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Self levelling compound on a tamped concrete garage floor

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RogerM

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I'm contemplating grasping the nettle and to try to put a smooth surface on an existing tamped concrete floor in my garage. The garage is attached to our house, has a damp course and I also think there will be a damp proof membrane under the floor slab as I have no issues with damp. The main problem is the unevenness of the floor which makes moving machinery around very difficult. I'm thinking in terms of using a self-levelling compound, but most advertise that this is only to prepare a surface for a floor covering, and is not a final surface.

Some people recommend covering with interlocking plastic tiles, and others a two part epoxy floor paint. Screwfix do Mapei Ultra 1210 at a sensible price, but it is unclear whether this would be up to the job if just painted. Ideally I want something relatively slow setting as I don't want to have to work like a paperhanger in a gale to get it all down in one coat. I have 30 sq metres to level.

Does anyone with any practical experience of using these products as a final surface in a workshop? And if so, what products did you use?
 

Max Power

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As you say self levelling compound is a substrate to prepare for a covering, tiles etc. It wouldn't last long dragging machinery around on it.
 

RogerM

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Those were my thoughts too Max. Favourite at the moment is to level it with Mapei Ultra 1210 and then to cover it with floor grade interlocking chipboard (about £200) or interlocking plastic tiles - but that would be close to £1,000 :(
 

screwpainting

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I would look into surface grinding/polishers, just machine hire and elbow grease.
 

large red

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If you are meticulous with prep and prime the floor with a diluted SBR primer (not PVA) prior to laying the self leveling material you will get away with painting the floor, if you use a quality 2 part floor paint.
 

mbartlett99

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I used latex screed from Jewsons 10 yrs ago and it still looks perfect so I'm not sure what the issue might be. It was a tricky job especially on a hot June day - you have to move like the devils after you. My floor was all over the place and as rough as a badgers buttocks so aI needed a fair amount of compound on it. If I were doing it again I'd want a 2nd person or a small cement mixer.

If you go ahead do it on the coldest day you can and add a little more water than they say. I finished it with floor paint and it still looks fine; my combi weighs 500kg and the bandsaw 200 so it can take the load.
 

Old.bodger

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I spent nearly thirty years laying this type of product. Firstly be aware that it is self smoothing don’t think of it as self leveling !

Avoid any that are water mix. F ball and Co do a good selection and they come with their own gauging liquids. Use the correct primer and follow the instructions. Throughly mix with a powered paddle in a large container. Don’t be mean with it, it can be feathered out but you loose the self smoothing properties. Use one that is rated for fork truck traffic, lay at min. 5mm thick, prime first and use a spiked roller. Do the whole floor in one hit, keeping a wet edge, you may need a second person mixing, (so two containers to mix in etc ) and if you can get a third person on the spiked roller.......

If the floor has any surface contamination/ or is polished/ power floated you may need to scabble first ( hope not!)

Once it is really dry, apply epoxy floor finish.

It will last for years if done correctly.
 

RogerM

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Old.bodger":1qbs6a4q said:
I spent nearly thirty years laying this type of product. Firstly be aware that it is self smoothing don’t think of it as self leveling !

Avoid any that are water mix. F ball and Co do a good selection and they come with their own gauging liquids. Use the correct primer and follow the instructions. Throughly mix with a powered paddle in a large container. Don’t be mean with it, it can be feathered out but you loose the self smoothing properties. Use one that is rated for fork truck traffic, lay at min. 5mm thick, prime first and use a spiked roller. Do the whole floor in one hit, keeping a wet edge, you may need a second person mixing, (so two containers to mix in etc ) and if you can get a third person on the spiked roller.......

If the floor has any surface contamination/ or is polished/ power floated you may need to scabble first ( hope not!)

Once it is really dry, apply epoxy floor finish.

It will last for years if done correctly.
Thanks. Nice to hear from someone with practical experience. F Ball & Co Stopgap 1200 Pro or Stopgap 800 Wearcoat look like the best products from their range for this type of application. However, I have about 30 sq m to do, and only me and my wife to do it. Time is not money for us, so is there some sort of retardent that can be added to extend the workable time? Given that it can be walked on in an hour, I can foresee us running into trouble. Or maybe just do it on a cold day - but I'll also need the weather to be reliably dry as everything will have to stay outside for one night at least.

For 30 sqm I would need approx 10 bags, so presumably you would divide the floor into 3sqm sections with a moveable batten "dam" to define the edges to ensure even coverage, and then move the battens for each section, using the edge of the previous section as the other edge, if you see what I mean?
 

Old.bodger

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Roger,
The Stopgap 800 looks the best for you, interestingly their product have moved on since I stopped working with them and I see that this is now water mix! (I take back my comment about avoiding water mix). I always found their tech department very helpful if you need them. No retardant that I know of but you can push the water content up to 5 ltr, that will help.
The primer is essential to get a good flow so make sure that is coated well. I can’t see that you couldn’t do it in ‘bays’ so long as you accept that you WILL see them afterwards how ever good you are with a float trowel. You will need to cover the ‘wet’ side of your dam with brown parcel tape, to avoid adhesion, and also seal to avoid leakage, a bead of ordinary silicone builders seal will do no harm. It is worth looking around the perimeter of the floor, and perhaps sealing around where the subfloor was cast inside the brick walls ( making assumptions here) as this stuff is quite liquid and it is very frustrating to have it all start to disappear down a crack , giving you a sink hole. Likewise seal any cracks in the subfloor. Also think about fixing the middle of your dam to stop it bowing with the weight of the compound behind it. Last thought is about mixing, firstly don’t try mixing ‘ part bags’ you need a container bigger than a bucket, I used to use 25ltr drums scrounged from the local garage that had had screenwash etc in and cut the lid off, put the 5 ltrs of water in first, get it moving with the drill whisk, and TRICKLE the powder in ........be prepared and dressed for splashes! Then dump it on the floor, spread quickly with a big float trowel and roll with the spiked roller........AND LEAVE IT ALONE !

Regards

Jim
 

RogerM

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Old.bodger":39lbmzkj said:
Roger,
The Stopgap 800 looks the best for you, interestingly their product have moved on since I stopped working with them and I see that this is now water mix! (I take back my comment about avoiding water mix). I always found their tech department very helpful if you need them. No retardant that I know of but you can push the water content up to 5 ltr, that will help.
The primer is essential to get a good flow so make sure that is coated well. I can’t see that you couldn’t do it in ‘bays’ so long as you accept that you WILL see them afterwards how ever good you are with a float trowel. You will need to cover the ‘wet’ side of your dam with brown parcel tape, to avoid adhesion, and also seal to avoid leakage, a bead of ordinary silicone builders seal will do no harm. It is worth looking around the perimeter of the floor, and perhaps sealing around where the subfloor was cast inside the brick walls ( making assumptions here) as this stuff is quite liquid and it is very frustrating to have it all start to disappear down a crack , giving you a sink hole. Likewise seal any cracks in the subfloor. Also think about fixing the middle of your dam to stop it bowing with the weight of the compound behind it. Last thought is about mixing, firstly don’t try mixing ‘ part bags’ you need a container bigger than a bucket, I used to use 25ltr drums scrounged from the local garage that had had screenwash etc in and cut the lid off, put the 5 ltrs of water in first, get it moving with the drill whisk, and TRICKLE the powder in ........be prepared and dressed for splashes! Then dump it on the floor, spread quickly with a big float trowel and roll with the spiked roller........AND LEAVE IT ALONE !

Regards

Jim
Jim - you are an absolute star! I was thinking only leave the dam in place until the mix has started to set sufficiently to hold its shape, and then remove it and pour the next batch to help with bonding along the edge. I'm not bothered about the shape of the bays being visible so long as I don't have a step between them. There are no significant cracks, and the surface is dry with no contaminants - this garage has never seen a car in it, it's as much as I can do to fit the bikes in between the woodworking toys.

When it comes to the edge by the garage entrance, can this stuff be feathered down to nothing to form a ramp, or should I just accept that there may be a 5mm step, which even I would find difficult to trip over?

And when assessing the surface after all the toys have been cleared, would you be tempted to fill the deeper hollows (where there were edges to the different mixes in the tamped floor slab) or just go straight in with the Stopgap 800 - after sweeping, vac'ing and priming of course?

I've already got some 40litre flexible buckets for mixing. Sounds like we have the beginnings of a plan!
 

Neil S

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Good luck Roger, I hope it goes well. :D
I've always wanted to do this but have been put off by the thought of emptying out the whole garage in one go and storing everything outside while it's done.

Let us know how it goes, perhaps you will inspire others by your success. =D>

-Neil
 

RogerM

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Thanks Neil. I'm in the middle of refitting the bathroom at the moment so it will have to wait a week or two. But it's definitely a project for some time this summer. Back in the winter, I wanted to move my planer thicknesser to a position where I could feed long pieces of stock through it. The wheels got stuck in a rut, and then when I pulled harder it came in a rush and went over my toe - all 165 kilos of it! So that was the last straw! It will be done!
 

RogerM

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Following the help offered here, I contacted F Ball tech dept and what a helpful guy I found! In his opinion, whilst Stopgap 800 would be the Rolls Royce solution, it is not cheap, and is designed for factory and commercial warehouse applications so probably overkill for a domestic workshop. He recommended Stopgap 300 HD which is considerably cheaper and certainly strong enough to take a car and to wheel around a 200kg machine over it. Of key importance is priming the surface. This not only helps adhesion, but also keeps the product workable for longer. He also suggested applying the Stopgap 300 HD on a cool day, and if doing it in the summer start early in the morning before it gets too warm. Temperatures much above 20C would make spreading a large area "challenging".

I asked about how to tackle the entrance to the garage, and could the Stopgap 300 HD be feathered to an edge? Yes it can, but a better solution would be to cut a shallow groove (about 5mm with a disk cutter, and chase back the floor for a few cms on the inside so that not only would I have a straight edge which would look better, but a 5mm thickness could be maintained right up to the edge which would help the structural integrity of the floor. Sounds like we have a plan!
 

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