Do you ventilate your shed and if so, how?

[Adsibob]

About to place my shed order and I notice that the Ts and Cs state "It is advisable whenever possible to ventilate your shed by leaving windows/doors open. This will allow any condensation to evaporate and help to avoid any humidity that may gather inside the building." The shed I'm getting does not have openable windows, just fixed, so only option would be open door every so often, which seems unlikely to be sufficient or convenient.

 

Options I can think of:

 

1. drill various holes either side of the shed to allow air in and out - this is the cheapest and easiest, but query whether this risks the integrity of the shed or encourages rodents or any other downsides? 
2. install some small extrator fans, and a solar panel on the roof to power the fans and the lightbulb i want to hang internally - seems like overkill to me.
3. ignore the Ts and Cs and hope for the best.

 

Thoughts?

[markc]

Think the T&C’s are a standard cop-out. Sheds often get stuff thrown in and then left shut for weeks on end. If you intend to use the shed then no additional ventilation needed. Plus sheds are rarely air tight

[JohnMo]

Mine came with a slot below the roof line that could be either filled in or left open, so just left the strips of wood out.

 

But its a bit of a cop out, there should be no humidity being generated, unless you sleep in it, plus they do leak like a sieve generally.

[Adsibob]

6 minutes ago, JohnMo said:

Mine came with a slot below the roof line that could be either filled in or left open, so just left the strips of wood out.

 

But its a bit of a cop out, there should be no humidity being generated, unless you sleep in it, plus they do leak like a sieve generally.

Why would a new shed leak? Most come with a five to 12 year guarantee (seems to vary from supplier to supplier), so surely one wouldn't expect it to leak within that time. 

[JohnMo]

They leak air not water, your topic is ventilation, not water leaks.  They will be water tight.  The T&G, the joints between panel all leak air.

[Radian]

because the envelope of a shed delays mixing between outside and  inside air, when conditions change outside, some of the moisture inside will condense on the cold surfaces and degrade the fabric of your shed - and your stuff within it. The more the air is exchanged between inside and out, the less this will happen. Hence why cattle sheds are so draughty with great gaps between boards.

[Adsibob]

49 minutes ago, Radian said:

because the envelope of a shed delays mixing between outside and  inside air, when conditions change outside, some of the moisture inside will condense on the cold surfaces and degrade the fabric of your shed - and your stuff within it. The more the air is exchanged between inside and out, the less this will happen. Hence why cattle sheds are so draughty with great gaps between boards.

Very helpful. So would you add more opportunities for air changes by drilling holes, for example, or would you rely on the non-airtightness inherent in the shed?
Normally it wouldn't be that important to control humidity in a shed, but I need to store some books and other items for about 4-6 months until our house is properly finished.  These are already in sealed cardboard or plastic boxes that have been covered with a dust sheet, but they've been in our shed for the last 12 months. That shed is very draughty, and just about waterproof, but will soon collapse it is so old and unstable, so trying to figure out what to do about ventilation in the new shed. Even in the old draughty shed, cardboard that I put in a couple of months ago has already gone a bit damp. We're in London where external humidity levels can be very high, particularly in Autumn.

[Radian]

Books are really hard to store in such conditions. The air that's contained along with them, be they in a bag or box, will still have a moisture content that periodically condenses and wets the paper. Only a vacuum bag will get around this because even if you seal them in dry conditions it's virtually impossible to do it in air with sufficiently low humidity. For instance air at 20^oC with an almost impossibly low RH of 25% has a dew-point of -0.5^oC which is possible even in London.

 

If you can't get them in a proper vacuum bag, you might be able to improvise, otherwise the shed ventilation should be as much as is practical while achieving the other goals such as keeping out the rain and vermin. Paradoxically, books might fair better outdoors with just protection from blown-in rain and mist, picture them outside in a big tent with a flappy door.

[Jilly]

I would dry the books out in the house and then put them in thick plastic sealed boxes to store in the shed because as you've noticed, the ones in cardboard will get damp and mouldy. However, Radian thinks that won't work.

Edited November 11, 2022 by Jilly

[Radian]

1 minute ago, Jilly said:

I would dry the books out in the house and then put them in thick plastic sealed boxes to store in the shed because as you've noticed, the ones in cardboard will get damp and mouldy. 

That might help them hold out if it really is only for a few months. It's amazing how difficult it is to get an effective seal as repeated heating and cooling makes the air expand and contract which pumps it out and in, along with whatever moisture is in the outside air.

[Bonner]

I didn’t put any vents in and last winter the shed was constantly damp with condensation. I put two vents each side, high and low level, dried out by the next day.

[Adsibob]

5 hours ago, Bonner said:

I didn’t put any vents in and last winter the shed was constantly damp with condensation. I put two vents each side, high and low level, dried out by the next day.

This sounds like a good idea. What type and size vents did you install?

[Bonner]

7 hours ago, Adsibob said:

This sounds like a good idea. What type and size vents did you install?

 

These https://www.screwfix.com/p/map-vent-fixed-louvre-vent-matt-anthracite-229-x-152mm/691hy

 

(Goes with this! https://www.screwfix.com/p/no-nonsense-garden-colour-wood-paint-semi-matt-slate-grey-2-5ltr/8397x)

[Adsibob]

So shed went up about 6 weeks ago. Not had time to do much to it until today. Had a damp and mould problem in another under-ventilated shed which materialised last week, mould growing on various rubber and fabric material parts of bikes, with condensation dripping from the inside roof, so was keen to avoid the same thing happening here, although this is a wooden shed, whereas the one generating mould is metal.

 

In a bit of a rush I've gone for a rather inelegant solution of attacking it with an 8mm drill bit. Have drilled:

• 16 holes on one side (which is not really visible from the house or garden, and they are tucked up high, just under the large overhang so no risk of water getting in there.
• 5 holes on the back of the shed, again high up near the roof line,
• 8 holes on the other side of the shed.

The front face of the shed, which is the one visible from the house and garden has no holes in it (other than the keyhole). Do people think this, together with the natural leakiness of the shed, is enough? Each hole has an area of 50mm2. If not enough, the side that has no holes on it currently, could easily get extra ventilation by shaving off 2mm or so off the top of the door to create a ventilation gap there, but maybe this isn't necessary?