Hi,

Looking for advice on a greenhouse I am looking to build in the sunniest (relative) spot in my London garden.

My garden is West facing, the patch is South facing and gets sun from 12:30 to 18:00 (5.5 hours). Last summer I grew cherry tomatoes and courgettes with fair success in this patch (birds got most of the cherry toms tbh). I got a bunch or large tomatoes which didn't ripen in time before the plants died at the end of the season (I didn't realise you could ripen them indoors).

I want to build a greenhouse on this spot to increase my success rate with tomatoes and other sun-lovers like peppers, cucumbers, squash and pumpkin.

Originally I was going to buy a 4 x 6 foot aluminium greenhouse as the space is awkwardly shaped and this is all I could find that would fit, but then I thought if I design and build my own I could make better use of the space and have a bigger greenhouse for the same money.

It's going to consist of a brick foundation (neighbours old driveway), wooden frame (scrap liberated from skips), kitchen flooring for floor (have this lying around) and a polycarbonate surface which I will need to source. The whole structure will be covered in polycarbonate as I don't want any wood exposed to the elements. See CAD drawing attached (dimensions in mm). I've got my brother visiting in Sept and he has some carpentry skills so planning to start work when he's over.

What I couldn't figure out how to get across in the drawing with my limited CAD skills is the panels A and B, I want the poly carbonate sheet at B to be fixed in place, and A to open upwards on hinges, like a grow box, except a 1.6 meter high grow box = ). This should give me good access to all the plants as the space behind B will be quite large for me to be able to duck under.

So questions:

1. What thickness polycarbonate and how many chambers is usual for greenhouses?
2. Does the pitch of the roof look OK? Is this important?
3. Will leaving the door open (A) occasionally be enough for ventilation purposes?
4. Does the design look practical?
5. Is it worth the effort considering limited access to sunlight?

BTW I will growing plants in self watering containers as used by this guy: How Self-Watering Containers Work |

Any thoughts/comments appreciated.

Oh yes, imagine the frame in the CAD drawing covered in polycarbonate sheets.

I am going to cross post this on a DIY forum for the construction nitty gritty but wanted to hear from the gardeners first if this is a good idea or not.

On 22/06/13 21:29, Howzit_China wrote:
Oh yes, imagine the frame in the CAD drawing covered in polycarbonate
sheets.

I am going to cross post this on a DIY forum for the construction nitty
gritty but wanted to hear from the gardeners first if this is a good
idea or not.

Be careful to understand the difference between a newsgroup and a forum
- newsgroups have grandfather rights and members can get rather testy if
they are confused with the rather crude arrangements for continuety in
a forum.

--
Rusty Hinge

"Howzit_China" wrote

Looking for advice on a greenhouse I am looking to build in the sunniest
(relative) spot in my London garden.

My garden is West facing, the patch is South facing and gets sun from
12:30 to 18:00 (5.5 hours). Last summer I grew cherry tomatoes and
courgettes with fair success in this patch (birds got most of the cherry
toms tbh). I got a bunch or large tomatoes which didn't ripen in time
before the plants died at the end of the season (I didn't realise you
could ripen them indoors).

I want to build a greenhouse on this spot to increase my success rate
with tomatoes and other sun-lovers like peppers, cucumbers, squash and
pumpkin.

Originally I was going to buy a 4 x 6 foot aluminium greenhouse as the
space is awkwardly shaped and this is all I could find that would fit,
but then I thought if I design and build my own I could make better use
of the space and have a bigger greenhouse for the same money.

It's going to consist of a brick foundation (neighbours old driveway),
wooden frame (scrap liberated from skips), kitchen flooring for floor
(have this lying around) and a polycarbonate surface which I will need
to source. The whole structure will be covered in polycarbonate as I
don't want any wood exposed to the elements. See CAD drawing attached
(dimensions in mm). I've got my brother visiting in Sept and he has some
carpentry skills so planning to start work when he's over.

What I couldn't figure out how to get across in the drawing with my
limited CAD skills is the panels A and B, I want the poly carbonate
sheet at B to be fixed in place, and A to open upwards on hinges, like a
grow box, except a 1.6 meter high grow box = ). This should give me good
access to all the plants as the space behind B will be quite large for
me to be able to duck under.

So questions:

1. What thickness polycarbonate and how many chambers is usual for
greenhouses?
2. Does the pitch of the roof look OK? Is this important?
3. Will leaving the door open (A) occasionally be enough for ventilation
purposes?
4. Does the design look practical?
5. Is it worth the effort considering limited access to sunlight?

BTW I will growing plants in self watering containers as used by this
guy: 'How Self-Watering Containers Work |' (http://tinyurl.com/km9fpqb)

Any thoughts/comments appreciated.


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|Download: http://www.gardenbanter.co.uk/attachment.php?attachmentid=15649|
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I built my own greenhouse glazed with twin walled polycarbonate roof and
acrylic glazed sides. What I have found is that some plants seem to elongate
as if fighting for light (eg. tomatoes) whilst others don't seem to have any
problems (eg. cacti & orchids).
The main problem is the dampness and humidity of the greenhouse rotting the
wood as the condensation always drips down towards the ground rotting the
wood from the bottom. Also a problem where any sloping roof meets wood
inside the house.
--
Regards. Bob Hobden.
Posted to this Newsgroup from the W of London, UK

Forgot to ask, would you not use polycarbonate for the sides?

Here's a quick drawing with the back adjusted to 2m.

The reason for the elaborate roof on my original drawing was to get around what is happening in this drawing, which is that the roof angles of the sides are different due to the different side widths so the polycarbonate will need to twist slightly to fit the frame, but maybe this will not be a problem.

Is polycarbonate strong enough that I could use one sheet for the entire roof and one for the front without any supports in the middle?

On 23/06/2013 09:28, Howzit_China wrote:
Here's a quick drawing with the back adjusted to 2m.

The reason for the elaborate roof on my original drawing was to get
around what is happening in this drawing, which is that the roof angles
of the sides are different due to the different side widths so the
polycarbonate will need to twist slightly to fit the frame, but maybe
this will not be a problem.

Is polycarbonate strong enough that I could use one sheet for the entire
roof and one for the front without any supports in the middle?


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|Filename: GreenHouseDesign3.jpg |
|Download: http://www.gardenbanter.co.uk/attachment.php?attachmentid=15650|
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OK lets throw a curved Ball
Why put a door at an end, why not have the front as 2 or 3 removable
panels, that way you wont be trying to put a path down the length and
will have more growing area.

Well yeah that was kind of my original idea, except I was picturing them opening upwards on hinges like a growbox.

Somebody raised the point that in winter (if I was to use it in winter) opening the panels would release a lot of the warmth, but I am with you on this one.

This would probably rule out the digging a deeper foundation to increase the height idea, it would be quite a big step down....but maybe I could strategically place steps on the inside to step onto.

This wood rotting business is putting me off, what do you think of the aluminium idea? Looks like I could pick up some aluminium beams quite cheap. I wouldn't have a clue how to build with the stuff but it can't be brain surgery

On 23/06/2013 09:28, Howzit_China wrote:
Here's a quick drawing with the back adjusted to 2m.

The reason for the elaborate roof on my original drawing was to get
around what is happening in this drawing, which is that the roof angles
of the sides are different due to the different side widths so the
polycarbonate will need to twist slightly to fit the frame, but maybe
this will not be a problem.

Is polycarbonate strong enough that I could use one sheet for the entire
roof and one for the front without any supports in the middle?


+-------------------------------------------------------------------+
|Filename: GreenHouseDesign3.jpg |
|Download: http://www.gardenbanter.co.uk/attachment.php?attachmentid=15650|
+-------------------------------------------------------------------+

BRINGING THE TOPIC BACK

On 23/06/2013 21:50, David Hill wrote: On 23/06/2013 19:29,
Howzit_China wrote:
Great thanks for all the responses.

Maybe I would be better off getting a blow away, especially if rot
becomes a serious problem, I will do some further cost benefit analysis.


I think the main thing to decide on before continuing is the
design/dimensions before dealing with ventilation and rot prevention.

As two posters have mentioned the height I have been giving this some
thought, I don't want to upset my neighbour by going too high above the
fence so what I could do is raise the height to 170cm, and dig down 30cm
into the ground giving a highest point of 200cm.

To be honest I didn't envisage myself spending too much time in the
greenhouse but I guess if I am going to go through the effort I might as
well do it properly.

Photo of the plot attached, taken 20 mins ago. There is just lawn in
front of the plot, It is West facing and gets sun approx 12:30 to 18:00


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|Filename: Hounslow-20130623-00166.jpg |
|Download:
http://www.gardenbanter.co.uk/attachment.php?attachmentid=15657|
+-------------------------------------------------------------------+



Having seen the picture I fail to see why you want to make it such a
problem, and so much more work for yourself.
Keep to a regular shape and move the path.
You could even remove the screen block wall and extend the present
conservatory/ structure another 6ft or so along the fence, you could
use the same small profile plastic sheeting that you now have on the
existing roof, Much cheaper than polycarb and line it in the winter
with large bubble film.

On 23/06/2013 21:55, David Hill wrote:
On 23/06/2013 09:28, Howzit_China wrote:
Here's a quick drawing with the back adjusted to 2m.

The reason for the elaborate roof on my original drawing was to get
around what is happening in this drawing, which is that the roof angles
of the sides are different due to the different side widths so the
polycarbonate will need to twist slightly to fit the frame, but maybe
this will not be a problem.

Is polycarbonate strong enough that I could use one sheet for the entire
roof and one for the front without any supports in the middle?


+-------------------------------------------------------------------+
|Filename: GreenHouseDesign3.jpg |
|Download:
http://www.gardenbanter.co.uk/attachment.php?attachmentid=15650|
+-------------------------------------------------------------------+

BRINGING THE TOPIC BACK

On 23/06/2013 21:50, David Hill wrote: On 23/06/2013 19:29,
Howzit_China wrote:
Great thanks for all the responses.

Maybe I would be better off getting a blow away, especially if rot
becomes a serious problem, I will do some further cost benefit
analysis.


I think the main thing to decide on before continuing is the
design/dimensions before dealing with ventilation and rot prevention.

As two posters have mentioned the height I have been giving this some
thought, I don't want to upset my neighbour by going too high above the
fence so what I could do is raise the height to 170cm, and dig down
30cm
into the ground giving a highest point of 200cm.

To be honest I didn't envisage myself spending too much time in the
greenhouse but I guess if I am going to go through the effort I
might as
well do it properly.

Photo of the plot attached, taken 20 mins ago. There is just lawn in
front of the plot, It is West facing and gets sun approx 12:30 to 18:00


+-------------------------------------------------------------------+
|Filename: Hounslow-20130623-00166.jpg |
|Download:
http://www.gardenbanter.co.uk/attachment.php?attachmentid=15657|
+-------------------------------------------------------------------+



Having seen the picture I fail to see why you want to make it such a
problem, and so much more work for yourself.
Keep to a regular shape and move the path.
You could even remove the screen block wall and extend the present
conservatory/ structure another 6ft or so along the fence, you could
use the same small profile plastic sheeting that you now have on the
existing roof, Much cheaper than polycarb and line it in the winter
with large bubble film.

If you are thinking about getting a flimsy then have a look at
http://www.robertdyas.co.uk/P~149009~Walk-In-Greenhouse
http://www.robertdyas.co.uk/P~155280...-In-Greenhouse
Spend £40 or more for free delivery
Use promotional code DD10 if you spend over £50 and get £10 off before
30th June

On 23/06/2013 21:55, David Hill wrote:
On 23/06/2013 09:28, Howzit_China wrote:
Here's a quick drawing with the back adjusted to 2m.

The reason for the elaborate roof on my original drawing was to get
around what is happening in this drawing, which is that the roof angles
of the sides are different due to the different side widths so the
polycarbonate will need to twist slightly to fit the frame, but maybe
this will not be a problem.

Is polycarbonate strong enough that I could use one sheet for the entire
roof and one for the front without any supports in the middle?


+-------------------------------------------------------------------+
|Filename: GreenHouseDesign3.jpg |
|Download:
http://www.gardenbanter.co.uk/attachment.php?attachmentid=15650|
+-------------------------------------------------------------------+

BRINGING THE TOPIC BACK

On 23/06/2013 21:50, David Hill wrote: On 23/06/2013 19:29,
Howzit_China wrote:
Great thanks for all the responses.

Maybe I would be better off getting a blow away, especially if rot
becomes a serious problem, I will do some further cost benefit
analysis.


I think the main thing to decide on before continuing is the
design/dimensions before dealing with ventilation and rot prevention.

As two posters have mentioned the height I have been giving this some
thought, I don't want to upset my neighbour by going too high above the
fence so what I could do is raise the height to 170cm, and dig down
30cm
into the ground giving a highest point of 200cm.

To be honest I didn't envisage myself spending too much time in the
greenhouse but I guess if I am going to go through the effort I
might as
well do it properly.

Photo of the plot attached, taken 20 mins ago. There is just lawn in
front of the plot, It is West facing and gets sun approx 12:30 to 18:00


+-------------------------------------------------------------------+
|Filename: Hounslow-20130623-00166.jpg |
|Download:
http://www.gardenbanter.co.uk/attachment.php?attachmentid=15657|
+-------------------------------------------------------------------+



Having seen the picture I fail to see why you want to make it such a
problem, and so much more work for yourself.
Keep to a regular shape and move the path.
You could even remove the screen block wall and extend the present
conservatory/ structure another 6ft or so along the fence, you could
use the same small profile plastic sheeting that you now have on the
existing roof, Much cheaper than polycarb and line it in the winter
with large bubble film.




Sorry to break in on David's post, but this is the first time I've seen
the photograph and made sense of the site and the quest for your greenhouse.

In your position, I would stick to buying an off-the-shelf
aluminium/poly greenhouse, as you first thought. It would have
(presumably) some sort of guarantee *and* be a whole lot more attractive
for you and your neighbours. You could then choose to supplement it
with homemade coldframes or mini-greenhouses to suit your own
requirements. These would free up a lot of space in the main greenhouse
when seedlings/plants reached hardening off stage and still give you an
interesting project. The height would be less of an issue with
neighbours if the structure was traditional and halfway decent to look at.

--
Spider
from high ground in SE London
gardening on clay

On 23/06/2013 07:22, Howzit_China wrote:
Thanks for the responses

Bob Hobden;985645 Wrote:

I built my own greenhouse glazed with twin walled polycarbonate roof and

acrylic glazed sides. What I have found is that some plants seem to
elongate
as if fighting for light (eg. tomatoes) whilst others don't seem to have
any
problems (eg. cacti & orchids).
The main problem is the dampness and humidity of the greenhouse rotting
the
wood as the condensation always drips down towards the ground rotting
the
wood from the bottom. Also a problem where any sloping roof meets wood
inside the house.

Yes rotting is a big concern. The best I can do is give the wood a
couple of layers treatment. I am thinking of coating the base in tar
(don't know where I got that idea but sounds like a good one). Not sure
what else I can do.

Are you saying where sloping roof meets wood is prone to rotting? I was
thinking maybe it would be a good idea to have rubber spacers at
intervals so the poly never actually touches the wood.

David Hill;985647 Wrote:

Firstly I'd make the front a lot taller, Min of 1.25m I'd make the back

2m, and slope the roof in one piece not 2 ,
I can't see where youu intend to have a door,
What are the ground measurements, I have no idea what 3477 0677 is.
What is the back wall? part of the house or what.

3477 0677 is 3.48 meters. The base is 1m (left) x 3.2m (back) x 1.5
(right) x 3.48m (front). The space narrows as you move right to left.

I had difficulty getting across my idea for the door but what I had in
mind was for poly sheet A to be on hinges and open like a growbox.

The back wall is the garden fence, there will be a small gap between the
greenhouse and the fence. The back will be poly too as I don't want any
wood exposed to the elements. The fence is 1.5m which is why I made the
height 1.6m, didn't want to upset my neighbour but I will speak to her.
Maybe a traditional pitched roof would be better.

I will take your comments onboard re the height and roof and do another
drawing, I am curious why you would have the rook in one piece?


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A picture of the plot would be a big help.
So you have a wooden fence behind, what's in front?

"Howzit_China" wrote
Bob Hobden;985645 Wrote:

I built my own greenhouse glazed with twin walled polycarbonate roof and

acrylic glazed sides. What I have found is that some plants seem to
elongate
as if fighting for light (eg. tomatoes) whilst others don't seem to have
any
problems (eg. cacti & orchids).
The main problem is the dampness and humidity of the greenhouse rotting
the
wood as the condensation always drips down towards the ground rotting
the
wood from the bottom. Also a problem where any sloping roof meets wood
inside the house.

Yes rotting is a big concern. The best I can do is give the wood a
couple of layers treatment. I am thinking of coating the base in tar
(don't know where I got that idea but sounds like a good one). Not sure
what else I can do.

Are you saying where sloping roof meets wood is prone to rotting? I was
thinking maybe it would be a good idea to have rubber spacers at
intervals so the poly never actually touches the wood.


What happens when it's cold is that condensation slides down the sloping
roof inside onto the wood where it sits and rots the wood. Probably only a
problem if you intend to heat your greenhouse in the winter as I do. I gave
my wood three coats of Sadlin but still in places it rotted after time
requiring a refurb. The glazing at the bottom now sits on plastic embedded
in cement and the legs are held by metal brackets also embedded in the
cement capping. If I made it again I would be even more careful to ensure it
could be taken apart again and mended, wood replaced, as required.
--
Regards. Bob Hobden.
Posted to this Newsgroup from the W of London, UK

On 23/06/13 07:22, Howzit_China wrote:

Yes rotting is a big concern. The best I can do is give the wood a
couple of layers treatment. I am thinking of coating the base in tar
(don't know where I got that idea but sounds like a good one). Not sure
what else I can do.

Old sump oil is probably your best option. Kills rot, kills woodworm.
Diseasel oil is if anything, better.

--
Rusty Hinge

On 22/06/2013 21:06, Howzit_China wrote:
Hi,

Looking for advice on a greenhouse I am looking to build in the sunniest
(relative) spot in my London garden.

My garden is West facing, the patch is South facing and gets sun from
12:30 to 18:00 (5.5 hours). Last summer I grew cherry tomatoes and
courgettes with fair success in this patch (birds got most of the cherry
toms tbh). I got a bunch or large tomatoes which didn't ripen in time
before the plants died at the end of the season (I didn't realise you
could ripen them indoors).

I want to build a greenhouse on this spot to increase my success rate
with tomatoes and other sun-lovers like peppers, cucumbers, squash and
pumpkin.

Originally I was going to buy a 4 x 6 foot aluminium greenhouse as the
space is awkwardly shaped and this is all I could find that would fit,
but then I thought if I design and build my own I could make better use
of the space and have a bigger greenhouse for the same money.

It's going to consist of a brick foundation (neighbours old driveway),
wooden frame (scrap liberated from skips), kitchen flooring for floor
(have this lying around) and a polycarbonate surface which I will need
to source. The whole structure will be covered in polycarbonate as I
don't want any wood exposed to the elements. See CAD drawing attached
(dimensions in mm). I've got my brother visiting in Sept and he has some
carpentry skills so planning to start work when he's over.

What I couldn't figure out how to get across in the drawing with my
limited CAD skills is the panels A and B, I want the poly carbonate
sheet at B to be fixed in place, and A to open upwards on hinges, like a
grow box, except a 1.6 meter high grow box = ). This should give me good
access to all the plants as the space behind B will be quite large for
me to be able to duck under.

So questions:

1. What thickness polycarbonate and how many chambers is usual for
greenhouses?
2. Does the pitch of the roof look OK? Is this important?
3. Will leaving the door open (A) occasionally be enough for ventilation
purposes?
4. Does the design look practical?
5. Is it worth the effort considering limited access to sunlight?

BTW I will growing plants in self watering containers as used by this
guy: 'How Self-Watering Containers Work |' (http://tinyurl.com/km9fpqb)

Any thoughts/comments appreciated.


+-------------------------------------------------------------------+
|Filename: GreenHouseDesign2.jpg |
|Download: http://www.gardenbanter.co.uk/attachment.php?attachmentid=15649|
+-------------------------------------------------------------------+

Firstly I'd make the front a lot taller, Min of 1.25m I'd make the back
2m, and slope the roof in one piece not 2 sections,
I can't see where you intend to have a door,
What are the ground measurements, I have no idea what 3477 0677 is.
What is the back wall? part of the house or what.
David @ a damp and windy part of Swansea Bay