How does one redo a concrete floor in an existing garage?
My old floor was shifting and cracking all over the place due to the soil.
The floor was divided into 6 segments and at the joints gaps of 1 inch had
formed. Not only had gaps formed but some slabs were 1/2" different in
height/level - so I removed all the concrete in the garage.
Now I am unsure as to how the concrete should be laid since it is not as
simple as laying concrete slab in an open area.
If someone could give me some insight as to how concrete is poured into an
existing structure that would be great!
Advice is much appreciated.
Length: 8.5 metres
Width: 5.5 metres
Desired concrete thickness: 100mm
Is the existing subgrade acceptable?
Are you preparing that so that the "same" does not occur?
In any case, pouring concrete in a confined area presents problems.....
The same story as painting yourself into a corner.
There must be some doors....and or windows? (access)
You can use overhead screed boards on the left and right sides so that there
will be no stakes in the concrete pour.
Down the center a person can use a metal buried screed form, that represents
top of concrete and rod off of that. It remains in the concrete and acts as
a "cold" joint, or expansion / contraction line.....
I would make sure to use a "grid" of re-bar in the slab to keep the concrete
together. I have had more luck with re-bar and cracking than any concrete
wire or 6-6 10-10 mesh used.....
Also keeping the rebar at the right height is important so that it does not
get imbedded in the sub-grade.
Are you using a vapor barrier?
If so, I always make sure it is deep enough to cover with a layer of sand to
facilitate concrete pouring.....I never pour on plastic alone....
It can create problems with water and finishing.......
With concrete tools, I always jitter bug the top layer of
It helps bring up the fines for the top finish, and set some of the larger
rocks below top.
Using a float on a long pole is helpful in a confined area....
I have several mag floats for preliminary surface prep. and then steel
trowels on poles for finsih work.
In the past 4 years I have purchased a power float.....that goes on poles
It is a lifesaver......works wonderful.....can bull float the concrete as
well as finish it all from outside the slab..........
It weighs 24# and has a small gas engine......works great.
Knee skids are also beneficial for finishing concrete in confined areas....
I use metal, knee skids, and like "snow" skis.....you can move out over
concrete without leaving board marks......of course there is a time when
they are most successful as when the concrete is hard enough to use them.
some of my inside pours I have pre-set boards high enough on the walls that
a plank can span the area being poured......
You can "walk" a plank out and finsih an area without even getting in the
concrete......an aluminum "rental plank works well......or a 2x12.....or
I do this a lot for colored or stenciled concrete where the surface cannot
be walked on......
I am sure I have missed something......
jloomisconstruction and concrete
I was getting total "rookie" vibes base on the OP & his
reply .......... but flat work scares me, so maybe its just my fear.
I've done a little flat work & I've seen experts do it......I prefer
to watch it done. :)
The results are much better.
Plus his original post, noting 1" gaps & 1/2" differentials has me a
I'd hate for him to do all this work & have the new floor not work out
any better than the one he's replacing.
Thanks for the replies guys.
Pretty much am a total rookie, but didn't plan on doing this all myself
unless it was fairly straight forward, which it doesn't sound like it is.
Was hoping to get some info on how it is done (which I did so thank you)
so when I get quotes I can access if their method is good. I also have a
friend that does concreting but he is fairly new to it.
Yeah, it would not be good if the concrete turned as bad as before. But
most likely will be paying someone to do a proper job :)
Thanks again for the info
On Mon, 12 Oct 2009 17:14:35 +0000,
sakatumi21_at_gmail_dot firstname.lastname@example.org (saka) wrote:
Good. I'm relatively experienced at construction (not a pro, but I can
build) and I'd not try that slab myself. (I did a 10m x 20m
building/slab a couple of years ago, the only think I contracted out
was... The slab!)
On Tue, 13 Oct 2009 05:55:42 -0700 (PDT), RicodJour
Actually both turned out very well. I'd use the contractor again in a
minute, he did a credible job on the slab. The building turned out
very well too, better than I'd expected.
I've had to tell several friends that they can't move into my
I would bury a pressure treated 2x4 on the left and right side to act as a
screed and the form since you do not have any forms....
I cannot see exactly the situation so, I have to guess...
The metal buried screeds would work, yet ordering and getting them is
Subgrade depends on what it is and what its compaction is all about.
A person could put sand and or gravel on a lousy subgrade and end up with no
So, if the ground under the "to be poured concrete pad" is good, then a
layer of sand and or gravel is fine....I use sand since it retains concrete
moisture and facilitates in pouring....
gravel lets the moisture drain down quick.....anyway, either will work.
You are in a cover area so the sun factor will not be present.
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