looking for solutions to an old concrete floor

[hoffman912]

Hi Gang,

So i have a 100 year old garage is a stick building on a concrete pad, with no vapor barrier. the concrete is like the craters of the moon, has some moisture come up with efflorescence/salt. None of which is conductive to storing or working on a classic car. I need to fix a gutter causing some water to pool next to the garage, but that really does not seal in or fix all of the issues.

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there have been some sections where additional concrete was poured over top about 3/4-1"

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there is also evidence of where the garage was expanded at one point -black top about a foot into the garage and a spot where a post once was

I want the garage to have a durable, flat and very dry surface. I want to be able to work on cars, have them on jack stands, maybe a scissor lift. I want to be able to drag engines around on engine stands and floor jacks and build and create and restore. I want to weld too, but i realize a welding blanket can save different floors from slag.


I was thinking of tearing out the floor and pouring new, but the garage foundation is the slab.. is that doable with out lifting the building? is it safe to cut out the floor, leaving the old floor in where the walls as a foundation and pouring new in the middle? i worry that is too risky... (fwiw the foundation is solid, nothings moved, its just seen better days). Also i need a vapor barrier!


i was thinking of putting a vapor barrier down and pouring a few inches on top. The challenge with this is that the new floor might not be as strong since it cannot adhear to the old floor with a 12mil vapor barrier in between. Also there is concern that this would be over the existing top plate...


a friend suggested using quickrete to fill in any crators, and break up the extra concrete poured in the one section so that everything is level, and then put a 12 mil vapor barrier over that, and cover it with race deck, garage trek, or garage deck. would this be a good solution? would the vapor barrier over the existing concrete trap in moisture and would it cause the concrete below to break up more and deteriorate more? would i need to worry about the vapor not going anywhere or causing further damage to other parts of the garage?


Bottom line i need a flat and durable work space that is bone dry and will not compromise the garage or my cars. It also needs to be affordable (2K preferable, less than 3.5 - 4K max). What would you guys do?

 

[kwfloors]

At your budget, your going to do the work. No mention of how big it is. Pretty ugly, I would say build a new building.

 

[dfndr]

Really don't think any of your ideas are workable. Maybe pour a thick new slab with 2-3 inch left around the sides so you'll have kind of a gutter between the higher new slab and the walls for the moisture coming under the walls. A cement contractor should be able to seal the old surface. Concrete in my neck of the woods is $2 a square foot poured with rebar. Good luck. Let us know.

 

[hoffman912]

Sorry its a two car garage (17x24) with a lean-to on the side (8x19). the lean-to is fine, it has a different floor from the garage and is in good condition and covered in tile.

here is an older pic before i replaced the roof. the building itself is in good shape, now the roof is replaced. i will need to replace dry wall and run new electric but neither of those is a big deal. other than that and the pad, its got good bones. tearing down and building a new garage is not an option at all -not just financially, but due to city codes i would have to come 3 more feet forward and 3 more feet to the left, and would loose my yard, also i would have to lose the lean-to due to size. i have a larger garage and its on the lot lines because it was built before that was placed into the code.

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[benchracer1]

In my novice opinion you should talk to a couple Reputable concrete contractors. You may be best starting with a fresh slab. You could possibly sawcut the old slab out and start fresh. Not cheap I'm sure but you might be happier years down the road...steve

 

[hoffman912]

thats one of the items i was wondering.. can i cut out the old slab (leaving the perimiter around the footer so i would not need to jack up the building), and pour new for the rest of the floor? I am not sure if that would leave the areas under the footer weaker though..

 

[hoffman912]

anyone else? Its not cracked or falling apart or brittle, and the foundation is really stable, its just some really bad craters in it for god knows what in the past, and moisture coming through.

 

[thegarageguy]

that floor can be diamond grinded, anything loose can be chiseled away and re-filled, then a 1/4" urethane concrete self leveling system can be applied.

Urethane concrete will address your moisture issue, your unevenness and will hold up to work shop environment.

I'm guessing with all the repair work you'd be in the $15 ish per sqft

Call a few urethane concrete manufacturer's and ask for a certified installers info.

Good luck!

 

[FOWLER]

thats one of the items i was wondering.. can i cut out the old slab (leaving the perimiter around the footer so i would not need to jack up the building), and pour new for the rest of the floor? I am not sure if that would leave the areas under the footer weaker though..

Maybe a pro will chime in but I don't see why this wouldn't work fine, drill the old perimeter and epoxy in rebar to tie the whole thing back together. Good luck with it!

 

[hoffman912]

Yeah, i am just worried about the engineering.. if there is any reason to worry about the perimiter under the footer being weakened by doing this.

I like the urethane idea, but not sure i have $15/sq to spend.

I guess i will need to call some concrete professionals, but i know they wont be engineers of course. should i worry about that or should a good concrete company know enough about what they can or cant get away with?

 

[pauls340]

Hoffman, go on www.imcotechnologies.com and track down Chris Burford, he's the rep in Ohio. He has Vapor Lock 20/21 and Mg-Krete Lock the Top. Both products will waterproof and vapor proof either your new slab or your overlay. Lock the Top is self leveling and comes in light beige but can be colored any color you want with powder colors.

 

[Zeke]

First, you say the walls are on slab but is the slab actually over the foundation? Dig out from outside and see what kind of foundation is there. You could very well find a decent footing. If so, yes, you can cut out the whole middle section. Excavate, fill and compact. lay your barrier down and dowel rebar all around into the old. Place new concrete at desired thickness level with the old.

Now, the old may be out of level and you don't want to necessarily follow that especially if it's at all low in the back. Slope your new slab towards the front but don't bury any wood. So, you see, if conditions permit, you can do this. If not, you might raise the garage (it's not that bad a job) and do the whole thing level.

In 2009 I put a massive footing under the center of a 2 story 2500 sq ft stucco home. I raised the house 1/4" and packed it in as high and tight as I could for 25 feet in a form. A ******** helped. After a week I let the house down and it settled in nicely overnight. Our reference line was perfect on with what we had before jacking. I did all the work myself except for the actual digging of the new footing. I really had to hire day labor for that. But that was under the middle of this big house.

Did it all with 3 HF bottle jacks and a shitload of cribbing plus a few beams. I placed the jacks on 2' x 2' 3/8" steel plates. I was lifting 10 times what you have.

 

[Amritsarao]

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[hoffman912]

First, you say the walls are on slab but is the slab actually over the foundation?

Sorry, maybe im not being confusing, i apologize.

its on a slab. i guess i was wondering if i could cut the slab around the perimeter and leave the slab that is under the footer as a foundation, and pour new in the middle, rather than jack up the building etc.

 

[Zeke]

Harry, you're not listening.... slab, foundation, mono pour — all terms that collide. I did say you could cut the slab out if certain conditions were right. I also said you could do the whole thing, new level footings and slab w/o a huge amount of trouble. The outside of your 'slab' has to be thicker, how much? Is it level enough?

There, I've said it again.

 

[hoffman912]

Thanks Zeke, sorry didnt get it the 1st time. loud and clear now. I'll see if i can dig and get some pics after i take care of some of the other stuff on my to do list for the day.

 

[NUTTSGT]

Harry, If I was in your situation, I know exactly what I would do and it'll include alot of sweat equity.

If the foundation is deep enough where the walls sit, I'd jack up the garage, and lay 3 courses of block. Cut/break out the front section of concrete where it was added on in the front for a footer. Once that's down, set the garage back down and attach it to the new foundation.
Once this is done, set a form up across the door ways and pour a new 4" floor. Use the block foundation as the form, just add a little expansion joint at the walls. After the new floor is dry, reframe your door ways.

Sorry if it sound complicated but if you stroll through my refurb thread, you'll see what I'm taking about.