 1/2" different and practically everyone stumbled on it.

hot_rod

It's amazing how a small fraction can be noticed on stair tread rise. Code allow up to 3/8" difference.

HVACNUT

Put in an elevator. 

PC7060

What is the projected increase in floor thickness?  Code is very particular but there are plenty of home with hardwood added to first floor with no changes to stairs.

I’ve found the first tread delta to be less impactful than changes in tread height from that point on. 

EternalNoob

If it's an inspected / permitted job then the delta rise on first riser will definitely be a violation. In practical terms probably not a big deal, and as others pointed out, a delta on the first step would be easy to get used to. A delta mid-flight would be asking for a trip to the ER.

Thinking way outside the box here, if you picked up the stringer footing by the increment needed for radiant (guessing 1 1/2" - 2"), i.e., increasing the stringer angle, this would translate to a minor and undetectable increase in slope on each tread. Doing the napkin math here, if your story height is 10 ft, your stringer will be about 18 feet long, and a 2" lift at the bottom changes the angle by 1 part in 108, or about a 1% slope, actually .9%. Hardly detectable. The inspector would never notice and i bet you never would either.

nibs

Specialized in stairs way back when I was a carpenter, The way it is done is to rebuild the staircase with the riser heights calculated for the new height. There is a way to cheat if it is close enough. Assuming the stair is a straight run, no winders and no landings, your contractor can unfasten the stair at top and bottom, pour the floor then reinstall the stairs, the treads will slope a little towards the back, but if it is not noticeable when using the stair bobs your uncle, You can calculate the slope of the tread, count the risers, measure the height increase at the floor and divide it by the number of risers.
EG lower floor is raised 2 inches, 12 risers, slope on the treads 2 divided by 12 =.16 of an inch, not noticeable when you use them, inspector will pass them no problem. But it may be easier and less expensive to build new.

hot_rod

lay a board down and try it out. Do a trial in the dark also😗. Have another family member try it out without telling them

Zman

hot_rod said:

lay a board down and try it out. Do a trial in the dark also😗. Have another family member try it out without telling them

Just have them put on a helmet, wrist and elbow pads first