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Old July 16th 05, 06:07 PM
 
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Default Expansion joint for 8x4 concrete walkout slab?

Hello. I'm planning to pour a small 8' x 4' (4" thick) concrete slab for a
walkout from my sliding basement door. I think I have just enough height
from the bottom of the door threshold to slope the slab away from the house
slightly. Anyway, while doing some reading about it on the quickrete.com
website, I noticed their mention of fiber "expansion joints" that are
recommended when pouring a slab that will butt up against a concrete
foundation (which IS what I'll be doing). My slab will essentially go right
up to the concrete wall foundation of my basement.

So, should I place one of these fiber strips down in my small "pit" (against
the concrete foundation), extending down from the basement door threshold,
so my newly-poured concrete doesn't bond directly to my concrete basement
wall/foundation? This would make my new slab a separate structure from the
basement wall. Is the gap that this strip would create a water seepage
concern? Is there a recommended thickness for this joint strip? Thanks.


[email protected]



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Old July 16th 05, 06:49 PM
Edwin Pawlowski
 
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"[email protected]" wrote in message

So, should I place one of these fiber strips down in my small "pit"
(against
the concrete foundation), extending down from the basement door threshold,
so my newly-poured concrete doesn't bond directly to my concrete basement
wall/foundation? This would make my new slab a separate structure from the
basement wall. Is the gap that this strip would create a water seepage
concern? Is there a recommended thickness for this joint strip? Thanks.


Yes, it is apart from the foundation and should remain that way. Just put
the strips against the wall and pour right up to it. If you think seepage
is going to be a problem, use a caulk like material after the concrete is
set up. With no expansion allowance, you could end up with a cracked or
heaved slab.


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Old July 16th 05, 07:00 PM
 
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"Edwin Pawlowski" wrote in message
...


Yes, it is apart from the foundation and should remain that way. Just put
the strips against the wall and pour right up to it. If you think seepage
is going to be a problem, use a caulk like material after the concrete is
set up. With no expansion allowance, you could end up with a cracked or
heaved slab.



Thanks. Now, do you see any problem if my basement door's threshold
overhangs the location of the expansion strip (which would really prevent me
from adding anything to the top of the expansion strip after installation)?
Like this:

CURRENTLY:
------
| Basement door threshold (overhang)
------
X |
X | Basement concrete wall
X |


AFTER INSTALLING STRIP:
------
| Basement door threshold (overhang)
------
X | |X|
X | |X| Expansion joint strip outside basement concrete wall
X | |X|

My basement sliding door's threshold overhangs the basement slab slightly.
Is that the way it should be?


[email protected]


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Old July 16th 05, 10:07 PM
Edwin Pawlowski
 
Posts: n/a
Default


"[email protected]" wrote in message
Thanks. Now, do you see any problem if my basement door's threshold
overhangs the location of the expansion strip (which would really prevent
me
from adding anything to the top of the expansion strip after
installation)?
Like this:

CURRENTLY:
------
| Basement door threshold (overhang)
------
X |
X | Basement concrete wall
X |


AFTER INSTALLING STRIP:
------
| Basement door threshold (overhang)
------
X | |X|
X | |X| Expansion joint strip outside basement concrete wall
X | |X|

My basement sliding door's threshold overhangs the basement slab slightly.
Is that the way it should be?


That would be OK. The expansion joint is maybe half inch thick. You can
place it so that the top of the material is the same as the top of the
concrete when poured. If a little of the concrete gets on top of it, no
problem, it may even help make a seal.


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Old July 16th 05, 10:25 PM
Norminn
 
Posts: n/a
Default



[email protected] wrote:
Hello. I'm planning to pour a small 8' x 4' (4" thick) concrete slab for a
walkout from my sliding basement door. I think I have just enough height
from the bottom of the door threshold to slope the slab away from the house
slightly. Anyway, while doing some reading about it on the quickrete.com
website, I noticed their mention of fiber "expansion joints" that are
recommended when pouring a slab that will butt up against a concrete
foundation (which IS what I'll be doing). My slab will essentially go right
up to the concrete wall foundation of my basement.

So, should I place one of these fiber strips down in my small "pit" (against
the concrete foundation), extending down from the basement door threshold,
so my newly-poured concrete doesn't bond directly to my concrete basement
wall/foundation? This would make my new slab a separate structure from the
basement wall. Is the gap that this strip would create a water seepage
concern? Is there a recommended thickness for this joint strip? Thanks.


[email protected]



There is caulk that can be used over expansion joints to keep water/ice
out. Leaves them flexible, which is the whole idea so it doesn't crack
or push against your basement wall.



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Old July 17th 05, 12:27 AM
 
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Default

"Norminn" wrote in message
...


There is caulk that can be used over expansion joints to keep water/ice
out. Leaves them flexible, which is the whole idea so it doesn't crack
or push against your basement wall.


Thanks for the tips, guys. I'm glad I didn't start this project without
planning for the expansion strip.


[email protected]


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Old July 17th 05, 04:45 AM
Don Young
 
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I am not sure of your situation but if you have a door at the same level as
a weather exposed slab you will have trouble with rain water running under
the door. Even the best of seals and a slope away from the door will not
prevent wind driven water from entering. Unless you can tolerate this you
need a step down from the door to the outside slab if at all possible. I am
lowering a 6'x12' concrete porch because of this problem.
Don Young

"[email protected]" wrote in message
news:[email protected]
"Norminn" wrote in message
...


There is caulk that can be used over expansion joints to keep water/ice
out. Leaves them flexible, which is the whole idea so it doesn't crack
or push against your basement wall.


Thanks for the tips, guys. I'm glad I didn't start this project without
planning for the expansion strip.


[email protected]




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Old July 17th 05, 04:46 PM
 
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"Don Young" wrote in message
...
I am not sure of your situation but if you have a door at the same level

as
a weather exposed slab you will have trouble with rain water running under
the door. Even the best of seals and a slope away from the door will not
prevent wind driven water from entering. Unless you can tolerate this you
need a step down from the door to the outside slab if at all possible. I

am
lowering a 6'x12' concrete porch because of this problem.
Don Young


Hmm. How much of a step down are you talking about? If I bring this one down
more than a couple of inches, the outer edge of the slab will be well below
the ground; I'd need some sort of "curb" surrounding the slab.

What I'm looking at right now would put the top of the slab just below (1/2
inch or so) the bottom of the door threshold. Sounds like you're saying
that's too close, and that wind-driven rain could still come in under the
door.

Really, I'm mostly concerned with yard drainage/runoff coming down a slope
and "wandering" toward the basement door (which I'm controlling effectively
with simple diverters). I mean, right now, it's just dirt outside the door
(again, coming up to within a half inch of the bottom of the door), and I'd
like to "finish" it with a slab. If I'm not experiencing a problem with
blown-in water now (with the dirt), are you saying the addition of concrete
would increase the possibility?


[email protected]


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Old July 17th 05, 09:13 PM
Edwin Pawlowski
 
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Default


"[email protected]" wrote in message
Hmm. How much of a step down are you talking about? If I bring this one
down
more than a couple of inches, the outer edge of the slab will be well
below
the ground; I'd need some sort of "curb" surrounding the slab.

What I'm looking at right now would put the top of the slab just below
(1/2
inch or so) the bottom of the door threshold. Sounds like you're saying
that's too close, and that wind-driven rain could still come in under the
door.


I guess it may be a reasonf or concern, but how much rain and snow do you
get? If the water level builds up that much you probably have other
problems to dealw ith. As longs as the slab is pitched, it should not be a
problem. Just like the curb cuts for wheelchar access at the curb. Water
still stays in the street because the sidewalk is still higher than the
street regardless of the sloped access it now has.




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Old July 18th 05, 03:26 AM
Don Young
 
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Default

Unless you have a lot of water 1/2 inch will probably be enough. The
concrete will increase the possibility of water entry simply because it will
catch and direct the water, just like a paved parking lot does as compared
to an unpaved area. I don't think you will have a problem but wanted you to
be aware of the potential.
Don Young

"[email protected]" wrote in message
news:[email protected]

"Don Young" wrote in message
...
I am not sure of your situation but if you have a door at the same level

as
a weather exposed slab you will have trouble with rain water running
under
the door. Even the best of seals and a slope away from the door will not
prevent wind driven water from entering. Unless you can tolerate this you
need a step down from the door to the outside slab if at all possible. I

am
lowering a 6'x12' concrete porch because of this problem.
Don Young


Hmm. How much of a step down are you talking about? If I bring this one
down
more than a couple of inches, the outer edge of the slab will be well
below
the ground; I'd need some sort of "curb" surrounding the slab.

What I'm looking at right now would put the top of the slab just below
(1/2
inch or so) the bottom of the door threshold. Sounds like you're saying
that's too close, and that wind-driven rain could still come in under the
door.

Really, I'm mostly concerned with yard drainage/runoff coming down a slope
and "wandering" toward the basement door (which I'm controlling
effectively
with simple diverters). I mean, right now, it's just dirt outside the door
(again, coming up to within a half inch of the bottom of the door), and
I'd
like to "finish" it with a slab. If I'm not experiencing a problem with
blown-in water now (with the dirt), are you saying the addition of
concrete
would increase the possibility?


[email protected]






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