Building a lean to greenhouse

[danlightbulb]

Hi all,

Im building a back to wall greenhouse out of wood to bespoke dimensions approx 2.4m high at the back, 1.2m wide, 0.6m deep, and 1.8m high at the front. There will be opening doors at the front and an opening lid.

I have the main framing timber and 4mm twin wall polycarbonate sheeting for the panels. But Im not sure how to attach it. I was planning to use some quadrant beading pinned into the framing and sandwiching the sheets between that. But, its really adding to the cost. The framing timber (38x63mm) was £3.50 per 2.4m length and Im using about 8-9 lengths. The beading is a similar price and I'd need double that amount because of needing beading both sides of the polycarbonate sheets. Its a crazy price for a 6mm x 6mm strip of wood.

Does anyone have any other ideas for how I can secure the polycarbonate sheets to my framing?

Thanks

 

[Semple]

Is it a wrap, or panels?

Can't really picture what you're describing but as you're using a timber frame, if it's a wrap can you not overwrap and then staple? You're going to want something exceptionally strong as gusts of wind will find the weak spots and tear it apart.

Also ensure the polycarbonate is of decent quality, I had a friend who made a dome greenhouse out of smaller triangular panels, I think he had it outside for 2 years before the UV had degraded the plastic and it only took one winter to rip through it - as soon as one panel was gone it had exposed all the others and they didn't last either.

 

[danlightbulb]

Im using 4mm twin wall polycarbonate panels https://www.ebay.co.uk/itm/144812670260

 

[danlightbulb]

Can't really picture what you're describing

Im building something like this: https://www.buyshedsdirect.co.uk/5x...OZmFLaz8ewlNvINbGxvF190b92BZ6mcoaAtLAEALw_wcB

 

[Welshman]

Hi all,

Im building a back to wall greenhouse out of wood to bespoke dimensions approx 2.4m high at the back, 1.2m wide, 0.6m deep, and 1.8m high at the front. There will be opening doors at the front and an opening lid.

I have the main framing timber and 4mm twin wall polycarbonate sheeting for the panels. But Im not sure how to attach it. I was planning to use some quadrant beading pinned into the framing and sandwiching the sheets between that. But, its really adding to the cost. The framing timber (38x63mm) was £3.50 per 2.4m length and Im using about 8-9 lengths. The beading is a similar price and I'd need double that amount because of needing beading both sides of the polycarbonate sheets. Its a crazy price for a 6mm x 6mm strip of wood.

Does anyone have any other ideas for how I can secure the polycarbonate sheets to my framing?

Thanks

I used drywall screws and caps……and made sure all the twin polycarb sat out side of the frame, so if the wind blew it had the frame as extra support.

As per picture

 

[Armageus]

Could you use a router to cut a groove into your framing and then slot the polycarbonate in?

 

[danlightbulb]

@Welshman thanks for the pic.

I could do that but it would cover up all my framing and wouldn't look as nice I don't think. You've managed to still keep some of the top and bottom framing visible so it looks integral, but mine wouldn't look like that if I just surface mounted the panels.

Could you use a router to cut a groove into your framing and then slot the polycarbonate in?

Maybe, Ive never routed before so I'd have to buy one, and can it be done without a decent workbench and proper guides to keep the groove straight?

 

[danlightbulb]

This is my rough design so you can visualise. I wanted the polycarbonate sheets to sit within the framing i.e recessed within it, like a piece of glass would be.

 

[danlightbulb]

This is a £50 quid cold frame type thing off Amazon. They have grooved in the PC panels by the looks of it, so that's what I'd ideally like to do.



Can I do this with a basic £30 router and what bit would I need to cut a 5mm wide by 5mm deep groove?

 

[Mercenary Keyboard Warrior]

My allotment one is pretty similar to welshies but I went cheaper, just normal screws with penny washers for cross beams, but I used thin strips over the top of the battens for the verticals. I think they were 16mm or something like that. (1/2 inch in effect)

If you want to frame them inside you need to router out 5-10mm all round and insert the panels then put something in to fill the gaps to sandwich the panels in place. At least partially.
You need a fairly decent step, or they may pop out however.

Edit to add, i actually surface mounted mine as its better for preventing water ingress. My expensive wooden greenhouse at home leaks as water runs down the panels and manages to find ways in.
Its sealed with silicon where the instructions said to do so but even so it still finds ways in.
My allotment one doesnt leak from the side panels, but dont mention the roof
I am planning to redo the roof as the timbers warped and it means there isnt enough slope so water pools and drips in between the corrugated panels.

 

[danlightbulb]

If you want to frame them inside you need to router out 5-10mm all round and insert the panels then put something in to fill the gaps to sandwich the panels in place. At least partially.
You need a fairly decent step, or they may pop out however.

Do you mean a rebate?

I'd prefer to do a groove in the centre of the framing timber, rather than a rebate at the edge. I can then slide in the PC panels from the top before securing the top framing piece in place.

Like this I suppose?

The groove would need to be cut along the entire length of all my frame timbers. And when I make the doors, the groove cut along the inside frame of all the door timbers too.

Perhaps 5mm isn't deep enough and I should go 10mm deep for extra strength? This could also give me enough room to drive some securing screws in as well from the inside.

 

[Armageus]

Maybe, Ive never routed before so I'd have to buy one, and can it be done without a decent workbench and proper guides to keep the groove straight?

I don't know - I've not got a router, but always looking for an excuse to get one

 

[danlightbulb]

Routers quite expensive aren't they. Seems to be at least £70 for a corded palm router. £200 if I wanted a cordless Dewalt one to go with my other tools.

Would a full size router be too big? They are cheaper.

 

[200sols]

Sandwich it between 2 timbers, e.g battens.

 

[964rs]

Trend TR03X1/4TC 1/4" Shank Double-Flute Straight Router Cutter 5mm x 16mm - Screwfix

Order online at Screwfix.com. Produce a good clean finish to the cut edges. For housing, grooving, mortising and performing plunge cuts. Extra long shanks. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

That's the bit you need for a 5mm groove.
Depth is set on the router usually and it will have a guide you can set up to keep you straight.
You will need to clamp you wood in or to something while you do it to keep it from moving.
You can easily do it if your reasonably competent and put the effort in

 

[danlightbulb]

Sandwich it between 2 timbers, e.g battens.

That's what I was planning to do with the quadrant beading, but it's too expensive for what it is and how much I need.

 

[200sols]

That's what I was planning to do with the quadrant beading, but it's too expensive for what it is and how much I need.

2x1 battens are cheap from a merchant. 4.8m lengths are like £4. Quadrant beading will be a lot more. Costs in wickes etc will be double that probably.

Good plan though, I need to build something like that myself.

 

[danlightbulb]

What do you mean 2x1 battens? Inches or cm? And how are you attaching these to the framing structure?

 

[Diggsy]

Do you mean a rebate?

I'd prefer to do a groove in the centre of the framing timber, rather than a rebate at the edge. I can then slide in the PC panels from the top before securing the top framing piece in place.

Like this I suppose?

The groove would need to be cut along the entire length of all my frame timbers. And when I make the doors, the groove cut along the inside frame of all the door timbers too.

Perhaps 5mm isn't deep enough and I should go 10mm deep for extra strength? This could also give me enough room to drive some securing screws in as well from the inside.

I wonder if you can achieve this sort of thing with a biscuit cutter? Lidl often have them at a reasonable price (£35).

Edit - seems you can, and this would be a lot easier than using a router…

How to cut a barndoor slot with a biscuit jointer

Dusty shows how to cut a barndoor slot with a biscuit jointer#barndoor #woodwork #biscuitjointer

www.youtube.com

 

[scarps]

That's what I was planning to do with the quadrant beading, but it's too expensive for what it is and how much I need.

I just used normal timber, no fancy beading when I did mine. I even used normal cheap timber to do my wooden glass one I made, just put some clear silicone between glass and wood.