# looking for prefab ideas



## bryand1249

So my boss is wanting to try and do more prefab for these jobs that we are doing. We're not a large company with a huge warehouse so I'm kind of strapped for space. The couple times that I've done prefab has been just saw horses, plywood, and riser clamps where I could clamp the pvc in place. We just finished up our first ground rough with the prefab that I put together and seemed to work out ok. I'm just looking for any ideas on how to make this work for us.


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## pianoplumber

I have no clue how pre-fab plumbing could be possible.


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## kinzel27772

I did it one time on an underground. We just prefabed the long runs with y's and t's on it and then did the rest on site. It worked out okay.


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## Rando

bryand1249 said:


> So my boss is wanting to try and do more prefab for these jobs that we are doing. We're not a large company with a huge warehouse so I'm kind of strapped for space. The couple times that I've done prefab has been just saw horses, plywood, and riser clamps where I could clamp the pvc in place. We just finished up our first ground rough with the prefab that I put together and seemed to work out ok. I'm just looking for any ideas on how to make this work for us.



Do you have CAD? Are you just scaling off the prints or what? One of the main cost savings prefabbing is having cheaper less skilled labor assembling the stuff in the shop then your higher paid guys in the field use less hours installing. Are you going to hire a grunt to glue the pipe together? I don't see where you're going to save much doing everything your self.


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## CT18

I have pre fabbed bathroom groups for some larger jobs. It was all assembled on a bench like what flyout has posted pictures of. i have also worked with a house contractor who tried to pre fab the underground for a condo complex we were doing. The underground did not turn out well, low pay kids putting the wrong openings in the wrong spots. We had to jack hammer many a floor because the floor drain was in the wall and the stack was in the middle of the room. We also had trouble trying to dig with the backhoe without connecting pipe to give him a line to follow.

What are you guys looking to pre fab. i am in the middle of a Ford job were i am breaking out my CAD drawings and making fab sheets to be made here in the shop. They are chilled Water, Comp. Air and Domestic City Water mainly. I have a few Natural gas lines to get in the design still.


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## GAN

Rando hit it on the head. If you don't have space, or even if you do unless it is many multiples of the same layout, it will take up space and without lesser paid people won't save a lot of labor.

If it is residential, you can gain with pre-made shower & tub valves, laundry drops, H & C risers. But constancy on your layout when you hit the job counts.


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## Flyout95

Pre fabbed pvc under grounds seems a little nuts to me. I mean, is plastic, and glue. Sure you save time, but how much? 

We've fabbed under grounds before, but it all depends on who is putting it in. Do you Trimble? Or are you pulling of a string? 

We fab up our carrier groups, water pipe, We fab cast and copper risers and branches, then snap or cut to length, but to fab a whole under ground is rough. That being said, get pipe stands, 2x4s to fab your own jigs.


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## pianoplumber

Years ago, I pre-fabbed a couple hundred feet of water mains and heating mains for an apt. bldg. cause it was winter (like now), and it was busy work. Couple months later, when it came time to install, it made more work than it was worth. Plans change during construction. Since then, I like to wait until the last minute and do things once. 
I can't see how DWV could be pre-fabbed. Framers seem to have different measuring tapes than us.
Maybe your boss is just trying to keep you busy during the winter?


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## marc76075

It seems like more trouble than its worth. Best case senario, it goes right in and your good. Realistic senario, a few things dont line up right and then your cutting and adjusting pipe, defeating the purpose of prefab. I think it would take less time doing it on the job.


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## Rando

Flyout95 said:


> Pre fabbed pvc under grounds seems a little nuts to me. I mean, is plastic, and glue. Sure you save time, but how much?
> 
> We've fabbed under grounds before, but it all depends on who is putting it in. Do you Trimble? Or are you pulling of a string?
> 
> We fab up our carrier groups, water pipe, We fab cast and copper risers and branches, then snap or cut to length, but to fab a whole under ground is rough. That being said, get pipe stands, 2x4s to fab your own jigs.


Our main reason is lay out time. We build the pipe off CAD drawings in the shop. Then we use Total station (you guys call it Trimble) to lay out the risers and ditches. Dig, drop the pipe in, line up the risers...done. Way faster than pulling string lines and measuring off plumb bobs. I even have Total Station come back after rough grade to check risers again. 
I just did an underground on this new project I got that way. It took two days to get in, including the excavation. The old way would have taken at least five days.


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## Flyout95

We use Trimble for under ground too. But most of our under grounds are push gasket, hard to fab those up in the shop.


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## Plumbus

Flyout95 said:


> We use Trimble for under ground too. But most of our under grounds are push gasket, hard to fab those up in the shop.


In high school (late 60's) during the summer break, I used to prefab push gasket with a can of crisco and a home made lead hammer. All hand measured off real blue prints. A friend's shop has used a fork lift to push sections together.


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## Plumbus

Rando said:


> I just did an underground on this new project I got that way. It took two days to get in, including the excavation. The old way would have taken at least five days.


....plus the cad time using high cost office help.


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## bryand1249

We use the cad drawings to get all the dimensions. I have access to operate the auto cad program at the shop in case I need any extra measurements. We bought a total station 2 years ago. Its the spectra ranger which is the sister company of trimble from what I was told. That's worked great for us since day one. We've only used it to do layout on metal decks and core drilling. I just started a job a few weeks ago and were using the total station for the first time on a ground rough. I prefabbed a bunch of bathroom groupings and took that out to the jobsite, dropped them in place where the total station put it and it worked out great. What my boss had figured for about 7 days on a wing of this building, me and two other guys finished and tested in 3 days. With me and another journeyman making the prefab, we completed 50 pieces in about 2-3 days at the shop. Even with the higher cost at labor we're still coming out ahead so far.


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## ironandfire

bryand1249 said:


> So my boss is wanting to try and do more prefab for these jobs that we are doing. We're not a large company with a huge warehouse so I'm kind of strapped for space. The couple times that I've done prefab has been just saw horses, plywood, and riser clamps where I could clamp the pvc in place. We just finished up our first ground rough with the prefab that I put together and seemed to work out ok. I'm just looking for any ideas on how to make this work for us.


What kind of jobs ?


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## bryand1249

We do strictly commercial work. We have a hospital job coming up, some student living at one of the big colleges here, and a very large senior living complex along with other numerous jobs at this time.


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## Flyout95

bryand1249 said:


> We do strictly commercial work. We have a hospital job coming up, some student living at one of the big colleges here, and a very large senior living complex along with other numerous jobs at this time.


Where are you located?


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## Rando

Plumbus said:


> ....plus the cad time using high cost office help.


Still cheaper than Man hours in the field.


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## Rando

bryand1249 said:


> We use the cad drawings to get all the dimensions. I have access to operate the auto cad program at the shop in case I need any extra measurements. We bought a total station 2 years ago. Its the spectra ranger which is the sister company of trimble from what I was told. That's worked great for us since day one. We've only used it to do layout on metal decks and core drilling. I just started a job a few weeks ago and were using the total station for the first time on a ground rough. I prefabbed a bunch of bathroom groupings and took that out to the jobsite, dropped them in place where the total station put it and it worked out great. What my boss had figured for about 7 days on a wing of this building, me and two other guys finished and tested in 3 days. With me and another journeyman making the prefab, we completed 50 pieces in about 2-3 days at the shop. Even with the higher cost at labor we're still coming out ahead so far.


Sounds like you guys have a pretty good handle on it.


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## ironandfire

bryand1249 said:


> We do strictly commercial work. We have a hospital job coming up, some student living at one of the big colleges here, and a very large senior living complex along with other numerous jobs at this time.


 Looks like there's some places to use it.


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## TXPlumbBob

Doing multi story office buildings that had bathroom groups one on top of the other we would fab everything on unistrut, carriers, waste and revents, water. Then as they flew out the forms from one floor we would fly in the prefabs, wheel them in place and with 4 bolts and 3 connections they were done. This worked on 5 story buildings to 25 story buildings. A ******* sink here and there and a couple of relief vents and it went very smooth. 
We tried the underground on a job similar to this but found that after the CI gaskets sat for awhile them were moved and tweaked some leaks formed. Then we went to lubri/fast adhesive instead of the regular "soap". We cut down on leaks but still had a few. And moving bathroom batteries around open ditches was a pain. 
For PVC projects, mostly apartments and motels, I would layout bathroom groups upside down on floor we made out of plywood. Then we installed closet flanges upside down at each riser and connected the dots. We did one that we fabbed the first (underground) and second floor at the same time. It was cool looking before they poured the slabs. The framer threw a fit at first but we had chase walls between bathroom groups and a little education and a couple of cases of beer all was good. 
I no longer am around large projects like those but I can fab a house on the deck of my flatbed while the guys are opening ditches and then it is just drop, plug and play. Remember to put grade on the deck so your risers are straight and plumb.


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## Cajunhiker

Here's a chair carriage prefab for a ladies room and men's room back to back made at the shop and delivered on site by the company I'm working for right now. 
I haven't installed a prefab before, but hopefully I'll get to help out on the install. Tying into PVC underground, CI for vent, and copper for water via propress.


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## TXPlumbBob

Cajunhiker said:


> Here's a chair carriage prefab for a ladies room and men's room back to back made at the shop and delivered on site by the company I'm working for right now.
> I haven't installed a prefab before, but hopefully I'll get to help out on the install. Tying into PVC underground, CI for vent, and copper for water via propress.



That looks good.


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## Flyout95

Cajunhiker said:


> Here's a chair carriage prefab for a ladies room and men's room back to back made at the shop and delivered on site by the company I'm working for right now.
> I haven't installed a prefab before, but hopefully I'll get to help out on the install. Tying into PVC underground, CI for vent, and copper for water via propress.


Search some of my threads for my pre fab pictures.


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## Cajunhiker

Hahaha funny you suggest that I look at your prefab photos @Fly. 
In looking for tidbits of tips, I actually read every single thread you started here. (It's 73 btw lol). And yes, I picked up a lot of tips.


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## titaniumplumbr

Sounds like someone is micro managing hmmm.


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## Flyout95

Cajunhiker said:


> Hahaha funny you suggest that I look at your prefab photos @Fly.
> In looking for tidbits of tips, I actually read every single thread you started here. (It's 73 btw lol). And yes, I picked up a lot of tips.


You wasted a lot of reading!


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