DIY Wooden Greenhouse

10 Jan 2017
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United Kingdom
I'm considering building a greenhouse and wondered if anybody on here has done the same, or can offer a bit of advice construction-wise. Decent new ones are very expensive (around the £400 mark) and only come in set sizes. I'm confident working with timber, having built the framework for a few sheds as well as a gazebo out of 5x4.

We do grow quite a bit of veg, but have never had the luxury of a greenhouse! The back bedroom was used to grow the seeds. Now my son is here, the seed trays are on all the window sills and it's not very practical.

I have an area at the bottom of the garden and my plan was the below:

- Lay a concrete slab
- Lay three courses of a single skin blocks around the perimeter (and space for the door, of course...)
- Build a wooden frame on top of the blocks
- Clad in some sort of transparent/translucent sheeting, with overhang down the face of the blocks to prevent water ingress.

That's my plan. Does anybody have any recommendations on which material to use?
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Have you considered using second hand double glazed window units instead of sheeting material? Have a look in skips or ask your local glazing installers. On our allotment site there are some lovely greenhouses build that way (by handy people).
As above I did that with second hand windows CLS frame and polycarbonate second hand roof lasted for years.
Pic is its replacement same sort of idea but with larch cladding fully insulated to current underfloor heating and quarry tile floor.


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In place of a slab I'd lay foundation and use engineering bricks on that to build your frame on. Then you can plant into the ground and gain growing height.
Your choice of timber, cedar is traditional but pricey, I used treated 2x4 and painted in creocote.
Think about the glazing before designing timber layout as the least cutting you have to do the better. I used safety glass but it sounds like you're ok with polycarb which means you'll be ok with smaller timbers too.
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If you can buy a greenhouse for £400 do so.
or perhaps one of those growhouses, if you need something cheaper, otherwise keep an eye on the for sale list.

I had a look @T&M and you can have an affordable greenhouse tomorrow if you can spare £50 - a larger version is available for £80.

Do you plan to grow on seedlings to plant in the garden or have somewhere safe to grow tom's and cukes?
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Thanks for the advice, all. I can get 2x2 at 9ft lengths for £2 so I think the framing is pretty much sorted. It's rough-sawn so would need to be put through the sander before assembly and painting.

@Odds -- I'd need something bigger and sturdier than that. We get very high winds living in a valley and I've seen one very similar end up across multiple gardens. Yes I grow from seed to plant in the garden.

As it happens, next door (very old lady) is potentially giving away her 6x6 aluminium greenhouse. 3 broken panes, but still cheaper.
You can peg them into the ground but i hear what you're saying. By the end of March the weather should give you a helping hand.(y)
You bolt the frame to the brick courses (regular bricks on top of engineering bricks). Poly blowing out is a common issue usually sorted with battens
There's often free greenhouses on Facebook marketplace if you haven't checked already
Decided against doing this due to costs. I've bought the slabs, sand and cement to lay the base for this (extension of an existing patio) and I'm already at £300. This is more than twice what I paid two years ago.

Instead, I acquired two greenhouses for free (from next door, who didn't want them. One aluminium one at 7ft x 7ft and one polycarbonate at 6ft x 8ft. The poly one only required a single replacement roof panel, however I had to buy a pack of 14 sheets at £52.

The aluminimum one had lots of smashed panes, so I used the excess poly panels to replace the roof and used glass (at 28" x 56") to replace the side panels which were £25 each. Total spend for the two is about the same or cheaper than a hand-built timber one.

Here's me demonstrating our method of removal....


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