Hi everyone.
Straight to the question, then a bit more background:
The slab of my garage (50sqm (538 sq ft)) unfortunately has a height difference of about 4cm (corner rear right to corner front left), not perfectly flat but rather slightly wavy and bumpy in the middle.
Similar to the attached picture (3D printer build plate).
A car lift is supposed to fit in the garage, and the slab was designed accordingly (35cm (14 inches) thick).
At the spot for the lift, I have about +/- 2cm (around 1 inch) difference compared to the extreme points.
How can I effectively and durably level this?
Long story:
About a year ago, I built my dream garage with sufficient height for a car lift as a hobby project.
Everything was done by myself except the floor...
That part was contracted out and unfortunately turned out badly...
Besides the fact that less reinforcement was used than the structural engineer had specified... the whole thing ended up quite crooked.
(I have been disputing with the company for over a year now... and I’m slowly running out of energy).
[[Two layers of steel mesh were laid over the entire area.
The usual 3-5cm (1-2 inch) spacers to the ground, then the first overlapping mesh layer, followed by steel rebars arranged as spacers for the second overlapping steel mesh layer.
According to the structural engineer, steel cages should have been installed at the edges as well as in the middle, from left to right and front to back.]]
When masonry started (everything planned and scheduled), I didn’t notice much at first.
(Of course I leveled the first row on the bitumen layer to be absolutely flat, so it didn’t seem so crooked yet.)
But after the first rain and the large amount of water collecting in the corner... unfortunately, then I noticed.
The ring beam and roof were quickly installed to prevent the aerated concrete walls from absorbing too much moisture over time.
It was plastered, windows installed, and everything painted.
The garage door has been stored in the garage for a year as I want to wait for the final height before installing it.
Of course, I shouldn’t have started masonry before the floor was as I ordered/expected, but what’s done is done.
I’m hoping for good advice. I’ve already had various tradespeople here and everyone suggested different solutions, with quotes ranging from 5,000 to 16,000 euros!
Straight to the question, then a bit more background:
The slab of my garage (50sqm (538 sq ft)) unfortunately has a height difference of about 4cm (corner rear right to corner front left), not perfectly flat but rather slightly wavy and bumpy in the middle.
Similar to the attached picture (3D printer build plate).
A car lift is supposed to fit in the garage, and the slab was designed accordingly (35cm (14 inches) thick).
At the spot for the lift, I have about +/- 2cm (around 1 inch) difference compared to the extreme points.
How can I effectively and durably level this?
Long story:
About a year ago, I built my dream garage with sufficient height for a car lift as a hobby project.
Everything was done by myself except the floor...
That part was contracted out and unfortunately turned out badly...
Besides the fact that less reinforcement was used than the structural engineer had specified... the whole thing ended up quite crooked.
(I have been disputing with the company for over a year now... and I’m slowly running out of energy).
[[Two layers of steel mesh were laid over the entire area.
The usual 3-5cm (1-2 inch) spacers to the ground, then the first overlapping mesh layer, followed by steel rebars arranged as spacers for the second overlapping steel mesh layer.
According to the structural engineer, steel cages should have been installed at the edges as well as in the middle, from left to right and front to back.]]
When masonry started (everything planned and scheduled), I didn’t notice much at first.
(Of course I leveled the first row on the bitumen layer to be absolutely flat, so it didn’t seem so crooked yet.)
But after the first rain and the large amount of water collecting in the corner... unfortunately, then I noticed.
The ring beam and roof were quickly installed to prevent the aerated concrete walls from absorbing too much moisture over time.
It was plastered, windows installed, and everything painted.
The garage door has been stored in the garage for a year as I want to wait for the final height before installing it.
Of course, I shouldn’t have started masonry before the floor was as I ordered/expected, but what’s done is done.
I’m hoping for good advice. I’ve already had various tradespeople here and everyone suggested different solutions, with quotes ranging from 5,000 to 16,000 euros!
Hi,
this sounds like the classic case of “structurally stable but visually and functionally a mess,” which doesn’t help much if you want to install a lift precisely. A 4cm (1.6 inch) deviation over 50m² (538 ft²) isn’t a disaster, but it is significant for point loads. Having only about +/-2cm (1 inch) at the lift’s position is almost lucky under the circumstances.
Honestly, I wouldn’t start patching this up wildly. Thin leveling compounds won’t work at this thickness—they will crack or compress under load, especially with a 2–3 ton (2.2–3.3 US ton) vehicle on top. It’s important to have compressive strength above 30 N/mm² (4,351 psi); anything less is more decorative than functional.
The proper solution would be a cement-based industrial leveling screed or self-leveling concrete, bonded to the slab, with a layer thickness of 10–40mm (0.4–1.6 inch), after shot blasting or milling the surface and applying a bonding agent. Of course, this costs money, but the quotes you mentioned from 5,000 to 16,000 show that many either don’t want to bother or are trying to upsell you on a premium system.
As a somewhat more pragmatic alternative: just level the area where the lift will be installed, roughly 2.5x5m (8x16 ft) precisely, and accept the rest of the garage floor as is. It might not look perfect, but it works technically. More people do this than they admit.
What concerns me more is the reduced reinforcement. Are you sure the 35cm (14 inch) slab will really carry the loads long-term, or are you just hoping it “will be fine”?
this sounds like the classic case of “structurally stable but visually and functionally a mess,” which doesn’t help much if you want to install a lift precisely. A 4cm (1.6 inch) deviation over 50m² (538 ft²) isn’t a disaster, but it is significant for point loads. Having only about +/-2cm (1 inch) at the lift’s position is almost lucky under the circumstances.
Honestly, I wouldn’t start patching this up wildly. Thin leveling compounds won’t work at this thickness—they will crack or compress under load, especially with a 2–3 ton (2.2–3.3 US ton) vehicle on top. It’s important to have compressive strength above 30 N/mm² (4,351 psi); anything less is more decorative than functional.
The proper solution would be a cement-based industrial leveling screed or self-leveling concrete, bonded to the slab, with a layer thickness of 10–40mm (0.4–1.6 inch), after shot blasting or milling the surface and applying a bonding agent. Of course, this costs money, but the quotes you mentioned from 5,000 to 16,000 show that many either don’t want to bother or are trying to upsell you on a premium system.
As a somewhat more pragmatic alternative: just level the area where the lift will be installed, roughly 2.5x5m (8x16 ft) precisely, and accept the rest of the garage floor as is. It might not look perfect, but it works technically. More people do this than they admit.
What concerns me more is the reduced reinforcement. Are you sure the 35cm (14 inch) slab will really carry the loads long-term, or are you just hoping it “will be fine”?
Hi, thank you for your contribution.
- With tile screed, I assume you would also use tiles? I’ve already requested quotes for thick-bed installation, but no one wants to take on “such a small project.”
- Industrial compensation? The screeders always recommended bonded screed to me. All with slightly different methods, but basically similar. As mentioned, the cost is in the range of 5,000-7,000 euros (approximately $5,300-$7,400), and one wasn’t interested at all and quoted 16,000 euros (about $17,000).
- Only properly screed the area around the lifting platform… and then use a “cheap” floating screed for the rest?
Regarding reinforcement:
I added this to the text. Basically, I’m relying on it serving its purpose. It’s not a commercial space, so it’s not like a car is on the platform every day, more like once a month.
I had repeatedly pointed out to the contractor (before the concrete was poured) that it didn’t currently match the engineer’s plan... he just replied, “we’ll still do it,” and then suddenly the concrete mixers arrived...
In hindsight, I should have stopped everything immediately at that point. Unfortunately, I wasn’t smart enough in 2024.
Some said it will hold, but I am sure I will have to expect cracks in the walls in 10 to 20 years, because the floor moves more than it should.
Everything turned out poorly. But what option do I have? Tear down my €40,000 garage again? I can’t afford that.
- Rebuilding the floor isn’t really possible. Then I’d lose the 3m (10 feet) height at the door that I need for the caravan.
- With tile screed, I assume you would also use tiles? I’ve already requested quotes for thick-bed installation, but no one wants to take on “such a small project.”
- Industrial compensation? The screeders always recommended bonded screed to me. All with slightly different methods, but basically similar. As mentioned, the cost is in the range of 5,000-7,000 euros (approximately $5,300-$7,400), and one wasn’t interested at all and quoted 16,000 euros (about $17,000).
- Only properly screed the area around the lifting platform… and then use a “cheap” floating screed for the rest?
Regarding reinforcement:
I added this to the text. Basically, I’m relying on it serving its purpose. It’s not a commercial space, so it’s not like a car is on the platform every day, more like once a month.
I had repeatedly pointed out to the contractor (before the concrete was poured) that it didn’t currently match the engineer’s plan... he just replied, “we’ll still do it,” and then suddenly the concrete mixers arrived...
In hindsight, I should have stopped everything immediately at that point. Unfortunately, I wasn’t smart enough in 2024.
Some said it will hold, but I am sure I will have to expect cracks in the walls in 10 to 20 years, because the floor moves more than it should.
Everything turned out poorly. But what option do I have? Tear down my €40,000 garage again? I can’t afford that.
- Rebuilding the floor isn’t really possible. Then I’d lose the 3m (10 feet) height at the door that I need for the caravan.
Hi,
if you didn’t hit the stop button before starting the masonry work with a floor height difference of 4cm (1.5 inches), you’ve now landed in the comfort zone of compromises. Installing tiles on a flowing screed that is strong enough to support the lifting platform is technically possible, but it’s not the most pleasant solution for a DIY enthusiast – and “small projects” are often the last thing professionals want to take on because effort and payoff don’t match. Bonded screed is actually what you need, and industrial floor leveling is basically a variation of that, focusing on the harder, more durable section. The 5,000 to 7,000 Euro cost is not unreasonable if you want quality and long-term durability.
The idea of making the area for the lifting platform perfect and leaving the rest “as is” is often the most pragmatic approach. But clearly, you will end up with different floor levels – if that doesn’t bother you visually, it’s a feasible way to go.
Regarding the reinforcement: you’re relying on “it’ll hold” – that’s an option if the risk is manageable. However, cracks appearing after 10-20 years are realistic if the reinforcement wasn’t installed as planned. But hey, for a DIY garage, that might just be a cosmetic issue, right?
if you didn’t hit the stop button before starting the masonry work with a floor height difference of 4cm (1.5 inches), you’ve now landed in the comfort zone of compromises. Installing tiles on a flowing screed that is strong enough to support the lifting platform is technically possible, but it’s not the most pleasant solution for a DIY enthusiast – and “small projects” are often the last thing professionals want to take on because effort and payoff don’t match. Bonded screed is actually what you need, and industrial floor leveling is basically a variation of that, focusing on the harder, more durable section. The 5,000 to 7,000 Euro cost is not unreasonable if you want quality and long-term durability.
The idea of making the area for the lifting platform perfect and leaving the rest “as is” is often the most pragmatic approach. But clearly, you will end up with different floor levels – if that doesn’t bother you visually, it’s a feasible way to go.
Regarding the reinforcement: you’re relying on “it’ll hold” – that’s an option if the risk is manageable. However, cracks appearing after 10-20 years are realistic if the reinforcement wasn’t installed as planned. But hey, for a DIY garage, that might just be a cosmetic issue, right?
Which offer looks more professional?
(I’m leaving out sanding, edge insulation strips, and top sealing since both include them identically.)
1. I once received the offer:
- Multifunction primer
- Cement-based self-leveling screed Maxit Turbo
2. From the other:
- maxit floor 4712 EC 1
2-component epoxy resin primer application
- maxit floor 4712 EC 1
2-component epoxy resin primer, including quartz sand broadcast, supply and installation
- maxit floor 4610 Duro Top
EN 13813 CT-C35-F10 cementitious industrial screed, 5 mm (0.2 inches) thickness, applied
I’m a bit unsure; I find the second offer “better” because the polished concrete is nicely primed and then coated again with quartz sand for good bonding to the screed.
However, the technical datasheet states that the Duro Top layer thickness should not exceed 15 mm (0.6 inches).
But I actually have a height difference of 3.5–4 cm (1.4–1.6 inches).
In offer 1, I can’t find any information about the layer thickness of the other screed.
(I’m leaving out sanding, edge insulation strips, and top sealing since both include them identically.)
1. I once received the offer:
- Multifunction primer
- Cement-based self-leveling screed Maxit Turbo
2. From the other:
- maxit floor 4712 EC 1
2-component epoxy resin primer application
- maxit floor 4712 EC 1
2-component epoxy resin primer, including quartz sand broadcast, supply and installation
- maxit floor 4610 Duro Top
EN 13813 CT-C35-F10 cementitious industrial screed, 5 mm (0.2 inches) thickness, applied
I’m a bit unsure; I find the second offer “better” because the polished concrete is nicely primed and then coated again with quartz sand for good bonding to the screed.
However, the technical datasheet states that the Duro Top layer thickness should not exceed 15 mm (0.6 inches).
But I actually have a height difference of 3.5–4 cm (1.4–1.6 inches).
In offer 1, I can’t find any information about the layer thickness of the other screed.
Hi
The second quote sounds more like it’s from someone who has at least considered tensile adhesion, bonding, and load transfer. The approach with epoxy plus quartz sand broadcast is more typical for industrial flooring, especially when point loads are expected later. Personally, I wouldn’t blindly trust a “just pour some fast-setting screed on top” solution for a car lift, even though the name does sound quite impressive.
But you’ve already identified the crucial point yourself. If the Duro Top data sheet only approves it for thicknesses up to 15mm (0.6 inches), then it simply doesn’t fit your 35-40mm (1.4-1.6 inches) variation. For me, the immediate question would be: does the screed installer plan to level the entire area or just the actual low spots? Many calculate based on averages rather than the maximum depth in the worst corner. This is often expressed a bit... let’s say creatively in quotes.
Some contractors first apply a rough base layer with a stable repair mortar or bonding screed and then fine-level it with a self-leveling industrial compound. Technically, that makes more sense than just pouring 4cm (1.6 inches) of leveling compound all at once. Pure flowable screed at that thickness gets expensive, heavy, and depending on the product can introduce considerable stresses. Especially if the substrate slab is already somewhat “flexible.”
Quote 1 sounds more like a standard solution from everyday screeding work. It doesn’t have to be bad, but honestly, too many details are missing for my taste: no exact layer thickness, no compressive strength, no system build-up, no mention of tensile adhesion preparation. I’d be cautious with that, especially on a subfloor like yours. Some go with the mindset “it’ll become level somehow” until hollow spots show up after two years.
One more thing: with 50m² (540 sq ft) and a 4cm (1.6 inches) slope, theoretically we’re talking about nearly 2m³ (70 ft³) of material if the entire area is leveled. That’s how you quickly arrive at 5-7k€ despite the initial sticker shock. I’d categorize the 16k€ quote more as a “not interested” offer.
By the way, I’d only do tiling once the subfloor is truly stable and firm. Otherwise, the grout will crack rather than the screed itself.
The second quote sounds more like it’s from someone who has at least considered tensile adhesion, bonding, and load transfer. The approach with epoxy plus quartz sand broadcast is more typical for industrial flooring, especially when point loads are expected later. Personally, I wouldn’t blindly trust a “just pour some fast-setting screed on top” solution for a car lift, even though the name does sound quite impressive.
But you’ve already identified the crucial point yourself. If the Duro Top data sheet only approves it for thicknesses up to 15mm (0.6 inches), then it simply doesn’t fit your 35-40mm (1.4-1.6 inches) variation. For me, the immediate question would be: does the screed installer plan to level the entire area or just the actual low spots? Many calculate based on averages rather than the maximum depth in the worst corner. This is often expressed a bit... let’s say creatively in quotes.
Some contractors first apply a rough base layer with a stable repair mortar or bonding screed and then fine-level it with a self-leveling industrial compound. Technically, that makes more sense than just pouring 4cm (1.6 inches) of leveling compound all at once. Pure flowable screed at that thickness gets expensive, heavy, and depending on the product can introduce considerable stresses. Especially if the substrate slab is already somewhat “flexible.”
Quote 1 sounds more like a standard solution from everyday screeding work. It doesn’t have to be bad, but honestly, too many details are missing for my taste: no exact layer thickness, no compressive strength, no system build-up, no mention of tensile adhesion preparation. I’d be cautious with that, especially on a subfloor like yours. Some go with the mindset “it’ll become level somehow” until hollow spots show up after two years.
One more thing: with 50m² (540 sq ft) and a 4cm (1.6 inches) slope, theoretically we’re talking about nearly 2m³ (70 ft³) of material if the entire area is leveled. That’s how you quickly arrive at 5-7k€ despite the initial sticker shock. I’d categorize the 16k€ quote more as a “not interested” offer.
By the way, I’d only do tiling once the subfloor is truly stable and firm. Otherwise, the grout will crack rather than the screed itself.
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