Difference between monolithic and floating foundation/slab on house
Doc
house and how do I determine what mine is? I'm told whether I have to
drill my slab to treat for termites depends on what kind of slab I
have. It's stucco over frame, in central Fla.
Thanks!
ghost-sniper
"Doc" <docsa...@yahoo.com> wrote in message
news:f0c1bc20.01122...@posting.google.com...
Pull the dirt away from the side of your house and examine the composition
of the *wall* between the top of the slab and the bottom of the footing.
If you see concrete block (CMU's), you have a stemwall.
If all you see is concrete, you have a monolithic slab.
Usually a stemwall is taller than a monolithic too.
A monolithic is usually only about 16"-24" high (from bottom of footing to
top of slab).
A stemwall is only 8" thick. from side to side.
A monolithic might be up to 20" thick, depending on where the holes are
drilled.
I'm in southwest Florida.
Lyle B. Harwood
<docsa...@yahoo.com> wrote:
€What's the difference between a floating and monolithic slab on a
€house and how do I determine what mine is? I'm told whether I have to
€drill my slab to treat for termites depends on what kind of slab I
€have. It's stucco over frame, in central Fla.
Monolith:
"A large architectural member or monument cut from one stone or cast as
one unit from concrete"
Means Illustrated Construction Dictionary, Condensed Edition, page 284.
That said, it seems that either there are different regional meanings,
the terms weren't used accurately, or some combination thereof.
Usually, with the guys I work with, the nearest word is grabbed and
used, as long as it's meaning was close enough that it could be figured
out.
Around here, a "floating" slab means that the slab is poured separately
from the footings, as opposed to a monlithic slab, which is poured as
part of the footings, with the walls then formed and poured (or built)
on top of it. With a floating slab, the walls are poured on top of the
footings, either monolithically or later, and then the slab is poured
inside the walls.
You could, therefore, have a cold joint at the top of the footing, and
still have a floating slab. (Not very likely, but possible.)
To tell, I would look around the perimeter of the slab, inside the
wall. If there is an expansion joint against the wall, the slab was
poured after the walls were in place, and it's a floating slab.
The difference your pest guy is looking for is probably which way the
joint runs. On a monolithic pour, the joint is horizontal, and on the
floating slab, the joint is vertical, right at the base of the wall.
I have no idea why he'd want to drill one, but not the other.
Best of luck, and let us know how it turns out!
--
Lyle B. Harwood, President
Phoenix Homes, Inc.
(206) 523-9500 www.phoenixhomesinc.com
Lazenby
"difference" between a floating slab and a monolithic slab. I wouldn't
penalize them unduely for that misunderstanding unless there are other
reasons you question their competence.
Your first reply is likely answering your real question. Do you have a
monolithic slab (also referred to as a thickened- or lug-footing slab),
where the thickened and reinforced edge of the slab provides sufficient
bearing (foundation "footing") for the slab edge and wall loads above. Or,
do you have a stem-wall supported slab. A stem wall (usually masonry block
in Florida) economically allows the floor slab to be more than a foot or so
above the adjacent, exterior finish grade. The stem wall extends from at
least 8" above finish grade to a continuous poured concrete footing at
bearing below grade.
There are two ways the grade slab may be supported by the stem wall.
One way is for the slab to abut the interior of the stem wall, typically
with a perimeter isolation joint between the slab and the wall. The masonry
stem wall extends up to the level of the top of the slab or even higher.
Often, basements are constructed thus. The compacted grade and drainage
fill below the slab supports the slab. The stem wall contains that fill and
supports the wall above only.
A second way is for the slab to extend over and bear upon the masonry stem
wall. Sometimes it extends fully to the outside wall edge, requiring form
work, and sometimes the top course of the masonry stem wall is made of
"L-shaped" masonry units, and the slab bears only on the inside portion of
the block, with the outside, vertical portion of the "L" shape forming the
outer edge.
The stem wall thus both contains the fill under the slab and provides
bearing or support for the floor slab edge.
(If the stem wall is poured concrete in lieu of masonry, it functions the
same way so far as your termite treatment is likely concerned, but is more
difficult for you to identify. A specialist might have to determine the
best method of post treatment.)
That's a lot of explanation . . . too much for responding to your post . . .
but poor communication prompted your inquirey initially. All slabs-on-grade
are "floating slabs" to some degree. The slab that extends only to the
inside of the stem wall is more of a floating slab than one that extends
over the top of the stem wall. A monolithic slab is the most "floating" of
them all.
Now, to address your question. A monolithic slab has a thickened edge,
which extends below finish grade and provides the "footing." A stem-wall
has a separate conctete footing, typically deeper below the finish slab and
connected to the slab by (typically) hollow concrete block.
I don't know why your termite treatment contractor can't visually determine
what treatment procedure he requires. He's only asking you to take
responsitility for that determination.
If there is a block stemwall, every vertical chamber of the block (that is
currently two chambers per 16" block) must be drilled from the exterior for
injecting poison. Additionally, the footing below the stem wall should be
treated. (Initial treatment during original construction requires at least
two stages of treatment: first, of the trench for the concrete footing;
and, second, of the footing and all the soil bearing on the inside of the
footing over the entire area of the house.)
In either type construction, under the perimeter of the slab-on-grade must
be continuously treated. With a monolithic slab (thickened edge footing)
this can often be accomplished from the exterior. Otherwise, and often with
a monolithic, the floor slab must be drilled periodically continuously
around the perimeter for injecting poison.
Your termite representative should have explained all that to you. Get him
to do it.
Good luck,
Jim
"Doc" <docsa...@yahoo.com> wrote in message
news:f0c1bc20.01122...@posting.google.com...
ghost-sniper
"Lazenby" <aa.la...@prodigy.net> wrote in
>
> A second way is for the slab to extend over and bear upon the masonry stem
> wall. Sometimes it extends fully to the outside wall edge, requiring form
> work, and sometimes the top course of the masonry stem wall is made of
> "L-shaped" masonry units, and the slab bears only on the inside portion of
> the block, with the outside, vertical portion of the "L" shape forming the
> outer edge.
> The stem wall thus both contains the fill under the slab and provides
> bearing or support for the floor slab edge.
The above is the single most common type down here in southwest Florida.
It allows for continuous reinf. rods from footer to tiebeam and allows for
lateral reinf. rods in the slab when the stemwall exceeds 6 courses of
block.