Recessed shower floor with i-joists
Jandpp
| Posted in General Questions on
Not exactly a home efficiency question here but hoping some builder had done this before.
I’d like to drop the floor of my shower to make a curbless shower. The usual way to do this is to drop the subfloor so that it hangs between the floor joists flus with the top of the joists. I’ve seen this done with dimensional lumber joist but not with i-joists. Anyone done this? I was thinking of adding block as in the attached picture. Screw the side blocking together through the web and then the support blocking into both the side blocking and the side of the flange.
thanks for any advice
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Replies
I would extend the blocking the full depth of the I-joist web, so you're not putting extra stress on the web itself, but otherwise that seems like a solid plan.
For a curbless shower you also need to account for the depth of a mud pan or prefab system, so you'll need to drop the subfloor another couple of inches or so.
Take a look at the side load details (ie stair opening):
https://www.weyerhaeuser.com/application/files/2115/5907/2648/9030.pdf
The filler block has to be much larger but with at least a 1/8" gap. There is also a nail pattern to follow but I would also glue.
Did you end up doing the curbless? I have the same question. Do you need to use web stiffeners on both sides of all the joists, for the full length? I’m assuming so.
When I did it with I joists, I made the floor thicker. It happened that I had a 4 foot 'hallway' in the bathroom, so I was able to have a slightly heavy threshold, unnoticeable slope level through the main part of the bath[~5 feet] then center drain in the shower [~41/2'x5']
Check with your Ijoist manufacturer. Boise Cascade sent me a detail similar to your drawing. But it involved notched 2x4s rather than two pieces. We are doing a recessed shower and heated floor in the bathroom/living room, so needed that 3/4" drop in those areas.
Fwiw I also found bracket kits from Ebbe and QM that they show without web stiffeners. You hang the plywood and/or 2x4 frame off the joists and walls with these brackets. I’m assuming the mortar layer over the joists is going to provide some structural integrity in lieu of an OSB layer.