Pouring Over Existing Decent Slab - Masonry - Contractor Talk

Pouring Over Existing Decent Slab

 
Thread Tools Search this Thread Display Modes
Old 01-15-2018, 08:57 PM   #1
Registered User
 
Stultzlawncare's Avatar
 
Trade: Landscaping
Join Date: Jan 2018
Posts: 4

Pouring Over Existing Decent Slab


I have a 15 x 20 foot garage floor poured about 12 years ago. It isn't in bad shape it just wasn't poured smooth and I'd also like a drain on it. I'd like to add 3 foot to the front also. It has one hairline crack on it but that's it. Could I rough the surface up and pour 3 inches over the existing slab and pour the new part 5 inches thick?
Stultzlawncare is offline  

Warning: The topics covered on this site include activities in which there exists the potential for serious injury or death. ContractorTalk.com DOES NOT guarantee the accuracy or completeness of any information contained on this site. Always use proper safety precaution and reference reliable outside sources before attempting any construction or remodeling task!

   

Advertisement

 

Old 01-16-2018, 08:03 AM   #2
General Contractor
 
greg24k's Avatar
 
Trade: New Home Construction-Additions-Remodeling
Join Date: May 2007
Location: NJ
Posts: 7,307
Rewards Points: 7,672

Re: Pouring Over Existing Decent Slab


Enclosed garage... Go ahead, you don't need to rough anything up since heaving is not a concern. If you want Concrete Bonding Adhesive to the existing floor, other than that the slab is not going anywhere.

Advertisement

__________________
I never lost a cent on the jobs I didn't get!
greg24k is offline  
Old 01-16-2018, 09:33 AM   #3
Registered User
 
Stultzlawncare's Avatar
 
Trade: Landscaping
Join Date: Jan 2018
Posts: 4

Re: Pouring Over Existing Decent Slab


Ok thanks man. Since the front of the new slab will only be covered with stone up to it level should I dig down 2 or 3 feet to avoid lifting in the winter?
Stultzlawncare is offline  
   
 
Old 01-16-2018, 01:44 PM   #4
Pro
 
Fishindude's Avatar
 
Trade: Industrial
Join Date: Aug 2017
Location: Indiana
Posts: 233
Rewards Points: 490

Re: Pouring Over Existing Decent Slab


Tear it out and start fresh or you will have problems. Any cracks in the existing slab will telegraph up thru the new slab.
Fishindude is offline  
Old 01-16-2018, 01:47 PM   #5
Registered User
 
Stultzlawncare's Avatar
 
Trade: Landscaping
Join Date: Jan 2018
Posts: 4

Re: Pouring Over Existing Decent Slab


Even if I use the fiber mesh 4000 psi?
Stultzlawncare is offline  
Old 01-16-2018, 04:20 PM   #6
Pro
 
Windycity's Avatar
 
Trade: Masonry
Join Date: Oct 2015
Location: chicago
Posts: 1,632
Rewards Points: 6,616

Re: Pouring Over Existing Decent Slab


A Concrete contractor that I know bought an old building to use as a mechanic and storage shop for their equipment and did just that since the mechanic wanted a smooth floor instead of the pitted, cracked and uneven floor that was in there.

I believe their pour was 4 inches right over the top and they drive heavy trucks (semis) on it...


Sent from my iPhone using Tapatalk
Windycity is offline  
Old 01-17-2018, 08:19 AM   #7
http://penncoatinc.com/
 
PennCoat's Avatar
 
Trade: Painting / Epoxy Flooring / Polished Concrete
Join Date: Apr 2014
Location: Lancaster, PA
Posts: 91
Rewards Points: 706

Re: Pouring Over Existing Decent Slab


make sure the existing concrete is sealed. dump some water on the surface and see if it beads up. If it does, then it's sealed. If it gets absorbed in the concrete, then whatever you top it with will likely dehydrate. And if the new pour dehydrates, then it likely won't bond very well, and you could hear some hollow spots down the road. Or you could get some alligatoring in the finish.
PennCoat is offline  
Old 01-20-2018, 11:35 AM   #8
Pro
 
Fouthgeneration's Avatar
 
Trade: Masonry
Join Date: Jan 2014
Location: Mid west
Posts: 1,998
Rewards Points: 7,179

Re: Pouring Over Existing Decent Slab


Option B: Polish/ grind old surface, caulk crack. Rent a terrazzo grinder and edger. Use the welder outlet or electric dryer plug in?

Leave old crete, drill (as far out of plumb as practical) in 1/4" holes with hammer drill, install a U-shaped, galvanized 1/4" wire 'Staple' between two holes that the is about 1.5" above the old floor to mechanically bond the slabs together.

Two pieces of material fastened together are twice as strong in bending as two pieces just laying on one another....

At some point it is cheaper to demo the old crete, dig down the rock/ sand base, (for max load capacity, at least 2 x concrete thickness for base material) for the replacement products.
__________________
I might be an Idiot, but I know things that You don't: Please wait till after you get my know-how to insult me....
Fouthgeneration is offline  
Old 01-20-2018, 11:46 AM   #9
Registered User
 
Stultzlawncare's Avatar
 
Trade: Landscaping
Join Date: Jan 2018
Posts: 4

Re: Pouring Over Existing Decent Slab


Thanks for all the replies. I ended up tearing it all out and it is kinda muddy under and was actually frost under the first 4 feet. I'm thinking I'm going to dig down to solid ground then add Maybe 6 inches of 3a modified with a power tamper then my 2b then concrete. Also dig down around the edges about 2 foot for frost.
Attached Thumbnails
Pouring over existing decent slab-20180119_173714_1516466792573.jpg  
Stultzlawncare is offline  
Old 01-20-2018, 04:40 PM   #10
always building
 
parkers5150's Avatar
 
Trade: general constructiion
Join Date: Dec 2008
Location: North County San Diego Fallbrook CA
Posts: 1,814
Rewards Points: 2,224

Re: Pouring Over Existing Decent Slab


Quote:
Originally Posted by PennCoat View Post
make sure the existing concrete is sealed. dump some water on the surface and see if it beads up. If it does, then it's sealed. If it gets absorbed in the concrete, then whatever you top it with will likely dehydrate. And if the new pour dehydrates, then it likely won't bond very well, and you could hear some hollow spots down the road. Or you could get some alligatoring in the finish.
nope
__________________
"Building trust one job at a time."
www.RDPontheWeb.com
San Diego Contractor Deck and Patio Cover Builder
parkers5150 is offline  
Old 01-20-2018, 08:52 PM   #11
Pro
 
fjn's Avatar
 
Trade: mason
Join Date: Aug 2011
Posts: 4,702
Rewards Points: 9,666

Re: Pouring Over Existing Decent Slab


Quote:
Originally Posted by Stultzlawncare View Post
Thanks for all the replies. I ended up tearing it all out and it is kinda muddy under and was actually frost under the first 4 feet. I'm thinking I'm going to dig down to solid ground then add Maybe 6 inches of 3a modified with a power tamper then my 2b then concrete. Also dig down around the edges about 2 foot for frost.


2 " High density foam made specifically for placement under concrete would give you better results. It would work as a vapor barrier and insulation.
fjn is offline  
The Following User Says Thank You to fjn For This Useful Post:
Fouthgeneration (01-21-2018)
Old 01-20-2018, 09:58 PM   #12
Pro
 
JBM's Avatar
 
Trade: Masonry
Join Date: Mar 2011
Location: Mass.
Posts: 7,473
Rewards Points: 6,222

Re: Pouring Over Existing Decent Slab


Is there a frost wall there?

Advertisement

JBM is offline  


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pour a slab around existing 6x6 PT Columns? LewLew General Discussion 4 01-14-2015 06:15 PM
Pouring a 12x20 concrete slab for a garage. CJ21 Concrete & Paving 26 05-12-2013 09:24 AM
Framing addition - Matching existing roof plane ncornilsen Framing 18 01-11-2013 12:47 PM
Flagstone over slab paulbronson Flooring 2 10-26-2009 07:15 PM
granite slab handling archibaldtuttle Kitchens & Baths 3 10-12-2009 07:25 PM

Join Now... It's Fast and FREE!

I am a professional contractor
I am a DIY Homeowner
Drywall Talk is for
PROFESSIONAL CONTRACTORS ONLY!

At DrywallTalk.com we cater exlusivly to professional contractors who make their living as a contractor. Knowing that many homeowners and DIYers are looking for a community to call home, we've created www.DIYChatroom.com DIY Chatroom is full of helpful advices and perfect for DIY homeowners.

Redirecing in 10 seconds
No Thanks
terms of service

Already Have an Account?