# Wood greenhouse framing



## OttoW (Feb 13, 2016)

I'm planning a 6'x6' with 24" spacing greenhouse build. 

I don't care for the kits available in my price range so I would like to build it myself. 

I would like to use either redwood or cedar but the cost might force me to use treated lumber. 

Here lies the problem treated wood around here is very wet, dripping when cutting or screwing into it. I'm afraid if I build it wet the 24" spacing it won't be enough to keep its shape and it will twist like crazy. I may be up for some drying time but I'm not sure how long it might take or how to prevent it from twisting as it dries. 

Is there a way I can dry it and keep its shape? Perhaps screw them together with a spacer between for air circulation?

Forget drying and build with 16" spacing and hope for the best? Or keep it at 24" and use scraps for support to keep them in place?


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## Ghidrah (Oct 21, 2008)

Consider using the PT for the deck frame only, everything above the joists go with 2X spruce framing.


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## Cherryville Chuck (Sep 28, 2010)

I agree with Ron. There are local wood frame greenhouses that are built with just conventional SPF lumber and they've been standing for years. The inside of the greenhouse will be humid but it shouldn't get wet enough for a long enough period that it will cause rot.


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## DaninVan (Jan 1, 2012)

Otto; I built my 9X15 glass panelled greenhouse out of PT lumber. I think it's about 8 years old now; no sign of algae or rot...but I do wash the interior down with TSP/bleach solution at least once a year to kill spores and insects. This is essential greenhouse practise!
I treated *every cut with Copper Napthanate*, after having air dried all the lumber under cover for a number of months. My thinking was I was only going to do it ONCE! I've had to tear down too many sheds, greenhouses and garages for clients that hadn't maintained them, over the years.
Whatever size you make it it'll never be big enough... (I wish mine was at least 30' long. *sigh*)

The vertical stud/posts and roof rafters are about 30"+/- o/c to accept the tempered glass patio door panels (single glazed 'cause I'm cheap). The tempered glass roof is about 45 deg. so snow won't pile up...not that it's snowed much in the last couple of years. But if snow's an issue where you are, you might want more rafter support under your glass.


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## OttoW (Feb 13, 2016)

DaninVan said:


> Otto; I built my 9X15 glass panelled greenhouse out of PT lumber. I think it's about 8 years old now; no sign of algae or rot...but I do wash the interior down with TSP/bleach solution at least once a year to kill spores and insects. This is essential greenhouse practise!
> I treated *every cut with Copper Napthanate*, after having air dried all the lumber under cover for a number of months. My thinking was I was only going to do it ONCE! I've had to tear down too many sheds, greenhouses and garages for clients that hadn't maintained them, over the years.
> Whatever size you make it it'll never be big enough... (I wish mine was at least 30' long. *sigh*)
> 
> The vertical stud/posts and roof rafters are about 30"+/- o/c to accept the tempered glass patio door panels (single glazed 'cause I'm cheap). The tempered glass roof is about 45 deg. so snow won't pile up...not that it's snowed much in the last couple of years. But if snow's an issue where you are, you might want more rafter support under your glass.


That is a nice garden area. Have you had any problems with the PT dripping on your plants? It sounds like you didn't seal the lumber with any paint or stain. 

I originally designed the greenhouse to be 8x6 but scaled it back to 6x6 for cost and I'm not sure how much my wife will use it, though I should think about going back to an 8x6 before I finalize the plans. If I use 2x4x12' I should be able to utilize 90% of the lumber with only 16 (? I think that was the count) boards. 

Picture of the design at the moment. 









I'm planning on wrapping it in clear polycarbonate roofing panels. Hopefully I can get by using 14 of the 26"x6' sheets.


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## OttoW (Feb 13, 2016)

Cherryville Chuck said:


> I agree with Ron. There are local wood frame greenhouses that are built with just conventional SPF lumber and they've been standing for years. The inside of the greenhouse will be humid but it shouldn't get wet enough for a long enough period that it will cause rot.


What would be your opinion on sealing the wood with a stain or paint of some sort? 

I've been wondering about my local SPF lumber and using a decking water seal to help minimize the abuse the wood may take.


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## DaninVan (Jan 1, 2012)

Otto; yes, I did refresh the surface with a coat of exterior semi-transparent stain after a couple of years. Again mostly for aesthetics and disease control in the greenhouse. Never had any issue with any PT dripping; it's locked in. Let's not forget that the bad old Arsenic issue is a thing of the past. I'm more concerned with breathing in fungal spores than I am with the PT solution. I try to do a thorough cleaning/sterilizing inside at least once if not twice a year. Takes longer to move all the growing benches etc. in and out than it does to actually do the cleaning.


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## DaninVan (Jan 1, 2012)

On the off chance that someone might think I've been partaking of the largest local cash crop...
https://www.emlab.com/s/sampling/env-report-03-2012.html
B.C. scientists to help American researchers study deadly fungus - Nanaimo News Bulletin
And that would be why, at least in part, I'm obsessive about spores in the greenhouse.


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## Ghidrah (Oct 21, 2008)

If all or most of your glass is facing south your problem will be keeping moisture in the room not removing it. For what its worth, most framing grade PT lumber is warranted for something like 20(+/-) yrs on the ground, prop it on blocks an add yrs to it, maybe decade. The older ACC and the current ACQ lumber treatment, (our area) outside of ACQ eating all fasteners not SST, weighing much more than ACC and having a sort of waxy coating I never got any drippage out of them. 

Whatever dripping you may see is probably more likely from rain or snow in your area and or from the area the mills and treatment plants are located. When we were building condos we had a lumber holding area within the development, we got tractor/trailers coming in directly from the mills up north, (usually Maine, Hampster and Canada) much of it frozen, still laden with snow and or rain in late March. Its been a long time since I read up on it, (80s) the problem with PT lumber is off gassing via heat within the 1st yr. On the ground it was something like 17% of the ACC could leach from the lumber into the soil within 2 yrs, so don't use it within enclosed areas or for vegetable gardens.


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## Cherryville Chuck (Sep 28, 2010)

Otto I think most around here are just painted white. PT lumber should also be painted or stained according to info from the company I bought some decking from for a deck I put in in northern Alberta. I didn't get to it the first two years after I put it in and by the third year it was starting to weather pretty good.


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## JFPNCM (Dec 13, 2009)

If you can find it you might consider Yellawood as tomp913 used for his turtles (see Turtle redux post). If you do use PT lumber be certain to use the appropriately rated nails and screws. 

Personally I would use PT for the base frame that contacts the ground and then standard or better for the walls etc with the latter being painted with high quality rain sealer similar to that used for decks.


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## OttoW (Feb 13, 2016)

JFPNCM said:


> If you can find it you might consider Yellawood as tomp913 used for his turtles (see Turtle redux post). If you do use PT lumber be certain to use the appropriately rated nails and screws.
> 
> Personally I would use PT for the base frame that contacts the ground and then standard or better for the walls etc with the latter being painted with high quality rain sealer similar to that used for decks.


I've come across KDAT before in my reading but since I wasn't looking for it I didn't really pay much attention. Reading up on it more it looks like it would be very beneficial to some of my projects.... However searching for a local source I'm coming up empty . 

There are several distribution centers in my area and it looks like at least one of them offers KDAT lumber but I am not seeing a local retailer. In the past I have purchased my wood at the big box stores, I guess it's time to visit a builder supply yards. Last year I had one of them provide a quote for my shed build but they came in a lot higher than HD, I'm sure it was better lumber but I just couldn't pencil in the extra $ specially for my first build. Plus the larger commercial yards aren't very friendly to the small homeowners wanting to buy in smaller quantities. Ugh.


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## bwilling (Jul 14, 2015)

I built this green house with PT wood and grooved siding with corrugated fiberglass panels from Menards. No problem, The GH is 9 X 9. Not sure why the pictures are up side down?


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## OttoW (Feb 13, 2016)

bwilling said:


> I built this green house with PT wood and grooved siding with corrugated fiberglass panels from Menards. No problem, The GH is 9 X 9. Not sure why the pictures are up side down?


Did you build the whole frame in PT or just the walls? 

What made you choose fiberglass over polycarbonate?

What kind of flooring did you go with?

I was thinking of building the greenhouse on a bed of gravel a foot or two bigger than the greenhouse for better draining.


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## Stick486 (Jan 4, 2013)

OttoW said:


> Did you build the whole frame in PT or just the walls?
> 
> What made you choose fiberglass over polycarbonate?
> 
> ...


all of the green houses around here are on gravel beds...
flooring got got ripped out over time...
easy to salt the gravel to control unwanted growths...


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## DaninVan (Jan 1, 2012)

"easy to salt the gravel to control unwanted growths.."
-Stick
Great idea! Thanks for that, Stick.


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## Ghidrah (Oct 21, 2008)

Here on the cape, way back when most structures/homes were summer retreats and still built on blocks people purposely planted sea grass under the floors to act as an insulator and draft stop. One of the most hated jobs was trenching grids under houses so we could insulate the floors. Everyone felt punished.


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## DaninVan (Jan 1, 2012)

A couple of other essentials; 
ventilation, ventilation, ventilation! A sunny day will cook your plants in short order if you don't keep the heat buildup under control.
Leaving the door open works well but bugs and birds get in...the birds can't seem to find their way back out...they fly up and bang off the ceiling (I'm speaking of glass here. Less clear products may not be as much of a problem)
We finally resorted to this... (different brand but same idea)
http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=0QXCBT5V38NM83HNGAST


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## OttoW (Feb 13, 2016)

DaninVan said:


> A couple of other essentials;
> ventilation, ventilation, ventilation! A sunny day will cook your plants in short order if you don't keep the heat buildup under control.


I was thinking about an auto vent http://www.amazon.com/Auto-Vent-Kit...&sr=1-2&keywords=auto+vent+kit+for+greenhouse using the window area opposite of the door as a vent. Or should I have a vent as close to the top ridge as possible?


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## Stick486 (Jan 4, 2013)

the more the gooder...


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## Ghidrah (Oct 21, 2008)

Old passive air movers drew air from the north side floor and vented out the ridge or ceiling. The rising expanding hot air draws the cooler air up.


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## DaninVan (Jan 1, 2012)

*Yes!*



OttoW said:


> I was thinking about an auto vent http://www.amazon.com/Auto-Vent-Kit...&sr=1-2&keywords=auto+vent+kit+for+greenhouse using the window area opposite of the door as a vent. Or should I have a vent as close to the top ridge as possible?


Spot on, Otto; that's what I use...the auto openers.
The higher the better, and you need a lot of relief air coming in from down below. The cool side of the greenhouse would be my choice...or as I suggested, the open door.

Bayliss Autovent Opener - Greenhouse Cooling | Greenhouse Megastore


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## JFPNCM (Dec 13, 2009)

@OttoW:

Not sure what part or the country call home but those materials are not available here in the NW. 

The points on gravel for the floor and ventilation are well made. 

A neighbor lays old water bed heaters (on GFI circuits) over a layer of sand in his starter beds to keep the soil warm. Gives him quite a head start on the spring.


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## OttoW (Feb 13, 2016)

JFPNCM said:


> @OttoW:
> 
> Not sure what part or the country call home but those materials are not available here in the NW.


I'm coming to that conclusion. I'm in Idaho:frown:. but how do I miss the Oregon (coast) I grew up in.


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## bwilling (Jul 14, 2015)

OttoW said:


> Did you build the whole frame in PT or just the walls?
> 
> What made you choose fiberglass over polycarbonate?
> 
> ...



The upper sides are poly panels honeycomb style, the flooring is PT plywood. The structure is on 6" X 6" PT timbers than 2" X 6" studs covered with PT plywood 3/4". The top is corrugated fiberglass. I basically went with what Menards had, HD had nothing. The structure and frame is PT 2" X 4"'s. The door is an aluminum door cut down to fit my opening. I also put three drains in the floor to carry away water from watering plants. There are two vent windows on top and the door has a screen to vent the hot air.


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## bwilling (Jul 14, 2015)

Finished GH
Well I flipped the photo and still ended upside own.

Anyone notice the solar panels in the back ground? Produced 17.4 Mw since June 2012.


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## OttoW (Feb 13, 2016)

Edit:

I noticed the solar panels. Depending on you're area they can do well. Right now in my area power is still relatively cheap and small scale solar isn't used much, though we do have a lot of large scale wind power plants. 

I would love to get a wind turbine but I just don't have enough sustaining wind to make it pencil out.


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## OttoW (Feb 13, 2016)

bwilling said:


> The upper sides are poly panels honeycomb style, the flooring is PT plywood. The structure is on 6" X 6" PT timbers than 2" X 6" studs covered with PT plywood 3/4". The top is corrugated fiberglass. I basically went with what Menards had, HD had nothing. The structure and frame is PT 2" X 4"'s. The door is an aluminum door cut down to fit my opening. I also put three drains in the floor to carry away water from watering plants. There are two vent windows on top and the door has a screen to vent the hot air.


Thanks.

6X6 runners with 2x6 floor joist and 3/4 plywood sounds like a basic shed flooring, easy enough. How has the plywood held up to watering? As I wrote in an earlier post I think I will build it straight on a bed of gravel for easy drainage. Though it might be nice I'm not sure if a greenhouse needs to be elevated. 

How long have you been using the greenhouse? 

What would you change if you could?


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## Stick486 (Jan 4, 2013)

bwilling said:


> View attachment 194674
> 
> Finished GH
> Well I flipped the photo and still ended upside own.
> ...


you from Australia???


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## Stick486 (Jan 4, 2013)

OttoW said:


> I would love to get a wind turbine but I just don't have enough sustaining wind to make it pencil out.[/quote]
> 
> don't waste your money...
> 
> ...


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## JFPNCM (Dec 13, 2009)

OttoW said:


> I'm coming to that conclusion. I'm in Idaho:frown:. but how do I miss the Oregon (coast) I grew up in.


Certainly understand that point Otto. I enjoy the coast but living on the outskirts of Boring has a tendency to keep me at home in the country.


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## bwilling (Jul 14, 2015)

Stick486 said:


> don't waste your money...
> 
> Router Forums - View Single Post - Solar power prices
> Router Forums - View Single Post - Power to the People!


I have had the GH for 1 year. 

Don't go with the wind cost more and produced less 1.1 mega watt since 2009, solar 17.4 mega watt since 2012. I had the wind installed and the solar I did myself.

The poorest months here (UP of Michigan) for solar are October thru Feb, the remainder of the year is great. My system is grid tied which is cheaper than off grid.


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## OttoW (Feb 13, 2016)

Rained and few time that set me back but it's coming along. 

When the paint was drying I expanded the deck around my shed/shop ??


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## DesertRatTom (Jul 3, 2012)

Winds here get a little too fierce for wrapping with plastic. Two of my three sheds are on rock surfaces about 6 inches thick. Use crushed rock, pea gravel shifts too easily. Third shed is set on concrete blocks with 4-4x4 beams beneath the floor. This shed is about 12 inches off the ground so I have a small porch that acts as a step up. We have caliche below the surface, so for rain relief, I dug several holes below the hard layer under each shed and set some 4 inch drain pipes in place, then filled the holes and pipe with crushed rock so water runoff from the roof wouldn't flood the gravel pads. Used to have standing water for days after a rain before I started digging below the hard pack when planting almost anything, trees in particular. Now those painfully dug holes all drain the puddles fast.

I really like the use of an auto opener and screens to keep bugs out. In the desert, even plants in a greenhouse burn up fast, so I would also string up wires the length of the greenhouse, then put in shade cloth I could draw across to cut the total amount of light. I would also use double pane panels to hold down the solar heat. I liked the idea of the water bed heaters in the soil. Winter can get down to the 10 degree mark during much of winter. Electrical service is also a must if you have to heat to grow during winter, and double pane would also be a must. 

If the bottom 3-4 feet is 2x4 frame, there would be room for insulation. Just have to keep the temp above 40, right. Last word on a gravel floor. I would consider putting some sort of heavy duty liner down, angled so that the water flows into a channel (French draibn) and gets carried away from the gravel bed. Can't recall what they call it, but there is a thick rubber used for roofing that would work for that purpose. And/or make a floor with 2x2 or 2x4 redwood slats so water drains through to the gravel below.

I think the size would depend on usage. Something to keep orchids live would be smaller than something in which you want to grow veggies year round.

Just my thinking on the matter.


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## DaninVan (Jan 1, 2012)

"Can't recall what they call it, but there is a thick rubber used for roofing..."
EPDM, Tom. Kind of pricey though.


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## DesertRatTom (Jul 3, 2012)

DaninVan said:


> "Can't recall what they call it, but there is a thick rubber used for roofing..."
> EPDM, Tom. Kind of pricey though.


Thanks Dan. A family member redid the roof over the sunroom with it and I've used the leftovers for many things since. It was pricey.


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