Bathroom & Office PEX


Bathroom PEX for Floor Heat

The ‘waste’ heat from our mechanical refrigeration system will be captured by a water heater exchange. From there some of it will be able to be dumped down into the slab below the bathroom and inspector’s office through PEX oxygen barrier water lines.

The rocks are temporarily holding down the PEX lines as I work at getting them to cooperate with the curves I would like to have on the floor. I ran hot water through the tubing to get it to relax.

The foil backed foam below the PEX lines will help reflect heat back up towards the slightly isolated floor slab above. It is connected to the structural building around the edges where heat will then bleed up the walls. The structural building is insulated from the foundation and outside world to slow the escape of heat.


Concreted PEX Tubing

Once the PEX was the way I wanted it I lifted it half an inch off the foiled foam and encased it in concrete. This little hand pour was just along the lines of the PEX. Later we’ll pour the entire hard coat of these rooms.

Outdoors: 58°F/38°F Sunny
Tiny Cottage: 60°F/56°F

Daily Spark: I’m a firm believer in global warming – I’m for it.

About Walter Jeffries

Tinker, Tailor...
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13 Responses to Bathroom & Office PEX

  1. Patrick says:

    Hot melt glue and PEX clips have worked for us. Might be faster for you. The glue won’t melt the insulation.

    My brother has done over 200 hydronic systems in New York and knows about a thousand tricks, it seems. He installed our system – 333,000 BTUs and hour, 500 gallons of water, two forced air furnace exchangers; two water heaters and a hydronic floor – and runs the whole thing with just one low-wattage, low pressure pump (has 40 foot of lift in there, too).

    It’s amazing that we (nationally) don’t put more emphasis on these technologies. I think it’s just because the rack-n-stack lego houses they build would take more time. It’s faster to just run vents and a gas furnace be done in three days, I guess.

    • Good trick. The reason I did the sand concrete to hold it down is this produced a uniform contact with the PEX containing no voids, no changes of density around the pipe and thus no places where thermal expansion and contraction of the PEX could damage the PEX on sharp edges. Of course, the fact that the concrete was the tool in hand is always a significant factor. When you have a hammer all the world looks like a nail. :)

      I think you are right that the ‘lego’ method, combined with complex regulations and zoning, has dampened creativity and thwarted the use of better ways of building and better technology.

      Witness our cottage. We built smaller than is allowed in many zoned locations. I suspect a big part of the zoning requirements for size is the towns want more money, simple greed. They get to tax bigger houses more so they want people to build bigger houses. Fortunately, we have no zoning and such. I picked where we live in part because of this. As a result of being small and high thermal mass (construction which would be not allowed in many places) our cottage needs a mere 0.75 cord of wood a year to keep warm and it will naturally float above freezing on its own despite our cold winters. Imagine how much energy would be saved if all homes were built along those lines – fortunately I am not about to legislate such a rule! Additionally our cottage requires very little maintenance and will last for hundreds of years – a better use of resources than stick built houses that last only a few decades. The result is our cottage only cost $7K to build and we save about $10K per year in maintenance and utilities – enough to build a new house each year.

      • Peter says:

        I would disagree to a nominal extent about that. It’s not hard these days to find builders out there who are out in front on using innovative systems like hydronics, PEX, geothermal, foam insulation, etc. in order to increase energy efficiency and build homes better.

        Good example: Mike Holmes talks about this stuff constantly and how builders need to adapt to new techniques and new technologies, in order to build houses better. I would think also that the modular home constructors out there are also pushing the envelope in terms of building more efficient structures with less waste and whatnot.

        • The issue is not one of “do they exist?” but rather “why aren’t they common?” There are techniques that are so much better than the common structure yet they are rarely used when you look at the scale of construction as a whole. A very small percent of construction is advanced. Most is conventional and often that is caused by over regulation and zoning short sightedness. This is why I chose to live where I live – no zoning.

          • Peter says:

            Weeelllllll….that is a yes and no situation also. I mean, Vermont is one thing….zoning someplace like New York City is totally another (there is ample sense that armored electrical cable is required in high-rises there for example!)

            I think it is also a question of how fast building codes/regs in municipalities can keep up with technological change. Yeah I agree that, for example, we should make heavier use of hydronics since it is more efficient. That said, if the building code does not mention it, what’s the inspector to do about it if s/he sees it installed at some new residential job? Hopefully you see what direction I am pointing to here, it’s a vicious circle you know.

            As for building to the maximum zoning that is allowed…well, I would put the onus of that one ultimately on builders and consumers, since the former is building to what the latter wants, not necessarily to what the latter NEEDS.

            Just playing devil’s advocate of course. :-)

          • Agreed, as the density of people goes up there are problems which are what zoning and regs are supposed to deal with. The issue I have is when those city rules are applied to places they’re not needed. Unfortunately all too often zoning is not used to solve real problems but to control other people’s activities and their property for personal gain.

            Myself, I prefer to avoid cities.

          • Julia says:

            The flip side of zoning is when it saves people from their own cheapness. The lack of tornado proof basements in “tornado alley” in Oklahoma comes to mind.

            Whenever you have regulations, you develop inertia that fights against new ideas, and that’s not good. Erica and Ernie (I’d link to their web site if I was better with html) worked hard to get code written for rocket mass heaters in Portland, Oregon (where I live now). It helped that the local government is open to new ideas. I don’t know if I can convince my husband to put a RMH in our house, but we could! I’m glad to know I could put one into an outbuilding and get it inspected and approved.

          • This raises the question of should people be saved from themselves… I know I want the right to fail.

      • Patrick says:

        We’ve used ‘dollops’ of concrete to hold down PEX, as well. Especially when they cross a threshold or sill.

        I have a shop/barn/office to build and want high thermal mass. That got me looking at Insulated Concrete Forms but I did not like the polystyrene variety. Two forms offer a wood cellulose fibre form, but they are limited availability and more expensive. I think I’m down to using them for the more complex forming areas, but then the concrete contractors can use knock-down metal forms for the major walls. As much as I like DIY, I don’t want to schlepp that much liquid rock. Ideas from the crowd here welcome.

        To your zoning thought: I think the largest factor I have seen nationwide in the minimal size of housing is conformity with community standards. Our area is pretty open to anything, but also requires a minimal size. Some of it is safety (HVAC air volume in a warming structure – small volumes fill with CO faster) but most of it is community driven. If a neighborhood has a series of 3,500 foot houses, then the 700 foot house is out of sorts. One focus is on restricting population growth and managing development – we live on a peninsula, so some of this is practical minded.

        Also, it is a way of limiting rental houses without saying so explicitly. My area has a requirement for a 2,500 foot minimum and you cannot do a multi-unit on any land in our community (except for owner/in-law/family residences that cannot be rented to anyone and non-residential buildings have no limits). The entire goal is to build owner-occupied communities. Love it or hate it, they have lower crime and hold value longer.

        I live in a rural farm area. Suburbs are much more controlled. I have lived in NY, LA and many places. Cities are a jumble of conflicting ideas.

        • I looked at the commercial insulating concrete forms but did not like them because:

          1) They created bridging from the inside to the outside of the building where rodents and insects could penetrate – a big no-no in our butcher shop;

          2) They were fixed sizes I didn’t like so it would have limited our ability to use our spaces efficiently; and

          3) We built bottles within bottles type thermos construction for energy efficiency which did not look feasible with the commercial forms.

          For building a more conventional home I think they might be quite good. The videos I’ve seen of them were impressive.

  2. Norm says:

    I really like your solution of encasing the pex pipes with an initial layer of concrete before the pour. Hope you don’t mind if I start using that. We have had problems with the concrete workers dislodging and damaging pex pipes. Major major major hassle. Your solution solves that problem completely and if done within a few days of the pour the concrete you added will still be green and bond well with the pour. Love it.

  3. Peter says:

    By the way…why not attach the PEX lines to wire lath (which is what we usually see) ?

    • No wire lath, or actually 661010 Welded Wire Mesh (WWM) in this situation. I have done it that way in other places such as the reefer sub-slab. Of the methods I’ve used I like this one the best. It was a little more work to do but the long term result is better. The metallic wire grid is a point of corrosion in the long term. I did one with attaching the mesh to basalt mesh which does solve the corrosion concern and I liked that.

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