# prestressed concrete for garage floor with basement below



## TimelessQuality

Damn! Tinbenders must make more than I thought!!

I see you have been on here longer than I, but I'm only finding Threads and Posts that pertain to your own home... Cedar Impressions, 40 yr roof, Vinyl Windows, and now a garage over a basement... 

:shifty:

Sorry If I'm off-base, I've been pretty grumpy lately:laughing:


Good Luck!


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## NJ Brickie

jomama said:


> I guessed at the thickness because it sounds like he's looking for a 9'+ tall basement, all of which will be buried & then some at the front of the garage.


I wasn't judging your estimate on 10" wall thickness. Sounds about right to me. My point was let the engineers work that out, if they can figure out how to work plank on a 8" steel stud wall, they can most likely work plank on a 6" concrete wall?


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## shopman

Timelessquality,
You are correct, I dont fequent the hvac forum here too much I use the site HVAC-talk for my hvac forum hang out. if you ever have any hvac questions they have a very good forum of profesionals who dont mind giving advice, as long as its not a DIY hack trying to do it himself.

I have found this site very helpfull over the years to get advice from professionals before I take on/ have a project done as you can see from my past posts (my new windows, roof, siding, etc...). I get info on the proper materials, installation methods to make sure the contractor I higher does it correctly.

I will always consider myself a tin banger I have worked in the HVAC industry since I was 16 (now 42). The past 10 years I have been out of the construction aspect and I now work for the military working on aircraft HVAC systems. I still keep my HVAC master license current because I never know when i will have to go back to construction. 

This garage is going to be a huge investment for me especially using pre stressed panels. I want to make dag gone sure it is done correct. That is why I am on the forum getting advice from the guys who do it everyday.

Thanks again for your reply and any helpfull hints/advice are greatly appreciated. As I said i am about 6 months out from doing this job but I am starting all the planning now.


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## TimelessQuality

shopman said:


> they have a very good forum of profesionals who dont mind giving advice, as long as its not a DIY hack trying to do it himself.


I think this is one as well... Just tryin' to weed out the HO's and DIY'rs.


Thanks and Good Luck- 

Need any carpenters on those military planes?:laughing:


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## concretemasonry

Timesless -

A great point.

Just because a person is a "contractor" in HVAC, he could very easily be an amateur DIYer and be a "babe in the woods" when it comes to having buiding designed piece-meal and the getting it done properly with all the small detail concerns posted, so it can have a good HVAC system installed later.


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## jomama

NJ Brickie said:


> I wasn't judging your estimate on 10" wall thickness. Sounds about right to me. My point was let the engineers work that out, if they can figure out how to work plank on a 8" steel stud wall, they can most likely work plank on a 6" concrete wall?


 
I hear what you're saying, but I'd be aprehensive to the "making it work" part myself. Giving the engineer free reign over the design of he system (with zero input by an individual who's on the ground everyday) means it only has "to work" in theory & on paper. I've done enough of these to see what works logistically on the jobsite. Laying block on top of cambered pre-stressed plank is not ideal IMO. Flashing the open webs of the planks at the exterior of the building isn't either.

Pre-stressed planking definately takes a little forsight (and experience is even better) to incorporate efficently. Any leak into the plank can be a royal PITA to troubleshoot later.

As well, the wall not only needs to carry the weight of the plank & subsequent floor, but more importantly cover the lateral soil load.

To get back on topic, all of the engineering for the pre-stressed is done by the pre-stressed manu. as part of the package price. They do the stuff everyday, far more often than a generic SE or the like. Yet, they will have very little input on the construction of the foundation walls, other than the amount of bearign they require.


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## jomama

shopman said:


> Guys,
> 
> 1. I assume my best option is a poured wall using concrete forms. I will never use this space as finished living area so I don’t need the insulation of an “ICF” type form. Excuse my ignorance but can forms be adjusted for height or are they standard heights? How are forms adjusted for thickness? I assume my walls will need to be 8” min, maybe 10” depending on the engineer’s specs? Is this possible with standard forms or will I have a hard time finding a contractor with forms for this application.
> 
> We've done all of our in maonry (block) with no problem. Poured walls are no issue either, it just depends on what method is more common in your area. The width of a poured wall is merely set by consumable steel wall ties, which are readily available in many lengths for whatever thickness wall you want. Don't let this bother you one bit.
> 
> 2. How much above the ground grade should I have the finished garage floor start? I was thinking to minimize the back of the garage being too much underground the finished floor will be about a foot above the grade of the property. It should be no problem. My biggest issue is the back corner where I want the garage door too much underground.
> 
> Let the excavator have some input on setting the elevation.
> 
> 3. For the 2 to 3 “finished floor on top of the planks, do I need to make sure they use wire? I am 99% certain yes just want to be certain.
> 
> Generally, the upper concrete floor will be completely isolated from the plank, so it needs to be constructed very similar to an independant slab on grade. I'd expect more than 2-3" concrete thickness, especially since the 24' plank should have about 1.5" camber in the length of the plank.
> 
> 4. I still don’t have a handle on how they will finish the concrete once the planks are set in place. Once the planks are set how much room is there between the end of the planks and the end of the concrete wall? I would assume if the outside measurement wall to wall is lets say exactly 24’ the planks will probably be 1” to 2” shorter to give room for error in wall, etc….
> 
> Usually, at least here, about 12-16" shorter than your outside dimensions.
> 
> I was thinking if possible I would like a foot more wall on top of the planks before the wooden framing starts. This will keep snow/rain from getting the wood wet. How would they build the form from the top of the foundation form up past the planks to a foot above the planks?
> 
> It's simply called a "floor ledge" or "sunken floor ledge". You really don't want to build on top of the plank IMO.
> 
> I know the planks are hollow. How do you keep concrete from filling in all the hollow core of the planks?
> 
> This is where you're missing a very key element to the equation. You really need to have a membrane of some sort to keep water that enters the upper floor from running down into the lower level.
> 
> Sorry for all the questions just want to make sure it is done right when I have it done.


 
...............


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## concretemasonry

jomama -

A little off track of the OP. - I am well versed in the design and use of both concrete masonry and prestressed concrete in structures. One of the best used that I saw/participated in was a series of 2 story homes with basements (about 24-30 x 40 to 56 feet) that had NO columns or beams that obstructuted the use of the space. They were built with the old style Flexicore (16" wide) or the 24" wide plank because of the ease and lower cost of construction/reliability. The same principles apply to wider planks and longer spans with some erection/construction differences.

I knew Henry Nagy, the founder of Spancrete (born in Europe, immigrated to the U.S. and then used a Hungarian name of Nagy, which means gross instead of Gross, which was a German name). A very great person that allowed access to the use of the product and personnel that were also friends. Lunch at Karl Raschs or with Frtiz Usinger when I was in Milwaukee.

On the OP's subject - The concept of concrete floor panels is great for many applications, but far too many people do not appreciate the advantages of concrete masonry and precast floors in the U.S., but they are very common in other developed countries. The precaster can be very valuable in the sizing of the planks and pass on the use suggestions to the ultimate designer to incorporate if the owner does not interfere if he is not familiar with the building design, details and construction.

An amateur should not get too far into the details, since it will scare off many professional designers and contractors.


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## jomama

concretemasonry said:


> jomama -
> 
> A little off track of the OP. - I am well versed in the design and use of both concrete masonry and prestressed concrete in structures. One of the best used that I saw/participated in was a series of 2 story homes with basements (about 24-30 x 40 to 56 feet) that had NO columns or beams that obstructuted the use of the space. They were built with the old style Flexicore (16" wide) or the 24" wide plank because of the ease and lower cost of construction/reliability. The same principles apply to wider planks and longer spans with some erection/construction differences.
> 
> I knew Henry Nagy, the founder of Spancrete (born in Europe, immigrated to the U.S. and then used a Hungarian name of Nagy, which means gross instead of Gross, which was a German name). A very great person that allowed access to the use of the product and personnel that were also friends. *Lunch at Karl Raschs or with Frtiz Usinger when I was in Milwaukee.*
> 
> NOW your speaking my language Dick............. :thumbup:
> 
> My brother actually races his dirt track car regularily with the current owners.
> 
> Wasn't Spancrete originated in the Green Bay/Valders area though? I didn't think they mover the HQ's to the Milwaukee area until recently, bt I could be wrong..........
> 
> On the OP's subject - The concept of concrete floor panels is great for many applications, but far too many people do not appreciate the advantages of concrete masonry and precast floors in the U.S., but they are very common in other developed countries. The precaster can be very valuable in the sizing of the planks and pass on the use suggestions to the ultimate designer to incorporate if the owner does not interfere if he is not familiar with the building design, details and construction.
> 
> An amateur should not get too far into the details, since it will scare off many professional designers and contractors.


 
I'd tend to agree with all of that.


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## shopman

Timelessquality,
Believe me I understand your concern. If you are questioning my credentials as a contractor, pm me and I can scan/fax my professional state licenses. I dont know about your trade but I had to do 4 years of night trade school as an apprentice, work under as a journeyman for several years, then take a 5 hour test for my full masters license (which is the hardest one in my trade), they have partial masters in certain areas. 

I will be doing the carpentry, i need to save money where i can. I am subbing out the excavation, concrete, and roof (roof because i am not crazy about working on a 12//12 pitch). I am pretty handy (change my own oil, cut my own grass, and do most of my own house/car repairs, etc...). But i know my limits. If you think i am going to get out a shovel and move tons and tons of dirt, or try to build forms (that will collapse and waste thousands of dollars in concrete) you got to be nuts. If you new nothing about concrete would you do this? As I said Some things need to be left to the profesionals and i am not penny wise pound foolish.

I apoligize for one tradesman asking another for advice. I am ignorant when it comes to concrete work (which is what I have admitted since my first post), I will have a structural engineer stamp the prints (required). Myself and my family (which is the most important thing to me) will be in and out of this basement and it scares the [email protected]## out of me knowing i will have tons of concrete overhead. I want to be certain without a doubt it is built correctly. I respect the opinions of guys who do it everyday over some 24 year old engineer who has PE license sayings its OK. 

I am just looking for advice so when i get quotes from concrete contractors that they will build the foundation X way I know from talking with you guys that it is the correct way. I will probably also ask your guys opinion once I get quotes ( not on the price, just on how they want to do it). I work very hard for my money just like you and this is a huge investment to me. I apoligize for trying to ensure it is done correctly. Isnt that the purpose of these forums, to ask questions when you are unsure? 

I am not trying to start an argument, I really appreciate any advice you guys can give me, and Timelessquality, I know where you are comming from.

Just curious in my trade (HVAC) we get tons of DIY's trying to do thier own work. Is that really a problem in your trade? I just cant see the average DIY'r renting a front end loader and rying to dig footings/ pour/ build forms.

Thanks again


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## concretemasonry

jomama -

I think the original plant was in Valders and they still have that. I think they also had a plant near Waukeshaw. Henry was a very broad-ranging person because of the machines and franchises he sold in other countries. One of the managers of a Spancrete plant in Minnesota split off his own new plant and called the product SpanDeck. Henry loved to eat with friends/customers for plants and knew all the Europeans in the area and liked to go to see them. - An old man that was great and contributed a lot to the industry and most people were shocked when he died because they thought he would never die.

Much of my background is Wisconsin and looking at the genealogy that I spend time developing, many there (Whitewater area) came from Europe in the 1850s before the counties were how they are now. My other side is the Norwegian and Swedes that came to NE Wiscinsin a few laters later. At thast time, it was bad for a Norwegian to marry a Swede.

Wisconsin was a great place for concrete masonry, but the habitual use of 10" block walls that does not fit into the 4" masonry module easily, especially when it comes to details and exposed masonry.


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## mudpad

Here is a detail of the bearing condition for precast on a project I did recently. 

Your topping slab does need wire mesh, make sure you get the flat sheets cause you will never get the rolled stuff to lay down flat enough.

Slab should be 1.5 to 2 inch minimum. Once your planks are in place, use a laser or grade level to find the high point in the plank camber and figure your edge elevations from there.


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## shopman

Thanks for all the great responses/ advice. I will look at them later today when I get off work. I really appreciate it.


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## CJKarl

This spring was my 1st job with concrete planks. It was a roof, but the detail is almost exactly the same as your floor. I was amazed that 26' roof planks only beared on 3" of the wall. We did pour a reinforced bond beam the next day.


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## jomama

concretemasonry said:


> jomama -
> 
> I think the original plant was in Valders and they still have that. I think they also had a plant near Waukeshaw.


 
Thanks for the interesting background Dick, I appreciate it.

Spancrete is surely based out of Waukesha now.

Their roots in Valders are pretty apparent when you're in the area as well. As soon as you get near the town, you start to notice remnants of pre-stressed plank everywhere: sidewalks, steps, retaining & garden walls, you name it, and these people have found a use a use for it! :laughing:

I'd agree that they must still be running out of Valders as well, as most of their bridge girders and such always come from the North.

Joe.


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## oldrivers

last job i worked on that had those for the floors a plumber was drilling through the floor to run a drain pipe and cut a cable , $20,000 repair. 2 million dollar condo 4rth floor. ...  2 guys 2 days to fix ... im in the wrong trade.


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## mudpad

oldrivers said:


> last job i worked on that had those for the floors a plumber was drilling through the floor to run a drain pipe and cut a cable , $20,000 repair. 2 million dollar condo 4rth floor. ...  2 guys 2 days to fix ... im in the wrong trade.


Just guessing but that was probably a post tension slab. Prestressed still has cables, but not quite a critical as the PT tenons, engineers rule of thumb on the prestressed I have done is that you can cut one cable per plank, and you can cut it as many times as needed, but only the one. Usually there is plenty of room at the hollow cores for MPE penetrations without cutting the web, which is where the cable is on prestress.


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## remster

Check what this guy did.

http://www.garagejournal.com/forum/showthread.php?t=12234


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## mudpad

remster said:


> Check what this guy did.
> 
> http://www.garagejournal.com/forum/showthread.php?t=12234


Now I know where to go in a tornado!


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## mudpad

Here is an example of a Post Tension blow out. This was at an intermediate pull location. As bad as that looks, the rodbusters made it worse by cutting the tendons off so close to the slab edge that you couldn't get the jack back on them. Then we were chipping out concrete all the way back to the column:w00t:


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## shopman

Here is another example of a residential garage with a hollow core floor. If you scroll all the way down it has finished pictures. I dont see the adnantage of why he used ICF's for a detached garage that the bottom will never really be used for a conditioned space. 

http://ths.gardenweb.com/forums/load/build/msg0117530824767.html


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## covaltleveling

I will look through our vendors and refer someone in your area for this product. Good luck!!


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