On Wednesday, May 25, 2016 at 9:49:03 AM UTC-4, trader_4 wrote:
On Monday, May 23, 2016 at 8:50:39 PM UTC-4, HerHusband wrote:
Have a small project I'm working on and need some advise. Pouring a
small concrete slab that I have formed on two sides, the side buts up
to an existing slab and the back is concrete blocks. I am in zone 5,
do I need expansion joints? if so what is best?
Where it joins the existing concrete, I'd put one in. Otherwise if
you just pour it up even, there will be a crack between the two almost
immediately. And an expansion joint would look cleaner, IMO. Might
want it at the block wall too, depending on how important aesthetics
are. Whether you need any control joins mid-span depends on the length
of the slab.
Yes, there WILL be a shrinkage crack between the new slab and the
blocks/old slab. However, this will be tiny compared to any kind of
expansion material that may be used to fill the gap. I've seen those
expansion fillers rot out, then you're left with a big half inch or larger
gap.
That would depend on whether aesthetics matter where it's going.
It could be for a place where something like a storage box or
grill is going over it anyway. He doesn't have to use strictly
expansion joint material. I'd consider even a piece of cardboard
or similar that will rot away quickly. Then he'd have a small,
clean gap. To me that's preferable to the tiny more irregular
crack he'll have if he does nothing. That crack would be so small,
you can't caulk it, etc. The other type of gap looks like it's
intentional.
Aesthetics? You want aesthetics?
I was in Burlington VT a few years ago and notied this sidewalk behind
The Firehouse Gallery in the Church Street Marketplace. Each section
appears to be sitting in it's own "tray", although it may just be a
open bottomed frame:
http://i440.photobucket.com/albums/q...9317823080.jpg
http://i440.photobucket.com/albums/q...9317718938.jpg
In addition, each section had a something that looks like a valve in the
exact center. I sent an email to the Burlington Historical Society asking
about it, but I never got an answer. I don't know if the fixture is
functional or purely for aesthetics.
http://i440.photobucket.com/albums/q...9317653551.jpg