What defines a TT as a "True Four Season"?
So, I have heard this phrase tossed around, "True Four Season", and I am wondering if there is literal exact definition that applies here. The fact that the word "True" is added to the term "Four Sea...
Forum Discussion
Most TTs use open cell insulation in the walls of fiberglass side units. That has an R-value of about 3.6 per inch so if your walls are only an inch thick, that's not much insulation. Outdoors RV states their walls are 2" thick but if they use open cell insulation, the wall R-value would be about 8 which still isn't that great. If Outdoors RV used closed cell insulation, they could get an R-value of about 14 which would be way better than the typical TT. Can't see where OR states what type of insulation they use.
Our KZ TT has a fiberglass exterior but only the side walls have foam and the front and rear have batt insulation.
Some TTs (like ours) use Reflectix blankets to supposedly increase the R-value but from what I've read, the jury is still out on whether they actually help much. I don't think it does much for us and they would have done better by insulating the ceiling correctly.
TTs aren't built right in terms of a moisture retarder/vapor barrier. With open cell insulation moisture migrates to the exterior skin in cold temps and will condense, leading to rot, corrosion and delamination. If they were to use the closed cell, that prevents moisture from migrating through it. A house usually has a type of insulation that does not stop moisture migration but there is a barrier on the interior side of the wall (sheet plastic) that a TT does not have.
Outdoors RV units have two or three layers of batt insulation in a ceiling. That is good, but it depends on how it is installed. If it is compressed at all, it loses it's R-value. And if moisture is allowed into it, the R-value also drops. So unless they have a vapor barrier on the underside of the insulation, I think the actual R-value will be less than stated.
In our TT, we have an arched ceiling and there is no batt insulation around the entire perimeter about 6" inward because there is too little space to install any. As well, there are many voids and in many locations, gaps because of wiring laying across the joists. With the greatest heat loss being in a ceiling, I would guess that the insulation in most or all TTs is poor.
In cold weather, you can have the best insulation possible but you must vent out the moisture laden air by opening a window(s) and running a roof fan and/or using a dehumidifier. Some will even seal up every opening possible, including the weep holes in windows in an attempt to retain heat and reduce propane consumption. Big mistake. The average adult human body gives off around 2 pints or more of water per day depending on activity level, plus you've got moisture from showering and cooking. That's a lot of water to expel to the outside and if you don't will lead to damage to the structure. I read of one case where a person was staying in a FW over the winter in Seattle and water was raining down on him from the ceiling from a failure to expel moisture laden air.
Many enclosed underbellies heat the space from a couple of ducts off the furnace which is very inefficient. I'd look for a TT that has heating blankets under the tanks and better insulation in the floor instead or even do that yourself.
If you have shore power available, I would consider electric heating over a furnace if the TT has good insulation. We run our TT on 2,000 watts total of 3 permanently mounted heaters on 30 amps and it works well down to near freezing for our 29' unit (overall).
Outdoors may be ahead of the pack on 4-season TTs but could still be less than technically possible and desirable. Overall, their units are much better built & designed than most of the rest tho.
Our KZ TT has a fiberglass exterior but only the side walls have foam and the front and rear have batt insulation.
Some TTs (like ours) use Reflectix blankets to supposedly increase the R-value but from what I've read, the jury is still out on whether they actually help much. I don't think it does much for us and they would have done better by insulating the ceiling correctly.
TTs aren't built right in terms of a moisture retarder/vapor barrier. With open cell insulation moisture migrates to the exterior skin in cold temps and will condense, leading to rot, corrosion and delamination. If they were to use the closed cell, that prevents moisture from migrating through it. A house usually has a type of insulation that does not stop moisture migration but there is a barrier on the interior side of the wall (sheet plastic) that a TT does not have.
Outdoors RV units have two or three layers of batt insulation in a ceiling. That is good, but it depends on how it is installed. If it is compressed at all, it loses it's R-value. And if moisture is allowed into it, the R-value also drops. So unless they have a vapor barrier on the underside of the insulation, I think the actual R-value will be less than stated.
In our TT, we have an arched ceiling and there is no batt insulation around the entire perimeter about 6" inward because there is too little space to install any. As well, there are many voids and in many locations, gaps because of wiring laying across the joists. With the greatest heat loss being in a ceiling, I would guess that the insulation in most or all TTs is poor.
In cold weather, you can have the best insulation possible but you must vent out the moisture laden air by opening a window(s) and running a roof fan and/or using a dehumidifier. Some will even seal up every opening possible, including the weep holes in windows in an attempt to retain heat and reduce propane consumption. Big mistake. The average adult human body gives off around 2 pints or more of water per day depending on activity level, plus you've got moisture from showering and cooking. That's a lot of water to expel to the outside and if you don't will lead to damage to the structure. I read of one case where a person was staying in a FW over the winter in Seattle and water was raining down on him from the ceiling from a failure to expel moisture laden air.
Many enclosed underbellies heat the space from a couple of ducts off the furnace which is very inefficient. I'd look for a TT that has heating blankets under the tanks and better insulation in the floor instead or even do that yourself.
If you have shore power available, I would consider electric heating over a furnace if the TT has good insulation. We run our TT on 2,000 watts total of 3 permanently mounted heaters on 30 amps and it works well down to near freezing for our 29' unit (overall).
Outdoors may be ahead of the pack on 4-season TTs but could still be less than technically possible and desirable. Overall, their units are much better built & designed than most of the rest tho.
