Concreting indoors

Anyone done this?
I’m going to remove the tiles in our entrance, because its stuck in the 70's, like the rest of the house lol. But the concrete underneath is lower than the adjoining room by about 50mm. So I need to level it up. I worked out the area will require about half a cubic metre of concrete.
Will this be the best option or should I be doing it another way?

Once it level I will be laying a timber floating floor over this area and into the adjoining room. Then plastering the walls.

Cheers
Attachment 79302


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Just been looking into this coz I just ripped my shower out..

Looks like you just use a screed.. like a dryish concrete mix. 4/1 sand to concrete ratio at like a wet sand mix. You can also use a product on top of your slab to help the bond.

This is only from my google research haha.. use at your own peril.

Attachment 79303

i have seen it done in the past in a shop. you can buy a mix of "self levelling" concrete. essentially it is just a wet mix of conc, but due to the wetness it levels itself.

something like this i believe

https://www.bunnings.com.au/lanko-20...eller_p0966662

Mark, I have executed around 100 slab upgrades over the years so can pass along some learnings. If the slab is 50mm, which it looks like its less from the photos, you are on a hiding to none - it will crack and fall apart. There isn't enough depth for any reo, and you need it for any cement base product. The interface will be a distinct problem as the slab will dry out quicker on the concrete side as the concrete tries to dry. Your surface needs to be scabbled and very coarse. If this was a floor I was doing, it would get a scabble, or at worst a rough grind, then around the edges I would have some low level anchors punched into the floor like ramset nails so you get a mechanical key, then the surface would be primed with a penetrant sealer, then the floor would be coarse filled with a synthetic aggregate that has a primary layer of coarse material to bring the floor up to say 3-5mm below finished height. From there a primer is applied after a night of curing, a second layer of material of finer aggregate is applied, could be trowelled or could be a pour on self levelling/semi levelling applied. This will give you a brilliantly flat base to work with. I know you said its going to have a floating floor, but if you prep it right, the job will be magnificent. This is the same prep for a commercial vinyl floor, tile floor, synthetic floor etc.

I have been thru this recently at home where we laid Karndean plastic boards over the top of tiles. The tradesman was spectacular in every sense. He ground the tiles first to break the polish/surface, then to get all the high spots off, then he did a primary floor level with self levelling grout, followed by another full day of grinding and re-levelling, then, and only when he was happy the floor was level and free from any grout lines - these will show up on direct layed floors, he started the plank laying.

He did a massive living/kitchen/laundry and 2 bathroom/ ensuites, and 3 billion cut-ins, took him 8 days. It is a perfect job in every way, but the foundation is the base floor. I am going to get him back for upstairs and thats a timber floor and creaky and un-level. It wont be cheap but it will be perfect. Spend the money on the base and you will reap the results 10 fold. If you want this guys details I can dig them out, highly recommended. Hope this helps!

What if you build it up using a timber frame. Then you can run your boards over that. Only thing is you might have different sounds as you walk over it

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Originally Posted by rusty_nail

i have seen it done in the past in a shop. you can buy a mix of "self levelling" concrete. essentially it is just a wet mix of conc, but due to the wetness it levels itself.

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Originally Posted by rusty_nail

something like this i believe

https://www.bunnings.com.au/lanko-20...eller_p0966662

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I saw this, I reckon I'd need a lot of bags to make up half metre of conc. Plus the depth I have too Nic. Is near 50mm.

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Originally Posted by PeeBee

Mark, I have executed around 100 slab upgrades over the years so can pass along some learnings. If the slab is 50mm, which it looks like its less from the photos, you are on a hiding to none - it will crack and fall apart. There isn't enough depth for any reo, and you need it for any cement base product. The interface will be a distinct problem as the slab will dry out quicker on the concrete side as the concrete tries to dry. Your surface needs to be scabbled and very coarse. If this was a floor I was doing, it would get a scabble, or at worst a rough grind, then around the edges I would have some low level anchors punched into the floor like ramset nails so you get a mechanical key, then the surface would be primed with a penetrant sealer, then the floor would be coarse filled with a synthetic aggregate that has a primary layer of coarse material to bring the floor up to say 3-5mm below finished height. From there a primer is applied after a night of curing, a second layer of material of finer aggregate is applied, could be trowelled or could be a pour on self levelling/semi levelling applied. This will give you a brilliantly flat base to work with. I know you said its going to have a floating floor, but if you prep it right, the job will be magnificent. This is the same prep for a commercial vinyl floor, tile floor, synthetic floor etc.

I have been thru this recently at home where we laid Karndean plastic boards over the top of tiles. The tradesman was spectacular in every sense. He ground the tiles first to break the polish/surface, then to get all the high spots off, then he did a primary floor level with self levelling grout, followed by another full day of grinding and re-levelling, then, and only when he was happy the floor was level and free from any grout lines - these will show up on direct layed floors, he started the plank laying.

He did a massive living/kitchen/laundry and 2 bathroom/ ensuites, and 3 billion cut-ins, took him 8 days. It is a perfect job in every way, but the foundation is the base floor. I am going to get him back for upstairs and thats a timber floor and creaky and un-level. It wont be cheap but it will be perfect. Spend the money on the base and you will reap the results 10 fold. If you want this guys details I can dig them out, highly recommended. Hope this helps!

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Phil the photo doesn't show the true depth. The tile you can see is near 50mm thick and half of is below the level you can see. Then theres around another 25mm under this to the existing concrete base.

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Originally Posted by jay see

What if you build it up using a timber frame. Then you can run your boards over that. Only thing is you might have different sounds as you walk over it

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I thought of this too, but yeah the sound difference will be annoying.

I think TJ's idea of a screed might be the go. I might have to ring the local concrete mob and see what they have to say. I'm just busting to get these damn ugly tiles up and then I can plaster over the bricks and bring the entrance area into atleast the 90's.

Madness. What a lot of stuffing around. Waste of time and money mate.

You need 50mm plus the floating floor or including the floating floor?

Graded Battens straight on top of the tiles. No brainer mate. The sound will be pretty solid as the Battens are straight on the slab rather than spanning.

If your really concerned just 20mm yellow tongue floor over 20mm Battens. Then floating floor. If you want to deaden it more out double thick yellow tongue.

Leave the tiles there mate. Pointless pulling the up. Straight over the top. Go.

Looking at the pic. Are the tiles on a wet bed? So you want to smash out the wet bed too? They look higher in the pic?

If your committed to scrabbling out the tile bed then Battens down on the slab. I am in over 500 houses a year mate and walk on plenty of floating floors, I stamp my feet in every house to determine structure and Battens on slab sounds solid mate. No way I would screed that.

I can't speak for levelling the gap in floor.
But...

Leave the tiles. IMO.
Our whole ground floor was tiles..and I laid floating floor straight over the top,the whole area . Insulation ,then boards right over the top. Been perfect for 10 years the only time it makes a sound while walking on it , is if it's stupidly hot 35+ inside as they expand.

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Originally Posted by MudRunnerTD

Madness. What a lot of stuffing around. Waste of time and money mate.

You need 50mm plus the floating floor or including the floating floor?

Graded Battens straight on top of the tiles. No brainer mate. The sound will be pretty solid as the Battens are straight on the slab rather than spanning.

If your really concerned just 20mm yellow tongue floor over 20mm Battens. Then floating floor. If you want to deaden it more out double thick yellow tongue.

Leave the tiles there mate. Pointless pulling the up. Straight over the top. Go.

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I don't think you have read this right Daz. Or I haven't explained myself right. I want to lay a floating timber floor from this entrance and into the rumpus area. As it stands, the tiled area is about 25mm higher than the adjoining rumpus room, which is just concrete. I removed two tiles to inspect whats underneath. Well the tile is really thick, at around 25mm. Then theres another 25mm from under this to the concrete base. So when I remove the tiles the existing base is actually lower than the floor in the rumpus.

So I cant go over the top of the tiles.

Ok here’s a pic of the actual difference when I remove the tile. See how much lower it is.
Attachment 79305


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Originally Posted by mudski

Ok here’s a pic of the actual difference when I remove the tile. See how much lower it is.
Attachment 79305


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How high is that? I can't really tell on my phone.

Looks like half a brick so your 50mm. So Yellow Tongue is 19mm board. Down on 30mm Battens will get you your 50mm. 100% batten it out mate.

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Originally Posted by MudRunnerTD

Looks like half a brick so your 50mm. So Yellow Tongue is 19mm board. Down on 30mm Battens will get you your 50mm. 100% batten it out mate.

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The issue with battens is the sound and feel difference under your feet from one room with battens to the next room with a solid base. I helped a mate years ago do similar, while he was happy with the outcome, you could hear and feel the difference, as it was hollow under the foot.
But. Its worth thinking over. I will see how much it will be for half a cube of conc to do it and think about it.

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Originally Posted by mudski

The issue with battens is the sound and feel difference under your feet from one room with battens to the next room with a solid base. I helped a mate years ago do similar, while he was happy with the outcome, you could hear and feel the difference, as it was hollow under the foot.
But. Its worth thinking over. I will see how much it will be for half a cube of conc to do it and think about it.

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Battens down on concrete will feel very similar to floating floor straight on conc. I walk on it all the time in customers houses. If your really concerned then 12mm lining boards as Battens then 2 x yellow tongue on top of each other is another 38mm of solid chipboard. Floating floor over that and it will feel and sound like conc.

I stamp my feet in houses every day to check for floor construction when determining if I'm walking on a slab l/ sub floor or Battens. You can tell if a floor has big Battens or small ones and you have to stamp hard to hear it. I really would by or be concerned here at all mate.

I prefer to fix T&G 19mm flooring to timber battens or joist spaced at 450mm centers. Another method for laying timber flooring over your existing tiles is to use ply sheeting. The sheeting is laid over the tiles to create a good surface for the timber flooring to be laid on. Thickness to suit desired finished floor level. The floorboards are then glued and nailed to the ply. Use a polyurethane sealant / adhesive like Sikaflex 11FC or what I have used is Bostic Seal N Flex1. Great for fixing plasterboard to masonry as well.

https://www.bostik.com/australia/Bos...ethane-Sealant

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Originally Posted by Bidja

I prefer to fix T&G 19mm flooring to timber battens or joist spaced at 450mm centers. Another method for laying timber flooring over your existing tiles is to use ply sheeting. The sheeting is laid over the tiles to create a good surface for the timber flooring to be laid on. Thickness to suit desired finished floor level. The floorboards are then glued and nailed to the ply. Use a polyurethane sealant / adhesive like Sikaflex 11FC or what I have used is Bostic Seal N Flex1. Great for fixing plasterboard to masonry as well.

https://www.bostik.com/australia/Bos...ethane-Sealant

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Yeah ply or Yellow Tongue chipboard works great. 450 centred Battens will be great straight on the concrete will feel and sound solid too.

@mudski to bring your low slab up and level to obtain common datum throughout maybe ARDEX K 900 BF could help mate (Ideal for levelling up to 90mm thick). Need expansion joint and recon use a polyurethane flexible adhesive between timbers/ply etc.

https://ardexaustralia.com/product/ardex-k-900-bf/

http://cdn.ardexaustralia.com/pdf/pr...0Datasheet.pdf

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Originally Posted by Bidja

@mudski to bring your low slab up and level to obtain common datum throughout maybe ARDEX K 900 BF could help mate (Ideal for levelling up to 90mm thick). Need expansion joint and recon use a polyurethane flexible adhesive between timbers/ply etc.

https://ardexaustralia.com/product/ardex-k-900-bf/

http://cdn.ardexaustralia.com/pdf/pr...0Datasheet.pdf

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This looks pretty good, have not heard of it or used a system like this. I am guessing you could actually partition the slab as well if the job is done by hand, do one bit per night for example.

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Originally Posted by PeeBee

This looks pretty good, have not heard of it or used a system like this. I am guessing you could actually partition the slab as well if the job is done by hand, do one bit per night for example.

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Hence the reason for an expansion joint, being between the two different sectional thicknesses ((eg: low slab(1st section) to tile area (2nd section)). If tiled area was stable, would seriously consider leaving as is and place a timber substrate (ply, chipboard battens etc) between tiles and proposed flooring.

I have been building a house for too many yrs now (must get back to it), Rammed earth(walls are 300mm thick used road base stabilized with 4% cement and used a product (AVS Special M), used as primer to key old concrete to new pour. I used this stuff to make up a render(up to 50mm thick) to level out window sills and has lasted 10yrs no movement. Similar product constituents would say.

ARDEX are a well known established company.

Not sure if AVS are still around, Mark try ringing them 03 97984994 (Keysbrough)

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Originally Posted by Bidja

Hence the reason for an expansion joint, being between the two different sectional thicknesses ((eg: low slab(1st section) to tile area (2nd section)). If tiled area was stable, would seriously consider leaving as is and place a timber substrate (ply, chipboard battens etc) between tiles and proposed flooring.

I have been building a house for too many yrs now (must get back to it), Rammed earth(walls are 300mm thick used road base stabilized with 4% cement and used a product (AVS Special M), used as primer to key old concrete to new pour. I used this stuff to make up a render(up to 50mm thick) to level out window sills and has lasted 10yrs no movement. Similar product constituents would say.

ARDEX are a well known established company.

Not sure if AVS are still around, Mark try ringing them 03 97984994 (Keysbrough)

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Given he is putting a floating floor over the slab the need for an expansion joint really is mute. You would only do that if he was going to tile down onto the new slab. In which case flexible tile adhesive and a managed caulked expansion joint in the time bed and that junction should be mandated.

How many square metres are we talking about @mudski ?

Expansion joint in the form of inserting expansion foam along length of vertical faces of the existing tiled slab and the new pour.

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Originally Posted by Bidja

Expansion joint in the form of inserting expansion foam along length of vertical faces of the existing tiled slab and the new pour.

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Yes but the point of that is to control the shrinkage crack when the new pour dries and shinks. If a new floating floor is going down over the top with underlay then it not would really matter at all to be honest. Assuming it's the other way though, tile and mud bed scabbled out then add an pour to the existing slab level as a basic infill. Then new floating floor over that joint.

If still just use yellow tongue or ply.

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Originally Posted by MudRunnerTD

Yes but the point of that is to control the shrinkage crack when the new pour dries and shinks. If a new floating floor is going down over the top with underlay then it not would really matter at all to be honest. Assuming it's the other way though, tile and mud bed scabbled out then add an pour to the existing slab level as a basic infill. Then new floating floor over that joint.

If still just use yellow tongue or ply.

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Just putting up options for consideration @mudski .

Would only consider concrete poor for lower slab only if it was way out of level to obtain a good datum to come up from. Yeah preference remains yellow tongue or ply with use of battens if req'd.

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Originally Posted by MudRunnerTD

How many square metres are we talking about @mudski ?

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Hey mate. Sorry been a busy last 24hrs. It’s not a big area. 3.6 x 2.6 by about 50mm deep. Battening it and then board over the top sounds the best option now after reading all this I think. But I still prefer the idea of filling the area in with conc or similar. Not sure. I have time to think on it.

Thanks.


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