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Discussion Starter · #1 ·
Hi everyone, I'm trying to build a small shack on stilts.
I found a spot - ground is kinda loose and dump cos its located close to marshes/swamp

I wanted to build it on a ground but I couldn't make up my mind as to how big it's suppose to be or how to position it and then it hit me that it would look awesome if it was on stilts(pillars?)

So i want it to be 8x4m platform (2 x 4x4m) with 7x4 building and 1x4 balcony
building with a 1side sloped roof
2m20cm high in lower (back) part of the roof and however necessary higher on the other side
I'd like to have the floor level at 2m so that a normal sized human could walk underneath without hitting his head on the joists
(building is in europe and no planning is needed - i just need help with measurements - I've been looking at different stilts houses plans and I can't figure out how deep and how should i bury the stilts
and how many of them should i use
and how thick do they have to be

at first I thought about 40cm logs in every corner of the 4x4 platform so 6 logs in general but I'm not sure if its gonna hold or if I need any cross support system (no clue what the official term is - X like wooden planks holding stilts together)

below are the pictures of a SketchUp plan I made

https://postimg.cc/qtrJJ3L0 - stilts + joists

stilts 2m above ground lvl - not sure how much should go into the ground - is it 1m or more?
how big should i make the hole? 20cm wider / more or less
gravel on the bottom + concrete on the sides?

shack with window and door frames - the position of the rooms and the shack itself might change cos I'm still not sure what i want in it but its probably gonna be just couches, table and a stove

https://postimg.cc/T5jwqJQk
https://postimg.cc/pyKpHPxD

I'd appreciate any help with this, it's my first build ever
 

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Unless your vertical members are sunk into the ground, put struts between the vertical & horizontal members to make triangles, which cannot change shape.

How big a triangle depends on wind force & many other variables.
 

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Discussion Starter · #3 ·
Unless your vertical members are sunk into the ground, put struts between the vertical & horizontal members to make triangles, which cannot change shape.

How big a triangle depends on wind force & many other variables.
I want the stilts in the ground but im just not sure how much of them should i bury

should i get a 3m stilts with 1m underground and concrete around it at the base or should i use more then 1m?

and what about the width of the stilts - should they be 40cm in diameter if i want to use only 1 in each corner of the floor


the shack will be in the forest-ish with trees all around it - not much wind in there
 

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A civil or mechanical engineer might chime in.
(building is in europe and no planning is needed
There's a risk here of personal injury.
I might build such a thing for myself but I'd never have visitors in it.
 

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Discussion Starter · #5 ·
A civil or mechanical engineer might chime in.

There's a risk here of personal injury.
I might build such a thing for myself but I'd never have visitors in it.
that's why i wanna build it more sturdy and make sure it doesnt fall down - if it comes to that ill have to hire someone, it is a build for fun but i dont want it breaking down any time soon
 

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Civil or mech engineer or double up everything, triangles everywhere. Will not be pretty but will probably work.
 

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Civil or mech engineer or double up everything, triangles everywhere.
Even in our bridge design section, the motto "When in doubt, make it stout" is something we follow. Granted, we're not in doubt as much as most people, but still...

Anyway, the triangles are good advice. For something small, the buckling capacity of the posts and diagonal struts will be the limit to be concerned about.

If you're not getting an engineered design, I would suggest running the diagonals from the bottom of posts (ground line or top of pedestal, etc.) at no steeper than a 45 degree angle (if the post is 2m tall, go at least 2m horizontal to attach to a beam, or go all the way to the next post), making it a full "truss" system, and size the wood timbers to maintain a length to nominal width/thickness ratio of 12 or less (if the diagonal will be 2.4m long, it should be at least 20cm in each dimension).
 

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Discussion Starter · #10 ·
Even in our bridge design section, the motto "When in doubt, make it stout" is something we follow. Granted, we're not in doubt as much as most people, but still...

Anyway, the triangles are good advice. For something small, the buckling capacity of the posts and diagonal struts will be the limit to be concerned about.

If you're not getting an engineered design, I would suggest running the diagonals from the bottom of posts (ground line or top of pedestal, etc.) at no steeper than a 45 degree angle (if the post is 2m tall, go at least 2m horizontal to attach to a beam, or go all the way to the next post), making it a full "truss" system, and size the wood timbers to maintain a length to nominal width/thickness ratio of 12 or less (if the diagonal will be 2.4m long, it should be at least 20cm in each dimension).
thanks a lot for the advice - I've been looking around the internet for already built shacks/houses on stilts for reference and i found this one
https://postimg.cc/NLmHFRsp - but i think they only got stilts because of the slab underneath right? or is it because of those big planks on the side of the stilts right under the floor of the house?

i just want to have the least amount of diagonal posts holding the stilts - or if possible none - i can even double the amount of stilts if that's gonna solve the issue

but the house in the picture is just a bigger version of what i want - except mine is gonna be a shack to hang out and not a place to live 365/year

if it's not possible to have stilts without the slab - i could settle for something like this https://postimg.cc/Zv8BQz71


but since i want it to have an old look and its close to a sort of a swamp - this would be the best look https://postimg.cc/YGgh4wHh and they didnt use any diagonals either

https://postimg.cc/V0qgWTjN - there is no diagonal planks here either but it looks like they have a solid foundation - i do want the stilts to be as tough as possible so i could pour a slab under the house and then put some dirt on it to make it look more natural/wild

or would it be possible to pour concrete around the part of the stilts underground - to make sure that they wont move around at all? - how much concrete would i need - and should i use rebar in it?
 

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i just want to have the least amount of diagonal posts holding the stilts - or if possible none - i can even double the amount of stilts if that's gonna solve the issue
Well, if you don't have diagonals, the posts have to resist the lateral forces in bending, which means they have to be buried in the ground deep enough, or with large enough concrete piers, to hold the building in place when the wind blows. The posts themselves also have to be strong enough not to bend excessively or break. I can't help you with that type of foundation and support structure. I have my doubts about you being able to accomplish that economically since the "ground is kinda loose and dump cos its located close to marshes/swamp", which means large and deep piers. If you go that way, you should get a local engineer to design it. You'll probably suffer from major sticker shock when you see the price for a foundation without diagonals, though.
 

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Discussion Starter · #12 ·
Well, if you don't have diagonals, the posts have to resist the lateral forces in bending, which means they have to be buried in the ground deep enough, or with large enough concrete piers, to hold the building in place when the wind blows. The posts themselves also have to be strong enough not to bend excessively or break. I can't help you with that type of foundation and support structure. I have my doubts about you being able to accomplish that economically since the "ground is kinda loose and dump cos its located close to marshes/swamp", which means large and deep piers. If you go that way, you should get a local engineer to design it. You'll probably suffer from major sticker shock when you see the price for a foundation without diagonals, though.
that's a bummer - so something like this is my best option? https://postimg.cc/Zv8BQz71
what about the stilts in this set up - would it be 1m deep anyway + concrete pour around it with 30-40 cm logs as stilts?
 

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that's a bummer - so something like this is my best option? https://postimg.cc/Zv8BQz71
what about the stilts in this set up - would it be 1m deep anyway + concrete pour around it with 30-40 cm logs as stilts?
Yeah, something like what's shown, except you likely need bracing in the other direction in at least one bay.

If you have bracing, the foundations don't have to resist bending, just the weight and lateral thrust, so you could attach the posts with brackets on top of the piers.

I don't know what length of your members will be, so I'll refer you back to my earlier suggestion of L/D not greater than 12.
 
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