# Concrete Floor Question



## Bob N (Oct 12, 2004)

After the recent flooding we had around our area and having experienced a little of it myself in the shop, I am considering raising sea level on my shop floor about 3 inches. My building is concrete block all the way around except for my wooden entrance door and is the only place water entered the shop. My floor is old poured concrete (rather rough) and painted with gloss latex porch paint. What I am thinking I would like to do is simply pour and smooth about 3 inches of fresh cement over what is there and cut 3 inches off my door to re-fit. This means the floods would have to be 3 inches higher than the last to get in again.

Will this work doing it this way? What am I missing and would it require any additional measures?


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## RStaron (Sep 25, 2009)

Hi,Bob. I think that should be OK to do what you suggest, as long as the old floor is not sinking and very uneven. If by "rather rough' you mean not a smooth surface. I would put some expansion material around the new floor and walls though. Maybe even drill some 1/2" holes in old floor and drop in short pieces of re-bar to anchor new floor to old so it doesn't slide or shift and move your walls. Is there any way to raise the door frame at all to keep the same door height, if you can I would do that. If not you will just have to live with a short door way.


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## bobj3 (Jan 17, 2006)

Hey Bob

It maybe time to build a new cabin in the back yard and use the old one for storage  

You may want to build the new one on pontoons  LOL just in case..

You don't need a concrete floor,,just 4 walls and a roof and one or two sliding glass doors and you have it done,,I'm sure Jerry will give you a hand and maybe with some luck some of the nice hardwood for the floor  I know you have the room in the backyard..

Or you can cheat a little bit and have them drop off one of the premade building, I have done that once or twice the one car size, I'm trying to recall what I paid for the last one I think it was 1200.oo,they back in drop it off in about 1 hour and you have a new shop more or less, that will float LOL more or less LOL..that you can sale off or take with you when it comes time..


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## xplorx4 (Dec 1, 2008)

Sure I can help, but do you think you want my help?? A mite accident prone maybe. The rebar thing might be left out so long as you go wall to wall. Where will you store every thing while doing the the floor? Let me heal-up and we can give it a go.


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## Bob N (Oct 12, 2004)

Thanks for the advice guys.

Ron, that is a good idea on raising the door frame rather than cutting the door shorter. :thank_you2:

BJ, I have looked at the possibility of a new shop, but it would run a minimum of $6000-$8000 time all was said and done, not to mention, I'm not sure how happy I would be with "minimum"  

Jerry, I'm thinking Pod storage and a good contractor to do the work. :yes4:

I wonder if it would cure/dry being an inside pour like that? I guess with windows and door open it would eventually get there.


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## Hamlin (Dec 25, 2005)

Hi Bob,

I have to second the idea of using rebar to help hold the new floor in place. I'm sure, since you mentioned possibly having the pro's do it, I'm sure they'd do the same thing. A good "cook"/cure time should be around the 3 week mark, maybe a little longer.


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## Bob N (Oct 12, 2004)

Hi Ken,

Thanks for the additional info. It is going to be hard to live without my dog house err.... shop for 3 weeks though


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## levon (Sep 14, 2008)

hi Bob

just my dumb opinion,

i would use rebar, but i would make the pour about 4 inches. 4 wont cost you that much more than 3 and would eliminate the spalting and cracking of pieces. in addition to rebar, i would use the reinforcing material that looks like fencewire on steroids. like i said this is my humble opinion.


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## Bob N (Oct 12, 2004)

Levon!!!!!

How in the world have you been my friend? Long time no hear from and I think of you often.

I picked 3 inches to raise the floor because every inch I add lowers my 8' ceiling :cray: Of course if 4" is what is necessary, then that is how it will have to go.

So glad to hear from you and your opinion is always valued.


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## RStaron (Sep 25, 2009)

If I recall right concrete is fully cured or as strong as it gets at 28 days. You won't need to open the doors, the slower it dries the better. If you are not putting a car on it you could move back in in a week or week and a half. I put all my tools and workbench in after a week and haven't had any cracks yet. I believe this will be my fourth winter with the new floor. I also used a six bag mix for the concrete, Stronger floor, and did not use any reinforcing wire.


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## seawolf21 (Jan 19, 2007)

*concrete floor*

I just had my garage floor ripped out because water and ice was undermining it for the last 20 years. Back in the 40's they poured concrete right over the dirt with no gravel underneath. This time the contractor left a 12 inch perimeter of concrete around the sides and drilled holes every three or four inches for rebar then poured 5 inches of gravel and 5 inches of concrete so the slab would not shift. I also had corrugated perforated 4 inch plastic drain pipe put in a trench all around the garage and run into a catch basin under the center of the new driveway we also had done. From the catch basin solid pipe runs under the driveway to the street. The downspouts on the garage are also connected to this system. One clown wanted to raise the garage but no way could I get all the junk and spare wood out from the loft, afterall I had to rent two 5X8 foot containers from U-Haul and lock them to keep all the stuff I didn't want to get stolen while the garage door was up for a week while the floor cured.
Gary


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## levon (Sep 14, 2008)

hi Bob,

we have had a ton to do here and still do. that was just an opinion about raising the floor.

right now im starting on a bathroom redo. im gutting it and starting anew. i wont be posting pics , as it is not something relevant to the router forum. i never wont to bore people with renovations like a few ive seen here. or at least it seemed boring to me.


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## Bob N (Oct 12, 2004)

WOW! Y'all have been very helpful and I have much to think about and go on now. I just was not sure how concrete over concrete would work especially with the orginal being painted and where the water/moisture would go.

Sounds like you have given me enough info to feel good about it and contact a contractor with the plan.

Thanks again to each that replied.


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## xplorx4 (Dec 1, 2008)

levon said:


> hi Bob,
> 
> we have had a ton to do here and still do. that was just an opinion about raising the floor.
> 
> right now im starting on a bathroom redo. im gutting it and starting anew. i wont be posting pics , as it is not something relevant to the router forum. i never wont to bore people with renovations like a few ive seen here. or at least it seemed boring to me.


Nice to hear your back, guess I'll keep that in mind when I start my bath down stairs. How about if it's close to your shop, would that count? Just wondering, seriously good to see you post my friend, good to have you back for however long
Your friend
Jerry


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## levon (Sep 14, 2008)

hey Jerry, my friend!

you post anything you want, your posts have always been enjoyable. 

this will be my 3rd or 4th bathroom and im not here to see pics of me doing remodeling. i think most people here are capable of doing a bathroom remodel and instead of boring them with my bathroom, id like to post more about woodworking, but thats just my opinion. i have built a linen cabinet and vanity, but think that is under the category of remodeling.

i do look forward to being around here more and a big thank you for making sure ive been doing ok!

your friend levon


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## TwoSkies57 (Feb 23, 2009)

Raising the jam for the door would no doubt be the cheapest way to go. However, just remember to leave yourself an out in case the water goes 5"s next time! I'd consider a full block, even if th is means a bit of a step or slope to enter with.. Having a bowl for a shop floor can be rather annoying.. I believe you'll need some kind of mechanical fastener between the old and new floor. Doesn't have to be much since the floor isn't much of aload bearing area. Cure time on concrete will vary dependent on thickness, type, location, appliacation etc... They say the Hoover dam is still curing!!


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## Old_Chipper (Mar 30, 2009)

Bob,
Guess I need to jump in here, since my friends call me the concrete man! Normally it is not a problem pouring one floor over another. It is recommended that you clean the old floor to remove the old paint and oil etc. This can be chemical or blasted. Then you will use a bonding agent. However my concern is your location. From what my son tells me, (he is not far from you) You all have trouble with foundations shifting, cracking etc. in GA. Your old foundation needs to be able to support this additional weigh. If your slab was just poured on the ground without proper footings then you have a problem. Are you in a location were you are going to need a permit. Codes will most likely require you have an engineer tell if your slab is okay. They do here! I hear all the time; “It’s just a shop” or “It’s just a garage”. But codes are there to help us, even if they seem like a pain.
Bob have you looked the possibility of doing some landscaping to divert the water away from your shop. Might be cheaper and easier in the long run.


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## Hamlin (Dec 25, 2005)

The "wire mesh" that levon spoke of, IS for helping the concrete not have those cracks in it. It's not exactly 100% either. Remember, the earth does move and with it, so does the ground. Right now, the best advice is, speak with the pro's. Techniques used today have changed and constantly change. For instance, they add some plastic strips to the pour mix that acts just like rebar does.


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## bobj3 (Jan 17, 2006)

Hi Bob

It's no big deal,,they say in about 50 to 80 years or so your back yard will be prime ocean front prop.. 

Think stilts  like they say jack up the cap and put a new one under it..the oldest in Valdosta and they have water problems all the time but it has also been real dry for the last 2 years also..so to say you may want to think about redoing the floor real hard..a one time thing in 25 years...

Good Luck

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## radios (Sep 30, 2009)

this is a detached garage used as a workshop right? you could have a house moving company move it off the foundation, then you could lay down cement blocks, properly mortared, even 2 rows high! for those really rainy days, that'll give you about 2 feet higher, then they can put the garage back in place. you won't be losing any inside height this way..


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## BigJimAK (Mar 13, 2009)

Bob said:


> After the recent flooding we had around our area and having experienced a little of it myself in the shop, I am considering raising sea level on my shop floor about 3 inches. My building is concrete block all the way around except for my wooden entrance door and is the only place water entered the shop. My floor is old poured concrete (rather rough) and painted with gloss latex porch paint. What I am thinking I would like to do is simply pour and smooth about 3 inches of fresh cement over what is there and cut 3 inches off my door to re-fit. This means the floods would have to be 3 inches higher than the last to get in again.
> 
> Will this work doing it this way? What am I missing and would it require any additional measures?


 
Bob,

I can't speak about Georgia soil conditions, I'm not and never have been a soils engineer and its been about 30 years since I had the only soils enginering classes of my life.

What little I do remember is that concrete is very strong in compression but is rather weak in tension and bending. The concrete on top would make a genrally compressive force on the existing base, which is good, but I don't know how well the existing base will hold up the weight. Dried concrete is about 150#/cubic ft. That's about 37#/square foot for a 3" pour, or about 15,000# (4 cubic yards) for a 20x20 shop. I also remember that the strength depends upon the base under it, moisture conditions and enough other stuff I can no longer remember.

I recommend spending $100 or so to get the a few minutes time and the opinion of a soils engineer. He'll likely tell you its OK and whether or not you need rebar but (IMO) its cheap insurance. Otherwise, if you pour it and it starts cracking, you're right where you are now except you have 3" less headroom, you've wasted your money and might then need to remove an additional 15,000# of cured concrete to make everything right.

Yes, I've gotten increasingly conservative as the years have gone on! I've also gotten increasingly adverse to the thought of jackhammering out and removing an additional 15,000# of rubble!<g> 

I'm not proclaiming this as the BEST answer, just the <perhaps dumb> one I'd use.


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## BigJimAK (Mar 13, 2009)

levon said:


> hi Bob
> 
> just my dumb opinion,
> 
> i would use rebar, but i would make the pour about 4 inches. 4 wont cost you that much more than 3 and would eliminate the spalting and cracking of pieces. in addition to rebar, i would use the reinforcing material that looks like fencewire on steroids. like i said this is my humble opinion.


 
Nice to see back online, Levon.. we've missed ya!


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## levon (Sep 14, 2008)

thanks Jim, i hope to be here a little more


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## TRN_Diesel (Feb 24, 2009)

Bob said:


> After the recent flooding we had around our area and having experienced a little of it myself in the shop, I am considering raising sea level on my shop floor about 3 inches. My building is concrete block all the way around except for my wooden entrance door and is the only place water entered the shop. My floor is old poured concrete (rather rough) and painted with gloss latex porch paint. What I am thinking I would like to do is simply pour and smooth about 3 inches of fresh cement over what is there and cut 3 inches off my door to re-fit. This means the floods would have to be 3 inches higher than the last to get in again.
> 
> Will this work doing it this way? What am I missing and would it require any additional measures?


I have a few suggestions Bob if thats ok on raising the floor.

1) What you want to do is called "scratch coating". If you floor is not cracked now and then I would not go with the rebar and just do the scratch coat. This stuff is a little different than concrete. IF you want I can call Con-Spec a place that specializes in concrete and get the product information for you. Usually the scratch coat is 2".

2) Before you do apply anything on the floor you need to clean it really well with a brush and some concrete cleaner. Muriatic acid in a 5% concentration works well to clean the concrete. Make sure you have the door open and watch the fumes. Where a respirator if you have one to be safe.

3) When I fixed my floor the guys at Conspec gave me a small 4" grinder wheel to scuff the concrete up so the patch filler I was using would adhere to the concrete. From the sounds of it your pad is rough but it never hurts to touch it up a bit to make sure. Only you can say for sure how rough it is. 

4) I agree with taking your door jamb out and removing the header to raise it up so you do not cut the height of the door down. It will take a bit of work and it will be a lot easier if you have a sawsall ( reciprocating saw). I am assuming the door is a load bearing wall and will have a header in it to carry the load of the trusses. If there is no header than put one in using 2 ply 2x10 with a bottom sill attached matching the thickness of the wall (either 2x4 or 2x6) When I do my headers I like to make the header flush with the inside of the wall rather than the outside. Just make sure to staple on some insulation on the back side of the header before you slide it into place. This gives you something solid across the span of the opening for nailing into. I used this technique when I was framing houses years ago and it works well especially if you want to hang drapes for a window opening. 

5) Not sure if you have considered raising the exterior grade around the garage to stop water from getting in. This works well and will help prevent any future water from getting in. I am thinking weeping tile would be a waste of time.

Post a few pictures of the outside so we can get a better idea what you are dealing with.

Good luck


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## Bob N (Oct 12, 2004)

A little additional information would be helpful as Dan suggested. The shop floor is 12 1/2' X 17 1/2' and I have no idea of the age or underlayment format of the pour. My guess is that it was poured in the 50's or 60's and done within the existing structure of the building. It is solid with no cracks what so ever and it looks like it was possibly mixed/poured by hand as it is a little bumpy and wavey. This building is used for nothing but my shop and no vehicle could really ever be garaged in there. Landscaping would be difficult if not impossible and really not necessary as drainage is really pretty good except when you have 25" inches of rain fall in a 24 hour period. Water did not really rise as in a lake, but the flow of the "river" increased above the door threshold allowing water into the building. This is only the 2nd time I have had a water problem in the 8 years I have lived here, the first time was from an inland hurricane which was another of those 100 year history breakers.

My wife, bless her simple natured heart, says maybe all I need is some sand bags on hand when the prediction looks bad. She may really have a valid point when all is said and done 

Here are a couple of pictures of my shop setting. If you look close at the floor shot, you can see the bumps I am talking about in the concrete. I appreciate all the input from you good folks.


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## levon (Sep 14, 2008)

hi Bob,

you said a couple of important words. 

1. landscaping would be difficult. youre very right and im not sure of your siding, but you dont need to raise the ground elevation if your siding is wood, or even other materials. it will rot or compromise the siding. and raising the grade around a building also will hold moisture close to the building.

2. drainage is pretty good until you have 25' of rain in a short time. i think most people's shops would be in trouble with that much water. you may just want to leave it as it is.

lots of these suggestions are good, but you could spend enoough to build a shop if you know what i mean.


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## Bob N (Oct 12, 2004)

Good morning Levon, the building is solid cinder block construction so no fear of rot 

You are right about spending more on a fix than a new shop if one is not careful. I have been studying the idea of a new and larger shop, but just have not found a way to make that work (yet )


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## bobj3 (Jan 17, 2006)

Hi Bob

The BOSS is right on ,,,call the sand and gavel company and have them drop off a truck load of sand,,,make a sand box for the little ones, and a place to keep the sand in place and buy a box or two of the sand bags, then your all set for the next storm...


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Bob said:


> A little additional information would be helpful as Dan suggested. The shop floor is 12 1/2' X 17 1/2' and I have no idea of the age or underlayment format of the pour. My guess is that it was poured in the 50's or 60's and done within the existing structure of the building. It is solid with no cracks what so ever and it looks like it was possibly mixed/poured by hand as it is a little bumpy and wavey. This building is used for nothing but my shop and no vehicle could really ever be garaged in there. Landscaping would be difficult if not impossible and really not necessary as drainage is really pretty good except when you have 25" inches of rain fall in a 24 hour period. Water did not really rise as in a lake, but the flow of the "river" increased above the door threshold allowing water into the building. This is only the 2nd time I have had a water problem in the 8 years I have lived here, the first time was from an inland hurricane which was another of those 100 year history breakers.
> 
> My wife, bless her simple natured heart, says maybe all I need is some sand bags on hand when the prediction looks bad. She may really have a valid point when all is said and done
> 
> Here are a couple of pictures of my shop setting. I appreciate all the input from you good folks.


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## TwoSkies57 (Feb 23, 2009)

something along the lines of a watertight shutter for the door and a sump pump mid shop might work well, minimal expense. just throwing that out there...


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## TRN_Diesel (Feb 24, 2009)

Thanks for the pictures Bob that is a nice looking shop. I think your wife is right after looking at the pictures.

From what I see the sidewalk is sloped towards the shop and get the water flowing in your general direction.

The only option is to maybe raise the concrete outside. Build it up say 4" so you have a small concrete raised patio in front of the door. This would stop the water from coming in. This would still mean you would have to raise the door jamb up. Is the wall made entirely of cinder block from top to bottom? Are there any wood studs in the wall?


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## Hamlin (Dec 25, 2005)

Looks like more of a new sidewalk type job. Sand bags are a good idea too.


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## RStaron (Sep 25, 2009)

Looking at the pics it looks like the ground on the right side slopes away from the shop. You could cut out a 4" or 6" wide trench a cross your sidewalk and put in a plastic drainage trench, Not sure what it's called, but it has a grating on top that the water enters and drain it to the sloped area on the right side. this would help divert the water before it get to the door . the door is not on a load bearing wall, so raising the door and jamb will be ok. If you can do the trench. You could do the scratch coat,as Dan suggested, which would raise the floor and to get the floor smooth. This along with some sandbags might be all you need. Sump pump Idea might be good also


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## TRN_Diesel (Feb 24, 2009)

RStaron said:


> Looking at the pics it looks like the ground on the right side slopes away from the shop. You could cut out a 4" or 6" wide trench a cross your sidewalk and put in a plastic drainage trench, Not sure what it's called, but it has a grating on top that the water enters and drain it to the sloped area on the right side. this would help divert the water before it get to the door . the door is not on a load bearing wall, so raising the door and jamb will be ok. If you can do the trench. You could do the scratch coat,as Dan suggested, which would raise the floor and to get the floor smooth. This along with some sandbags might be all you need. Sump pump Idea might be good also


Thats a good idea making a open cut trench with weeping tile in gravel to divert the water that would be flowing on the sidewalk towards the door. But then again sand bags on the sidewalk would do the same thing I think. 

Sounds like the wife has the cheapest and probably the most rational solution yet Bob.


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## Bob N (Oct 12, 2004)

My pictures must be a little mis-leading as the side walk does not really slant toward the building at all. It falls toward the right mainly and allows normal rain and even heavy rain to run off with no problems. There is a little pocket dip on the porch that collects a tad of water and that is probably giving the illusion that water runs toward the door. The problem only occurs when we break the weather record of a 100 year flood history that I have gotten any water in the shop, otherwise this is really not an issue. Even a drain system could not have carried that much water away fast enough to prevent back up at my threshold. My goal is to make it a non issue even when we break records :fie: Right now, the sand bag idea is sounding appealing from a cost stand point as it may not even ever happen again, but then again it could happen tomorrow, who knows when it comes to weather. Really never any damage in the shop, but sure works me to death to clean it up and prevent rust on tool surfaces from humidity. I am so glad I have everything mobile on 3 inch casters.


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## TRN_Diesel (Feb 24, 2009)

You could write a new Mastercard Commercial:

Cost to make shop $5,000
Cost to pour sidewalks $2,000
Minimial chance of flood damage with $5.00 sand bag .... PRICELESS


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## BigJimAK (Mar 13, 2009)

lol, Dan!


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## bdaniel (Oct 13, 2009)

Maybe you could slope the concrete around the entrance around the door so you didn't have to do anything to it. A little water may come in, but it would still keep the floor from flooding. Maybe the door could open out as well. 
\___/


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## Bob N (Oct 12, 2004)

Thanks Dave, I looked at that option, but can't make it work well with my layout.


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