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Gulf Island Building.

1M views 8K replies 149 participants last post by  Katie Cabana 
#1 · (Edited)
Hi all:
Since the summer of 1997, I have been building a cabin and house on our 1/2 acre lot here. Before I dive into that part, I am going to show a few photos to set the stage a bit. We are remote here. No services of any kind, except that which we provide for ourselves. So don't expect to see any paved roads with big trucks delivering any materials.
We live at the head of a small bay, which is both a blessing and a curse.
When the tide goes out, we have to clamber over hundreds of yards of rocks to get to our boat. When it is in, I can float logs right up to my little railway to move them onto the log deck. Well, not any more, but more about that later.
This is the bay in front of us.
 

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#7,432 ·
The Shoji screens, which will go in front of the closet in the MBR will be about 3 feet by 6 feet, so quite large.

I have the wood cut, and it is now a matter of figuring out how to cut all the joints. At first I tried cutting by hand, using an extremely fine cut Japanese saw and chisel.

After doing just a couple of cuts I decided that if I wanted to finish the joints this year, a faster method was in order. Here's the hand cut version.
 

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#7,433 ·
Then it became a game of trial and error - heavy on the error - using the dado blade in the table saw.

A difference of just 1/100" in cut width makes all the difference between a tight joint and one that is sloppy. Once the width of the cut is established, then the depth of cut comes into play. Here again, the most minute difference makes the difference between a good fit and one that looks way off.

I made many attempts to get this dead on, and the last one is on the right side of the pic here. It's OK.
 

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#7,436 ·
Once the dado blade was set, I didn't want to move it until after all the joints were cut. Mainly because the chances of getting it perfect again were probably pretty remote.

So the first thing I did was to cut the joints on the short kumiko. Basically no trouble there, as the wood was less than 36"long. No pic of that I'm afraid. Sorry about that.

Then it was on to the long wood. There needed to be some way of preventing the pieces from moving in relation to each other once I had made the initial cut. It turned out that just putting a dummy piece into the first notches worked a treat. And providing that I had marked out the cut lines correctly, everything should fit properly.

So, what I did was to gang cut the long kumiko in groups of 6, which - in theory at least - should keep any errors to a minimum.
 

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#7,437 ·
As you can see in the previous pic, the joints are cut on alternating sides of the kumiko as you progress from one end to the other.

But for some of us old guys with crummy memories, either that or a short attention span, Murphy managed to arrive just in time to screw things up.

Six pieces of long kumiko shot to hell when I managed to put two adjoining cuts on the same side. Didn't make that mistake twice I can tell you. I did salvage the good end to make some extra short pieces from, so it wasn't a total loss.
 

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#7,438 ·
Other than the screens, I need to get one of the old wood water tanks replaced soon in order to have enough water for the garden this year.

One half of the original pair of tanks has been demolished and the junk all burned on the bonfire. That was quite a job all by itself. Now the new tank is being assembled from the 14 panels which I made up last year.

Here's the first 10 sections in place...still some of the ground needs to be dug out and leveled off to finish the new tank. It looks like the weather just might be co-operating today so it can be done.
 

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#7,440 ·
Say something Keith, speak to me, are you there?:eek: Good grief talk about fouling things up, I just banned Keith, talk to me buddy, are ya back yet?:whistling2:
 
#7,442 ·
Hi there Jim...I was pretty sure I knew what had happened. There was that post from some Asian website that you were after and I posted right after he did and used the "ban" sign from the smilie list.

I thought it was quite funny actually...I knew you'd get it figured out right away Jim.

Thanks for that. No harm done!
 
#7,443 ·
I was reading through, scrolling post by post thinking "this screen project doesn't seem THAT bad." Then I saw this picture of all the wood to be cut:



and almost threw up. That is a LOT of cutting. I see why you didn't want to tackle that by hand!
Yep, there's a few pieces to do this job. Those little kumiko are only 3/8" by 1/2", so the joints are very small.

All the spots where the kumiko connect to the frames will need to be cut by hand, so that's going to take awhile. If I can do one frame every day I should be done in a week or so. 26 mortise and tenons for each frame. :eek:
 
#7,445 ·
It's high time the new water tank gets done, otherwise before you know it, we'll be out of the rainy season.

Today I rounded up a few bags of sawdust and planer shavings to spread on the ground inside the tank area. The idea being that it would cover up any small sharp rocks that I may have overlooked when trying to clear the ground.
 

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#7,446 · (Edited)
After I got the sawdust all spread out, I found a bag of fibreglas pink in one of the woodsheds and I thought I would add that next.

That didn't cover the whole area, so it needed some Roxul to cover the inside area of the tank.
 

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#7,447 ·
And to top it all off, my rummagings through the shed unearthed a piece of pond liner which fit the bill perfectly. No idea where it came from, as it is different from the other liners I have here. But beggars can't be choosers, so...
 

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#7,449 ·
Jim, I'm hoping this will work something like a small swimming pool. I have the 14 sections pretty well nailed together using galvanized spikes.

The fact is that most of the weight bears right on the ground.

If my memory serves me, I think the tank can hold up to 25,000 pounds of water. The maximum side thrust arrives at about 1/3 the way up from the bottom of the tank. I don't know what portion of the weight actually pushes outwards, but when it is divided among 150 square feet of wall area and about 112 square feet of ground it shouldn't be that much.

Let's say, for example, that 1/3 of the weight is pushing sideways, that works out to just over 50 lbs per square foot against the walls.

I can always add more nails if I get nervous. :)
 
#7,451 ·
I haven't dealt a lot with water like that but I have concrete and it is just amazing how much pressure there is on the walls, I was just thinking along those lines. Personally I would be a little leery of nails to hold the water in like that but you know way more than I do about things like that.
 
#7,453 ·
Typical concrete weighs around 140 lbs per cubic foot, which is something more than double the weight of water, at 62.43 lbs per cubic foot.

Not only that, but add to that the force added when the concrete vibrator does its' work and you have some substantial pressures building up. And let's face it, many concrete pours can easily be 8 feet tall or more, so we are talking about a huge amount of weight here.

Something we learned in carpentry school is that the maximum pressure when a concrete wall is being poured is NOT right at the bottom of the wall, as you would suspect. It is 1/3 of the way up from the bottom. This is why we usually go around a basement form (for example) in two foot lifts. It lets the first batch get a head start on setting up before you get all the weight in.

Now, whether or not this applies with water as well I really don't know. Just going by the bowing on the old water tanks it might indeed be the case. I'll see what I can dig up about these pressures.

Your turn. :)
 
#7,458 ·
Yesterday afternoon I got 4 layers of 6 mil poly inside the tank for the liner.

If you have never tried to do that with poly, you're missing out on one of life's great experiences. The stuff goes everywhere except where you want it to, it's so slippery.

The hose is on now draining the remaining water out of the original back tank. There is maybe 500 gallons at the most in there. So once I have 1,000 pounds or so of water in the new tank, then I will try pulling the poly straight and fix it to the top of the walls.

Once the back tank is empty, then I can demolish it as well.
 

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#7,463 ·
A Squared...WOW! Fantastic post, many thanks.

I'll go through each section to make sure I have things straight here.

Firstly, I think I have pressure and force mixed up somehow. I'm going to claim my recent brush with CO poisoning for that. It really does serious damage to the memory, hopefully I will get that back.

It seems to me that we usually use pounds per square inch (psi) when we refer to water pressure. So it is easy enough to figure out what pressure a column of water would have if it was exactly one square inch in area and 4 feet high. I believe that would be 1.7341 psi + a very small amount. So an area of one square foot should be the weight of four cubic feet of water, or 249.72 pounds.

Now, as to the pressure - or force if you wish - being greatest 1/3 up with concrete, I believe that is true. Concrete is not a homogenous material as is water. The instant that concrete hits the bottom of a form it starts to become a solid. Then there is the friction on the sides of the form itself. Water has no such friction, or at least it is very nearly immeasurable. In any event, we are discussing water here.

So I do agree with you that the pressure of water will be greatest at the very bottom of a given vessel.

You are quite right in your description of the old water tanks, I used some mill cut 1 1/2" by about 3" lumber of whatever stripe I managed to pull out of the ocean. And yes, it was obviously nailed as you suggest.

One thing against these tanks was the fact that they were square. This produced a greater outforce in the middle of the 10' long sides which eventually caused the bowing. However, they did stay intact until the wood itself started rotting. I am hoping that the more round design of this new tank will more evenly distribute the outward pressure, actually, I'm certain that it will.

There are 14 sections each of 32" in width.

As far as the nailing itself goes, I have driven the nails in from both sides of the adjoining pieces of 2 x 4, and they are driven at an angle, rather than dead straight. I honestly doubt that they will pull out.

The cable idea is a good one, and to that end there is a very large water tank on the island here which utilizes several such cables. I have heard rumours that this tank is 53,000 gallons, which means it could contain over 1/2 a million pounds of water when full. I think it is about 8 feet high but I can't remember for sure. Which means, I guess, that there would be something like 500 pounds per square foot pushing outwards on the bottom of that tank!

I haven't looked at this tank in several years - it's at the far end of the island. But if I get a chance I'll take a trip down there and take a pic or two.

Somewhere around here I have some numbers for cable (or steel rod) heights above the bottom of a 4' tank. You actually wouldn't put them at 1/3 and 2/3, but rather much closer to the bottom of the tank where the pressure is greatest. But then, I have a hunch you probably already know that.

Alternatively, I could simply use some steel strapping right at the bottom since that is where the maximum force will be exerted. I'll have a look around here to see what's on hand.

And thank you very much again for such an informative post. :thumbsup:
 
#7,464 ·
OK, for what it's worth, I've done some testing to see how much force is required to extract a 3" galvanized nail right from the 2" x 4"'s I have used in the water tank.

The results tell me it takes about 264 pounds of force on a direct pull to extract one nail.

Given that there are at least 8 such nails in the bottom 12" of every section of the tank framing, I'm no longer the least bit concerned as to whether or not the tank will hold. I think a safety factor of 8+ will do the job. :)
 
#7,465 ·
Well maybe that will work might work for you then, and I certainly hope that it does. I may tend to discount tthe nail's strength more than necessary. And worst case scenario, if they do start to pull apart, you could retrofit with a cable/band/strap reinforcement without too much trouble. It wouldn't be like you'd have to go back and redo everything.
 
#7,466 ·
Well maybe that will work for you then, and I certainly hope that it does. I may tend to discount the nail's strength more than necessary. And worst case scenario, if they do start to pull apart, you could retrofit with a cable/band/strap reinforcement without too much trouble. It wouldn't be like you'd have to go back and redo everything.
Something else I think I will do, purely as a safety precaution, is to add some steel strapping right at the very bottom of the framing on the outside, which would prevent the possibility of anything pulling apart.

I was able to speak with a retired physics professor from the local university as well about this. He pointed out that the force of the water is not actually pushing directly sideways on the nails as was the case when I did the nail pull test. Unfortunately, he wasn't able to give me any sort of formula to determine what the actual force really is. He pointed out that he is a scientist, and I would need an engineer to try and determine the final answer.

I think I'm well covered, but the strapping will do it for sure.
 
#7,468 ·
Good grief Batman, you're not kidding about the rain. It hit here yesterday around 4 PM and it is only just now stopping. There's 26" in the tank already! Or just over 14,000 pounds.

This guy is outside over Vancouver Island as we speak.
 

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