A base on a slab that is not level- how to?

[chickade]

I managed to get a slab completed, but since I am utterly new to this kind of work, it is far from level. It slopes down from the front to the back, and the back is at least 6 inches lower than the front. Do you have any suggestions for how to make the base level? Thank you.

[david s]

Re: A base on a slab that is not level- how to?

If it were mine I would be resetting the form work ensuring that it is level and then pouring more concrete on top. 6" is a long way out of level. You probably don't need to add reinforcing to this new layer. It is also a good idea to hump this new slab about 1/4" higher in the middle, sloping down to the outsides so water will not be encouraged to sit under the vermicrete layer, should it penetrate after a deluge of rain.

[jim81147]

Re: A base on a slab that is not level- how to?

I would have to agree with David I think . There are other ways to accomplish a level base , but a repour would be the easiest fix and take the least amount of know how.

[chickade]

Re: A base on a slab that is not level- how to?

Thanks! I was thinking of doing that, but I talked to someone who implied I can't put another layer on the base because I didn't make it rough while it was curing. Should I prepare the base in any way before adding the new layer?

[david s]

Re: A base on a slab that is not level- how to?

I wouldn't bother the sheer weight will hold everything in place, but there are products you can use to help bond the next layer on. Bondcrete is one that is used for this purpose in Australia, don't know if you have that there.

[mrchipster]

Re: A base on a slab that is not level- how to?

I wouldn't bother the sheer weight will hold everything in place, but there are products you can use to help bond the next layer on. Bondcrete is one that is used for this purpose in Australia, don't know if you have that there.

Yes there are many similar bonding products, available at any building supply store HD, LOWES, Menards etc. I would recommend adding enough new material to have a minimum of 2 inches of thickness at the thinnest addition, and use a concrete mix and not a sand mix.

Tscar do you want to chime in on this it is your expertise.

Chip

[chickade]

Re: A base on a slab that is not level- how to?

How should I build the form so that one end is higher than the other?

[brickie in oz]

Re: A base on a slab that is not level- how to?

How should I build the form so that one end is higher than the other?

You need a spirit level.

[david s]

Re: A base on a slab that is not level- how to?

Yes there are many similar bonding products, available at any building supply store HD, LOWES, Menards etc. I would recommend adding enough new material to have a minimum of 2 inches of thickness at the thinnest addition, and use a concrete mix and not a sand mix.

Tscar do you want to chime in on this it is your expertise.

Chip

That means one end will be 8" thick!
This thing could double as a bonb bunker.

[chickade]

Re: A base on a slab that is not level- how to?

I got a level and it appears that the back is 3 1/2 inches lower than the front, so I'm making a form out of 2 x 4s. I will build up concrete at the back and try to level it off by hand toward the front. I will draw lines along the side 2 x 4s that are level to the back so that I have a guide, and then I will attempt to add more concrete in the center of the form so that water runs off. How does that sound?

[mrchipster]

Re: A base on a slab that is not level- how to?

I got a level and it appears that the back is 3 1/2 inches lower than the front, so I'm making a form out of 2 x 4s. I will build up concrete at the back and try to level it off by hand toward the front. I will draw lines along the side 2 x 4s that are level to the back so that I have a guide, and then I will attempt to add more concrete in the center of the form so that water runs off. How does that sound?

If you can stake and nail 2x4s all arround possibly 2X6s at the thick end of your slab and then use a long 2x4 to go across the top of the forms, with one person on each end you should be able to slide the 2x4 back and forth as you push the wet concrete across the existing slab to level out the wet concrete. check out videos on youtube screeding concrete.

chip

[david s]

Re: A base on a slab that is not level- how to?

Yes that's the way to do it, but then you need to add more to the centre so it mounds up slightly for the water run off. You need a concrete float to do this. Find a friend or neighbour who's had a little experience, to help you.

[chickade]

Re: A base on a slab that is not level- how to?

I wish I had someone with more experience to help me but I don't. If I rent a large bull float would that make it easier to make the right kind of mound?

Here is a picture of the form I built to level out the area. Tomorrow we are planning to mix the cement by hand. Any suggestions?

[mrchipster]

Re: A base on a slab that is not level- how to?

I wish I had someone with more experience to help me but I don't. If I rent a large bull float would that make it easier to make the right kind of mound?

Here is a picture of the form I built to level out the area. Tomorrow we are planning to mix the cement by hand. Any suggestions?

Your picture did not show up.

Here is my home made bull float. I worked quite well and minimal troweling required after using it.

It is a 2X6 with a 2X3 attached for a handle The bowed and now cracked arch is a 1X2 but you could easily use a piece of metal strapping or plywood for the bowed stabilizer.

It has served me well on 3 pours. and is almost 3 years old.

If mixing concrete by hand make sure you have enough to continue your pour without needing to go to the store for anything. I assume you are using sack concrete mix?

Have a few extra bags over your estimate, You can always take a few bags back.

What are you mixing in? Deep Contractors wheel burrow is recommended That way you can roll the mix to the desired spot for pouring and it has nice rounded surfaces making it easier to get a consistent mix. For hand mixing and use a garden hoe and small spade/shovel it makes the hand mixing easier. Do not use a rake to mix, mix no more than 2 sacks at a time as it is difficult to hand mix more than that. and you may want to start with one sack at a time.

Chip

[brickie in oz]

Re: A base on a slab that is not level- how to?

I wish I had someone with more experience to help me but I don't.

If you are having trouble at getting a level foundation slab then the oven will probably be a real struggle for you, sorry to say.