Tag Archives: flooring

Porch floor pour

When you work with concrete, you have one chance to get it right. That left me with some frayed nerves from the work on the back porch footings and foundation wall. Even though everything turned out exceptionally well in the past (if I ignored my sprained ankle), I was interested in having someone pour the back porch concrete floor for me.

The pour itself didn’t worry me too much. But the finishing work did.

I had the chance to watch the pros when we installed the concrete floor in the basement. They had a large bull float, a trowelling machine and some skills. That made for a concrete floor with a nice finish.

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The back porch floor was too small for a trowelling machine, and it was to small to get any of the pros interested in the job. So it landed back in my lap after all. And once again, I dug out a fence post and had a concrete truck sitting in our back yard.

Pouring the concrete to the right elevation was fairly straight forward. The top edge of the bond break served as a guide for a two by four, which we used to screen the surface. I also got myself a wood float which I used to get the initial finish.

Once the concrete started to set, I used a magnesium float to refine the finish. I did that twice, each time letting the concrete cure some more. The finishing touch or last pass required a steel float or trowel. It allowed me to completely smooth out the surface paste. Not as easy as with a troweling machine, but I managed.

Last but not least, I removed the plugs I put proactively into the two floor drains and checked the slopes. Let’s say it was a very happy ending to this long day!

What I did different…

…this time around were a number of things, all based on my reflection after we had poured the basement floor a few years ago.

I used sturdy zip ties to attach the PEX tubing to the welded wire mesh … zip ties that were hard to break.

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I didn’t fold the polyethylene sheet over the bond break, but taped it to the edge. That gave me a much cleaner finish around the margins.

I did not use a concrete vibrator, as I concluded I should have a few years ago. But I made sure that the concrete got into all nooks and crevices around the edges during the pour.

And I was careful about how I staged and sequenced the pour so that I could access any part of the freshly poured floor as needed for the trowelling.

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Adding more floor components

I get to play a game that I know! And the game is called “installing a radiant floor slab”.

I outlined in the last post the installation of the aggregate base for the concrete floor. The gravel had to be carefully screened to assure that I have the right slopes towards the two floor drains.

And now I get to play with the next four components of the radiant floor slab assembly:

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  1. Insulation
  2. Vapor barrier
  3. Welded wire mesh
  4. Pex tubing

Insulation

Installing the insulation was a bittersweet process. Bitter, because the four inch XPS boards I used came from the very carefully installed attic insulation assembly, which I had to take down again. Sweet, because I got to reuse the insulation and it didn’t to go waste.

I mentioned that the aggregate base was finished with the correct slopes towards the floor drains. That means that I had to line up the seams of the insulation boards with the slope ridges and valleys. If not, I would end up with suspended and wobbly boards that would crack or break.

I again paid attention to the bond breaks around the future radiant floor slab. A bond break is a piece of vertical insulation that will thermally separate the concrete floor from the adjacent foundation wall and footings. This assures that the heat in the radiant floor slab is effectively transferred into the room and not syphoned off into the foundation wall or other thermal mass structures.

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Vapor barrier and wire mesh

Even though I had an effective capillary break with the open graded aggregate base, I still needed an effective vapor barrier under the concrete floor slab. A large 6 mil polyethylene sheet would do that job. I carefully cut it to size and fit it around the sump, floor drains and footing. To prevent it from shifting around while installing the welded wire mesh, I taped it along the edges.

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PEX tubing

The radiant floor slab will be heated with hot water. To get the hot water into the slab, I used ½ inch PEX tubing, which I attached to the welded wire mesh with zip ties.

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I opted for two heating zones. Zone number one is heating the future workshop to the west. Because this section needs to be kept reasonably warm, I spaced the PEX tubing six inches on center along the edges and 12 inches on center towards the center.

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Zone number two is the eastern half of the space and just needs to be kept above freezing. For that reason I spaced the PEX farther apart. I also made sure avoid PEX tubing in areas where I need to anchor into the future concrete floor, such as under the future steps and bottom plate that separates the workshop from the rest of the space.

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Porch floor aggregate base

I feel I’m getting seasoned – like a routine is setting in. It is a nice feeling, supported by the confidence that you know what you are doing.

The underground plumbing for the back porch is done. I now can focus on the concrete floor installation. And I’m dealing with literally the same principles, design and process as for the basement floor.

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The basement section of the back porch will be enclosed. And we would like to heat the enclosed portion during the cold season as needed. That means we will have insulation under the floor slab, bond breaks around the edges, and PEX tubing in the concrete for the radiant floor slab.

But first things first: I have to install a proper aggregate base on which I can install the next layer, the XPS insulation.

We used a 100% recycled ¾ inch stone (ASTM C33 #57, or IL DOT CA7). The beauty of this material is that it is “open graded.” In other words, it has no fines and a lot of pore space. As such it is an effective capillary barrier and prevents soil moisture from rising up towards the concrete slab – which in turn helps with the issue of moisture management.

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Shoveling the gravel into the hole was the easy part. But I also had to screen the gravel so that I end up with a consistent surface on which I can lay the insulation. The screening was complicated by the two floor drains, because I had to make sure that all the various floor sections slope into the right direction.

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Getting philosophical – and practical

A big essential question has been sticking to my back like burdock seeds to my dog’s coat: What do we want from the back porch?

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Any simple answer to this question vanished down the rabbit hole once we started thinking about the potential use of this new space, now and in the future. But let’s start with…

…the past.

The old back porch was enclosed and had a full basement level. Originally, we had planned on another fully enclosed back porch, until it dawned on us that this may be more of a want than a need.

The now…

… is reflected in the permit drawings for the new back porch.

  • An enclosed basement level
  • An open 1st and 2nd floor level
  • A staircase extension to the roof level to access the future vegetable garden and solar panels

The future…

… could be as simple as leaving the porch as described above, turning the 1st and 2nd floor level into a screened-in sleeping porch for the dog days of summer, or enclosing each level with operable windows and converting it into an unconditioned three seasons room.

The devil is in the details

Take the enclosed and conditioned basement level, for instance. How do we heat the space, and more importantly, how do we insulate it? But more about that later.

Because the 1st floor porch level will start as an open porch, I will need some level of waterproofing. Simply put, I need a roof over the enclosed basement level. Not only that, I also need a roof over the 1st floor porch level, because I don’t know if, when and how I may or may not convert the 2nd floor to a sleeping porch or three seasons room.

The practical part

The first floor as well as the second floor level was built with a two percent slope away from the building. Once the plywood was in place, we installed a torch down roofing system. That took care of the “roof” we needed at each level.

To accommodate the deck, we installed sleepers that followed the two percent slope, with a depth of half inch at the house and two and a half inch at the opposite end. That provided us a level deck over the sloped roofing.

Any driving rain will drain through the deck board joints and then intercepted by the roof below and drained out to the face of the porch.

We applied the same principles to the staircase landing between the first and second floor, which will allow us to enclose the basement level as planned.

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Typical open porches are built without the in-between roofing systems. In our case, it seemed a good future proofing practice to take this extra step.

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Terminating the temporary

I mentioned the old grease trap in the back porch. It was a hot mess back in 2010 when I cleaned it up. The intent at the time was to temporarily re-purpose it as a sump pit.

 

 

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Back then, I connected the interior perimeter drains to it. We also terminated and stubbed the new sewer lines, which allowed me to install and connect a sump pump.

This temporary band-aid has lasted long enough. With the old back porch being torn down sometime soon, I had a sense of urgency to demo the old grease trap. Before I could do that, I had to install a new and proper sump pit. And before I got to that, I had to rip out the old concrete floor.

That put me back into recycling mode. We threw the concrete chunks into the back of my truck and hauled them to the recycling company down the street at Kedzie and I55.

Next step: Getting the excavator and starting to dig.

Related posts:

The back porch project

Grease trap cleaning

Nail biter

Perimeter drain installation

Finished sewer

Where did all the concrete go

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