poly on a slope

[binley100]

Quick question. Our poly will have to go on a slope... only a gentle slope from end to end. Any tips or advice please on putting in the anchor plates.

[Aberdeenplotter]

In my last plot, my tunnel was on a one in ten slope but it sloped not just from south to north downwards but also from east down to west. Sounds an odd combination but I just followed the ground contours and it worked ok. I used ground anchor plates as well and just dug them in down to the hard before back filling.

[Glutton4...]

I would imagine that providing you erect it as the appropriate angle to the ground, it shouldn't be a problem. However, if you want the roof-line to be horizontal, then I guess you'll have to build up the lower end. Not that I actually have any idea what I'm talking about, I'm just guessing they're far easier than a rigid-built thing like a greenhouse.

[Bill HH]

If it was me I would dig into the high ground and make it level, If any construction leans it puts stress on the framework. Building up the low end is not really as satisfactory as digging out the high end.

[binley100]

'tis only a gentle slope Bill ..in the pic it's on the LH side ..

[Martin H]

That should make the levelling easier anyway

[Alison]

I laid mine to the line of the land, less work in the first place and it also has the really handy advantage that I can gravitate water from one end to the other which has really helped with my autowatering system. My slope is pretty similar to yours too and the only levelling we did was to remove a bit of a hump in the middle.

[Bill HH]

[ATTACH=CONFIG]42961[/ATTACH]'tis only a gentle slope Bill ..in the pic it's on the LH side ..

SO less digging, any construction built with a slope is (a) liable to eventualy fall down (b) looks orrible.

Get it level you will not regret the extra bit of effort.

[Alison]

SO less digging, any construction built with a slope is (a) liable to eventualy fall down (b) looks orrible.

a) every structure is liable to fall down eventually but a slight slope for a polytunnel will not affect it's integrity and make it happen any sooner, you still put the hoops vertically so the structure doesn't think it's on a slope anyway so it's load path is still vertical with no induced eccentricities.

b) no it doesn't, if it fits with the lie of the land then it blends much better so actually stands out less

[Bill HH]

a) every structure is liable to fall down eventually but a slight slope for a polytunnel will not affect it's integrity and make it happen any sooner, you still put the hoops vertically so the structure doesn't think it's on a slope anyway so it's load path is still vertical with no induced eccentricities.

b) no it doesn't, if it fits with the lie of the land then it blends much better so actually stands out less

I have to disagree Allison, apart from it will eventualy fall down, whereas i should have said it will eventualy fall down quicker than it would have done.
How can you put the hoops vertical to a structure that is leaning? Gravity is pulling down verticaly against hoops that are not vertical to the ground. The load is not running through the hoop into the ground but pulling the top of the hoop downwards.

As for looking orrible, I have an engineers eye and find anything not square or not vertical when it should be to be offensive to my eye. Why do you never see houses built following the lie of the land any architect will tell you its because the loads do not travel into the base footings and is an inherent weakness. Also your gin and tonic could well overflow the sides of the glass.
Bearing in mind this is only a minor slope I cannot beleive anyone contemplating not doing the job properley.

[Alison]

I have to disagree Allison, apart from it will eventualy fall down, whereas i should have said it will eventualy fall down quicker than it would have done.
How can you put the hoops vertical to a structure that is leaning? Gravity is pulling down verticaly against hoops that are not vertical to the ground. The load is not running through the hoop into the ground but pulling the top of the hoop downwards.

As for looking orrible, I have an engineers eye and find anything not square or not vertical when it should be to be offensive to my eye. Why do you never see houses built following the lie of the land any architect will tell you its because the loads do not travel into the base footings and is an inherent weakness. Also your gin and tonic could well overflow the sides of the glass.
Bearing in mind this is only a minor slope I cannot beleive anyone contemplating not doing the job properley.

You may have an engineers eye but I am an engineer . If I had the time I'd do a full load path diagram to demonstrate it's not a problem to show to the original poster that they've no need to worry structurally. My structure doesn't lean, the hoops are indeed vertical, I spent a lot of time ensuring this. As it goes down the slope the level the base plate was founded at goes down relative to the previous one on a constant grade and the base rails match this gradient hence it slopes rather than leaning. This could be a problem if we were looking at a steep gradient but we're not.

Aesthetics is a different issue and personal to the individual. I think it looks better blending into the land, you prefer to regrade locally. Both can be acceptable in the same way that I prefer Thai food over Chinese, doesn't mean that Chinese food shouldn't be available


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[Alison]

Oh and slight rant time, architects don't design buildings, they come up with concepts, structural engineers design buildings. This is so often misquoted and really annoys me.


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[Mikey]

Oh and slight rant time, architects don't design buildings, they come up with concepts, structural engineers design buildings. This is so often misquoted and really annoys me.


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Not wanting to start a heated debate here, but I would say its a bit like baking a cake its no good using one ingredient. There are good and bad exponents of design in both professions I'm very fond of Santiago Calatrava's work he's a remarkable architect and structural engineer, and proof that when both work in unison you can create something of remarkable beauty.

[Bill HH]

You may have an engineers eye but I am an engineer . If I had the time I'd do a full load path diagram to demonstrate it's not a problem to show to the original poster that they've no need to worry structurally. My structure doesn't lean, the hoops are indeed vertical, I spent a lot of time ensuring this. As it goes down the slope the level the base plate was founded at goes down relative to the previous one on a constant grade and the base rails match this gradient hence it slopes rather than leaning. This could be a problem if we were looking at a steep gradient but we're not.

Aesthetics is a different issue and personal to the individual. I think it looks better blending into the land, you prefer to regrade locally. Both can be acceptable in the same way that I prefer Thai food over Chinese, doesn't mean that Chinese food shouldn't be available


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So you are proposing having the hoops vertical to the ground but stepping down the grade, in which case you are correct the load will be placed correctly onto the hoops, but assuming the poly has side rails and a top rail which are made to fit a level construction then none of them will line up. attempting to line up the pre drilled holes will pull the construction back into square. The only way this can work without leveling the ground is if the hoops lean to accomodate the slope or new side rails are made, in which case it would be easier to just level the ground first..


I dont have much confidence in structual engineers I used to do a lot of welding for builders and on several occasions pointed out massive howlers in the structural engineers advice.

[Bill HH]

Not wanting to start a heated debate here, but I would say its a bit like baking a cake its no good using one ingredient. There are good and bad exponents of design in both professions I'm very fond of Santiago Calatrava's work he's a remarkable architect and structural engineer, and proof that when both work in unison you can create something of remarkable beauty.

No heated debate here Mikey I am British.