Greenhouse question

Reckless Abandonment

Block work so far. As I'm rebuilding and old conservatory have to build back wall. Luckily will have double doors on both ends and windows will open on all sides. Only thing I dont have yet is roof vents. Added some vent to the back wall for now.

Calahonda52

Lumen wrote: »

I wouldn't worry about access, although the sheeting will be a bit slippy you can sling a strap over the apex and hang off it.

Is that diagram indicative of the pitch?

Low pitch and high apex braces means the apex braces are going to be under a lot of tension (compared to a more normal pitch with triangulation at top of walls), that design seems to be for a metal construction rather than timber. Do you really need that much uninterrupted clear space above head height? But in any case, threaded rod, washers and bolts ought to do it (maybe some else has a better suggestion).

Or, given how incredibly light multiwall polycarbonate is, could you maybe get away with a ridge beam design? Go thicker on the polycarbonate for better insulation, and then it'll be more rigid so will need lighter roof members. I used a 300mm x 150mm douglas fir ridge beam for a 5m clear span, and my spreadsheet said that would cope with a 1500kg roof structure. If you keep the roof MUCH lighter, you can bring the ridge beam dimensions down to standard lumber sizes (cheaper and safer to work with).

25mm multiwall polycarbonate is 3.4kg/m2, so 20sqm of roof would only be 70kg (light transmission ~50%).
16mm multiwall polycarbonate is 2.6kg/m2, so 20sqm of roof would only be 52kg (light transmission ~75%).

https://www.twinfix.co.uk/products/multiwall-polycarbonate/25mm-multiwall-polycarbonate

So I reckon go the Colin Chapman route: simplify, then add lightness.

Thanks Lumen, much appreciated, the picture was just for the names of the joints etc so it will be a more conventional A roof

Interesting the light transmission numbers for the different material.

What would normal glass be?

Does reduced light transmission equate to reduced solar gain?

SHMBO not gone on the polycarbonate so looking at glass for two sides that don't face walls, so you can see in/out.

Carey Glass are down the road so will go down to then for a look see on glass

Lumen

From memory, normal glass is about 90% transmittance per layer.

The total energy transmittance figures for the multiwall polycarbonate are also in that link I posted.

Problem with glass is weight and fragility. I remember someone at Russborough House saying that they had to replace panes in their glasshouse every winter, and that was sheltered in the walled garden.

Also, unless its double glazed the heat retention will be appalling, but if you don't care about that you can use single layer polycarbonate which will look less industrial than the multiwall. Also, I think there's a company in north Dublin that coats polycarbonate to improve scratch resistance.

Did you put in a damp proof course?

rolion

Hi,

Nice to see people interested in the area...
Ive built my own DIY grenehouse couple of years back. Link H E R E

Is very important to get things right and set from beginning,otherwise you will work as a "slave" adapting and improving and cleaning.Never ever ending work around it...

Very important is to get your wife / husband approval adn support.On my own,i will not have been able to get here,today,as despite looking small,is a very hard thing to keep it working,it has to be clean as a hospital,workign as you are living in there and constantly monitored and adapted...too much heat for tomatoes and they gone,too much cold and the flowers have dropped,too much or too less water has its own troubles.
Not lastly,plan how you will defeat the small nasty bugs...you leave the salad green and healthy today and in the morning half is gone.
Same with the trees,leafs healthy and green,in few days they are ondulated,dried and brown / or in half the size.

But the answer to all these stays in hard work,enjoyable results and hit and miss experiments until you get the right satisfaction.

Either way,enjoy the journey,the adventure in getting built and populate it with the first greenie wonders seeds /roots / plants.

Few photos taken few days ago,still finding something to work around,to keep your mind occupied.
Got some SONOFF devices and i hope to be able to automate most of the things in there.Also,installing a second monitoring and reporting/logging temperature system for checking how the temperature/humidity of weather, fans and geo works over a period of time. I had over 40 degrees in there last summer and i hardly try to avoid it this year...

uck51js9zml2yt

rolion wrote: »

Hi,

Nice to see people interested in the area...
Ive built my own DIY grenehouse couple of years back. Link H E R E

Is very important to get things right and set from beginning,otherwise you will work as a "slave" adapting and improving and cleaning.Never ever ending work around it...

Very important is to get your wife / husband approval adn support.On my own,i will not have been able to get here,today,as despite looking small,is a very hard thing to keep it working,it has to be clean as a hospital,workign as you are living in there and constantly monitored and adapted...too much heat for tomatoes and they gone,too much cold and the flowers have dropped,too much or too less water has its own troubles.
Not lastly,plan how you will defeat the small nasty bugs...you leave the salad green and healthy today and in the morning half is gone.
Same with the trees,leafs healthy and green,in few days they are ondulated,dried and brown / or in half the size.

But the answer to all these stays in hard work,enjoyable results and hit and miss experiments until you get the right satisfaction.

Either way,enjoy the journey,the adventure in getting built and populate it with the first greenie wonders seeds /roots / plants.

Few photos taken few days ago,still finding something to work around,to keep your mind occupied.
Got some SONOFF devices and i hope to be able to automate most of the things in there.Also,installing a second monitoring and reporting/logging temperature system for checking how the temperature/humidity of weather, fans and geo works over a period of time. I had over 40 degrees in there last summer and i hardly try to avoid it this year...

What was the function of the pipes?

Calahonda52

Mara Hissing Shellfish wrote: »

What was the function of the pipes?

Read here
https://www.boards.ie/vbulletin/showthread.php?t=2057719469

uck51js9zml2yt

Calahonda52 wrote: »

Read here
https://www.boards.ie/vbulletin/showthread.php?t=2057719469

Read it and made no sense hence the question

Calahonda52

Mara Hissing Shellfish wrote: »

Read it and made no sense hence the question

On the bottom of the ground, installing 7 pieces of 110mm pipes that will connect to a central manifold of 160mm that will recirculate the air in the greenhouse, summer and winter.

Calahonda52

Thinking of building a normal portal frame in tanalised timber.

Will us ALu plate brackets for bracing and ss fixings

Roof it with polycarbonate, with gutters to collect rain water.
Then line the inside, including the rafters with polythene from here
https://www.thepolytunnelcompany.ie/cat/polythene

Ventilation through the gables at each end


A plus I see is that the timber will never get wet from condensation
A minus is that I wont be able to easily use collars to ease the pressure on the portal knee joint.
Any thoughts?

Zzippy

Calahonda52 wrote: »

Thinking of building a normal portal frame in tanalised timber.

Will us ALu plate brackets for bracing and ss fixings

Roof it with polycarbonate, with gutters to collect rain water.
Then line the inside, including the rafters with polythene from here
https://www.thepolytunnelcompany.ie/cat/polythene

Ventilation through the gables at each end


A plus I see is that the timber will never get wet from condensation
A minus is that I wont be able to easily use collars to ease the pressure on the portal knee joint.
Any thoughts?

Are you roofing with polycarbonate and also putting polythene inside this? Seems like overkill. Would you not get a lot of condensation between the two?

Calahonda52

Zzippy wrote: »

Are you roofing with polycarbonate and also putting polythene inside this? Seems like overkill. Would you not get a lot of condensation between the two?

No it will be open at the eaves, and maybe at the apex: there are a few trees around so falling branches etc

Lumen

Would you even need tanalised timber if it's not going to get wet?

When I eventually get round to building a greenhouse I reckon I'll do this:

- "Ring beam" of untreated oak sleepers at ground level, on top of gravel for drainage.
- Four stud walls, using untreated CLS framing timber, screwed into the sleepers.
- Couple of cross members to stop wall spread, nailed through the top of the studs. I've always fancied using wire for this but I guess it might be a bit lethal if it snapped.
- Multiwall polycarbonate on the outside, tek screwed to the studs for racking strength and weather protection.
- Multiwall polycarbonate arc roof, tek screwed to the tops of the walls with a bit of overshoot into gutters.
- Maybe a couple of ground anchors to counter lift.

Calahonda52

It will get wet from the rain but dry off, not like if in the damp GH.
A few turnbuckles with 6mm plastic covered braided wire should do as your collars

rolion

Calahonda52 wrote: »

No it will be open at the eaves, and maybe at the apex: there are a few trees around so falling branches etc

Just to mention that you need proper ventilation,mechanical better,subject to size and build of the unit.
As today, my GH ground level reached 32 degrees. Keep it like this for few days and you can say to plants good byeeeeee ...

Calahonda52

rolion wrote: »

Just to mention that you need proper ventilation,mechanical better,subject to size and build of the unit.
As today, my GH ground level reached 32 degrees. Keep it like this for few days and you can say to plants good byeeeeee ...

Thanks
My plan is to have the apex open at each end in hot weather

rolion

Calahonda52 wrote: »

Thinking of building a normal portal frame in tanalised timber.

Will us ALu plate brackets for bracing and ss fixings

Roof it with polycarbonate, with gutters to collect rain water.
Then line the inside, including the rafters with polythene from here
https://www.thepolytunnelcompany.ie/cat/polythene

Ventilation through the gables at each end


A plus I see is that the timber will never get wet from condensation
A minus is that I wont be able to easily use collars to ease the pressure on the portal knee joint.
Any thoughts?

Personal experience after 2 years with polythene.
It gets so "dirty" and steals the visibility of the greenhouse.
I will love to be able (afford) to replace the front (where visibility is at maximum) with clear acrylic 3-5mm or even glass, on the whole surface. Leave foil only on the sides,where not so visible to eyes.

Advantage is that i can see through while sipping a coffee in the garden major disadvantage is that light and rays direct coverage may affect the plants leefs...