# Forum Home Renovation Sub Flooring  Removing concrete to match wood floor levels

## jags

Hi All  
I am about to start a reno where i am going to remove the wall between the laundry and the kitchen to make the kitchen bigger my proplem is that the kitchen has a jarrah floor and the laundry is concrete . 
My plan was to  
1) get recycled floor boards that match the ones in the kitchen 
2) dimond cut evenly spaced 4cm cut in the concrete .
3) hammer dill each channel out to the depth of 4cm 
4) attempt to make the concrete slab level with some kind of leveling compound .
5) direct stick the new boards to the concrete slab so that the new boards are at the same height as the old ones (kitchen floor ) 
The kitchen boards have not been polished yet so i figure that if the new boards are a little high i can sand them down to match the kitchen  
Am i nuts  :Cry:  or on the right track any help would be greatly appreciated . 
Regards Rob  :Cry:

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## SilentButDeadly

If the laundry slab is elevated (not sitting on the ground) then you'd better off totally removing it and putting bearer and joist floor in. It'd be way safer and stronger than if you chop the best part of half the slab out!!

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## Stringy

Jags, 
This is what I did!  Attachment 47767  Attachment 47768  Attachment 47769 
Before I installed kitchen I made a cut around the are to be removed, I did not remove any concrete from where the kickboard would hide the floor.
Jackhammered the surface off the old laundary floor below the level of the floor joists, had heaps of depth.
Cut and jackhammered out 50mm deep and wide trenches the width of the area to be covered with boards, make sure the concrete floor is deep enough!
Epoxied in 40x45mm battons/joists. The pictures show levelling and spacing with floor boards.

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## jags

Hi guys thanks for the replys  
It took me a minute to work out what the white strips where for but then realised that this was to show the existing floor level (right ?) the finished product look great . 
As the two floors are the same level i should have enough meat in the slab to cut it down . i have attached a pic of what i am try to do and the wall that is going to be removed currently both floor are covered in lino. 
Regards Rob :Cry:

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## Stringy

Yeah the white strips are straight edges (vertical blind tracks) sitting on the existing floor at one end and packed level at the other, with the spacers (actual floor board offcuts) and battons suspended underneath with screws, this kept everything in place whilst epoxying. 
I built a tent with the black plastic that goes under concrete slabs and ran my dust extractor inside whilst cutting and jackhammering.

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## jags

Hi guys  
Thanks for the help  
Now I'm worried !!!! 
Silentbutdeadly :I've only now realised the importance of what you said ...SORRY thank for the help ...  
How can i determand how thick the floor is in the laundry ?
Is there a minimim thickness used for subfloors ? 
If i try and get under the house will i be able to see how thick the slab is ? 
Is removing the slab and putting in bearers and joists a major job the floor that needs to be leveled is only 6m2 
And are there any structural issues to consider ? 
do you think reducing the slab by only 2cm them sticking the floor directly to the concrete would work ? 
any help would be greatly appriciated .  
I'm now stressing .... :Biggrin:   :Biggrin:   :Biggrin:

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## Stringy

Hey Rob, 
You may need to PM SBD if he has missed this thread! 
While I'm here; _How can i determand how thick the floor is in the laundry ?_
You can work this out by measuring getting under the house and measuring to the underside of the timber floor compared to the underside of the cement floor.  _Is there a minimim thickness used for subfloors ?_ No idea.  _If i try and get under the house will i be able to see how thick the slab is ?_
Yep.  _Is removing the slab and putting in bearers and joists a major job the floor that needs to be leveled is only 6m2_
I decided to remove the minimum from the surface and cut in the trenches and see how it went.  If it had of gone to s**t then the cement floor would have to be taken out, or maybee a pier in the center of the slab.  It would have been a big job to take the slab out, as it ran under the supporting walls into the toilet and doorway outside.  I definitly did not want to take the slab out :No: ,  
And are there any structural issues to consider ?
Yep, it could collapse (really just put this bit in to cover my ass :Wink: ).  The slab should definitly have mesh in which means you can punch great holes in it and it will still be quite strong.  _do you think reducing the slab by only 2cm them sticking the floor directly to the concrete would work ?_ I don't know how you would remove the 20mm to get a smooth surface to glue anything to!  I used the battons so this piece of floor resembled the rest with nails every 450mm thru the top of the boards. 
Rob, hope this helps.

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## SilentButDeadly

Stringy is spot on.......typically a floor slab is about 100mm thick but if it's an older house (as it appears to be) then the floor may be both thinner and unreinforced......in which case you're in trouble since you're planning on taking out minimum 20&#37; of the thickness. 
Get underneath if you can and what that floor holds up and how it's made/supported.  Just for your info though......pulling out a suspended slab is not a tricky job as long as there aren't any walls sitting on it. In other words, if it has been cast in situ. 
If you MUST cut the floor......then I strongly suggest that you fit some additional reinforcing underneath to support the choped up concrete..... 
Building a new floor is straightforward enough in such a small space especially in a brick house.  All you need is deep joists (Hyspan would be good) sitting on galvanised angle bolted to the brick walls and blocked in between to stiffen. New floorboards go straight on top.  Of course the actual arrangement and structure depends on how your foundations look........

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## jags

hi guys  
Thank you both for all the help . 
From what has been said it seems as though it would be easier to remove the floor and replace it with joists . the house is double brick on a limestone foundations so i presume (depending on the depth of the brick work ) that rather than bolting into the two walls i may have to set some posts up to carry the wieght of the new floor as drilling into limestone and useing angle iron would not be a good idea i'm think ?  
i attached a sketch to show the area better where the blocks are is where the wall is , that will be removed . Opening up the area and making the space more usable .
As you can see i got a little carried away with google sketchup it's a great free download . 
thanks again  
Rob

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## jags

well it been bloody ages since the last post but i thought i would up date this as it might be relevant to some people .  
In the end i did remove the hole slab .thank to the way the concrete slab was made with linestone blocks on the sides i was able to use these to support my bearers but once they where in place i reinforced the linestone with cement at the sides of the blocks .as i had to remove to surounding floorboards so that it would all match up it was quite easy to set the levels for the bears and joists and as they where standard sizes it made the job even easlier and only a little planning was required . i found that by drawing a plan it was easy to work out what needed to be done  
to get the right floor boards was a plain and on two occasions i was sold crappy board but i ended up getting some from the salvage yard at the end of my road . I used the old style floor clamps ( the one that lock to the joists ) to put the boards down and they worked a treat (see the gap i was left with in the pic it's aboat 1.5m .The trick i found was to not get cocky and try and do to many board in one go about five worked well .And to not use to much force all you are trying to do is get the boards together and not to compress them .in the end i am really happy with the result and the new kitch look great and even thefloor sander guy could not pick where the old room and concrete floor used to be . 
anyway here are some pic ......we move in over easter  
thanks for all the help .
Regards Rob

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