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?
If what you want is "advice" I recommend you ask a building inspector... that's their job.
Yeah, right. Then he can require a permit and increase your property assessment after it's poured.
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.
What is "small"?
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.
I would rather have a small shrinkage crack than a large filler up against the wall. If it ever opened up it would be easier to fill with sealant too.
I would use an edger to round over the exposed edges of the slab to minimize chipping on the edges. And, as you mentioned, add control joints mid-span if the slab is large (or pour the slab in smaller sections).
I have poured several slabs around our place right up to the concrete foundation walls. I've never had an issue, but we do have a mild climate.
Anthony Watson
I'd put in a joint. Not seeing the entire setup I can't be more specific to say it is not needed but it won't do any harm and potentialy save problems.
If what he said about the size of the project being small an inspector would gladly volunteer the information and probably tell the op not to bother with a permit. That was my experience when I built my shed and during the final inspection I asked a few questions about later adding electrical. He answered all my questions and said don't bother with a permit.
Why do you think "inspectors" are "instructors"? These days they are getting pretty busy. The departments cut way back after the crash and they are pretty slow adding new head count until they figure out if this recovery is real.
I don't think they are -- I know they are from my limited experience with them.
If the ground freezes in your area, you'll have frost heave to consider.
snipped-for-privacy@aol.com posted for all of us...
+1 Too busy inspecting the "new" housing. Some will put time aside in the morning for questions/answers. Also because what they are being asked may not be actual plans or conditions and the resultant disaster is quoted as: But that's what the inspector told me.
There might also be legal ramifications. If you have an open permit and the inspector is just giving you opinions on compliance issues they are protected by sovereign immunity but giving advice outside the scope of their job can void that immunity. I know guys who will remove their ID before they walk into a Home Depot because they are afraid they might get sued over something they tell someone. I tend to blame the lawyers, not the inspectors. 40 years ago I sat down at a table with PG (Md) county inspectors and they helped me draw my plans. I doubt you will see that anywhere today unless you live in Mayberry.
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.
You could always stick some plastic or tape on the wall before you pour the concrete. That would isolate the slab from the wall, ensuring the tiny crack is regular and intentional.
You could also just run the edger along the wall to round over the edge and create a consistent gap that you could caulk later if you wish.
I'm not a fan of installing something that's designed to rot. :)
Anthony Watson
When we were building our house back in 2003, I would always ask my inspector questions when he was finished. It helped build a relationship rather than just him coming out telling me what I did wrong. I got the feeling that he appreciated that I wanted to know how I could improve things. More importantly, he suggested a few things I wouldn't have thought of otherwise, even though they weren't code issues.
Many building departments (mine included) have reference documents online that tell you the most common building situations (joist spans, wall construction, foundation details, etc.). Mine even has free plans for pole barns and other basic structures.
You could always call the building department and ask basic questions. You may not get an inspector, but I found the receptionists could usually answer simple questions.
Except for the associated permit fees, I had nothing but positive experiences with our building department.
Anthony Watson
Use a piece of cardboard that extends about 3/4" below the surface, with the rest sticking out above. When it's partially cured, pull out the cardboard.
As for fees, how to you expect them to pay for those "free" plans and the answers to "basic questions"?
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:
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.
That is why I said they are more accommodating to homeowners with an open permit. Her Hubby confirmed that with his anecdote.
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