So, I was in Oakland (well, Richmond) California for a week, working on my nieces place. It's a ranch style home, built as one of four models in a subdivision.

One of the tasks that she had outlined for me was to install porcelain tile in the two bathrooms and in the entryway. When we were lining this project out, I was stationary and happened to watch the floor when Andy (the husband) stepped on it. It flexed a good quarter of an inch.

That's pretty much incompatible behavior with tile, so I went down into the crawl space under the house for a look and found that there were no floor joists. Instead, the builders ran 4x6 beams the length of the building on 4' (four foot) centers. Adjustable supports were installed every eight feet or so, which rested on concrete pads. 1 1/8" plywood was installed over the beams. Probably tongue-and-groove, probably nailed down.

Clearly, this technique works well enough to have lasted since the 1970's.

I ended up adding joists under the bathrooms and entry, and improved the interim supports as well. Those three areas exhibit no flex and are ready for tile.

Anyone else ever encounter this kind of approach? I've seen it done with 2x6 T&G lumber over 6x6 beams, but only for roofs or lofts, never the main living space.

I've seen that done for main and second level floors in log cabins down east. Probably common when buildings are framed with timbers like that.

Given that this is a seismically active area, I'd imagine you'd want to do more than rest the house on its concrete piers, like you'd want to strap it down. I did a quick Google search and came up with an entire instruction manual from the state of California on exactly this topic. Where would we be without the web?

http://www.abag.ca.gov/bayarea/eqmaps/fixit/manual/PT11-Ch-6.PDF

Our house (we bought it in '97, it was built in '61) came with floor joists at 24" offsets. The hardwood flooring is really squeaky! A few years in, the kitchen floor tiles started popping out. After a few more years of taping the tiles down (really!), we finally stopped dithering about our renovation and redid the kitchen floor. We cross-braced the joists every 18" or so and installed thick and sturdy sub-flooring.

We did that in 2004. The tiled floor has just begun squeaking; I'm worried...

We did similar bracing in our front hall where we installed tile during our extensive renovation in '13. <sigh>

-jk

My house is four stories, and every floor/ceiling is 14 inch thick steel-reinforced concrete resting on heavy steel beams. I cannot get a portable phone signal to reach from one floor to another.

The foundation was set on bedrock, three meters below ground level. I have had no problems with tile and floor flexing.

tanstaafl.

I once had to wire a building in London similar to yours. We ended up running cabling out an upstairs window and back in through a downstairs window. Far (far!) easier than punching through the floor.

-jk

Tell me about it! I am faced with an analogous situation at the moment. There is a 500 liter propane tank on my roof that feeds gas to the two top floors for cooking and hot water. The gas lines are half-inch copper tubing, embedded in the walls and floors when the house was constructed. With every gas-fired appliance in the top two floors shut down including pilot lights, we were losing 25 liters of propane per day. Yes, 25 liters! The really scary part is, we have no idea where it went.

No amount of careful sniffing or checking every room in all four stories of he house, particularly the two bottom floors because propane is heavier than air, has revealed any hint of leakage or accumulation. All we know for certain is that more than 700 liters of propane are unaccounted for. Of course we have now turned off the valve on the tank itself so nothing more is leaking, and the pressure regulator on the tank is now completely quiet.

Clearly we are not going to start tearing out concrete walls and floors looking for a leaking copper tube. Instead, we will drop a new tube on the outside down to the level of the fourth floor kitchen, drill a hole through the wall to get into the house, and run the new pipe behind the dishwasher, the sink, and the cabinetry to connect to the stove.

The hot water heater for the fourth floor is up on the roof next to the propane tank, and that 15 feet of line has been checked thoroughly and is not leaking.

For the third floor we will just install a new system from scratch: storage tank and lines to the existing hot water heater and stove. Basement and ground-level floors already have their own system which does not at present have problems.

Presently the woman who occupies the third floor is out of the country, so she is not suffering the lack of hot water or cooking equipment, but she is returning in about three weeks so we have a deadline.

Coincidentally with discovery of the gas leak, we installed a solar hot water heater for the 4th floor. I am extremely impressed with it. With a 130 liter storage tank, it provides hotter water than the gas-fired heater, and more of it. Mid November, temperatures during the day in the high 70's, at night in the 60's (F), even before the sun comes up in the morning water temperature is 150+ degrees. Even without the gas leak, it will pay for itself in about a year and a half.

tanstaafl.

In the U.S., most areas don't permit long runs of copper tubing for the delivery of L.P. or natural gas. Instead, black pipe (similar to galvanized pipe) is used, with a thread sealant specifically for gas. You'd probably use 1" or 3/4" for the main run.

Since you are essentially always at home (you don't leave for months at a time) theft is less of a problem, so running the pipe down the outside is probably okay. I know that unattended buildings in Mexico are oft targeted for quick pipe removal by n'er do-wells. You remember Geoff Orth from the Tuesday Night rides -- his place has had stuff removed twice.

Have you tried the soapy water test? Get a very soapy solution of dishsoap in a cup, use a paint brush to "paint" it on fittings and even where the pipe comes out of the wall. You may or may not find a spot where it blows bubbles. Test everything you can find.

25 liters a day. Wow.

Never thought about solar water heating before. Hmm. My house currently has two 50-gallon gas fired heaters, connected in series. Needless to say, if the upstream one fails first, I'm effectively down to one 50-gallon heater. If the downstream one fails first, then I'm hosed.

My "I'll deal with it when it's a problem" plan has always been to replace both tanks with a single tankless system. But we get plenty of sunlight here in Houston. We're not as far south as Mexico, but still... I hadn't given any serious thought to a solar heater. My roof is now mostly covered with solar panels (*sigh*) but there's certainly still room up there to shoehorn in one of these things. (Fun, fun: Google's satellite imagery now includes my solar system, so the pictures are less than a year old.)

So... pros and cons of going gas-fired-tankless vs. solar-heated-water-tank?

How old is the building? Is the piping actually embedded into concrete?

It's quite possible that if it is, and it's been there for years, you've got cracks/holes in the piping itself, either caused by alkaline conditions in the concrete damaging the copper, or possibly thermal expansion and contraction fatiguing it. Plus there is a known issue with copper pipe developing pinhole leaks over the years for unknown reasons.

If this is happening it might be that your missing gas is leaking inside the concrete and soaking into the pores of the stuff, which could quite possibly absorb a remarkably large amount of it over time. It would probably eventually make its way to the outside and evaporate, likely over a large area making the concentration low. Although 700 litres of the stuff is rather a large amount to misplace.

As the smell is not inherent to the gas itself, LPG (which in your part of the world is probably pure propane) being odourless, it's also feasible that the ethyl mercaptan odourant is being filtered out by the concrete, I suspect. If this is indeed the case the only way you'd find the leak would be with a flammable gas detector and a lot of time and effort.

Re-piping it is probably the best solution.

That said, are you certain someone didn't install a sneaky tap-off point and run it into an adjacent building when it was built?

pca

You can always do both. Use the solar to pre-heat a tank of water, and then feed this into the tankless gas to bring it up to temp. Although in Texas you should have enough sunlight year round to do without the gas step.

I made my own hot water heater from mostly garbage when I lived in Belize and it worked great. Cost $100 and I had hot showers whenever I needed it. I can only imagine how much more efficient the commercial units are.

If you're interested, I used these instructions, although the materials available varied a bit in my area. For example, my tank was a small trash can inside a larger trash can. I insulated it by breaking up a styrofoam cooler and shoving it in between the walls of the two trash cans and shooting a can of "Great Stuff" foam in to fill any voids. Worked great. Although it only had capacity for a two quick showers. If I did it again I'd do a bigger tank.

The building is... 18 years old for the bottom two floors, 10 years old for the third floor, 7 years old for the fourth floor. And yes, the pipe is embedded in concrete.

Yes. The leakage only appeared over the past 30 days. I suspected something was wrong when the last tank fillup came at 54 days instead of the usual 110. Then, when the solar heater was being installed, I mentioned to the installer that there might be a leak. He checked with soapy water all of the exposed pipes on the roof, no leaks, but noted that the gauge on the 500 liter tank was dropping at 5% per day with no gas appliances being used in the house. There are no structures adjacent to my house, the nearest one being 50 meters away and it was built two years after my house was complete. No-one could tap into my line without knowing where the line was buried and digging trenches in the wall and hanging pipes 20 feet in the air. I probably would have noticed that.

tanstaafl.

Did they install the sub-flooring with nails or screws?

OK. You've got a leak

It's also possible, I suppose, that if the pipework goes to the ground floor it might actually go into the foundations, and be leaking into the ground under the building. Which again could absorb a lot.

Porous structures like concrete and earth can hold a large amount of gases such as propane or butane, which if they are sufficiently concentrated to catch fire, can burn for a remarkably long time and be quite difficult to extinguish. Don't ask how I know...

But in my defense, I was 12.

pca

I don't know what your weather is like in Houston, but I suspect that it is warmer than what I have here. Where I live, the average daily high temperature year-round ranges from 76 degrees to 86 degrees. In other words, it almost always gets up into the 70s during the day, rarely into the 90s. At night it drops down into the 60s and 70s, rarely into the high 50s. When the temperature gets into the 60s, people walk around wearing parkas with the hoods up, and their dogs are wearing fleece vests. Really.

I can tell you that on a day this week when the temperature never reached 80 degrees, the next morning I had 130 liters of water at a measured temperature of 154 degrees. That considerably outstrips the performance of my dual-burner "tankless" [it actually keeps 10 liters of hot water per burner] gas heater which is rated as being sufficient for a house with two and a half bathrooms.

I am now in the position of using gas only for cooking, and I actually do most of my cooking out on the deck with my barbeque grill. I may never have to fill my roof tank again, and I had been spending about $900 USD per year there.

The cost of the heater itself was $10,800 pesos. An additional $2,200 pesos was required for water pipe and connecting fittings to plumb it into the existing system. I don't know what the installation labor will be, but probably in the vicinity of $3,000 pesos, so total cost is $16,000 pesos. That sounds like a lot, but at present exchange rate, that's an even $1,000 USD.

One downside to the solar heater is that the logical place to mount it is on your roof using about a five foot by eight foot piece of real estate. That means that your hot water tank may end up a long ways away from your faucets, and you'll be sending a good bit of cool water down the drain while you are waiting for the hot water to arrive. In my house, it is 40 seconds to start a hot shower, 50 seconds to get hot water in the kitchen sink.

The technology of the heater is interesting. The tubes are double wall glass with a vacuum between them, and a copper core in the middle to transfer the heat to the storage tank. No water circulates through the tubes. Even though the tank is full of 150 degree water, the tubes are actually cold to the touch, noticeably cooler than ambient air temperature.

So, would I recommend my solar heater to others? Unreservedly, if you live in a climate that will support it. No moving parts, no heating elements, no maintenance. It just sits there and makes hot water. For free.

tanstaafl.

I'm not that big a fan of solar heaters. In the warmest periods of the summer they may overheat and then you have actually cool them with an additional circuit containing cool water. It's also not always easy to bring the water circuitry on the roof.

In my opinion, it's a better idea the install install a heat-pump boiler, and also some additional photovoltaïc panels to feed it. A much simpler installation.