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?


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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Porch 2nd floor level

The old back porch left us with a few holes in the wall – the old joist pockets. Unfortunately, they didn’t line up with the new ones. In preparation for the 2nd floor porch level construction, my first task was to mix up some lime-based mortar, grab some of the leftover common bricks and fill in the old joist pockets.

Because we already had the post extensions in place, the second floor level went up like a breeze, including ledgers, joists and decking. The new back porch began to actually look like a porch, once the railings were installed. It’s curious what a difference such subtle things can make!

We also had some excitement with more post extensions, lapped scarf joints and heavy duty carriage bolts. The two shorter extensions will support the porch roof level, while two really long ones are needed for the roof access level. Those six by six posts weigh a pound or two, particularly if they are still wet from the pressure treatment. I was left admiring the calm and confidence with which the carpenter crew conducted these balancing acts.

And then there were the stairs — the good old stairs with post extensions and all. They had occupied my mind for quite a while.

From long landings to little landings

The stairs in the old back porch made the most of the available space. They had a short flight with four cross steps between the two long flights. The new porch plans called two long flights only with a long contiguous landing connecting them.


The proposed layout would take away 20 inches from the porch deck to make up for the four cross steps that had been eliminated. That didn’t sit well with me. I didn’t see the necessity for a contiguous stair landing, but rather was intent on maximizing the usable porch deck area.

I asked our porch contractor for advice, and he pointed out that we could bring back the four cross steps by adding two more posts. The extra posts would allow for the supporting joists for each of the two landings, one below and one atop the three cross steps.

One of the posts would be anchored to the foundation wall, but the other post would need a separate spread footing down at the basement level. Because I had that discussion early on, I planned for and installed the footing.

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We were back to the same stair layout the original porch had, and with it we’ve made the most out of the space available to us. And I am still using that space daily, sitting in my rocking chair, sipping my morning coffee!

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Porch 1st floor level

The moment of truth has come! I have a nice looking and well insulated concrete foundation wall. I suspected that I got all the dimensions and elevations right, and was about to find out if that was indeed the case.

Our carpenter crew arrived and began with the layout for the porch posts, which are anchored to the foundation wall by means of a post shoe.


Even though I had exercised due diligence when building the formwork I had a nervous 30 minutes until the layout was done and all posts fit right in place. The post were followed by the ledgers and floor joists, and before I knew it, we had the 1st floor porch deck installed.

The next day, the crew started with the stairs and landing down to grade level and installed the post extensions leading up to the 2nd floor porch deck. Seeing the post extensions go up was quite something. To join the posts, the crew used a lapped scarf joint with five heavy duty carriage bolts.


But before the bolts were installed, the posts were tagged together with some nails. That allows for some flex which is important to set the extensions plumb, line them all up, and brace them so that they won’t move any more. Only then were the bolts used to secure the lapped scarf joint.

It felt that this – the new back porch – has been a long, long time coming. Cathy and I had porch envy for years, watching our neighbors enjoying warm evenings outside, while we were left dreaming about doing the same one day.

Needless to say that I didn’t waste a second to get the rocking chair out and soak up the moment we have been waiting for for so long…


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Back porch foundation wall insulation

One big ticket item that is still sitting on my to-do list is the exterior insulation around the basement. Well, I did get the chance to practice a little, because our brand-spanking-new porch foundation wall was asking for some insulation before I started with the backfilling.

I had researched the insulation strategy a long time ago and knew which direction to go and that I would need XPS boards totalling four inches in depth. The question about where to get the XPS boards was also solved, thanks to my snafu in the attic insulation strategy.

I had started to take down some of the salvaged four inch XPS boards we had mounted to the bottom of the roof joists. I was now ready to repurpose them as foundation wall insulation. That was a tiny bit of silver lining in my attic insulation dilemma.


We cut the XPS boards to size so that they fit from the top of the footing (or bottom of the foundation wall) to the top of the foundation wall. To help with the moisture management, we placed a drainage membrane over the insulation.


The drainage membrane is a HDPE sheet with dimples on one side, creating a ¼ inch air gap between the membrane and insulation. That air gap prevents hydrostatic pressure from building up against the foundation wall. Any bulk water that enters the air gap immediately drains down, where the membrane connects to the footing drain which is embedded in open graded aggregate.

This assembly should keep the foundation wall dry and reasonably warm (or cold for that matter). With four inch XPS boards in place, I can expect an R-value of about 20, not counting the thermal mass of the soil behind it. That exceeds the Chicago Building Code requirement of R-10 (Chicago Building Code, Chapter 18-13-102.1.1; Building thermal envelope insulation, Table 18-13-402.1.1) and the Chicago Green Homes requirement of R-19 (Chicago Green Homes Program Guide, Version 2.0 – 210 Energy Use Reduction [210.3]).

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3/8 inch and flowing

“I told you so!” – was coming to my mind while looking at the plumbing in a Swedish single family home built sometime in the 1970’s.

Some plumbing lines were partially exposed to keep them in the interior conditioned space. What caught my eye right away was a 3/8 inch branch (or twig) coming off of a 3/4 inch trunk line.


The use of 3/8 inch plumbing lines (or twigs) fits right with the material and energy conservation goals of an efficient domestic hot water delivery system, as was explained to me by the hot water guru Gary Klein. The problem for us in Chicago is that the smallest allowed pipe diameter per plumbing code is 1/2 inch. The rationale behind this limitation is, so I assume, concerns about pressure drop and insufficient flow capacity. But it also puts a limit on the efficiency of our hot water delivery system.

Seeing that a built 3/8 inch twig line didn’t cause the world to implode was rather exciting. Not only that, but the 3/8 inch cold water line services three fixtures: 1) the toilet, 2) a sink, and 3) a shower, while the ? inch hot water line only serviced the sink and the shower.

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The structured plumbing system that I have described in a previous post, recommends the use of 3/8 inch twigs. But each twig should just service a single plumbing fixture, not multiple fixtures.


Serving three fixtures with cold water and two fixtures with hot water using a 3/8 inch twig lines would take us – so one could argue – into deep water. That begs the question: Why would several fixtures on one twig be acceptable?

The bathroom in the Swedish single family home is meant to be used by a single person at a time. In other words, you shouldn’t need to worry about somebody flushing the toilet or using the sink while you take a shower.

And I used that shower. There was no problem with the water flow rate or the water pressure, despite the nine feet long 3/8 inch twig. And being the nerd I am, I let the shower run while flushing the toilet or turning on the sink faucet. There was a very brief but minor pulse in the shower’s water flow, but other than that, no detectable flow reduction or pressure loss.

For full disclosure, I should mention that the bathroom in question was on the 1st floor and only a few feet away from the water heater and water main. The second floor bathroom has a different set up. Here a 1/2 inch twigs (or branches) services the various plumbing fixtures, probably to mitigate pressure loss that may come with the elevation and friction that comes with the longer pipe run.

Now – is that 3/8 inch twig I observed an exception? Apparently not. I noticed almost the exact same setup in a restaurant men’s room — a 3/8 inch twig servicing all fixtures.

As unscientific and nerdy as this is, I am delighted to see proof that 3/8 inch twigs can work and can be safe. But to whom can I take my “I told you so?”

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