DIY Home Improvement Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter #1 (Edited)
I'm designing a home for myself and my SO with an unusual design, and even more unusual load bearing needs.

This house will have a concrete slab foundation, and the floor will be the concrete slab (no wooden joists). The only wooden floor part will be the bathrooms, which will be raised up slightly for the sake of easier plumbing.



This layout is 30x30' measured to the outer edges, to give you a sense of scale.

I have two hot tubs that will be close to each other, sitting directly on the slab foundation. Each one is sitting on 28.5 sq ft of floor space, and each one has a filled and occupied weight of roughly 2,000 lbs.

Any insight on areas that may need to be poured thicker or be given extra reinforcement would be greatly appreciated. I'd also love some insight on overall slab thickness. My intention was to use a 6" thick slab. How much better off might I be using 8" thickness?

I've also read a few things about slab foundations that are poured thicker around the perimeter to support the load bearing walls. Do you believe this would apply to my layout?
 

Attachments

·
retired framer
Joined
·
42,899 Posts
Usually the plumbing is done before the slab, no need to raise the floor.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #3
Usually the plumbing is done before the slab, no need to raise the floor.
I understand, but I want as little plumbing in/under the slab as possible. I'd prefer future repairs be simple, instead of a jackhammer-involved ordeal.
 

·
retired framer
Joined
·
42,899 Posts
I understand, but I want as little plumbing in/under the slab as possible. I'd prefer future repairs be simple, instead of a jackhammer-involved ordeal.
We don't see much of that with plastic pipe for the drains.
 

·
Registered
Joined
·
13,595 Posts
Plumbing supply lines Pex in 2" poly sleeves under slab, HVAC ducts under the slab for heating/cooling efficiency. One must have his ducks in a row but this is as good as it gets.
 

·
Hammered Thumb
Joined
·
3,446 Posts
Typically a slab edge would be thickened to support the walls if you have no frost depth to deal with. But if you are trying to raise your subgrade by 3' of fill (other thread), you will probably be going to a stem wall and not a mono slab.

There's no need to have more than a 4" slab under the remainder of the rooms, so you would just thicken any areas with larger loads.

RE the plumbing I don't know if you're hedging against more of a long-term maintenance issue or if this endeavor doesn't pan out and you want to rip it out, but if you have the public in here for the tubs, changing and massage rooms, having no steps takes precedence over in-slab plumbing.
 

·
Registered
Joined
·
3,665 Posts
The foundation you need depends on the annual temperature, location, seismic activity, loads, drainage and soil type. I could make suggestions but you need advice from a design professional who designs in your area. Sure, you could probably vastly over design it and make it work but you will spend more than paying for a design.
FYI, your hot tubs are about 70 lbs. per square foot. Typical codes for residential first floors are 40 lbs. per square foot, so it needs more.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #8
Typically a slab edge would be thickened to support the walls if you have no frost depth to deal with. But if you are trying to raise your subgrade by 3' of fill (other thread), you will probably be going to a stem wall and not a mono slab.

There's no need to have more than a 4" slab under the remainder of the rooms, so you would just thicken any areas with larger loads.

RE the plumbing I don't know if you're hedging against more of a long-term maintenance issue or if this endeavor doesn't pan out and you want to rip it out, but if you have the public in here for the tubs, changing and massage rooms, having no steps takes precedence over in-slab plumbing.
Thank you. It's not for the public, the hot tubs are personal.
 

·
Registered
Joined
·
3,009 Posts
Thank you. It's not for the public, the hot tubs are personal.
If they are for personal use why do you have them enclosed in the tiny rooms? There are also several other things in that area that would lead one to believe that it's not for personal use only.
 

·
Concrete & Masonry
Joined
·
3,865 Posts
If they are for personal use why do you have them enclosed in the tiny rooms? There are also several other things in that area that would lead one to believe that it's not for personal use only.
I was asking myself similar questions, but decided I'd rather not actually know the answers, lol........

Without spending too much time, if it were here, it would likely require a thickened edge and a 4" floor minimum. 6 or 8" thick is likely gross overkill with zero benefit. The hot tubs aren't that heavy, less than half the weight of a full sized pick up truck, which there are millions of parked inside garages in the US right now with 4" or less thick floors........
 
1 - 11 of 11 Posts
Top