Let's talk about tents.

[Profpointy]

Can't you also get dampness inside the tent if the air outside is particularly dewy/moist?

I awoke in my Lodge 2 a few months ago to find the outside of my sleeping bag sodden. I am pretty sure I had left some vents open but on getting out of the tent I did notice that the air seemed particularly heavy mosture. It hadn't rained though and my faithful Lodge 2 hadn't leaked, though from seeing my sleeping bag you would have thought it had.

I think the first bit is wrong. The cold air outside can only hold so much dampness, but the warmer air inside can hold more. Thus the warm, breath laden, damp air inside will condense out on the cold walls of the tent. Damp air from outside will not condense inside the tent - as it'll warm up and thus be able to hold even more damp. (I think)

 

[graham bowers]

Right so, if I'm understanding all this correctly, the warmer the tent, the more the condensation.

Why then is there a market for warmer tents? What's the advantage?

If the advice is to have as much ventilation as possible, why then inhibit that ventilation in the design?

I can't answer these questions. When picking a tent the attributes I consider are, in no particular order:

Stability in bad weather - normally i'd go for a 3 season tent.
Weight
Durability
Ease of pitching. I like the choice of inner first, outer first, both together.
Porch size
Established brand.

Warmth and condensation potential I've never even considered from the perspective of tent selection. My sleeping bag / liner / mat combination take care of warmth. I trust that a well designed tent will have sufficient ventilation. My tent has zippable ventilation high up at the foot end and at the door. If I get a bit of condensation from time to time its not the end of the day. It (the tent) has on occasion protected me well in some vile weather.

Context of all of the above is UK (including Scottish wild camping) / mainland Europe camping on foot or by bicycle. Normally March until October.

Having re-read your questions, is there a market for warmer tents, or put another way, are any tents being marketed as being "warmer"?

 

[classic33]

The tent should be treated as shelter from the elements, with clothing/sleeping bag(s) providing the final heat trap to keep you warm.

An idea if you walk in small groups is an old tent outer, no poles or guy lines, and use that as a shelter when you stop. It'll keep the worst of the weather off you and provide a windbreak.

 

[HobbesOnTour]

Maybe I'm a bit of a tent nerd, but I'm enjoying this conversation!

My understanding of the complex world of tents is;

In a typical tent, there is the fly the purpose of which is to keep the rain out and divert the wind. In snow it's supposed to keep the snow off you and in sun to protect you from the worst of the rays. It normally has some ventilation options to allow air to circulate.

Then there's the inner. At a minimum, that's supposed to keep the bugs out. 3/4 season tents will use less mesh than 1/2 season tents with a view to keeping the inner warmer. These 3/4 season tents will often incorporate a layer over the mesh that can be zipped off to increase ventilation.

Ventilation is required to prevent (minimise actually) condensation forming on the inside of the fly when the warmer air inside comes into contact with the colder air outside through the fly.

And of course there is the floor of the inner, sitting on the ground, or perhaps a footprint/groundsheet.

So, a question:

In a 3/4 season tent with less mesh and if the mesh that exists is covered there will be greater condensation, right? Is this due to less ventilation (because the lack of mesh means that the air coming from the vents in the fly cannot easily flow through the whole tent) or is it due to the "sealed" inner becoming warmer, and heating the air under the fly. Or a combination of the two? Or something else altogether?

In that scenario, if I unzip the covering on the mesh, all things being equal, I should have less condensation. Right?
So why are there covers on the mesh in the first place?
(This is what I was getting at mentioning a "market" for warmer tents.)

As I type, I'm thinking that if a tent is going to be pitched for a long time, then condensation on the fly is not such a big issue and a bit of extra warmth might be beneficial.

But if a tent is going to be packed up every day, then condensation is going to cause more problems.

It seems to me that for what we do, cycle touring, we should be looking for tents with as much mesh as possible and as much ventilation in the fly as possible.

And then we come to the floor. Heat from your body in close contact with the colder ground = condensation on the floor under your mat = damp/wet mat. If there's no chance to dry it out, then you've a wet mat the next night.
How to solve this? I don't think any ventilation will help here. I don't think the size of the tent is a factor either.
I use a Thermarest pad with a good insulation value, on top of a foil insulating sheet, on the floor of the tent that sits on a waterproof groundsheet. And the floor is still wet underneath.

For context, I'm talking about Netherlands/Germany/Belgium, winter time, temperatures from 2/4 C to -8/-10.

Many thanks for all the contributions so far!

 

[reppans]

In my experience, in cold weather condensation is expected and is intended to form on the underneath of the fly of a double wall tent. If heavy enough, the condensation will bead on the inside of the fly and run down to the ground outside of the inner tent's bath tub floor... (ie. not drip on top of the inner tent). Below freezing, the condensation will be frost.

The inner tent, whether all mesh or all fabric, will 'breath' allowing air humidity to pass through to fly. Therefore the inner tent will stay dry for the occupants and should not touch the fly as that's where water transfer will occur. The inner tent floor should generally not condense water (warm humid air rises).

When taking down, frost and condensation on the fly can be shaken off and mopped up with a bandanna - with the bulk of the moisture off, it can sun dry quickly. Also no big deal if you pack the fly damp (but fold separately so it doesn't get anything else wet) - just don't ever leave it wet stored for days.

 

[HobbesOnTour]

Thanks for the reply.

In my experience, in cold weather condensation is expected and is intended to form on the underneath of the fly of a double wall tent. If heavy enough, the condensation will bead on the inside of the fly and run down to the ground outside of the inner tent's bath tub floor... (ie. not drip on top of the inner tent). Below freezing, the condensation will be frost.

That's my understanding too.

The inner tent, whether all mesh or all fabric, will 'breath' allowing air humidity to pass through to fly. Therefore the inner tent will stay dry for the occupants and should not touch the fly as that's where water transfer will occur.

Here's where I want to dig a little deeper.
Does the proportion of mesh to non-mesh on the inner have an effect on the overall amount of condensation?
In simple terms, 2 identical flys pitched side by side, one with an inner that is almost 100% mesh and one with as little mesh as possible.
Will these tents generate the same amount of condensation, or will one have less than the other?
I'm thinking that the temperature in the enclosed inner will be warmer than the mesh inner. This warmer air will eventually migrate out to the fly and condense. Therefore the enclosed inner will generate more condensation. Or does the lack of mesh mean that there is less airflow from the inner to the fly, so even though warmer, there is less condensation on the fly?
My own experience is that by exposing as much mesh as possible will reduce the condensation on the fly. Back in March, temp about 3C I slept under a fly only on a groundsheet and had less issues with condensation on the fly.

When taking down, frost and condensation on the fly can be shaken off and mopped up with a bandanna - with the bulk of the moisture off, it can sun dry quickly. Also no big deal if you pack the fly damp (but fold separately so it doesn't get anything else wet) - just don't ever leave it wet stored for days.

I always wipe :-)
But here's the thing - a tent that is an all-in-one pitch is fundamentally flawed because the fly will be wet with condensation which will then transfer to the inner on break-down.

The only way to avoid this is to remove the inner first and pack the fly separately, which defeats the purpose of an all-in-one pitch.

In every discussion of tents that I've seen, there are always debates about the best design/brand/tent with people swearing by (or indeed swearing at!) various tents.

What is hardly ever spoken about is how often people pitch and breakdown their tents.

For someone who is pitching their tent every day, then condensation is a bigger factor than for someone who pitches their tent every 3 days, for example.

When I go off on my bike, I'm pitching my tent in a new location every day.
I don't mind the cold, but I hate being wet off the bike, because invariably I will get cold and then it's harder to warm up.

In winter time, the options to dry the tent are much less - less sun, shorter days. So, my logic (and here's where I'm looking for discussion) is that the best tent for cycle touring in colder weather is the one that generates the least condensation. Therefore 3-4 season tents should be out of the decision? A strong construction for the fly to keep wind and rain off you, an inner with a high mesh content and your sleeping mat/pad/bag keeps you warm.

And here we are back at the philosophical question! Is it the purpose of the tent to keep you warm or dry?

The inner tent floor should generally not condense water (warm humid air rises).

This is the only thing that in my experience I disagree with. All winter I've had issues with condensation on the floor, specifically under the mat. The only time I did not have an issue was when I didn't bother putting up the inner as a storm broke just as I was pitching the tent. My old tunnel tent with a thick, low tech floor never had these issues.
Anybody else have any input on this?

 

[Blue Hills]

But here's the thing - a tent that is an all-in-one pitch is fundamentally flawed because the fly will be wet with condensation which will then transfer to the inner on break-down.

The only way to avoid this is to remove the inner first and pack the fly separately, which defeats the purpose of an all-in-one pitch.

An excellent point. These days when moving on I always pack inner and fly separately - roll up the inner with its groundsheet and put it in the tent bag. Just stuff willy nilly the fly in a small light drybag. If room put that in the tent bag, if not pretty much anywhere else. Within 12 hours it will be up again to dry out. Apart from anythin6g else this avoids the palaver of rolling one inside the other with all the bother of checking that A doesn't touch B. Always makes me think of a technical jam rollypolly operation. Far faster to pack this way. And lack of faff is particularly welcome if free camping.

As a side issue, have always been suspicious of all in one pitching, and particularly those tents where the two bits are supposed to stay permanently connected. Sounds too "clever" and "designed" to me - Pretty sure I'd end up buggering something up and then it would be more of a problem to fix things.

Keep it simple has been my motto with both camping and cycling for the last few years.

If anyone has a good reason why your point is not a good/excellent one, feel free to post it of course.

 

[reppans]

IMHO, the proportion of inner tent mesh vs solid wall should not have a significant bearing on fly condensation - our bodies expel the same amount of moisture either way, and that's what is condensing on the fly. The fact that the solid wall might result in a few degrees warmer interior just means that that air might hold just a tiny bit more moisture at given point in time, but over the course of the night, both mesh and breathable solid will move about the same total body/breath moisture to the fly surface. The best way to minimize condensation on the fly would be to increase air circulation between the inner tent and fly, although I suspect too much circulation would both lose the insulation value of the dead airspace between the walls, and might even start a condensation problem on the inner wall. It's a compromise.

Good point on the all-in-one pitch tents - my mid w/nest can used that way, but my usual config (for space, access, bugs, rain) is fly and footprint only while awake. I only set-up my inner tent for sleeping.

I'm admittedly not a big winter camper, but have snow camped a few times... I just don't recall ever having a floor condensation/moisture issue, except where it has either dripped down from wall condensation, or pushed up though (compromised waterproofing) from the wet or evaporating ground. I always use footprints though (silnylon, tyvek or polycryo).

You sure it's not coming up from the ground? I wouldn't think you'd have enough breath/body moisture circulating under a groundpad to condense.

 

[classic33]

Anyone else use a survival bag under the groundsheet?

 

[HobbesOnTour]

Thanks for the reply.

IMHO, the proportion of inner tent mesh vs solid wall should not have a significant bearing on fly condensation - our bodies expel the same amount of moisture either way, and that's what is condensing on the fly. The fact that the solid wall might result in a few degrees warmer interior just means that that air might hold just a tiny bit more moisture at given point in time, but over the course of the night, both mesh and breathable solid will move about the same total body/breath moisture to the fly surface.

That makes perfect sense, but it's not matching my experience. If I leave the mesh covered in my "expedition" standard tent I will have more condensation on the fly and on the floor, than if I don't. In comparison, my cheapy tunnel (all mesh) has no such issues. Admittedly, the tunnel is larger than the other.

Good point on the all-in-one pitch tents - my mid w/nest can used that way, but my usual config (for space, access, bugs, rain) is fly and footprint only while awake. I only set-up my inner tent for sleeping.

As simple as it is, that is a very clever idea!

You sure it's not coming up from the ground? I wouldn't think you'd have enough breath/body moisture circulating under a groundpad to condense.

I'm as sure as I can be that the floor is not leaking. As I said above, leaving the mesh covered will result in a wet floor. Opening up the mesh will mean only the floor under the mat is damp.

Anyone else use a survival bag under the groundsheet?

I use building insulating foil under my sleeping pad, on the floor, which is on top of a groundsheet.

 

[Blue Hills]

What's this building insulation foil hobbes?

Sounds interesting, though I fear that it might not be economically available in small bits.

Unless you are in the trade.

 

[classic33]

What's this building insulation foil hobbes?

Sounds interesting, though I fear that it might not be economically available in small bits.

Unless you are in the trade.

Wickes sell it.

Thermawrap is one brand.

 

[classic33]

As for whether the tent is for protecting you from the weather or keeping you warm, try sitting in your tent with no clothes on when its cold, wet and windy.

 

[Blue Hills]

Thanks classic.

You mean this?

https://www.wickes.co.uk/Wickes-Thermal-Insulation-Foil-Roll-600mm-x-8m/p/210022

Tho you have to buy a fair bit.
So may be better using the dosh for a better mat.

 

[Blue Hills]

Or this?

https://www.wickes.co.uk/Thermawrap-Radiator-Reflective-Foam-Foil-500mm-x-5m/p/151452