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Author Expansion joint for 8x4 concrete walkout slab?
Fr@nk

2005-07-16, 6:25 pm

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.


Fr@nk


Edwin Pawlowski

2005-07-16, 6:25 pm


"Fr@nk" <Fr@nkATwizardDOT.net> wrote in message
quote:

>
> 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.


Fr@nk

2005-07-16, 6:25 pm

"Edwin Pawlowski" <esp@snet.net> wrote in message
news:CMbCe.2568$dX5.660@newssvr19.news.prodigy.com...
quote:

>
>
> 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?


Fr@nk


Edwin Pawlowski

2005-07-16, 11:25 pm


"Fr@nk" <Fr@nkATwizardDOT.net> wrote in message
quote:

> 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.


Norminn

2005-07-16, 11:25 pm



Fr@nk wrote:
quote:

> 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.
>
>
> Fr@nk
>
>


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.

Fr@nk

2005-07-16, 11:25 pm

"Norminn" <norminn@earthlink.net> wrote in message
news:42D97B98.2030608@earthlink.net...
quote:

>
>
> 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.


Fr@nk


Don Young

2005-07-17, 4:25 am

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

"Fr@nk" <Fr@nkATwizardDOT.net> wrote in message
news:AJgCe.53817$FP2.30130@lakeread03...
quote:

> "Norminn" <norminn@earthlink.net> wrote in message
> news:42D97B98.2030608@earthlink.net...
>
> Thanks for the tips, guys. I'm glad I didn't start this project without
> planning for the expansion strip.
>
>
> Fr@nk
>
>



Fr@nk

2005-07-17, 6:25 pm


"Don Young" <notme@nonesuch.com> wrote in message
news:11djl3266hon2b9@corp.supernews.com...
quote:

> I am not sure of your situation but if you have a door at the same level

as
quote:

> 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
quote:

> 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?


Fr@nk


Edwin Pawlowski

2005-07-17, 6:25 pm


"Fr@nk" <Fr@nkATwizardDOT.net> wrote in message
quote:

> 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.




Don Young

2005-07-18, 4:25 am

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

"Fr@nk" <Fr@nkATwizardDOT.net> wrote in message
news:z3vCe.53931$FP2.46608@lakeread03...
quote:

>
> "Don Young" <notme@nonesuch.com> wrote in message
> news:11djl3266hon2b9@corp.supernews.com...
> as
> am
>
> 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?
>
>
> Fr@nk
>
>



Norminn

2005-07-19, 12:25 pm

clipped
quote:

>
> 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?
>
>
> Fr@nk
>
>


I would be squeamish about putting the patio smack-dab against the
house. With so little space between patio and threshold, windblown
water would be one issue. Snow/ice melt another. I'm in Fla., have two
patios, but about four inch curb up to living space (on slab). Only an
8' storm surge or a busted pipe will flood us :o)

I don't know the likelihood, but settling could leave you with the low
end next to the door, or pitching against the basement wall. Can your
situation use a patio away from the basement wall, with soil border and
a paver or walk between? My daughter has a driveway smack dab against
her foundation, which is actually higher than her basement window sills.
Problem with snow and water accumulation.

Fr@nk

2005-07-19, 11:25 pm


"Norminn" <norminn@earthlink.net> wrote in message
news:42DCDC69.1080309@earthlink.net...
quote:

> clipped
> I would be squeamish about putting the patio smack-dab against the
> house. With so little space between patio and threshold, windblown
> water would be one issue. Snow/ice melt another. I'm in Fla., have two
> patios, but about four inch curb up to living space (on slab). Only an
> 8' storm surge or a busted pipe will flood us :o)
>
> I don't know the likelihood, but settling could leave you with the low
> end next to the door, or pitching against the basement wall. Can your
> situation use a patio away from the basement wall, with soil border and
> a paver or walk between? My daughter has a driveway smack dab against
> her foundation, which is actually higher than her basement window sills.
> Problem with snow and water accumulation.
>


Yep, I'm still trying to find pre-fab concrete slabs (basically large
stepping stones) to just lay in place here. The permanency of poured
concrete freaks me out a bit, for the reasons you mention. At least with
large rectangular concrete squares, I could always move them if necessary.

If I can find pre-fabs, I'll probably throw a couple of those down, and
forget about pouring concrete. But mixing and pouring concrete would produce
a nice walkout. We'll see...

Anyone know where you can get the nice big concrete slabs that (for example)
you see placed under heat pumps or outside AC units? Something 3' x 3' would
be fine, or 4' x 3' would be perfect. I definitely can't find these things
at HD or Lowe's. Thanks.


Fr@nk


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