[pipfit]

I am about to purchase an 8ftx10ft Halls greenhouse can put it on the axis NE/SW or     NW/SE.
What autovents would I require It has 4 manual openers and would fit a louvre.
Also is better on slabs or Teram with gravel .Any advice would be appreciated

[waddecar]

I'll have a go at this one

Axis: of your two choices not hughly important but if there are no other design issues I would go for the SW/NE as morning sun is reckoned better for plants than afternoon - something to do with higher humidity levels in the morning filtering UV rays

 Ventilation: most GHs are sold with too little ventilation the recommended (source - RHS from memory) minimum is that ventilation area should at least 1 third floor area so for your 80sq ft you need about 26sq ft of opening roof vents and ideally those vents should not be opposite each other in order to create circulatory air currents. If they are opposite each other thenair blows in one and out the other without changing much air. So you probably need as many louvres as you can fit - but they are no where nearas effective as roof vents. If you may need to rely on the door for a good air flow.

Gravel on teram will give you best humidity but will need changing from time to time depending on how much compost you spill, whilst slabs would harbour pests especially ants. I prefer concrete even though it needs damping down frequently.

Good luck

Brian

[Kristen]

I'm a fan of a low-down louvre providing the incoming air, without draught, and convection taking the hot air out of the ridge vents.

Draughts mean that the plants transpire more, and are either stressed, or have to work harder (rather than getting on with being best-of-breed

[Roll Roll]

Hello Pipfit, I asked the same question a while back about greenhouse bases. In the end I went for a slab base. It was a little more hassel and expence, but now it's done it's done. No more messing about .