Hello, generally post on Knots, but I am planning a new workshop/garage.
I am trying to get a foundation designed, and keep it a cost effective design.
It is 24 wide by 36′ long. I am building in to a embankment, so i will be able to get the front on grade and the other 2 sides and the back foundation wall will be out of the gound because the grade drops over 8 ft. The archcy says I need a 4 ft frost wall and then rebar that to go into 8 ft of exposed foundation wall. I will then be back filling this to lay a slab, and the outward pressure on the walls is the reason he says I need to rebar reinforce.
I am told 12 ft forms are very expensive, two pours are required and steel is high, and then the labor for the rebar work.
Cant raise the grade.
I thinking if would be better to go with a concrete floor to negate the need to rebar everything, and it would allow to have a full basement?
I need either a slab or concrete floor because I want to park a my tractor and p/u in it, and wood would not be able to do the job.
Any ideas? thanks very much
Replies
Hmm, do you know any structural engineers? (May be about to <g>.)
Might make a lot more sense to make two 24' "wing" walls, and run steel between them. This would then get a corrugated metal deck over which you'd have the concrete garage slab poured. You're re-arranging some of the costs, sure. But, you also don't need 72 feet of 12' forms, either.
If you have a good concrete supplier nearby, you could also use concrete "plank" construction, too.
Now, in all fairness, don't sell wood short--it's good structural material, just not in the the more common sizes used in residential work.
Want a concrete floor for the garage? No sweat, corrugated deck will screw down to wooden structure--just needs to be engineered that way.
One other thing you might look at is a hybrid foundation--poured on three sides into forms, and then ICF on the 8' tall "open" side.
Someone mentioned pre-stressed concrete which would alleviate outward pressure on walls and provide parking under. I am starting to research it now, pending cost may be the way to go?
Maybe also look at steel or a wood systems.(as opposed to concrets) What type and size of wood beams should I looking in to futher?
thanks joe p
With that much drop what about puting in the bassement and using that for the cars. Then the whole floor systme could be wood for the shop portion.And you would not need to make it as large.
if you go concrete block stem wall, there will be no concrete form
I am told 12 ft forms are very expensive, two pours are required
12' forms expensive ? Definitely more than 8' or 9' but you aren't talking about anything that involved or any significant length.
rebar definitely recommended, but again, nothing too extreme here.
two pours. wrong. we routinely do 12' to 14' pours in one lift. it's just a longer vibrator with skilled guys operating and filling the forms.
carpenter in transition
In reference to all who responded, thanks very much.
Alas,
I called a local form company (i am in RI) and got a quote of $125 per lf for 12 foot wall as opposed to $20 for a standard 8 ft per lf wall? He also said I may want to look at flexicore for the floor leaving a whole basement, which he could put in a footing and then a 3 ft wall and then use the standard 8ft forms which would cost me $38.00 lf. Sounds like a solution. I def want to be able to drive in on grade, so I need either a slab or some type of system to support tractor and p/u. Getting a basement would be a bonus. I cannot backfill any wall except for the front 24' wide going into the embankment.
Depending on flexicore price to buy, ship, rent crane and so on, if I use the $38.00 per lf estimate for the forms, and I need to rebar, is rebar labor and cost expensive? Am I going down the flex road needlessly?
I have already decided that if I go the rebar way, I will leave the back 12FT section open with a double wall so as to allow a small basement section, and still park in the first 24 ft on grade.
thanks for all the advise and sugestions.
joe p
you dont have a choice, there is no way you can do this without rebar.
Are you saying it would need rebar with a flexicore floor? I know I would need it if I fill in the walls to create a slab?
Is rebar work expensive?
Guess I'll make a few calls.
thanks joe p
Is rebar work expensive?
It's quite a bit cheaper than abandoning a new building.SamT
For my concrete guy, it wasn't a big deal to go higher. He charged a few bucks per linear foot more for walls over 8', but it wasn't too big a deal. He uses mostly 2'x4' steel forms, as shown in my earlier photo. Stacks them as high as he needs to, and uses 1' or smaller filler strips where necessary.
My foundation ended up costing about $5400 (this was last spring). When he gave me the initial estimate, he said that if it had just been a 4' frost wall all around, it would have been about $3600. He billed the rebar at $1 per foot, don't remember how much he used.
My floor cost me $1800 for concrete and finishing - I did all the prep work, including laying insulation, tubing for future heated slab, mesh and a couple hundred feet of rebar, and hired a guy to handle the pour & finishing. 5" thick in the back, 6" thick in the front where the cars are parked. 7 months now, and no sign of any cracks.
Don
1800 not a bad price, material for concrete alone would run $1000
Edited 4/6/2006 2:56 pm by brownbagg
"1800 not a bad price, material for concrete alone would run $1000"
We used 14 yards, he charges about $130 per yard. I think concrete was running around $90-95 or so at the time, he might get a better price. That means he got around $500 for a day's work. His helper was his 12 year old son. Seams like a decent pay for him, and cheap insurance for me - I had thought about doing it myself, but I know I wouldn't have done as good a job, and with my luck it would have set up faster than I could keep up with, and I'd have to look at a half-assed job forever.
If I was doing a much thicker slab, I'd probably object to this pricing method, as his labor doesn't change appreciably with thickness. All in all I was happy.
When I first saw the finished floor, I was a little disappointed with the flatness, but I think it really is typical of floors I've seen around here. He had a power screed and power trowel. Deepest puddle is probably only 1/4-3/8", and there's only one of those and a couple shallower ones, which aren't a problem now that I've got it enclosed. I think to get really flat floors requires more sophisticated setups, which probably involve much more $$$.
Now that I've got a bunch of junk in there, it looks fine. I took a lot of pains to get the gravel well compacted, and he used a nice stiff mix (except for the last 3 yards, which came from the plant a bit sloppy). We didn't use any control joints, and so far no cracks.
Don
Can you give me a link to Flexcore. Did a Google search and all kinds of stuff is called "flexcore", but couldn't find anything in a quick search that seems related to concrete. I have been looking into Lite-Deck and Insul-Deck for creating a concrete floor and would like to have any additional alternatives.Thankshttp://www.litedeck.com/
http://www.insul-deck.org/
Edited 4/7/2006 12:10 am ET by CaseyR
Casey, thanks for the links. I will look into them.
Flexicore comes out of Pittsburgh PA. There is also a company in Epsom NH, called NewStress that makes a similar product.
Here is Flexicore link though ;
http://www.pittsburghflexicore.com/whatsnew.htm
PS I called Flexicore, waiting for the sales guy to return call. Have not got a estimate yet.
joe p
Edited 4/7/2006 12:22 pm ET by joepez
Ah!, the "i's" have it. Doing a search on "flexicore" gives lots of links. If you get a rough estimate, let me know what they say. I have contacted LiteDeck and InsulDeck and hope to have some estimates in the near future. It would be interesting to compare costs. The LiteDeck and Insuldeck say they can do up to 30' to 40'. They also show guys walking around carrying the 2' wide sections - don't think they can do that with Flexicore planks. Insuldeck and Litedeck claim to be the low priced leaders, so we shall see.
I am still trying to get an estimate on Fleixicore. In the meantime, I was given another option. Steel web beams, covered with corogated metal, covered with 3-4 " concrete with wire mesh embeded, should support what I want. I can do this with no crane too. Its a normal commercial building process, so I should not have a problem with finding a contractor too.
What have they told you about the insuldeck? Price?
joe p
Insuldeck gave me the phone number of a local rep, but since I am too deaf to hear over the phone, I asked them to give me a fax no or email. Will probably be a while before I get the info.My first impulse was to go for the concrete over corrugated steel deck over steel trusses. For my application, I don't have the depth to use the trusses. I actually like the looks of the simple Warren truss and would be happy to use it on my ceiling. I looked into some commercially available steel trusses and the minimum depth sold was 16". I also then needed to insulate the roof which would have added to the thickness and the cost. I am hoping one of the concrete over polystyrene based roof/floor systems won't be too expensive. If you don't need the polystyrene insulation, then what you have suggested is probably more practical.
Casey, I have talked to several local contractors, and a archy, and and engineer. I have come to the conclusion, that based on my particular soil and grades involved, I am gonna do a modified slab on grade for the first 20 feet and then the last 16 feet will be a full basement with a wood deck cover. I will be able to park on the first 20 ', and have my shop on the 16' section. It keeps the cost affordable, yet I still get a small basement for the equipment. The cost no matter how I fiqured it, would be 3 times vs a slab.
good luck
joe p
Joe,
Insulated Concrete Forms.
I have a manual in my hand which has pre-engineered reinforcement specs for an unbalanced backfill height of 12', using blocks with an 8" cavity. Using 6" blocks, the tables go to a backfill height of 10'.
With a certain amount of care, pouring 12' of ICF form at a time is doable. I've done it. Finding bracing 12' high might be a problem, but you can make that if you have to.
Ron
thanks for the reply.
I talked with a couple of form companies. They can put in a 1' footing with a 3' frost wall which give me my 4 ' frost wall requirement, then put a regular 8 ' forms on top of that and I can get away a lot less expensive than a 12 ' form.
thanks for all the help
regards joe p
My garage is pretty similar: 24x36, front at grade, back corner is 12' down to bottom of footings. I did all the dirt work, and my foundation guy had no trouble pouring the walls.
The footings stepped down to the deep corner, and were wider and thicker at that point - standard 8" thick by 18" wide at the front down to about 2'x2' at the deep corner. That made for a 10' wall at the deep end on top of the 2' footing.
He put some rebar in the tall section - spaced about 2' apart for the verticals, and 2 or three courses horizontally, in addition to the course running around the top.
I backfilled the outside of the deep section to about 6-8' from the top last fall, and will bring it up a couple more feet as soon as I can get my dad to bring over some more dirt and his bulldozer.
The inside I backfilled to about a foot from the top and poured a floor.
As I was backfilling the inside, I got to thinking that I could have put a partition wall half way back, filled the front where vehicles will be parked, and had a basement in the back section. Would probably have added another grand or more to the concrete installation, and another floor to build, though.
Here's a photo of the foundation just after it was poured, and a couple of the current look. This got me through the winter with a place to park, now I need to add the second floor with gambrel roof, and replace the temporary fiberglass siding with shiplap pine. Looks like another busy summer. I keep telling my fiance that we might have to postpone the wedding in August if I don't have the garage finished ;)
Don