14' Series Top bunk insulation query

Crew family

Member
Mar 26, 2016
38
77
18
54
Melbourne
Hi all,
Just wondering if anyone has a solution for giving the top bunk of the 14.44-4 extra insulation during hot or cold weather? We have great storm covers that go around the main bed which keeps it coolish in hot weather and stops condensation during cold. Our oldest has the top bunk and feels the heat so we've recently had the light fitting changed to one with a 12V socket to have a portable fan plugged in, but wouldn't mind perhaps putting an extra bit of calico (or similar material) to protect the bedding from condensation during the cold mornings. Any ideas?
 

straydingo

Well-Known Member
Jul 4, 2011
1,137
645
113
Melbourne
Feeling it through the bed mattress or the pop-up skirt or from the old 'hot air rises' (which my kid complains about). You've mentioned heat and condensation which are two different issues in a thermal sense so would need to be addressed separately.

I apologise, but as this is what I base my business on you're about to get a lengthy answer about thermodynamics.o_Oo_O

The 2nd rule of therodynamics is basically that heat will conduct through any given material from the warmest location to the coldest to effectively balance out the whole material to the same temp. (it is "hot air" which rises, "heat" doesn't). So when we say we are feeling the cold come through something, we are actually meaning we are feeling the loss of heat. That becomes a distinction when we are determining what direction of the heat travel we are trying to prevent. In QLD we might want to prevent heat coming in, in Melb we might want to prevent heat escaping.

Insulation comes from two methods - a bulk material such as foam which has trapped air gaps (think pink batts, polystyrene, etc) or by a reflective surface (foil) against an enclosed air membrane/gap. The denser the material (eg rubber) the less the insinuative effect, but the greater the thermal lag, or storage of heat energy to slowly radiate it out later.
Foil alone has no insulation value, it can only work by reflecting radiant energy away, but allows conductive energy through - the air gap is a trap that slows thermal conduction. The thickness of the air gap determines the effect, and the location of the foil to that air gap is the direction it works in.

So for the insulation side of things, you could try a thin polystyrene board between the mattress and timber base. Its not a lot (10mm = R0.25) but might be enough to take a noticeable edge off. (try builders hardware for something like FoilBoard insulation)
Additional foam rubber below or on top of the mattress could also help - a strong foam under, or a softer comfy type (egg shell foam?) if on top.
Third option is a foil-faced bubblewrap product (google PermiFloor or Air-Cell) These are thin (3-5mm) foam or bubble membranes creating the trapped air, then with a foil coating top and bottom.
No real rocket science there and basically not much different from what I specify on housing really. Just a much lesser thickness.

Now condensation is another issue all together and may be contrary to insulation. Condensation forms when the warmer air contains moisture and meets a surface of a certain lesser temperature (usually the 'dew point'). If there is effective ventilation the condensation can be reduced or eliminated. So if you are actually lifting the mattress and finding condensation moisture there in the morning then you need to look at ventilation to let the moist air escape and prevent mould and mildew forming. (This has been common in expanda or camper type bed ends where the outside air is against a 19mm piece of timber directly under a mattress. Cold underside, warm body above.)
Where it is contrary to insulation is that the wrong sort of insulation reduces the air movement and doesn't let moisture escape - namely foil products and to a lesser extent polystyrenes. If using a non-breathable product (foil especially) it needs to have small holes poked through it (again google PermiFloor) The holes let the moist air and moisture out. But again problem - if laid on a timber bunk surface that timber material still can't breathe adequately...
There are products called HyperVent and HydraVent which can go under the mattress. This will allow moist air to escape out to the sides rather than down through the timber. (try a bedding store which sells latek mattresses). I think if installing with insulation, its probably best located between the extra insulation and underside of the mattress (but not certain)
Another option is to drill holes in the bunk timber base to let the moist air out.
If on a bed end where the under surface is external to the caravan, finding the balance of holes sizes and frequency is tricky. And can upset the function of insulation.

Condensation takes a bit of trial and error to sort out unfortunately - identifying the root cause in the first place and then treating it. Not sorting it out will damage timbers and bedding and the mould becomes a big health risk. But this is hugely more important than extra insulation. Tackle that first and foremost if there is condensation occuring.

Sorry for the long winded response but good luck
 
Last edited:

straydingo

Well-Known Member
Jul 4, 2011
1,137
645
113
Melbourne
just had another simpler thought - try a bamboo mattress protector. Just that alone might be enough to reduce the moist air travelling through the mattress.
 
  • Like
Reactions: chartrock

Crew family

Member
Mar 26, 2016
38
77
18
54
Melbourne
Oh wow! Thanks so much for your answer. I'll have a read through properly over the weekend and prepare a solution. The top bunk has also become a little squeaky, so will probably have to replace the ply too.