Crumbling garage floor. Pics added

Galaxy66

Galaxy66

Jeremy Beadle
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My name is Mal not Jeremy :)
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When I first moved into our present house, an old stone built cottage, I would employ tradesmen to do the various skills needed to convert and extend it.

This proved to be unsatisfactory due to the difficulty of finding genuine tradesmen and I now do all work myself as I am good with my hands.

So, to get to the point of my post, one of the jobs I had done for me was an extension incorporating a garage. Unfortunately the floor was laid using a weak mix on site and it has been crumbling ever since, I even have holes worn in the floor where the front wheels rest. the surface still has floor paint in places. (I completed the extension myself).

I intend laying a strong sharp sand and cement mix screed about 35-40mm thick, question is, how can I ensure the screed has a good bond with the old floor?, I do not want to dig the floor up:shake:.

Here you go.

1. the worst bit, where the front wheel sits.
IMG_9552.jpg


2. Surface is mostly like this.

IMG_9548.jpg


3. Larger view.

IMG_9550-1.jpg


4. They must have mixed it a bit stronger for the edge !.

IMG_9554.jpg


This floor was laid about 20 years ago and in my opinion was a weak mix.
 
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No more nails? :shrug: that stuff'll stick anything!
 
wegotitugetit said:
would it not be easier and better to buy the concrete pre done from a truck that drops it off as there mixes are good
Click to expand...

Not sure they would deliver the mix I require as it is not effectively a concrete mix just sand and cement, in any case I need to do this in two halves moving the contents from one side to the other, size is 6mtrs x 5 mtrs.
 
If it were me I would break up the old floor first and lay the new on top of the old. Mix in some studding or something for strength. This way the old floor will become your hardcore with sufficient gaps to allow a bond between rubble pieces. When finished apply a decent epoxy based floorcovering. I would avoid a sharp sand mix as too much cement will make it brittle and likely to crack, too little will make it easily eroded. A fine shale type concrete at around 2" would be better.
 
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Would 40mm concrete be thick enough to take the weight of a car if the floor underneath is crumbling?

Anyway, if it is I reckon scoring lines in the old surface with a chisel/hammer drill would make a good rough surface to bond to.
 
I was taking the mick :)

I know you don't want to break the base up, but it does sound like a good idea to give you a solid harcore base for the new floor, especially if it's crumbling already. I know busting up concrete a ball ache, but if you do it right, you'll only ever have to do it once!
 
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Also i used a product on my workshop that is epoxy based and uses a primer that adheers brilliantly to wet concrete, if you are interested could get a link to the company I got it from? Cost me £35 for enough primer and topcoat to do a 12' x 13' workshop.
 
Steep said:
Would 40mm concrete be thick enough to take the weight of a car if the floor underneath is crumbling?
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Should be fine as it wouldnt actually be 2" only in the sections where it hit the previous floor. Essentially with the gaps filled in by new material it would be a lot thicker. The highest section of the previous floor would still have 2" of fresh mix on top.
 
I know you can bond concrete to concrete using PVA in the mix
( not sure on the details though) but I would have also though that 40mm on top of solid concrete
wouldn't be thick enough
I would also go with breaking the top surface with a Kango or something similar using that
as hard core and getting a "few inches" down
I think I used 6 inches over 4inches of hard core for my drive that must be about 20 years
ago now and its "still all there"
 
Slipwave said:
If it were me I would break up the old floor first and lay the new on top of the old. Mix in some studding or something for strength. This way the old floor will become your hardcore with sufficient gaps to allow a bond between rubble pieces. When finished apply a decent epoxy based floorcovering. I would avoid a sharp sand mix as too much cement will make it brittle and likely to crack, too little will make it easily eroded. A fine shale type concrete at around 2" would be better.
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Problem is I can not raise the floor level more than 30-40mm as I step from the living room into the garage, any higher and it would breach building regs.

I do intend finishing with an epoxy based seal, I have had other floors finished the same way with a two pack product.

Steep said:
Would 40mm concrete be thick enough to take the weight of a car if the floor underneath is crumbling?
Anyway, if it is I reckon scoring lines in the old surface with a chisel/hammer drill would make a good rough surface to bond to.
Click to expand...

The floor was laid 150mm thick in case I converted it to living accommodation, it is just worn away in places.

Thanks for the interest so far:thumbs:
 
I accept it would be the proper thing to do by digging it all up but that is just not that easy, it'd be a nightmare job and would have a new DPC laid on top and would end up too high, besides I have nowhere to store the contents safely.

I just need it to bond securely.

Slipwave, what mix ratio do you recommend, off to google "shale mix":)
 
Cobra said:
I know you can bond concrete to concrete using PVA in the mix
( not sure on the details though) but I would have also though that 40mm on top of solid concrete
wouldn't be thick enough
I would also go with breaking the top surface with a Kango or something similar using that
as hard core and getting a "few inches" down

Mmm could do that to give it a rougher surface:thumbs:
I think I used 6 inches over 4inches of hard core for my drive that must be about 20 years
ago now and its "still all there"
Click to expand...
 
Steep said:
Would 40mm concrete be thick enough to take the weight of a car if the floor underneath is crumbling?

Anyway, if it is I reckon scoring lines in the old surface with a chisel/hammer drill would make a good rough surface to bond to.
Click to expand...

Sorry Steep missed your suggestion scoring the surface, I think this may be the way to go.:thumbs:
 
An alternative to breaking up the existing floor may be to use a concrete scarifier/scrabbler.
This will cut groves into the floor which should give sufficient key for the new floor to bond.

images
 
Slipper-one said:
An alternative to breaking up the existing floor may be to use a concrete scarifier/scrabbler.
This will cut groves into the floor which should give sufficient key for the new floor to bond.

images
Click to expand...

Great tool :thumbs:but a bit too costly to hire £230 per day:eek:
 
Rip old floor out if a floor is breaking up its breaking up for a reason, either the ground has given way a fraction over a long time or the concrete itself is losing its strength due to old age. believe me if you lay any concrete or screed on top of the old you will end up with just more problems in time. If there is a type-1 or suitable hardcore under the old concrete then do a few trial holes just to check the depth of it, if the ground under the hardcore is firm then you would expect to see at least 4 inches of hardcore but there could even be more depending if the ground was made up. If there are any low spots then top up with hardcore and compact with a vibrating plate. Idealy you would want to put polythene membrane down and a layer of mesh which would be a couple of inches off the ground before concreting.Depending what your funds are, you could mix the concrete in a mixer with a couple of mates, but premix will save you a lot of sweat plus you will have an even mix.
 
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I agree with u8myufo!

I've done this job before on a 7000sq ft building and it's a pain, it was done in sections so the area doesn't really matter. All the work is in the preperation.

I know you don't want to dig out the floor but it's the correct way to do it!

I would remove as much of the old floor as I could and order a floating mix from your local cement co, tell them what is for and they'll keep you right. Might even be worth asking them about it now as they are the experts and are usually quite good.

There is a Unibond PVA type stuff for concrete that would help bond the screed but I can't remember the name of it.

I doubt if 40mm is thick enough for the weight of a car.
 
Is the old floor breaking up just because its a poor mix or are there issues eg
damp?
deep enough?
solid enough sub base?
 
We need a photo of the damage, do you know anybody with a camera ;)

If it's just surface damage to the concrete then using a Kango to dress the concrete will do the job fine. Roughen the surface, give it a good clean then add your mix on top.
 
The thread is no good without pics :bonk: I will move the motor and get a few posted up..........:)
 
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The pics suggest the job is a botch up.

Was the original base laid on proper tamped down hardcore of adequate depth?

You may be able to buy a concrete stabilising solution to apply before laying more concrete, but that paint may hinder it in places.
 
who? said:
Is the old floor breaking up just because its a poor mix or are there issues eg
damp?
deep enough?
solid enough sub base?
Click to expand...

I actually prepared the sub base with at least 150mm hardcore (old bricks) then blinded it with sand to take the dpc membrane and then the monkeys came along mixed up and laid the weak concrete mix.
 
arclight said:
The pics suggest the job is a botch up.

Was the original base laid on proper tamped down hardcore of adequate depth?

You may be able to buy a concrete stabilising solution to apply before laying more concrete, but that paint may hinder it in places.
Click to expand...

If that be the case I will remove the paint, just don't fancy uplifting the whole floor, in fact it is not going to happen so a compromise is on the cards good enough to last 10 years then I am off to pastures new:).
 
Galaxy66 said:
If that be the case I will remove the paint, just don't fancy uplifting the whole floor, in fact it is not going to happen so a compromise is on the cards good enough to last 10 years then I am off to pastures new:).
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Don't use a blowlamp to take the paint off.
Did that once and the concrete exploded. Seemed like it tried to resist the heat expansion until all of a sudden it couldn't - then bang.
 
You need a two part epoxy repair material.

Clean off all loose material with a stiff brush, locally remove any loose lumps, wash over and allow to dry, prime (chemical bond) and apply two part material, finish with an epoxy floor paint for an even looking finish, if required.

Do not attempt to screed it with sand and cement 30 - 40mm thick, it will just crack up again.

Here is a link to the sort of thing you need LINK there are other makes, but there is enough info here to allow you to choose which you need. The first item on the page looks the stuff you need.
 
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arclight said:
Don't use a blowlamp to take the paint off.
Did that once and the concrete exploded. Seemed like it tried to resist the heat expansion until all of a sudden it couldn't - then bang.
Click to expand...

Good advice for anyone using heat near concrete!, I worked in the steel construction industry where heat is often applied in certain processes so was aware of the danger but thanks anyway for the warning, I will be removing it using a safe method.
 
Martyn... said:
You need a two part epoxy repair material.

Clean off all loose material with a stiff brush, locally remove any loose lumps, wash over and allow to dry, prime (chemical bond) and apply two part material, finish with an epoxy floor paint for an even looking finish, if required.

Do not attempt to screed it with sand and cement 30 - 40mm thick, it will just crack up again.

Here is a link to the sort of thing you need LINK there are other makes, but there is enough info here to allow you to choose which you need. The first item on the page looks the stuff you need.
Click to expand...

Thanks for the info Martyn that looks exactly the product I need but after working out how much is required checking and double checking it works out at £50 per sq mtr inc vat and I have 30 mtrs, that comes to a whopping £1500 :eek:and that is only at 5mm thickness.

I have a plan I will post it shortly.
 
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Thanks for all the helpful advice, although some of you may warn that a 30-40mm screed will crack I am going to try and get it closer to 50mm.

I will remove al the paint and thoroughly remove all the loose material and dust, then I will prime with a pva solution and when that is dry "paint" it with a strong runny sand cement mix just enough to give it a thin coating.

When this is dry-ish I will lay out chicken/rabbit netting over the surface nailed/glued down with 25mm slating latts 1 mtr apart, the mesh will be packed up with small spacers so it lies in the centre of the screed.

I could lay another 25mm latt temporarily onto the first latt to give me a level to work off, this can be removed later and filled with a flexible compound.

I will be using a 4-1 sharp sand and cement mix, or maybe a fine concrete mix using pea gravel.

When all that is dried I could always lay purpose made garage matting onto the new surface.

Unfortunately that will leave only a 100mm step through to a living area, not quite within building regulations.

Having thought of garage matting I could always give it quick repair and lay the matting on top of the existing surface :thinking:
 
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Galaxy66 said:
Thanks for the info Martyn that looks exactly the product I need but after working out how much is required checking and double checking it works out at £50 per sq mtr inc vat and I have 30 mtrs, that comes to a whopping £1500 :eek:and that is only at 5mm thickness.

I have I will post it shortly.
Click to expand...

You want cheap as well :D

I have not done any refurb / repair stuff for ages, but the two part epoxy is the only way to go with a thin coat application.

The only thing I would suggest is to ring round your local builders merchants and see what similar products that they stock, they may have an alternative at a more competitive price.

What you need to ask for is a two part epoxy concrete repair product.
 
Galaxy66 said:
Thanks for all the helpful advice, although some of you may warn that a 30-40mm screed will crack I am going to try and get it closer to 50mm.

I will remove al the paint and thoroughly remove all the loose material and dust, then I will prime with a pva solution and when that is dry "paint" it with a strong runny sand cement mix just enough to give it a thin coating.

When this is dry-ish I will lay out chicken/rabbit netting over the surface nailed/glued down with 25mm slating latts 1 mtr apart, the mesh will be packed up with small spacers so it lies in the centre of the screed.

I could lay another 25mm latt temporarily onto the first latt to give me a level to work off, this can be removed later and filled with a flexible compound.

I will be using a 4-1 sharp sand and cement mix, or maybe a fine concrete mix using pea gravel.

When all that is dried I could always lay purpose made garage matting onto the new surface.

Unfortunately that will leave only a 100mm step through to a living area, not quite within building regulations.

Having thought of garage matting I could always give it quick repair and lay the matting on top of the existing surface :thinking:
Click to expand...

Contact your local RMC / Ready Mix supplier they will do premixed screed material, they do one called fibremesh which is full of fibreglass fibres that reinforce the screed, although garage screeds should be a fine concrete, however they are usually thicker.

Now this is going to sound daft, but I am a Surveyor so believe me, if you lay a screed too thin, and unbonded to the sub base it can curl up like a dry sandwich.

At 50mm thickness you will need about 3.5 tonne of screed material.
 
Martyn... said:
You want cheap as well :D
Click to expand...

I did not even have it originally done on the cheap, the "builder" must have done a cowboy job just to save himself a few bags of cement and had emigrated to Spain by the time the surface started to break up.
 
Get some uni-bond and dilute it 50/50, make sure the floor is free from any dust and librally brush on, let it dry.then put your concrete over the top. personally i would use grano its mich stronger.:thumbs:
 
Galaxy66 said:
I did not even have it originally done on the cheap, the "builder" must have done a cowboy job just to save himself a few bags of cement and had emigrated to Spain by the time the surface started to break up.
Click to expand...

That would be the plenty to one mix ;)
 
Martyn... said:
Contact your local RMC / Ready Mix supplier they will do premixed screed material, they do one called fibremesh which is full of fibreglass fibres that reinforce the screed, although garage screeds should be a fine concrete, however they are usually thicker.

Now this is going to sound daft, but I am a Surveyor so believe me, if you lay a screed too thin, and unbonded to the sub base it can curl up like a dry sandwich.

At 50mm thickness you will need about 3.5 tonne of screed material.
Click to expand...

An expert:thumbs:.

So do you not think the mesh will reinforce a fine concrete mix, I was intending mixing and laying this myself, I have all the tools required, I own my own mixer and have laid a similar size floor before. Even if it cracks I am not that bothered so long as it is dust free and does not lift, I intend taking renewing the entire front edge as seen in the pic.

Still wondering whether I should just repair it in the worst places and cover with garage matting from Costco, works out IIRC about £200.
 
Galaxy66 said:
An expert:thumbs:.

So do you not think the mesh will reinforce a fine concrete mix, I was intending mixing and laying this myself, I have all the tools required, I own my own mixer and have laid a similar size floor before. Even if it cracks I am not that bothered so long as it is dust free and does not lift, I intend taking renewing the entire front edge as seen in the pic.

Still wondering whether I should just repair it in the worst places and cover with garage matting from Costco, works out IIRC about £200.
Click to expand...

1- The problem with fine concrete is the size of aggregate in relation to the finished thickness, if the gravel is too large and at only 50mm thickness your floor will break up with use. Pea gravel would not have enough fine material in it to fill the voids.

2- Its a garage, it still works, is it worth spending a fortune on it, isolated repair to the bad areas, and garage matting all over is economical, quicker and will do a good enough job
 
Martyn... said:
1- The problem with fine concrete is the size of aggregate in relation to the finished thickness, if the gravel is too large and at only 50mm thickness your floor will break up with use. Pea gravel would not have enough fine material in it to fill the voids.

2- Its a garage, it still works, is it worth spending a fortune on it, isolated repair to the bad areas, and garage matting all over is economical, quicker and will do a good enough job
Click to expand...

So that's what we will do Martyn :thumbs:we will go for the the late arrival no.2 plan, repair the worst bits, probably then give the whole surface a good lick of floor paint and lay the garage matting on top......job done :clap:
 
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