Hot Tub Suggestions Installed on Sloped Earth

[bud16415]

I outlined what I did in post 9. We live just inland of Lake Erie and have some of the coldest winter temps in the state. Two years ago it was 30 below for a week. The frost was really deep and we had issues with our porch and garage doors lifting because the frost got below the footings. On the other hand the 12x16 deck had no problems as it was supported only 6 inches below the surface but was designed to be free floating and not attached to the house. I built the deck 1 inch from the house and 3 inch step down from the door leading out. Out-swing door. The frost lifted the deck maybe an inch and in the spring it came back down. In your case a much smaller platform would work equally as well I think.

Soil is in a state of natural compaction unless it has been dug up in the last 10 years. I was careful when I dug down to keep the virgin soil flat and I did use a hand tamper when setting my post seats. I have them buried to ground level and the first freeze locks them in place solid. Then if the frost goes deeper they stay in location just move up and down. With this type of a deck you don’t rely on the posts for stability, it is all in the structure like your picnic table sitting out over winter. I could easily lift my deck and move it in one piece if I had a crane or something. People build them like this at campgrounds all the time and they hold up well. My power is going thru seal-tite so it will flex with a little movement.


With your footings and posts I never liked pouring right into water. Maybe you can bail your holes right before you pour or seal the ends of your tubes. 

[jukeboxpunk]

I have my 4 holes dug down to about 42" .  I also widened the bottoms out to about 16 inches and plan to do the garbage bag method of pouring the footings to get a wider base. Also now considering adding 2 more footings in the center. Currently the footings are 7' oc apart. 

The hot tub is a 7 person hot tub with a 7'7"x7'7" footprint. So it should overlap the footings once on top. The hot tub without people weighs about 5600 lbs. And to split that between only 4 footings seems a bit shy.

BTW water is dried up and gone, which I am happy about.

Ill post pics later

[bud16415]

To give you a feel for support my tub is 8x8 and 6000 pounds filled. Deck is 12x16  with 3 rows of 4 posts about a foot in from the sides. The tub sits in the corner more or less with access room on the one end for the cover lifter about 2 feet. But all the weight is over 2 of the 3 beams running the 16’ direction. 4 posts land under the tub is all and they are 4x4 about 20” long the 4 carry some weight thru the beam. I ran the column numbers and 4 posts that short were way more than enough.

I’m pretty sure your 4 piers you are pouring will be way more than you need. I would add rebar to them for the pour though.

What are you using for beams, joists  and decking. Will you be using hangers or stacking the joists over the beams?

[jukeboxpunk]

Going back and forth on using a post from the footings. If using a post ill probably use 6x6 notched for the beams. Beams will run parallel to the slope.

For the beams i was either going to triple up 2x8s or sistered 2x10s 10ft length. I would have a 1.5' cantilever all around, and it leaves me room should I want to add posts for something.  Tub will sit centered on deck so that each corner of tub is over footings.  The span between footing is only 7ft. tub is 7.4'x7.4'

For the joists i was planning on keeping it consistent with the beam size and maybe sister up some of the center joists. Also plan on adding blocking in between joists.

For decking I was going to with 2x6s. secured with Camo screw system. 

This deck wont be very high in the end. from ground level up to level is about 15-16" on sloped low end maybe less. I will either use a post or bring my concerete footing the height i need, then the opposite end will be either flush with footing or on a small post.  Trying not to exceed 30" height.

For steps for getting onto the deck I am going to get reclaimed granite curb. They sell it here cheap, being in the "granite state" afterall.   

[bud16415]

Triple 8’s or double 10’s will be plenty. So will 6x6 posts that short. 5/4 decking is more than enough but the 2x6 will work fine.

True PT posts made for below grade will outlast a couple hot tubs. I would hold the posts off the bottom of the holes about 6” and mix a bag or two of ready mix and dump in each hole. Back fill and compact as you go with a 4x4 post.   

[jukeboxpunk]

Joists 12" or 16" oc?  Probably 2x8's 12"oc and 2x10's 16 oc?

[bud16415]

For a deck that small you are only talking about a couple pieces of wood going from 16” to 12” OC. If it makes you feel better go with 12” but 16” would be fine. You mentioned blocking and for that short of a span using joist hangers and 2x decking all screwed down blocking wouldn’t be required. But again you will have scraps left over adding a few blocks won’t hurt anything.

If you ever get rid of the tub you can always donate the deck to NASA they can always use a good launch pad. Hehe.

[jukeboxpunk]

Launch pad for sure!

It sucks I am going these extra steps to make this thing secure.

I started down this path so I am going to finish it this way.

I listened to my engineer buds and they are like overkilling me here with this thing.

[bud16415]

Lots of farmers go out in the field with a water tub for livestock about the size of a hot tub and toss it off the back of a wagon fill it with water and it sits there for 20 years winter and summer. Frost bumps them around some but they stay put.

You are not doing anything much different except getting it off the dirt a few inches.

Your base as planned is going to rock! In the good way. We expect pics detailing the construction all the way up to filling it with water. 

[jukeboxpunk]

Currently I am in a holding pattern.

Have the holes dug but not filled yet. We have been having a series of storms with rain. This upcoming weekend I am going to attempt to set, add rebar, level and pour footings. Sometime this week I am going to string up my level lines.  I ran ran lines initially for the placement of the footings, however they got cut or moved from digging. So new lines and level. I have some room for deviation. Each footing is at different hieghts due to the slope. I can either run the m ground level or level them completely to the highest point. My plan is to ground level them and use posts to level beams.

I bought my PT wood for posts and beams along with 1/2" bolts. Going to notch the posts and bolt the beams to them. Each post will be set in a simpson tie. Deck frame and joists will set right on over the beams.  We do have high winds in the area im at.  We had a tornado go through my neighbors woods back in '08. Went for 60+ miles. So I will tie the joists and frame down to the beams some how.

Currently have the site covered with a tarp. Ill take some pics this weekend when I start back up again.

[bud16415]

The joists can be toe screwed to the beams and in addition maybe every other one can have a 2x4 PT block run the height of the beam + height of the joist. Kind of fit into the corner, screw thru the thin direction into the beam and then screw thru the joist into the block. That thing with 3 tons of water isn’t taking off. You may lose your cover in a high wind if you don’t keep it buckled down though.

The Simpson ties are the best way to attach the posts. Stick a J bolt in during the pour.

Good luck with the weather we got 5” of rain the other night in 3 hours. What a mess that made. 

[jukeboxpunk]

Trying to scope out my wire online figuring it would be cheaper. Looking at 6 awg 4 wire with a shielded ground enough to handle a 80ft run from main panel to spa panel. HT is 240v 50 amp Bullfrog.

Someone said I could get away with 8awg but guess it isnt rated for 50 amps for that distance.

My run won't be going underground, but through my eaves. I do not have a basement or crawl space. Instead my plan is to go from HT to spa panel underground, connect, then up the siding and into the eaves, run all the way down the length of the house and down to my main panel.

[bud16415]

Trying to scope out my wire online figuring it would be cheaper. Looking at 6 awg 4 wire with a shielded ground enough to handle a 80ft run from main panel to spa panel. HT is 240v 50 amp Bullfrog.

Someone said I could get away with 8awg but guess it isnt rated for 50 amps for that distance.

My run won't be going underground, but through my eaves. I do not have a basement or crawl space. Instead my plan is to go from HT to spa panel underground, connect, then up the siding and into the eaves, run all the way down the length of the house and down to my main panel.

I ran 6-3 w/ground Romex from my panel to the outdoor GFCI sub panel. When you exit the house you are not supposed to run romex outside. If you go down your wall and into the back of your GFCI panel that will be to code. You can also put a Jbox at the point you are leaving the house and then run single conductor in conduit down the outside of the house. I thought that was crazy it is the same wire and insulation only in an outer sleeve so I just transitioned to PVC conduit where I left the house and used the same romex all the way to the GFCI breaker. From there to the tub I would suggest single conductor in conduit under ground. In my case I ran #8 from there to the tub as mine required 7 conductors as I have a split GFCI breaker panel. Heater and tub are on separate breakers. In your case run 4 #6 wires.     

[bud16415]

By the way with #8 you will drop 6.3 volts or 2.6% at full load, with #6 drop is 3.9 volts or 1.6%

I was always told keeping it under 2% is a good thing.

Code says the GFCI subpanel has to be at least 5’ from the edge of the tub and has to be in eyesight of the tub.

[jukeboxpunk]

Yup I actually went with 6awg wire.

I was able to get my footings and post supports in. went with 6 footings, overkill. Just notching and cutting my posts to the heights I need. Some of my beams will be flush mount on concrete on the right side. 2x10s sistered for beams. beams are not in their finished position either. just there for reference leveling.   

This image is of the beams and posts just loosely in place. Haven't mounted anything. I want to make sure posts are level

My cell phone definitely has some distortion to the lens.  The image makes the slope look steep.