OT: Grrrr... Frigging Fyzics!

I was hoping it wasn't going to be revealed as something subtle like a fan blowing across one end creating a venturi effect, lifting the water column.

I suppose at very tight tolerances, water has 'high viscosity' or ????

fun times.

I think the sheer volume of water in the hose (100 ft) leads to the (wrong!) impression that there's a lot of mass working to tug on that trapped air -- pulling in more air, as needed. In fact, it's only the difference in the two *standing* columns that comes into play. So, there really isn't much pressure working at all!

I find these sorts of "obvious (after-the-fact) facts" delightful proofs of how easily we can be mislead by unrelated details. And, in the situation I described, how frustrating that misbelief can be!

E.g., The Earth's diameter is about 8000 miles. Consider it a perfect sphere with a circumference of ~25000 miles. Imagine a belt fit *snug* around the planet at the equator. I.e., a 25000 mile belt! Now, cut that belt and insert a 36 inch length so the resulting belt is now 25000 miles + 36 inches.

Obviously, this belt is no longer a "snug" fit.

Question: how big is the gap between this new belt and the Earth.

Most folks get distracted by the huge numbers and imagine the answer is "negligible" when, in fact, the gap is about 6 inches. (of course, in the grand scheme of things, that's pretty small for a ~8000 mile diameter sphere). If, OTOH, you ignore the actual numbers and look at the *math*, the answer is blatantly obvious and not surprising in the least!

That actually begs a question: does it, now? If it did, how come you couldn't just reference your new ceiling off the existing one? That one would have had to fulfill that same requirement, wouldn't it?

Not really. Hose-based water level has been the established method since the dawn of time. Not to mention that there are carpenter's levels available at lengths of at least 3 meters.

You know there is this business idea someone had a while ago, where you can have other people take care of that part for you, for a negligible fee? Rent-a-tool really makes more sense for cases like that.

If memory serves, that's not really how you're supposed to use a water level. There's supposed to be a reservoir at one end of the hose, which is much wider than the hose itself, and you're supposed to build the reference by moving the endpieces up and down, not by adding water. The trick being that the level in the reservoir will move basically not at all, compared to that in the narrow tubing.

Bingo!

But do not count on this ceiling to be perfectly level or even. Get a really long level (10ft+) or rent one for an hour. Or borrow one. Find the low point of the existing ceiling which is most likely somewhere near the center of the kitchen where the big fluorescents used to be. Or maybe the whole ceiling is a bit crooked and the low point is in a corner.

Then move the ladder in circles and mark the old ceiling roughly where the new hangers will attach. -1/8", -3/32", and so on. Now you know how to adjust. It is possible that the weight of the new suspended ceiling makes the middle sag a little more but that can be adjusted for at the end of the project. Just _don't_ do it the way I saw a contractor do it: He sat on top of a standing ladder sideways, twisted the hangers with an obvious feel for exactly how many twists each needed to make things level, then "walked" to the next hanger using the ladder sections as his extended legs.

This probably isn't the "correct" method versus traditional water-level but if it works, who cares? Again, do not do the ladder walk ...

Self-leveling laser level (in the US) don't have to be expensive. Now I am not a great Black&Decker fan but for a one-off job this looks like it might work if you really want to do it with in "modern" fashion:

But 15ft from center could be near its limit.

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

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You're obviously not familiar with the sort of flat roof construction that is used, here.

Of course, the roof isn't "flat" (in the sense of "level") as that would not provide drainage for rain, etc. Instead, it has a very slight pitch.

The roof (plywood underlayment) is supported by rafters. Or, "ceiling joists". Wile the roofing material is fastened to the top edge of these joists, the (interior) *ceiling* is fastened to the *bottom* edge of these same joists. As such, this transfers the "roof pitch" to the interior CEILING PITCH as evidenced by my comment:

"OK, so how come the roof line at that HIGH end of the room is closer to the water level there than it is at this LOW end of the room??"

In most rooms, the difference in "ceiling height" from one side of the room to the other isn't noticeable. E.g., over a 12 ft span, it may be two inches or so. (actually, the pitch varies somewhat being greater at the top edge of the roof so some parts of the house see a larger "difference" than others).

If your eye doesn't have anything to reference off of (blech... I'm sure there's a better way of saying that!), you can ignore the difference. However, if there is something NEARBY that your eye can (naturally) *follow*, the difference is disturbingly obvious.

E.g., the line formed by the tops of wall-mounted cabinets! Especially if those cabinets are intended to abut the ceiling itself!

In places where this might be noticeable, a soffit is usually added to drop (that portion of) the existing ceiling soas to obtain a "level" underside. Of course, this results in the ceiling being lower in some places than it had been previously.

If the height of the soffit is large (e.g., 12 inches), then the

*difference* in soffit height (thickness?) corresponding to the differences in ceiling height (brought about by the roof pitch) aren't very noticeable. OTOH, if the soffit has negligible height, then the differences can be *very* noticeable.

In our case, the soffit would have "0" height at one extreme and

2 inches at the other. I.e., it would look like a *slice* dropping down from the (original) ceiling. [trust me, I've seen houses like this... it looks "cheap"]

So, the problem becomes one of erecting a new *level* ceiling that maintains the height of the "low spot" in the room all the way across to the areas where the original ceiling rises a few inches

*above*.

You *could* do this by using "references from the existing ceiling" down to the new ceiling's height -- but, those references would be different on the "high side" and "low sides" of the room. And, the "edges" would, by necessity, transition between these levels.

Since the roof is known to have a variable pitch, I'd have to find engineering drawings for the house and *hope* they were followed "to the letter".

*Or*, measure for myself.

**Or**, use a *level* to mark reference data on the walls and offset

*up* from these.

Have you tried to use a spirit level over a 30+ foot span? Do you really think you can ensure both ends are "at the same *height*" (i.e., "level") over that long of a span?

Yes, you can also pay people to write your code and do your designs for you. So, as we each "mature" in our markets, we should do less of our *own* work assignments and, instead, subcontract it out at a discounted rate and live off the "cut"? :>

I could rent a "high end" (self-leveling) revolving laser level and hope that the N people who had rented it before me each took good care of it to ensure that it remained in calibration. (do you *really* think the tool rental company checks these things?)

I could also hire someone to do the whole job for me! :>

In either case, I don't *learn* anything! And, don't have any "experiences" to savor as I grow older. Notice the folks around you that "never did anything" and see how they deal with growing older. Most have nothing that they can reflect back on as "memorable" experiences. Even folks who have lost fingers, broken their backs, etc. as a result of their "adventures" tend to smile when they recount their actions at those times!

The reservoir has to be at the *end* of the hose. And, you have to

*fill* the reservoir -- "add water until the level is 'somewhere convenient' for your needs". If the meniscus (no relation! :> ) ends up 4 inches from where you *want* it, that doesn't do you much good! (e.g., I wanted that to be *at* the ceiling level)

The top has to be "open" (or, at least, "well vented" -- to eliminate the problem I had). You have to be able to cap-off the end(s) of the hose so that you can position one end at a time (lest the water run out the "low" end while you are fiddling around). And, you have to be able to *support* both ends wherever you are positioning them to mark your references.

The 18" clear tubes act as my "reservoirs". The 18 inch length gives me some "dynamic range" in positioning each end of the hose (i.e., one end can be ~18" lower than the other and still provide useful data).

Using garden hose fittings, I can *cap* each end easily so I don't have lots of water dripping on the floor as I reposition each end.

The hose end fittings lend themselves to a pair of 2" brads acting as supports to hold it in place -- I only have to support the weight of the (charged) hose instead of some extra volume of water "at the top".

And, when I'm done, I have 100' of hose that I can use in the yard and the "complete kit" -- (inexpensive) revolving laser plus homemade hose ends) fits neatly in the case that came with the laser!

Won't work. See my reply to Hans-Bernhard...

A friend did a similar trick when positioning a "net" (to keep thrown things from getting stuck there) among the rafters at a local school gymnasium. Except, he was on a scaffolding...

30 ft above the floor! (pulling himself *and* the scaffolding along by grabbing the next rafter, etc.)

He now walks very *upright* and *stiffly* :<

Correct. The cheapie that I bought was probably $40 (on sale -- it was

*insanely* cheap -- *and* came with a tripod for supporting from below)

Exactly. You have to worry about three issues:

- how far the laser can project

- how accurately it can be "set to 'level'"

- how much wobble is in the mechanism

The first wasn't a problem -- if you can afford to use it in low light conditions (e.g., I didn't even bother wearing the "special eyeglasses" to enhance visibility).

I side-stepped the second issue by *not* relying on the spirit vials *in* the device to tell me when the beam was level. Instead, I used the device as a "rotating line draw-er" and put my reference marks on the walls with other means (water level).

The third I had no control over. But, I don't *see* the red line bouncing up and down on each subsequent revolution so the "bearings (bushings) are tight (enough)".

Ahem. Note I didn't speak of any roofs at all. In particularl I didn't say you should use the _roof_ as the reference, but rather the pre-existing ceiling.

But now that I think of it, something makes me suspect you removed all traces of that old ceiling before even thinking how to build the new one, didn't you?

Hmmm... why would low or high "ends of the room" necessarily have anything to do with the _roof_ being skewed as opposed to, say, there being a step in the floor?

Such a level mark is apparently already a required step of the building process around here. It's put exactly one meter above (target) floor height, and marked as soon as the raw frame of the house is up, using as precise a levelling technique as available. All later installations (flooring, doors, wall sockets, dropped ceiling, ...) refer that line for their vertical position, both in the drawings and in actual work. The ceiling would be specified at, e.g. 2.10 meters above this "meter cut".

The spirit level itself isn't the problem with that job. The problem is that the carpenter's level it's mounted into is usually too short for that job. 10ft ones are standard issue, but ones longer than about 15 ft would become seriously unwieldy --- they just won't come through the doors. Thus the hose-based water level, and its more modern successor, the self-adjusting laser level.

As an intermediate approach, it's also possible to hang a spirit level from a strung wire to level that out.

And then of course, when all else fails, there's what I'm going to call the "Pinky and The Brain" way: just flood the frigging room and use the high-water mark on the wall as-is ;-)

Let's just say you can have almost as much fun suing their pants off if they didn't as you're currently having with that ceiling of yours ;-)

For no particularly compelling reason. Just because you want your ceiling there doesn't mean your horizon has to be there, too.

Draw your perfectly horizontal line at some random height around waist level, where you don't have to run up and down any ladders all the time, then put your ceiling a constant 6'2 1/8" feet above that ;-)

How about the floor ? If the floor is level, just mark a fixed height above the floor.

Alternative method: set up a spirit level on a table, and hang a cheap rotating laser from your ceiling. Now sit down on the floor behind your spirit level, close one eye, and with your other eye line up the top of the spirit level and the laser line. Ask a friend to adjust the laser.

I mentioned "roof construction" only as it corresponds to

*ceiling* construction -- i.e., the ceiling being parallel to the roof, separated by the fixed dimensions of the ceiling joists/roof rafters!

As I described, the "pre-existing' ceiling carries the same pitch as the roof. So, the pre-existing ceiling is NOT "level".

See above (but, no, the ceiling is still there).

Not true, here. Everything is keyed off the floor being level (at least for "platform" construction. "Balloon" construction keys off the sill plate being level)

In a kitchen, a 1m mark would not be visible as it would be just above counter height and *behind* any backsplash.

It also doesn't help you to have a mark on the wall from which you are trying to *offset* if, for example, there are things mounted on the wall *above* that mark. In kitchens, one typically finds

*cabinets* above or appliances, etc.

Anything using a spirit level requires "judgement calls" on the part of the user. Is that little air bubble *perfectly* centered between those two hash marks? If it's off by "just a little", the error over a 30 ft span can easily be a large fraction of an inch if not *inches*.

Try it.

The advantage of the water level is the error becomes "absolute" AT THE (end)POINT OF THE MEASUREMENT instead of being subjected to the "gain" of the span being measured.

I used exactly this analogy to explain the water level to a friend last night.

You don't "learn" anything in lawsuits (except how to win/lose). It's, at best, a "remedial" experience, not a "constructive" one.

Because I didn't want to have to make *more* measurements around existing appliances, cabinetry, etc. The advantage of the water level is you can bring the "business end" of the level right to the place it is needed instead of having to "be in the neighborhood".

E.g., I could use the *floor* as a reference (assuming it to be level) and measure up from there...

Note that the problem I described wasn't because of the height of the reference line but, rather, because the end caps I left (loosened) on the hose weren't "leaky enough" to allow the water to seek its level.

Look at your kitchen. How many places can you conveniently measure from floor directly to "ceiling"? Here, much of the walls are "broken up" with cabinetry (lowers and/or uppers). Or, appliances (stove, refrigerator, etc.) I suspect in most kitchens this accounts for the majority of the wall space -- not counting door openings.

It also assumes the floor is level (here, it *should* be) and "flat" (i.e., no high or low spots).

Everyone thinks a spirit level is Gospel. *Try* using one over a long span. No matter how *perfectly* you think you have it leveled, you will be embarassed at just how bad your "eyes" have misjudged the position of that little "bubble"!

E.g., the self-balancing ($1K) revolving laser levels quote accuracies of +- 1/16" over 100 ft. And that's with a calibrated manufacturing jig to ensure the adjustment of the laser wrt the mechanism. You don't really think there's a *guy* sitting on the assembly line with a spirit level tweeking the laser's mounts to get it to that degree of accuracy?

If you have (or can borrow) a laser level (any quality, rotating or otherwise) or "laser pointer" (!), hold a carpenter's against the wall so that you *think* it is level. Then, align the laser to the edge of the level and measure the height of the beam 20 ft away. Grin and give yourself a second chance... :>

Which pretty much brings us back to my original point: being level is, evidently _not_ a self-evident design criterion for ceilings. Not in your neck of the woods, anyway.

Which would throw the occasional spanner into project planning, since as long as the floor isn't done, _none_ of the other workmen knows where anything else goes.

The end result would, of course, be the same. Our reference line is just 1 meter higher than yours.

Well, if you can't judge the difference by looking at the bubble, you won't notice it any other way, either. Those things are _very_ accurate if used (and kept) properly.

The ceiling doesn't have to perfectly level. It only needs to be good enough that nobody is going to notice that it's slightly off. That should be within the margin of error you get when carefully adjusting a good spirit level.

Of course, if you have other reference points to see that the ceiling isn't level, you can use those to level it in the first place.

My comment was intended as tongue-in-cheek. What

*other* criteria would apply to a ceiling; it should be *white*? :>

Construction practices here are based on "slab" foundations. I.e., nothing *can* get done until the slab is poured. And, since it is *poured*, barring subsidence, it *will* be "level" (and "flat")

You notice the difference when you have a long span of something of known identical dimensions against which to compare it. E.g., a long run (10 feet or more) of "upper" cabinets will make even a 1/8" deviation over that span "noticeable". Or, a large picture window (one wall of this room is floor-to-ceiling glass for a span of 15 feet).

Patterned wall paper, etc. can also leave you vulnerable to this sort of thing (when your eye catches a difference in how the pattern fits against the ceiling at one end of the room vs. the other).

Your eyes tend to fixate on little discrepancies like this. E.g., laying floor tile "on the diagonal" is more forgiving of deviations in grout line widths, walls that aren't perfectly square, etc. (it also makes the room look larger because it throws off your ability to gauge sizes).

I try to pay attention to "little details" like that. (though I will admit to often having one black sock and the other navy blue...)

So IIUC you have a cathedral ceiling in the kitchen. If you don't mind my asking, why on earth do you want to cover that up?

--
Regards, Joerg

http://www.analogconsultants.com/

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No. The roof is "flat" (i.e., very shallow pitch). The common practice is to use the the "roof rafters" as if they were "ceiling joists". I.e., the top edge of the joist serves as the support for the roofing underlayment while the *bottom* edge of the joist serves as the "ceiling".

It's fine if the ceiling is "far enough" above the tops of everything that you have in the room. For example, if you walked into an *empty* room (nothing close to the ceiling to act as a reference for your eye), you would have to deliberately look for the "rise" from one side of the room to the other.

E.g., friends with 30 foot high ceilings of this type don't have the same problem. Instead, their kitchens look odd because there is

*so* much empty space above the cabinets... :-/

Architects take care to make this less obvious -- i.e., you put windows in the "high wall" or the "low wall" and NOT in the "side walls" (because the variation in the gap above those windows would be noticeable).

In kitchens, the placement of "upper" cabinets has an effect on this since your eyes see the differences in the "space above" those cabinets when they run in the same direction as the roof pitch (there is no difference if they are *normal* to the roof pitch!)

The common solution (here) is to build a soffit above those cabinets. This allows the bottom surface of that soffit to be "made level" so the upper cabinets can abut from below so that there is no "space above". If the soffit is a foot or more, the difference from one "end" of the soffit to the other is less noticeable (12 inches vs 13 or 14).

But, the space (volume) that the soffit occupies is "wasted". It seemed more efficient to extend the cabinets that extra

12 inches and bring that space *into* the cabinets where it could be used -- even if only for seldom used items (or, lightweight items that could be deliberately *knocked* off that shelf -- like paper towels -- for folks who are "height challenged" :> )

The taller cabinets also makes the room *seem* taller as they tend to draw your eyes upward (tall and skinny instead of "boxy").

Next battle is over the 4 ft square skylight I'd like to install. Some claim this increases the cooling load dramatically. And/or makes it less comfortable *under* the skylight. Of course, no one can tell you anything

*definite*. Or, if they can, they can only express it in numerical terms -- nothing that you can personally relate to... :<

I would *so* much rather have a *basement*!! :-/

And there is a reason you didn't go to your friendly local hardware warehouse and by a ready-made setup for $10 ???

I used one from 'Ace Hardware' to check level over a 100m span.

RK

Ok, that's different. That wuold have too much of an industrial look to it, not a high WAF.

Why don't they just install gradually thickening spacers or (smaller) parallel but horizontal beams which is what they did here? Are those few hundred Dollar or so in extra lumber and labor asking too much from a builder?

[...]

Nah. A skylight is something wonderful. We don't have any but sometimes I wish we did. Then I could just open it when the evap cooler is running.

--
Regards, Joerg

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Here, they just "arrange" to have soffits installed above the cabinets. For most folks, this is a practical solution since many people wouldn't be able to *reach* the "top shelf" of a cabinet at 7 ft (which is where the soffits are usually located).

We have them (small -- 2ft sq) in each bathroom where they add considerable light. I "need" lots of light when I am working/cooking (e.g., how can you tell if the chicken is *pink* or *cooked* when sauteing in a redish sauce?) and figure the skylight would work wonders in this regard (there are lots of lights in the kitchen but those burn electricity :> )

I think 4 ft x 4 ft of glass in the center of the cooking area would be stunning. And, as you say, serve as a great way to let heated air slip out of the space.

$10 for what -- a laser level or a water level?

Nobody had a revolving laser level for $10. And, the folks at the two Aces just shook their head when I asked re: "attachments" to add to a garden hose to fashion it into a water level.

(I can't imagine buying 100 ft of *any* sort of tubing of respectable diameter for $10...)