Securing Flange to New Concrete

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Rrmathome

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The concrete where the sewage basin, closet bend and flange will go has been removed. Now, I will dig the dirt and install it all.

When it comes to securing the flange to the concrete, it will need to be secured to new concrete--since I chopped away a good chunk. Even if I didnt, I would probably chop it away so I could put new concrete there--just because the existing 60+ year old concrete is a PITA to drill into.

So, I will put the pipes in, test, and then pour new concrete.

When it comes to securing the flange to this new concrete, should I put the flange at the correct height (top of floor + depth of tile and thinset) and then put the screws into the concrete when wet? Maybe a piece of threaded rod would be better so it could be undone in the future.

Or should I let the concrete dry fully and then use molleys or tapcons?
 

Rrmathome

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Are you thinking it's like sticking birthday candles in a cake?
Wel, if it was truly newly poured, then yes I would think so.

I guess after it is dried, though, the concrete will still be easy for a tapcon to get into. I guess that is the reasoning?
 

Gary Swart

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My favorite way to attach things to concrete is to use a small rotary hammer drill with a 5/16" bit then insert 3/8" lead sleeves. Then a #12 screw into the sleeve. You then have the ability to remove/replace the attached object if you ever need to.
 

Rrmathome

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FullySprinklered

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Mostly I was concerned that it might be difficult to accurately place the fasteners in wet concrete. It's full of rocks which would tend to steer your screw or bolt away from where you want it when you insert it.
 

Gary Swart

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Those sleeves are much too large. I are sold in plastic boxes of something like 12 (?) My hammer drill uses the SDS bits, and bore into concrete like soft butter. I have drill 1/2" holes into a concrete retaining wall and anchored supports for a deck walk. Still solid as new after 8 years. I have also attached outlet boxes on my basement walls, a toilet flange into a concrete floor, and flat 2x4's for walls. I do own my own, but they can be rented.
 

FullySprinklered

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You probably get the drift here. Gary has a system that works for him, and he carries stuff with him to do it the way that works best for him. Same for me. If you don't have a routine way of doing it, play it safe and don't experiment. You haven't done it enough to work the bugs out of your methodology. Drill, baby, drill.
 

Rrmathome

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You probably get the drift here. Gary has a system that works for him, and he carries stuff with him to do it the way that works best for him. Same for me. If you don't have a routine way of doing it, play it safe and don't experiment. You haven't done it enough to work the bugs out of your methodology. Drill, baby, drill.

So, let it dry and use tapcons as the least likely way to cause a headache? Sounds good to me.

Also, I had asked this on another thread but got no answer. Since this thread has a little life left I'll try it here.

When the pipes are in, many say to cover with sand and then gravel, and then pour the concrete. But, why do I need sand and gravel? Cant I just use the same dirt that came out (which in my case is a sandy mix here on Long Island) That's the way it was poured originally, right over the ground. No sand, no gravel.

Oh, and last one. I will be tiling the floor also. Is there any reason I cant use leftover modified thinset (either mixed with the mortor or in place of it) to patch up the floor?
 

Reach4

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So, let it dry and use tapcons as the least likely way to cause a headache? Sounds good to me.

Also, I had asked this on another thread but got no answer. Since this thread has a little life left I'll try it here.
Concrete should not dry. It is best to keep it moist or covered with plastic during the curing process for best strength.

Tapcons are available in a package with some screws and a concrete-drilling rotary drill bit of the appropriate size. This is very convenient for the occasional user.

I suggest the ones with the hex head. Then you can use your socket set to screw into place.
508900.jpg
 

FullySprinklered

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Sand would be best, but dirt and rubble are right there, so that's what I use. I fill it to around 4 inches of the top, then dump bags of Quickcrete, dry, to bring it up to 2 inches. Then I stir up mortar mix in my pan with a hoe, and fill the rest of the trench. The bag mortar mix is usually short on Portland cement, so adding some while mixing will make it finish up better. We're looking for a hard, flat surface here, nothing structural.
 

Rrmathome

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Sand would be best, but dirt and rubble are right there, so that's what I use. I fill it to around 4 inches of the top, then dump bags of Quickcrete, dry, to bring it up to 2 inches. Then I stir up mortar mix in my pan with a hoe, and fill the rest of the trench. The bag mortar mix is usually short on Portland cement, so adding some while mixing will make it finish up better. We're looking for a hard, flat surface here, nothing structural.

I would think Quickcreate (same as Sakcrete?) would do the job itself, no? Maybe overkill but I probably have no use for a leftover half-bag of Portland Cement.

And what is the purpose of the 2 inches of dry Quickcrete?
 

FullySprinklered

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Let's bring that cake back out here for a minute. Ok, mix up a pound of stick butter and a box of powdered sugar. Whip until smooth. Pour in a 12oz jar of dry roasted peanuts and smear it on the cake. Those peanuts are hell, aren't they?
Point is, it's easier to get a nice finish without dealing with all the rocks. The mortar mix doesn't have the coarse aggregate that will likely make a lot of grueling hand work for you trying to get a nice finish.
Dumping dry concrete mix into the trench first will give you thicker concrete for much less labor.
The book I read on concrete says to use as little water as possible, but keep it wet for as long as possible. Moisture in the earth will keep it wet for a very long time.
 

Rrmathome

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Let's bring that cake back out here for a minute. Ok, mix up a pound of stick butter and a box of powdered sugar. Whip until smooth. Pour in a 12oz jar of dry roasted peanuts and smear it on the cake. Those peanuts are hell, aren't they?
Point is, it's easier to get a nice finish without dealing with all the rocks. The mortar mix doesn't have the coarse aggregate that will likely make a lot of grueling hand work for you trying to get a nice finish.
Dumping dry concrete mix into the trench first will give you thicker concrete for much less labor.
The book I read on concrete says to use as little water as possible, but keep it wet for as long as possible. Moisture in the earth will keep it wet for a very long time.
Wow. Great explanation. Even I could understand that. Although, what is used to pour the floor of a basement to begin with? Mine is very smooth on the surface. There are rocks in it, but I only know because broke it up.
 

FullySprinklered

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The concrete is trucked in and poured into forms or a formed up area straight out of the mixer. The laborers work the concrete with hand tools, bull floats, and this upside down helicopter thing to settle the aggregate and bring up the fines which can then be worked smooth.

I have a basement bathroom coming up in a week or two. It's stubbed up, but they want to swap ends on the drain from right hand to left hand. They're digging the trench, bless their hearts, so I'll just be running pipe and covering the trench. There's a bar sink going in the other side of the bathroom wall needing a drain, so that will be killing two birds. Fortunately the whole trench will be under the fiberglas tub/shower unit, and shouldn't need the deluxe finish job. You can finish the regular sackcrete, but it's ugly when I do it.
 
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Rrmathome

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The concrete is trucked in and poured into forms or a formed up area straight out of the mixer. The laborers work the concrete with hand tools, bull floats, and this upside down helicopter thing to settle the aggregate and bring up the fines which can then be worked smooth.

I have a basement bathroom coming up in a week or two. It's stubbed up, but they want to swap ends on the drain from right hand to left hand. They're digging the trench, bless their hearts, so I'll just be running pipe and covering the trench. There's a bar sink going in the other side of the bathroom wall needing a drain, so that will be killing two birds. Fortunately the whole trench will be under the fiberglas tub/shower unit, and shouldn't need the deluxe finish job. You can finish the regular sackcrete, but it's ugly when I do it.

Very little of it will be visible. And the little that is will ultimately be painted the same gray as my basement floor. Even then, it will reside under table. So, I am probably ok.
 

Rrmathome

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Now I am really confused. The concrete is broken, the hole is dug. I am ready to install the sewage basin and pipe. I know I should install the flange over the finished floor, which will be tile. But, I need to first backfill and pour the concrete so I can put the tile on it.

So, how do I install the flange on top of the tile, if I need to first lay the pipe and pour the concrete?

Do I do all the piping EXCEPT the flange, then pour the concrete, then install the tile, then put on the flange? It just seems tough to do this way, especially since my flange slides OVER the 3" PVC that will be vertical in the floor. If I put in the 3" vertical and then pour the concrete up to it, I wouldnt be able to slide the flange over it.

Plus the concrete will be poured up to the PVC and the tapcons to hold in the flange will only be an inch or so outside that, so they will be going into the concrete near the edge of it. Normally, you dont want to install screws near the edge of something since it is weaker.

Im very confused.
 
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