Dug a hole

[javadog]

Some free advice...

You haven't shared the foundation details but I hope you're going to back fill that hole with structural fill and compact it, before starting on the foundation. You don't want your finished floor elevation to be anywhere near that low. I wouldn't wait, either. Any rainfall now is going to undermine the compaction of the subsoil.

You should also grade the surrounding area before you start the foundation, as doing it after the structure is built is orders of magnitude more difficult.

Originally Posted by JJ 911SC

This should be an easy decision, 14' celling = full size lift.

I love my scissor lift but if I had had the ceiling room, it would have been a full size.

Yes to the full-size lift--that's why I designed the high ceilings. Then I'll install the scissor next to it. Current plan is to have the lifts located at an angle along the south wall, so you drive into the garage and steer left, like into a diagonal parking space. And there will be lots of open space around the lifts.

The hole was dug down to the level of the footers, which need to be 24" deep around the perimeter. Here is the foundation detail.



Very little of the dirt removed will go back into the hole--just around the footer walls. Most of the dirt will be used to build up the area in front of the garage to backfill a retaining wall.

For the foundation, we'll bring in gravel and sand per the drawing. I plan to substitute a 20-mil reinforced vapor barrier (from my old company's crawl space kit).

[javadog]

That still leaves 18" of backfill under the specified sand and gravel...

Originally Posted by javadog

That still leaves 18" of backfill under the specified sand and gravel...

Correct. That will be fresh gravel/sand, which will then be compacted. The dirt guy said it's not a good idea to put the old stuff back in because it has lots of roots and vegetation in it that will decompose and cause voids under the slab. So will bring in the trucks . . .

I hired the same contractor as did my deck, since I was impressed with the crew.

[javadog]

Normally what takes place is that a soil test is done beforehand and the design follows from that. In this case, it looks like a typical footing detail was copied and pasted onto the drawing.

Building sites normally get excavated down to the point where all of the organic material on the top is removed and you're down to soils with a suitable bearing capacity. It may require additional material be brought in, placed and compacted, to get the elevation back up to the correct level. Putting in that much clean rock, topped with sand, will be difficult to compact and may result in settlement over time. Think of the sand working it's way down through the voids in the rock, over time...

If the organic material had been the typical 6" or so that is usually found in most locations, I'd have suggested digging a foundation trench 12" wide and leaving the middle undisturbed. Quicker, faster and less expensive in the long run.

Anyway, that option is now gone, so good luck with the project.

[dad911]

Why bother with the lowrise lift?

Having a 2 and 4 post lift, If I were to do it again, I would do a 1 post storage, like this: https://aclifts.com/lifts/m-1-single-post-car-lift/

and a 2 post.

As to the excavation, think seriously about what Java said. On a slab that large we pour 4-6 pads on virgin ground(when we pour footing), and dry stack open core cement blocks to grade. When you pour the floor, they will fill in with concrete. I would aim to place them in the vicinity of the lifts.

I also made a "grade beam" when I poured my current garage, when we levelled the stone I left a channel 4" deeper across the floor, in the vicinity of the 2 post lift, so the concrete was 8" thick in this area. Extra rebar in channel, make sure contractor supports it in the concrete, not lying on the bottom.

Originally Posted by dad911

Why bother with the lowrise lift?

Having a 2 and 4 post lift, If I were to do it again, I would do a 1 post storage, like this: https://aclifts.com/lifts/m-1-single-post-car-lift/

and a 2 post.

Love those 1 post lifts! I used to have a 4 poster, hilariously called a Backyard Buddy, that was a nice piece of equipment, but four posts get in the way. I left it back in Virginia when I moved. I'm currently figuring out which 2 post or 1 post to get for working on the car. I'm paranoid about cheapo lifts. Hopefully I'll find something good quality used.

I already have a Bend Pak low rise lift, and I like it a lot, so in the garage it will go. If I mount it flush in the floor, it will serve as a nice height-adjustable table for things like engines.

Originally Posted by dad911

As to the excavation, think seriously about what Java said. On a slab that large we pour 4-6 pads on virgin ground(when we pour footing), and dry stack open core cement blocks to grade. When you pour the floor, they will fill in with concrete. I would aim to place them in the vicinity of the lifts.

I also made a "grade beam" when I poured my current garage, when we levelled the stone I left a channel 4" deeper across the floor, in the vicinity of the 2 post lift, so the concrete was 8" thick in this area. Extra rebar in channel, make sure contractor supports it in the concrete, not lying on the bottom.

Yep. I appreciate advice from everyone. That's why I like this place.

My contractor likes his concrete guy a lot. I'll talk to him and get a good idea of what he plans and run opinions and ideas I get here and on my GJ thread at him. We are lucky that the grund here is really hard, almost clay. My house is over 70 years old and it had not settled much if at all in that time as far as I can tell.

[Shaun @ Tru6]

Great project Terry, looking forward to updates and some steam shovel video.

I can't imagine why you'd build this garage and not get a 2 post lift. But a 1 post does work pretty well too.

[cabmandone]

I get the appeal of the scissor lift recessed in the floor. I have hesitated to buy a lift simply because of the space it takes up. The ceilings in my shop are plenty high for a two post but the space those posts take up has kept me from pulling the trigger on one.

[javadog]

FWIW, clay is a very poor soil for a foundation, as it can change volume considerably with moisture content. That's why careful consideration needs to be given to grading the site, as subsoil moisture fluctuations from seasonal rainfall can be a real problem. Settlement isn't the only concern, it can swell and heave.

[RWebb]

yes, easy to embed the lift now

for heat, I suggest hydronic - easy to do when pouring a slab (and cheap as you can DIY) - the heat for the water/fluid can then be whatever you want - for PNW electric water tank is a good choice

hydronic is ultra-comfy heat and creates no dust - may be all you need, or can use it to boost the heat and reduce heat needed from other sources

Originally Posted by RWebb

yes, easy to embed the lift now

for heat, I suggest hydronic - easy to do when pouring a slab (and cheap as you can DIY) - the heat for the water/fluid can then be whatever you want - for PNW electric water tank is a good choice

hydronic is ultra-comfy heat and creates no dust - may be all you need, or can use it to boost the heat and reduce heat needed from other sources

Interesting idea. I wonder if I can sneak that in before the pour.

[RWebb]

the easiest is to use the pre-cut plywood 'forms' - they have some curves built up on them to hold the tubing bends - dunno if suitable for a concrete pour

it is not hard to place the tubing - I did it overhead after ripping out the ceiling (with helpers); the used reflective thin Al sheets to hold it n place and reflect some heat upwards - your task is a lot easier

[john70t]

Originally Posted by javadog

You should also grade the surrounding area before you start the foundation, as doing it after the structure is built is orders of magnitude more difficult.

^^This is good advice which should not be ignored!

Uphill water and soupy clay ground-shift will cause havoc later on.
Then everything is not 'finished'.
Foundation cracks. Walls shift. Cabinets attached to drywall fall off.
You will have to deal with another crisis again. Later on.

So do it right the first time.

It is your own investment.

[cabmandone]

Originally Posted by RWebb

yes, easy to embed the lift now

for heat, I suggest hydronic - easy to do when pouring a slab (and cheap as you can DIY) - the heat for the water/fluid can then be whatever you want - for PNW electric water tank is a good choice

hydronic is ultra-comfy heat and creates no dust - may be all you need, or can use it to boost the heat and reduce heat needed from other sources

Only problem with hot water in floor or through radiators is slow recovery. If you open a door it can take a while for the room to heat back up. I'd hang a "Resnor" and call it a day.

[Hugh R]

13' high door and you can drive in and park most RVs, resale, resale, resale.

[tcar]

Originally Posted by madcorgi

.... Here is the foundation detail.



Very little of the dirt removed will go back into the hole--just around the footer walls. Most of the dirt will be used to build up the area in front of the garage to backfill a retaining wall.

For the foundation, we'll bring in gravel and sand per the drawing. I plan to substitute a 20-mil reinforced vapor barrier (from my old company's crawl space kit).

You might consider dropping the interior slab slightly below the top of the foundation wall... say, 1" at the (back) end and sloping it about 1/8" per foot down toward the door to drain.

If you ever contemplate spraying/washing/squeegeeing the floor in the future.

So the drywall is up off the floor.
FWIW

[wdfifteen]

Originally Posted by madcorgi

The hole was dug down to the level of the footers, which need to be 24" deep around the perimeter. ).

Is that because the topsoil in your area is too unstable to support a slab?

[tdw28210]

Sub'd.

Looking to start a similar project next February. 22 x 24 with 10' walls and scissor trusses. about 22' at the peak. That is about all the space the lot and the HOA will allow. I've got a retaining wall about 14" behind the back of the planned pad. Could probably go deeper, but don't feel super comfortable get much closer to the wall. It will be a cathedral ceiling, drywalled in with a partial loft for storage in the back.

I am looking at doing a 5" pad pour and installing a single post lift. Like the idea of doing deeper concrete pour in the general area of the lift base. Debating between a storage or working style (no ramps). I will get a tall jack stand for support (or two) if I get the working lift.

[wdfifteen]

I’m going through something similar. Putting up a barn (can’t call it a garage) with a two post lift. I’m watching this thread too, looking for ideas.

Another azzhold neighbor thread - funny ending