Garden Room Ventilation

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A quick question regarding ventilation. I built this without much thought for ventilation apart from a couple of trickle vents in the door frames. All the windows are non-opening and the interior will be plaster boarded and that’s that. I now realise I might need a couple of passive vents for through flow. The internal room size is 2.2 x 3.2 x 2m. Does anyone know of a way to calculate what size vents would be required for adequate airflow? The room will be little used and there will be no moisture generating activities inside or even much storage of anything, so it’s just to prevent mildew and stale air.

Is one ‘hit and miss’ type vent enough, combined with the door vent, or is a second one necessary too. Is it OK to position both high up on opposite walls, or is important to have one high and one low down on the opposite wall. I would rather not have one low down to reduce insect and pest entry, as well as moisture.

I was thinking 22 x 15cm Louvre Vents on the exterior and sliding vents on the inside so they can be kept closed in the winter to stop drafts with the heating on. Is this about right? Any advice on this?

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Trickle vents are for background ventilation and opening windows for rapid ventilation. If it is built without building regulations approval I suppose you can do what you like but you will have to rely on the opening doors for rapid ventilation if you don't want to put in an opening window.
Trickle vents should be at least 1.75m above floor level .
 
if you're going to add vents, put them on opposite (or at least different) sides of the room so that you get some airflow.
 
Yes, thanks. I'll put one towards the top on the right hand wall, but wondered if I'd get enough through flow between that and the trickle vents in the door, or if I should instead place another in the left side wall? The space is about 15.5m3 and I was considering this type of vent:

http://www.builderdepot.co.uk/adjustable-hit-and-miss-ventilators-225mm-x-150mm-aluminium.html

Also, is placing all vents towards the top of the walls effective? Or should I ideally be putting one at the base of a wall to draw in cool air and one at the top of the opposite wall to let out warm air?
 
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Background ventilators should be sited to avoid draughts. This can typically be achieved at a position of 1.7m above floor level.
 
Background ventilators should be sited to avoid draughts. This can typically be achieved at a position of 1.7m above floor level.
Thanks. Where does this information come from and is there more detail regarding cubic volume etc? Is there advice within building regs that could help me? thanks
 
Thanks. Where does this information come from and is there more detail regarding cubic volume etc? Is there advice within building regs that could help me? thanks
If you want to see more detail you can see it in Approved Document F Ventilation on The Planning Portal or LABC websites ( good luck with that ), but do you want to go into that for a garden room, are you complying with bldg. regs anyway :?: ( Ventilation in dwellings Part F used to be quite straightforward until they amended it with various ways to comply :!: )
p.s. if you are forming openings in the walls for louvres and hit and miss vents why don't you just make a bit bigger opening on one side and install a small opening window for ventilation.
 
Yes, I did look at that document yesterday and it seemed to only be concerned about kitchens, bathrooms, utility rooms, etc. Places where a lot of humidity might lurk. The only figures I could find was for the smallest space (<50m2) a vent size of 35000mm2, which is even smaller than my little 127x150mm Louvre Vent. So there doesn't seem to be that much requirement for ventilation. My trickle vents are 2 x 30cm long so that alone seems to cover things.

Regarding windows, yes, in retrospect I would have done all sorts of things, including an opening window. However there doesn't seem to be any such thing as a simple, small, opening window. There are uPVC ones, but the frames alone are 7cm all the way around. So I would need to accommodate quite a large aperture for something like that. I think a small vent will suffice.
 
However there doesn't seem to be any such thing as a simple, small, opening window.
You can get windows made any size you want but if you are happy with the vents you are proposing that's solved (y)
 
cheapish ones with tiny frames? If so, please point me in the right direction.
 

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