Pumping Concrete to Make a Basement Floor

A slab is poured in the basement and work is underway to add two new dormers to the roof.

Clip Summary

A slab is poured in the basement and work is underway to add two new dormers to the roof that will match the original one. The concrete needed for the basement floor arrives by mixing truck and is dispensed by pump truck. Before the concrete is pumped into the house, the concrete finishers add a mixture of bentonite and water to the pump lines so that it will flow freely. Bob talks with Mike Walker, the concrete finisher, who is working with the crew to pour the concrete floor. It is an all-day job to spread it smoothly, let it set, and go over the work.
Hi, I'm Bob Villa.

Welcome home again to my Cambridge project. Today we're pouring a slab in the basement.

Even though there already is a slab down there it was pretty busted up and so we're improving matters down there.

And we're also working up on the top; on the roof. We're cutting in for two new dormers at the third floor level and today we're gonna be actually going to be cutting through the roof as well as showing you how you frame the dormer structure. And a trip down to Georgia to visit the mill where they make all the dimensional lumber.

Stick around, it's good to have you home again.

We're receiving the concrete in a regular mixing truck, but we've also hired for about five hundred dollars a day a pumping truck. And the pumping truck really is worth it because otherwise you'd spend more than that just in labor trying to get the concrete material to where it's going.

Before any of the concrete starts coming through the pumper, they add a mixture of about a tablespoon of Bentonite, a type of clay mixed with water, which creates this slimy liquid and as that goes through all the hoses it'll make the concrete flows through there very freely and this will be a job that will be going on, all day long.

Now I'm standing in the area of the basement where all of the plumbing pipes that were laid last week come together and you can see the gravel, that was put into the trenches right under our moisture barrier and of course this cast iron piping was laid to take the waste pipes from the new bathroom locations as well as the kitchen and everything leads back out here to the street. But right now lets hook up in here with Mike Walker, who's in charge of the crew that's putting concrete down. Hey Mike, you're in the area which is gonna be my woodworking shop, and so all of these PBC pipes stem through are for the different tool stations where we'll have a sawdust collection system, but let me ask you about some of the work that has already been done here like around everyone of these structural piers. What is this material that you've wrapped around?

This is a. fancy material. And what we're doing is, concrete expands and contracts with the temperature of the -

And -

And so it's -

The flexibility.

- coming up through all these piers. This will prevent some of the cracking .


Okay. And don't you need to put in wire reinforcing when you're adding a slab on top of a slab like this?

Not really, because this is very strong. You've got a sub floor here already. That will take all the stress. Just top it to make it level.

Yeah, yeah. And also, what's the mix? What's the PSI of the mix?

We have a 3,000 pound PSI. And we have two percent par receptor to add to the setting time.

Okay. Now this is an all day job for you guys.

Yes, it is.

Not just from the point of view of spreading it, but letting it -

Letting it set and then we come back and we have trowel it out a couple times for you.

Alright. Well, we'll just watch for a bit and then we'll come back later in the day to see how power trowels move. Well, that basement's gonna be terrific and we'll put in a stairs that'll go directly into the kitchen.

And then, of course, the rest of the house used the original staircase here, which goes up to the second and to the third and the third is where the action is today.

All right.
This is an exciting spot.

We've already cut out one of the holes over here.

Hey, Riley.

Hi, Bob.

Lookin' good.

We've already cut out one of the holes of two that we're making to create new dormers that'll match the one that was originally here at the other end of the house.
And we're gonna be talking lumber today.

We gotta break for some messages. But, when we come back, we're gonna be in Sterling, Georgia visiting a saw mill where they make all the new dimensional lumber.

So, stay with me.