Author Topic: 18 X 24 Island Bungalow in Tropics (Images)  (Read 823 times)

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Offline miller9091

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18 X 24 Island Bungalow in Tropics (Images)
« on: July 10, 2020, 09:22:16 PM »
Hey everyone,

Quick Facts:
1. Wife and I own land in a tropical climate.
2. This is a off grid area and isolated (access to lumber yards and hardware store)
3. No permits required (still needs built properly)
4. We are about to finish clearing the build site of trees and brush.
5. Dimensions 18X24
6. Pier and beam foundation
7. Soil is not a concern in this area thick lava after a 6-12 inches deep.
8. house will only be 21 feet the remainder 3 feet will be a deck/sitting area.
9. I'm a novice, I helped build a deck, once. :)

Hopefully that gives enough info for everyone to help me out, I'm looking for advice on my foundation, I'll attach an image. The plan is to have three rows consisting of four piers, spaced 8 feet apart, from the piers will be 6X6s. Resting on the top of the 6X6s will (2) 2x12's running long ways on each row of piers (3). Then I'll use 2X8's to build a box on top and as my floor joist, centered on 16 inches.

Does this seem like a proper foundation? Any suggestions or advice? Images in link.

Thanks in advance!!

https://photos.app.goo.gl/qQAuro32jiY3vCFv5

Offline Don_P

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #1 on: July 11, 2020, 02:56:28 AM »
Hi Miller,
How dense is the lava, it may be sufficient as a footing. The short post is hinged and unbraced at each end, what happens when the wind pushes against the structure above that. If the posts run from footing or rock all the way up to the top plate of the wall then the wall sheathing braces the posts.. Block between joists at each beam crossing not just the middle. Attach the floor to the girders well and also block the girders to the floor to prevent them from wanting to roll. Check girder spans. What species are you using?

Offline Dave Sparks

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #2 on: July 11, 2020, 09:27:47 AM »
I don't think you will ever stop clearing the brush and trees :P I have not....
Question on your build, Do you have to be concerned with hurricanes or trop storms? This is a full time living space correct? Where is it located? When does it have to be done?
"we go where the power lines don't"

Offline miller9091

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #3 on: July 11, 2020, 09:45:22 AM »
Hi Miller,
How dense is the lava, it may be sufficient as a footing. The short post is hinged and unbraced at each end, what happens when the wind pushes against the structure above that. If the posts run from footing or rock all the way up to the top plate of the wall then the wall sheathing braces the posts.. Block between joists at each beam crossing not just the middle. Attach the floor to the girders well and also block the girders to the floor to prevent them from wanting to roll. Check girder spans. What species are you using?

Thanks for the response! The lava below the small amount of soil is very thick and sturdy, the majority of homes in this area use a pier and beam foundation too, and place footer blocks on top of a squared pad, see new images in folder.

I'm not sure if we're on the same page, I've added a few more images to the folder to help convey the idea of the foundation, providing only an aerial sketch was not the best, especially since this is new to me. My three girder beams will provide support for my floor framing, floor framing built on top of the girder beams. If this is what you were thinking I’d like to revisit your questions just let me know.

I will be using a Home Depot for lumber supplies and have not looked into specific species but would use treated lumber. I’m a few steps at a time guy, so suggestions are welcome. :)

Offline miller9091

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #4 on: July 11, 2020, 09:55:39 AM »
I don't think you will ever stop clearing the brush and trees :P I have not....
Question on your build, Do you have to be concerned with hurricanes or trop storms? This is a full time living space correct? Where is it located? When does it have to be done?

lol, its not an easy process but two weeks later were about 75% cleared. Hurricanes and tropical storms are relevant, however I'm tucked away from the coast a good ways and deep in the jungle, plenty of a buffer zone, mud slides and flooding is not a concern. Yes full living space, small kitchen, gas stove, solar set up and water catchment but by design a very efficient space. Located in the pacific with a tropical climate, 80s year round with a gentle breeze. No specific deadline besides the arbitrary one I provided to myself, I figured 6 months. This is currently my full time gig, I've adjusted my life to make this priority and have the ability to devote most of my days to this project.

How long have you been clearing? What type of project?

Offline MountainDon

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #5 on: July 11, 2020, 03:05:00 PM »
I don't think you will ever stop clearing the brush and trees :P I have not....

 rofl   I know what you mean Dave.  This is our 14th year in our mountains. We have to do something every yer. Not so much as in the first half dozen years but "stuff" does keep growing and dropping branches is the winds once in a while.
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline MountainDon

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #6 on: July 11, 2020, 03:17:55 PM »
.............. I’m a few steps at a time guy, so suggestions are welcome. :)

Building a few steps at a time is fine. However, the build will proceed best if you have a clear plan of how the structure goes together from bottom to top before you dig any dirt or cut any lumber.

A three foot wide deck/sitting area is much too narrow to my thinking. That is barely enough room to have a chair without stepping off the narrow deck isn't it?  You might be best to consider building the deck on the end as a separate item. One reason for my suggestion is that if those main beams extend out from under the cabin floor into an area that will be getting wet in the rain, water will get back under the cabin floor along the beam ends sooner or later. That may soak up into the floor joists.  Even PT lumber of the variety commonly available at HD type stores may develop issues down the road. I would rather do my best to avoid ever having to make repairs under the main structure.

Don_P makes a good point about the short posts that sit on a pad/block and then have the beams sitting on top. An engineer would not call that a stable foundation.

Just because something has been done and has not failed, doesn’t mean it is good design.

Offline MountainDon

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #7 on: July 11, 2020, 03:26:03 PM »
Images note:   If you click on one of the preview images in google to enlarge it and then right click on that enlarged image and select
copy image address" from the drop down that appears you can then insert a link into the forum message.  After copying that image address link, you would them place the cursor in the compose message field on the forum. Then look above the compose field for the "insert image' icon (3rd item from left in the second row of icons). Click on the "insert image" icon and then paste the copied link in between the img links that appear. Right where the icon is flashing. That should make the selected image appear in the message once the message has been posted.

Like this...


Just because something has been done and has not failed, doesn’t mean it is good design.

Offline Don_P

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #8 on: July 12, 2020, 04:18:27 AM »
I took a look at your photos, yup, we're on the same page. Those foundations appear in the forensics shots after a high wind or seismic event overturned, building dropped off of some or all of the piers. They have low lateral resistance. Sort of like parking a car on the dining room table, it'll work as long as nothing bumps the table.

I was working in a furniture shop years ago. One of the suits came down out of the office "We have a question from a potential client, they want to put some heavy office printers on our rolling TV carts and be able to roll them around through their offices, they can't collapse if they bump something" The guys in the office were slide ruling out the design. Which is fine. I grabbed one of the guys that weighed about the same as the printer, sat him up top of the piece of furniture and we went for a bumpy breakneck stroll through the plant. That was the easy way with something I didn't mind real world testing to failure. I've tried to allow others to perform those kinds of experiments at house scale and learn from their examples

I quickly googled this "pier foundation overturning after hawaii earthquake".
This looks like one good return, I see some of the pics that made the rounds in trade pubs after the event;
https://seagrant.soest.hawaii.edu/wp-content/uploads/2018/05/2009-Post-and-Pier-Structural-Seismic-Retrofits.pdf

That was a seismic event but wind has the same lateral concerns. Its just another way of bumping that table. On the bad day when you need to run for shelter you don't want to have to run from your shelter. It is hard to think in that way when swinging a hammer on a beautiful sunny day.

I believe a stronger way to build this is to use post frame construction methods, that lets the wall sheathing, a large bracing area, do the lions share of the work.

Read the lumber stamps or take a pic of some of them at your home depot. Each species and grade carries different strengths. I imagine you are in a high insect problem place, I'd think about using borate treated wood throughout, that is probably an option at the big box.

Offline miller9091

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #9 on: July 13, 2020, 10:34:15 AM »
Building a few steps at a time is fine. However, the build will proceed best if you have a clear plan of how the structure goes together from bottom to top before you dig any dirt or cut any lumber.

A three foot wide deck/sitting area is much too narrow to my thinking. That is barely enough room to have a chair without stepping off the narrow deck isn't it?  You might be best to consider building the deck on the end as a separate item. One reason for my suggestion is that if those main beams extend out from under the cabin floor into an area that will be getting wet in the rain, water will get back under the cabin floor along the beam ends sooner or later. That may soak up into the floor joists.  Even PT lumber of the variety commonly available at HD type stores may develop issues down the road. I would rather do my best to avoid ever having to make repairs under the main structure.

Don_P makes a good point about the short posts that sit on a pad/block and then have the beams sitting on top. An engineer would not call that a stable foundation.

I do agree, I have all sides of the structure sketched out to scale, window and door placement, heights and roof pitch but my struggle is knowing how to put it together, but thankfully between everyone here and the internet I can have a solid plan by the time I start cutting lumber.

Yea its definitely a narrow deck, mainly just something to keep the rain off your back and sit, but I know what you mean. I’m glad you brought up the beams being exposed to the rain, slipped my mind, so yep that’s out and I’ll build the deck after the fact. It rains nearly every day.

I’m starting to follow what you and Don_P mean about the foundation. Thanks for the image tip!

Offline miller9091

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #10 on: July 13, 2020, 10:40:10 AM »
A shot of the property.


Offline miller9091

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #11 on: July 13, 2020, 11:07:26 AM »
I took a look at your photos, yup, we're on the same page. Those foundations appear in the forensics shots after a high wind or seismic event overturned, building dropped off of some or all of the piers. They have low lateral resistance. Sort of like parking a car on the dining room table, it'll work as long as nothing bumps the table.

I was working in a furniture shop years ago. One of the suits came down out of the office "We have a question from a potential client, they want to put some heavy office printers on our rolling TV carts and be able to roll them around through their offices, they can't collapse if they bump something" The guys in the office were slide ruling out the design. Which is fine. I grabbed one of the guys that weighed about the same as the printer, sat him up top of the piece of furniture and we went for a bumpy breakneck stroll through the plant. That was the easy way with something I didn't mind real world testing to failure. I've tried to allow others to perform those kinds of experiments at house scale and learn from their examples

I quickly googled this "pier foundation overturning after hawaii earthquake".
This looks like one good return, I see some of the pics that made the rounds in trade pubs after the event;
https://seagrant.soest.hawaii.edu/wp-content/uploads/2018/05/2009-Post-and-Pier-Structural-Seismic-Retrofits.pdf

That was a seismic event but wind has the same lateral concerns. Its just another way of bumping that table. On the bad day when you need to run for shelter you don't want to have to run from your shelter. It is hard to think in that way when swinging a hammer on a beautiful sunny day.

I believe a stronger way to build this is to use post frame construction methods, that lets the wall sheathing, a large bracing area, do the lions share of the work.

Read the lumber stamps or take a pic of some of them at your home depot. Each species and grade carries different strengths. I imagine you are in a high insect problem place, I'd think about using borate treated wood throughout, that is probably an option at the big box.



Don_P I love the example of the car on the dining room table and I think I get it.. In order to prevent lateral forces from pushing the house off its foundation I need to attach the 6x6 post to the girders and floor (as you mentioned), creating a Y, like this?



Good info in the link!


Post Frame Construction methods? I’ll google it and get back to you.

You mentioned in your first post about blocking along all three girders, not just in the middle, is that typical practice or just a good measure? I want the structure to last but I'm trying to avoid any overkill while building but obviously I'm a novice so my mind is open to either scenario.

Offline Don_P

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #12 on: July 13, 2020, 04:52:33 PM »
What the building code says is block or restrain wherever you cross a support. What is going on there is the joists under load want to lay over right there over the support.  A rim joist across the joist ends will accomplish the same thing out on the ends.

You'll notice in that article repeatedly they mention that poorly attached braces won't do the job and the need for shear walls on at least sections of the foundation.

This is some sketches I had uploaded of the type of construction I was talking about. The posts run full height so the wall sheathing above provides a good bit of post bracing... it still wouldn't hurt a thing to do the shear wall bracing below that the article talked about but this does get rid of that hinge at the top of the short post to beam joint.





A masonry foundation with braced corners;


For roof beam and truss connection, one thought;


Hmm, image linky doesn't seem to be working, try this;
http://timbertoolbox.com/sketches/1624barn.jpg

http://timbertoolbox.com/sketches/16x24postframe.jpg

http://timbertoolbox.com/sketches/pierwalls.jpg

http://timbertoolbox.com/sketches/posttruss.jpg
« Last Edit: July 14, 2020, 03:19:23 AM by Don_P »

Offline Dave Sparks

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #13 on: July 26, 2020, 01:16:11 PM »
 The clearing of brush is alot of work but since you are early into this, I would say to avoid using the roof for solar. Too much chance for weakening the roof from water penetration.

The truth is that I have never advised any of the 300+ homes I have consulted on for a power system to use the roof. You may be tempted to but I would look at building a mount system attached to an outside wall on the building. Use it for shade or? and ground everything really well. If you have really bad lightning on your island, use a wired disconnect that you can unplug for 8 feet or more. Use SPD's (surge protective devices) on any wiring coming into the place where the power system will live.

Where is the power system in your plans?

Mountain Don has a story here on the forum about his strike. Might want to read that one. I have too many stories and they never end well. It is funny to me as I have some folks who never want to ever lose power! I have some who just say I will worry about that later and use candles if I need to. They may be lighting candles after Douglas lands in Hawaii.

Good Luck!

« Last Edit: July 26, 2020, 01:30:18 PM by Dave Sparks »
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Offline MountainDon

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #14 on: July 27, 2020, 08:56:31 AM »
The only time solar panels on a roof make sense to me is when there is no usable yardspace as in my city-sunburban neighbors properties. The houses occupy most of the lot, shading on the ground spaces is terrible, etc.

Here in our mountains we mounted on a pole to keep the panels above the snow on the ground.

Lightning can be so destructive. If you are located where there is lots of lightning, plan for that. This week I have disconnected the feed from the panels (325 feet distant) from the charge controller input 4 times. After disconnecting and coiling the cable there is a 12 foot gap that lightning would have to jump to reach the house and the power gear.

Our lightning strike story of destruction is found here. (it is too bad that the images are no longer visible as hey were hosted on photobucket.) We had to replace almost everything that contained a circuit board with semi-conductors and that was plugged in. Somehow a $100 microwave survived. It was 6 years and 5 days ago.   

Last summer we had aniother strike while we were there.  [shocked]  The exterior special effects were grandBark flying off trees as we watched them get struck, instant flash-bang light and sound effects. We were disconnected then and the only damage was to an exterior GFCI receptacle. It ceased working. A simple repair.

We have several of the Midnite surge protectors.  I have had to replace the one at the solar array junction box so that shows it has been doing it's job.

After the first strike we did improve the surge capacity with better equipmemnt. When I installed the system the Midnite SPD's were not available.  After the first strike I also improved the grounding for the SPD's as well as installing a general lightning protection system of air terminals, heavy gauge grounding cables and deeply buried grounding/erathing plates and rods.

We still have burn marks visible on the eves on one end of the roof. Sort of a souvenir.

Take care.
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline Dave Sparks

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #15 on: July 27, 2020, 02:27:25 PM »
Good Post boss  ;)

Many do use the roof in the tropics because it is less land to clear as it gets you up high.  The buildings are often cement and water is not as big of a deal to seal out.
I still would use what I described earlier on an exterior wall. It is also easily expandable for more solar. Remember there are two kinds of people, those who want solar, and those who want more :P
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Offline JRR

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Re: 18 X 24 Island Bungalow in Tropics (Images)
« Reply #16 on: July 28, 2020, 08:09:18 AM »
I've never had occasion to do a post and beam, but if I did I would follow a scheme similar to what is shown in Don P's first link ... posts running from foundation to roof, avoiding the pivoting hinge of the short-post "platform" style.   More the "balloon" style frame scheme.   If the post are not solid cross section, but are assembled of two or more overlapped vertical pieces ... having them "grow" (with the construction) to any height seems a good plan to me.  I would treat the interior posts the same way.

 

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