Demolishing Basement Concrete Slab...

CarlsonRower

Hey folks,

I have a ranch house with an unfinished basement.

I am going to finish it and part of the scope is the following

1. Radiant in slab heating for the entire basement
2. Installation of new drains/plumbing connections for new bathroom
3. A few in floor power/data receptacles
4. Using stained concrete over much of the basement

With that much scope and with the existing concrete floor having an awful epoxy coating on it I feel that the most straightforward approach is to just demolish it and start over.

Here is what I plan on doing....

Get a wet concrete saw and create a 2ft by 2ft grid pattern across the entire basement. I was told that creating the grid will make jack-hammering 10x easier.

The only section of concrete I will not have demolished/re-poured is where the sump pump is, a 6" lip around the walls and beams, and the area under the water heater/HVAC (no point in removing it and I don't want to deal with that).

So a few questions....

1. Is this plan reasonable? Are there any problems with what I'm proposing?
2. When using the wet saw will there be enough concrete gunk (water/dust) that I need to suck it up as I go?

Thanks guys! Any input is appreciated!

Chris

psilva8

I can't think of many problems but the only thing that comes to mind is this isn't a job for the faint of heart. This is alot of work breaking up the concrete. I would suggest hiring a pro concrete finisher for the floor when you go to pour. Make sure you run conduit under the slab for your data/power receptacles.

You shouldn't have to vac the cement slurry.

Daniel Holzman

I strongly recommend you wear a NIOSH approved mask when cutting or breaking concrete, the dust can be extremely harmful to you, especially in an enclosed space.

CarlsonRower

I will be doing the concrete demolition but the new pour I am subing out for sure. I'd rather have one contractor be in change of the new slab pour and the staining process.

Yeah... I calculated the quantity of concrete to be between 15-18 tons... so I know that this work will be VERY labor intensive.

Is it ok to just let the slurry sit there? I am going to be cutting up the sections this weekend but it will be a few more weeks before I can jackhammer out everything after.

<*(((><

Check this out. I haven't used it personally, but know a contractor that swears by it.

Dexpan

And if I were you I would look into hiring a demolition labor company for a bid on removal of the concrete after breaking it up. Some companies have equipment (track elevators for stairs) that can make the job a lot easier. Your BACK told me to suggest that to you!

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psilva8

I don't see a problem with just leaving the slurry there. It will harden up.

Just make sure you wear a mask, close off any hvac, protect your furnace ( I had drywall dust ruin the exhaust draft motor on my furnace) and close up any openings to upper levels of the house. You will be using water but concrete dust will still be flying around.

CarlsonRower

Oh wow VERY good call on the furnace... that would have been a silly extra expense for this project...

I like the idea of using the expansion stuff! I think I'll try that before I go nuts with a jack hammer

CplDevilDog

You'll need a relief joint around the perimeter of the slab before using Dexpan. 2 or 3" removed from the slab, else risk damage to the footing/foundation joint.

Also, get your Radon level checked. If your going to have the slab out may as well get a sub-slab depressurization system in.

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CarlsonRower

Radon was already checked and it is very very low. I forget the number but it was laughable how low it came in at both times. This was done with two separate tests during two different times (one was a home kit and the other was a professional with his own calibrated unit).

If I do my phase one plan of cutting the 950sqft into 2'x2' sections wouldn't that give enough wiggle room for the Dexpan to do it's thing without cracking the foundation?

CplDevilDog

Dexpan's website may offer some guidance on the width. If you cut it into 2x2 you've essentially done what Dexpan will do. Wasted effort, IMHO.

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CarlsonRower

Hmmm a valid point...

So if I were to use dexpan just cut 3" around the perimeter and the beams to provide the wiggle room?

I'll read the website later tonight as well.

robertcdf

Be sure to post your progress... I think you'll hate it before long, this is not an easy task nor is it fun. We tear out slabs here and there for decks and they're never ever fun.

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CarlsonRower

Well I am going to call a few places today and compare the price to have guys come out to do the work vs me....

If the price isn't crazy I may just do that... because already we're talking about renting a $70/day cement cutter... $100+ for dexpan... a couple $100 more for a roll away dumpster that can handle 15-18tons of concrete... time will tell and I'll be sure to keep everyone posted!

concretemasonry

Carlson -

In some types of foundation/basement construction the slab is a critical structural element because it provides lateral resistance to the base of the wall. That carries the real foundation load - the soil it is retaining since the weight of the house is not important as long as there is still a basement wall in place. Many codes require the slab to have at least 3 1/2" of the slab in contact with the wall to guarantee positive lateral support.

I installed interior perforated drains at the base of the footing on a house with a strip footing with an inside floating slab. I had the 4" slab cut 24" out from the wall and left sections to brace the base every 6' or so to maintain stability during the process. The same principal applies to a raft or floating slab that supports the walls because the connection to the slab usually is very unreliable.

Dick

CplDevilDog

Missed that one. Thanks for keeping us straight.

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