Author Topic: Aquaponics greenhouse retrofit?  (Read 880 times)

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Offline mvk

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Aquaponics greenhouse retrofit?
« on: March 18, 2019, 02:35:19 PM »
Hi all
Haven't been around since 2013, my last plans to get out in the country fell apart. :(

Would like to hear whats wrong with this:

My friend has a 96' x 26' Rimol high tunnel greenhouse with an Aquaponics system in it. He has a wood pellet boiler for the water (4,500 gal but 6,500 gal option)  and an oil fired boiler for the air. It was designed to be heated and it works well if you want to pay.  He doesn't have the winter markets so this year he tried to cut back on the heat and he wasn't very successful, none of the water tanks, filters, grow troughs are insulated. It's really pretty poorly designed as far as any idea/plan for saving energy. My wife and I work up there one morning a week for food.

He would like to let the system go dormant for a couple of winter months, so I told him I'd like to help. I'd like to know if I can put 2" of XPS and a metal roof on the North side. Rimol doesn't have an engineer so not much help. The greenhouse is rated for 35 lbs/sf  The added dead load will be about 2 lbs/sf. I'll add a link to Rimol below, the cover picture is a greenhouse like Tom has. The greenhouse has 2" D galvanized pipe hoops on 4' centers. I'd like to extend the roof and eliminate the curved section, extend the side walls till it picked up the roof line. I'd then attach battens 2by? on 16"- 24"? then the XPS foam and the roof. I'd support the ridge to the ground some how. That  rafter run once I eliminate the curve will be about 17' so I'm thinking maybe a another set of posts of some sort. about half way?

I'm not really sure about any of this from a technical side, how it will affect the original design? I'm a carpenter I understand wood so as long as I get the load to the ground I should be alright? I'm just thinking what am I missing!

We are insulating the tanks and working on air leaks. He dumps air out side on sunny days I'd like to collect it. I have some other ideas I'd like to kick around but maybe a separate thread later. 

Thanks again glad to see some familiar names, Mike

https://www.rimolgreenhouses.com/

Offline Don_P

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Re: Aquaponics greenhouse retrofit?
« Reply #1 on: March 18, 2019, 05:24:14 PM »
I don't know that particular brand but it doesn't look any different than typical, they start to collapse at 10-15 psf snow load so no do not add any additional load to one of those. If the axis is east west and you have a 96' long north side it was set up incorrectly, the ridge should be north-south so the sun arcs over the roof, is this not the case?

Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #2 on: March 19, 2019, 03:43:10 AM »
Thanks Don

Don
"I don't know that particular brand but it doesn't look any different than typical, they start to collapse at 10-15 psf snow load so no do not add any additional load to one of those."

It's pretty well built, probably had that much weight on it before, but that doesn't mean it wont collapse next time. Snow can accumulate but it usually slides off when it heats up. Would it if it was insulated, It's a about a 6th pitch, how much snow would stay on a metal roof at that pitch? 

Don
"If the axis is east west and you have a 96' long north side it was set up incorrectly, the ridge should be north-south so the sun arcs over the roof, is this not the case?"

Is that to get more sun? There is no time of year when the sun is past the ridge line. What time of year, we visited another grower with the orientation you speak of, the insulated end wall blocked a lot of light? We came away scratching our heads about that. Tom has a solar electric set up and runs lights also during the winter. The orientation of the farm also plays a part he has 5 hoop houses in all. I think this setup works best as a solar greenhouse with an insulated north wall?

Thanks Don, Mike



Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #3 on: March 19, 2019, 07:31:22 AM »
I'm going to try dropbox for photos



Mike


Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #4 on: March 19, 2019, 07:37:00 AM »
I'm lost, Help I have dropbox pictures I click the image button copy from dropbox and insert it, it shows up on the message but doesn't on the post after sending?

Thanks Mike

Offline ChugiakTinkerer

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Re: Aquaponics greenhouse retrofit?
« Reply #5 on: March 19, 2019, 10:06:49 AM »
Mike,

For now, you can just paste the URL for the image into the text of your message.  It will show up as a link that we can click on.
My cabin build thread: Alaskan remote 16x28 1.5 story

Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #6 on: March 19, 2019, 10:09:30 AM »
Try again





Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #7 on: March 19, 2019, 10:47:00 AM »
Hi Tinkerer
I can't find my URL? I emailed pictures from a phone to me. I then made JPG as someone told me. I then needed a host, my SIL told me I could use drop box, which didn't work for me. But when I bring up the photo in dropbox there is no url except if I select the item>share>make file, it copies the URL. I can insert this after using the image button but it disappears when posted.

Is there someway to put the picture somewhere to get the URL to copy?

I went thru this before, whenever, quiet a few folks got me on Photobucket and I had an album. Makes me feel dumb . 

Offline Don_P

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Re: Aquaponics greenhouse retrofit?
« Reply #8 on: March 19, 2019, 03:03:08 PM »
I can't help you with linking them but I got the properties and viewed them. It is similar to our high tunnel which we clear when it snows and keep a knife ready to slash plastic if the snow looks like it is going to get ahead of us and collapse it. I would not bear anything on that frame.

With the orientation the north side is not doing anything for solar gain and is contributing to heat loss. I understand your idea. I would be tempted to frame it as a lean to greenhouse by building a framed 3 sided room on the north side and supporting the ridge on that frame, removing the north half of the bents and use them for another similar greenhouse. The open, 4th side, is open to the south and has a series of posts and beams under the ridge to support its roof and the greenhouse ridge.

Some friends have one that is similar to that, the north wall is dug into the hillside and there are stacks of black cans full of water as a heat sink against that back wall, it works well. They've turned what would be a heat loss wall into a heat storage wall.

Now on the comment that he doesn't have the winter markets... he can't sell greens in winter when people are craving anything fresh and green? He's missing a market there somewhere, we have people wanting to jump to the head of the line. We aren't paying for heat, its just a high tunnel so it may be he cannot find a market that can support the overhead, I can sure appreciate that.

Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #9 on: March 19, 2019, 05:14:34 PM »
Thanks Don

Here's his place http://ledgetopfarm.com/ Google earth it if you'd like. I get so frustrated with the picture stuff.

 Were are you located? I haven't seen many snow problems, but not that much snow this year. It does build up along the north side where it slides off, so we pull some away. We had a real big heavy snow storm a few of years ago, I think it was up then it's been up 4 years.

As I said his house is pretty well built and he has it well braced, I've seen some that cut back there and seem pretty flimsy. Not that it means you could put a roof on it.

I'd love to do it all over from scratch....... from the first time I saw it.

Most of his sales are thru a couple of farmers market and some close down in winter. He does have a CSA. He doesn't really want to do restaurants. If he wants to keep the water 68-70 he gets greens in 5 weeks but yeah the overhead.

Thanks again Mike

Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #10 on: March 20, 2019, 10:03:27 AM »
Try again




Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #11 on: March 20, 2019, 10:23:04 AM »

Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #12 on: March 20, 2019, 10:44:13 AM »

Offline MountainDon

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Re: Aquaponics greenhouse retrofit?
« Reply #13 on: March 20, 2019, 12:49:49 PM »
Using the link posted in reply #11 for an example....

When I open that link in a new tab, I see the greenhouse image (plus other advert images).  In the top left there is a button labeled "Share".

Click on "Share" and a list of 8 choices is displayed.

You want to use the info in the line labeled "Hotlink for forums:". Click on the symbol/icon at the right end to copy the needed info.

Return to the compose message field in the countryplans.com forum.  Paste the copied text into the compose field.

Click the "post" button or the "Preview" button if you want to preview before committing the post.



Give that a try with the links in reply #12.  You should be able to open the message and edit it. If you are logged in, can you see the "Modify" button off to the right side, above the posted message, in alignment with your user ID?
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #14 on: March 22, 2019, 01:44:00 AM »
Thanks Don
I did it and then hit preview it worked, but I don't know where that reply went d*, must have missed a button ? So I'll post this without a preview to see if it works. 

Thanks Mike


Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #15 on: March 22, 2019, 03:49:19 AM »


Anyway this was more Tom's idea than mine. Even if we could seal off the air from getting into that big cavity, it looks like a mess to me. Tom thinks he could get two more years out of the poly cover but they get harder and harder to put on as time goes by. So he would like to reglaze with a double wall something (?) that will out live him. Insulating the north wall makes sense to me and doing it under a metal roof seems like the way to go. Some back of the envelope math looks like about $3 sf for the roof materials including 2"of XPS foam? I don't know what the double wall glazing will cost but it could cost that much I would think?

I could get the weight of the roof load to the ground with post's, though they will be in the way. And I can brace it to keep it from moving side ways.

There's no foundation it's set on pipe driven about 3' into the ground?  I'm worried about the whole thing lifting more than setting? Right now it's real stable, Does the shape of the greenhouse help hold it down? I know those arches are pretty strong. What will changing the shape of one side do? Even putting in piers might cost to much.

Could use some help thinking this through. This comes to mind

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

But then again not failed might be good enough :-\

Mike

Offline Don_P

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Re: Aquaponics greenhouse retrofit?
« Reply #16 on: March 22, 2019, 06:31:13 PM »
Nothing you are describing or what I'm seeing is any different than what we have here. I've been debating a ridgebeam and posts in ours. Maybe the metal there is heavier gauge  ???. We've been in 50mph winds today locally, I doubt the house has seen that but it was definitely pumping. In other winds, there was one down in the open valley that was torn up by the wind but it didn't try to uplift. Another friend's was stripped of plastic but the frame survived, again no uplift. That is probably also soil dependent.

Google twinwall polycarbonate.

Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #17 on: March 24, 2019, 05:44:12 AM »
Thanks again Don

"Maybe the metal there is heavier gauge  ???"

I don't know, I just got on Rimol? Love to see a big button that said Specs. when i opened someplace like that. I did a lot of fencing and it's standard pipe I think. Tough to drill.

Have you seen one that collapse from snow, wonder what fails and how? Does the piping bend?

Thinking about uplift I remember all the temporary fencing that I installed pretty hard to pull some of those posts

Mike

Offline Don_P

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Re: Aquaponics greenhouse retrofit?
« Reply #18 on: March 25, 2019, 02:34:13 AM »
I was trying to be optimistic but I suspect they are the same as ours. Yes the pipe bends, basically they "snap through". I asked around at a dinner last night, General consensus is that the sidewalls push outward enough for the top to drop in, which is standard failure mode for most arch type structures. All depending they can twist enough to give that snap though and collapse if the diagonal purlin bracing is insufficient, same result. I've seen 10 or 12 in the past few years. The "truss" in your roof is the same as ours, it isn't a truss.  That upper truss tie is a small member in bending mode rather than pure tension or compression, but below that there isn't that much structure anyway. These are under designed buildings to start with. To my way of thinking any additional load should be self supporting and hopefully would beef up the existing structure. Same here when I get rich and famous  :D

Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #19 on: March 25, 2019, 02:12:02 PM »
Hi Don

From Rimol: Bows are 1.90″, 13 ga. galvanized steel tubing This must be what he has, I thought it was 2" but never measured, the other spec I got was 1.66, 14 gauge. Now that I think about it I think what we called 2" post in fencing where 1 7/8"

I found your simple Beam calculator, can't find a place for this idea though :)

I was trying to be optimistic but I suspect they are the same as ours. Yes the pipe bends, basically they "snap through". I asked around at a dinner last night, General consensus is that the sidewalls push outward enough for the top to drop in, which is standard failure mode for most arch type structures. All depending they can twist enough to give that snap though and collapse if the diagonal purlin bracing is insufficient, same result. I've seen 10 or 12 in the past few years. The "truss" in your roof is the same as ours, it isn't a truss.  That upper truss tie is a small member in bending mode rather than pure tension or compression, but below that there isn't that much structure anyway. These are under designed buildings to start with. To my way of thinking any additional load should be self supporting and hopefully would beef up the existing structure. Same here when I get rich and famous  :D

Yes I noticed that all the bracing is for wind I guess but it's not a real truss.

Don "To my way of thinking any additional load should be self supporting and hopefully would beef up the existing structure."

That's what I think and want to do. How to do it. What I'd like to do is attach 2x4 on the flat on top of the ribs on the north side, I'd run them out passed the curve. They would end plumb at a wall attached to the vertical section of the rib, along the north side. I'd then like to apply the @' XPS foam. I would then like to run 2x4 nailers perpendicular on whatever the recommended spacing for metal roofs. The reason I want to do it on the flat is ease of construction, and a larger surface to bear on the frame and also against the foam when the nailers are screwed to the frame.

So what about this sandwich idea, if I look at this separate, assume it's supported to the ground, I thought I could cut PVC spacers, drive them through the foam and screw or bolt through them if compression of the foam was a problem. I'd rather not do that though.  The hoops are on 4' centers, so I'm going to span the 4' between the the hoops with 2x4. I just grabbed a piece and set it up on some blocks, had a 4'8" span, I'm 190 and it hardly deflected at all. I'll need two rows of posts at least, I'm hoping to do every other frame member. I'm limited in the post spacing by the existing grow troughs so that is a factor.  From the north sidewall I have a 5' span to a header, then 6' to another header, it's another 1' to the ridge. Pretty small spans.

I think the length of the post in the center is a big problem they will be about 13' long  ??? I'd like to use 4x4's ?Strong back and x bracing, and 45 degree knee braces? I could pick up some weight off the south side of the frame with a knee brace?

It's getting pretty expensive. I'm also adding a bit of shading.

Something else you might know about, when Tom told me about his plans I thought he had researched the poly carbonate? Do they have curved pieces, I tried to call Rimol today but the number on the web site isn't in service? ??? Maybe after my first call I'm blocked?

I'm kind of building a carport under half of a green house, will it work?

Thanks Mike





 

 

Offline Don_P

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Re: Aquaponics greenhouse retrofit?
« Reply #20 on: March 25, 2019, 05:55:08 PM »
I think you're probably fighting an uphill battle. Putting it outside makes replacing plastic difficult and is also requiring some way of draft sealing the insulation to the envelope, if outdoor air gets between the foam and the interior then the foam isn't helping, with it outdoors I think that would be a tough sealing job. By the time you've done that work on a marginal house I think you'll wish you had simply built a better house from scratch.

The snow loads I'm seeing in the codebook up there range from 50-90 psf and a large swath of CS, case study, local higher loads. If that is the case a ridgebeam 8' between posts needs to be a triple 2x10. 13' rafters @ 2' oc would be 2x12's... getting out of hand quickly.

Let's back up, are you running double layer inflated plastic outside? You can add another layer inside under the truss as well. Polycarbonate at 8mm has a minimum bending radius of about 4' and needs a purlin every 40" at that snow load, I don't think that'll work.

Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #21 on: March 26, 2019, 02:17:38 AM »
Hi Don thanks for all the effort, I really appreciate it. I should have a drawing, I'm not sure we are on the same page.

The plastic on the north side will be gone, so it wont be replaced As far as sealing the foam it will all be attached to lumber on all exterior edges, all the foam joints will be on wood nailers also, we could tape all the seams. Tom will hire out the labor to do this, I'd like to come up with an easy straight forward way of doing it.

Don "The snow loads I'm seeing in the codebook up there range from 50-90 psf and a large swath of CS, case study, local higher loads. If that is the case a ridgebeam 8' between posts needs to be a triple 2x10. 13' rafters @ 2' oc would be 2x12's... getting out of hand quickly."

50-90 psf = 2.5-4.5' of snow, that's possible though unlikely. It went through a big wet early snow it's first year, put out power all over. Tom would rake between snows, it's only R 10 so it should melt and slide off the metal pretty quick or be easy to rake? I guess I'm looking at it wrong and that's why I came here, as I first said keep me from getting too dumb. I'm thinking well I have an insufficient structure so I'll add two bearing walls to it. I'm thinking more along the idea of a header for a 8' sliding door  on a ranch house? Knee braces would pick up some of the weight from the 8' span I think? I do think it will add to the strength of the existing greenhouse but I'm probably wrong.

I wish I could just do all the math myself. Years ago there was a book in the Manchester Library that did that, it's out of print and I don't even know the name. I remember thinking it's gone to get stolen and it was. I would have loved to find some kind of class for this. Is there one on line? I bet I told that story here, maybe more than once :)

About the poly carbonate, as I said he told me what he wanted to do and asked if I could help with the roof, I assumed he had found something that worked, and didn't think anymore about it till I needed to know how to end it at the ridge and tie it to the roof. He could continue to use double poly on the south install wiggle wire channel at the peak?

My wife and I will be working at the greenhouse this morning I'll look at again, don't think it's changed any though :) . We work for food, that's how this all started. If he wants to pay for the heat to keep that aquaponics water at 68-70 it's great, but he doesn't have the markets in the winter so he can't afford it. The whole place was built with the assumption it would pay for the heat, He had a partner, but he moved so Tom is running it alone.

Thanks again
Mike




Offline Don_P

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Re: Aquaponics greenhouse retrofit?
« Reply #22 on: March 26, 2019, 04:08:08 AM »
It's generally not a good idea to count on knee braces for taking gravity load, as one engineering professor noted, most knee braces, as installed, are simply something else to hit you in the head as the structure collapses. In other words most folks don't install them very well. When they are well installed and do take load, the post needs to be designed for that bending force. Which gets into your other question. There are a number of online sources of instruction, I've seen you tubes on various topics as well as websites with info. Another good description on simple beam design is in Wood Structural Design Data at awc.org. They are the folks who create the span tables and much of the wood portions of the building code. My online calcs were written using equations from their beam design equations publication and several other texts that are code referenced. For your design snow load it would be best to check with the local building department.

Offline mvk

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Re: Aquaponics greenhouse retrofit?
« Reply #23 on: March 27, 2019, 03:35:46 AM »
Thanks again Don

It's generally not a good idea to count on knee braces for taking gravity load, as one engineering professor noted, most knee braces, as installed, are simply something else to hit you in the head as the structure collapses. In other words most folks don't install them very well. When they are well installed and do take load, the post needs to be designed for that bending force. Which gets into your other question. There are a number of online sources of instruction, I've seen you tubes on various topics as well as websites with info. Another good description on simple beam design is in Wood Structural Design Data at awc.org. They are the folks who create the span tables and much of the wood portions of the building code. My online calcs were written using equations from their beam design equations publication and several other texts that are code referenced. For your design snow load it would be best to check with the local building department.
[/quote]

Are you an engineer, or are you just interested? Basic-Design-Issues-in-Timber-Frame-Engineering.pdf, I found this I'm not so good at the links.
There are a couple of pdf's and they do a good job of explaining the forces. Your point about knee braces,  It was really enlightening, it explains why posts are so big. The second pdf speaks to asymmetrical loading, that was what I was worried about and lead me back to this site.

I think this approach to insulating the greenhouse idea is over for a couple of reasons. I asked him will you need a permit, no it's not a "permanent building" what about the metal roof I asked. Well you can unscrew it he says!. ??? Also the poly carbonate, he showed me what he had in mind, it's about 3/8" thick and comes in 4x8 sheets, it's not very rigid. I was thinking of something else, and as I said I thought it came as some kind of option from the manufacturer.

Thanks again Mike


Offline Don_P

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Re: Aquaponics greenhouse retrofit?
« Reply #24 on: March 27, 2019, 04:56:40 PM »
I think that is probably a wise plan, these buildings are kind of what they are. You would more than likely not recover whatever is spent trying to improve it. We are getting ready to do some work on ours... I can only call it a hobby with what we'll spend vs what it will recover.

That TF Guild pdf is a good overview on how to think about designing a building structurally. It doesn't get down into the weeds but does explain the thought processes and reasons pretty well. I'm a carpenter not an engineer, I guess the license says Class A Contractor - Residential, Commercial. I also have a sawmill and have built a number of log and timber buildings, sometimes starting in the forest. All of that led to reading and taking short courses in basic engineering and grading. Since those materials are outside of typical tables I went back to the sources and created those beam and column calculators for the materials I use. Pre computer it could take me all evening to do the math to size a beam, I wanted to be able to play "what if" quickly. Others were interested so I put them online. Generally they use design values and equations from, or referenced by, the NDS, the National Design Standard for Wood Construction, a code referenced resource.

Anyway, good luck on the farm, spring is beginning and those ideas can mull till another winter. Although stuff made it through the winter in the high tunnel I think more has been harvested from under lights in the living room, 1 lb of lettuce yesterday  :D

 

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