Insulating the Belly of my TT
I’m interested in bolstering the insulation of my travel trailer… preparing it for 4 season camping. The walls and ceiling are fine - I just need additional insulation under the floor. The holding t...
Forum Discussion
You are fighting a losing battle from the start regardless. As mentioned, walls and ceilings are poorly insulated. I doubt the ceiling is insulated as well as you think. I've seen inside the ceiling space of several TTs now and the insulation is terrible. Lots of voids, lots of compressed insulation (reduces R value) and not enough R-value. Our current TT has no insulation along the sides about 6" inward. Most (all?) slide outs don't have any insulation under the floors and you can't add any underneath.
On top of that, you need to ventilate the interior, esp. during cold weather so you are pumping heated air outside. Heated underbellies are very inefficient because the heated air in the cavity also ends up outdoors. The furnace can run almost non-stop in cold weather.
IMO, insulating the floor will still help, mostly for in the heating season and esp. if doing cold weather camping. I come from a building construction background and have been involved with heating system design and I know insulating floors helps a lot and it's required by code anyway. Upgrading insulation under the floor will make it feel much warmer to your feet if you're not wearing slippers or shoes and will also make your lower legs warmer.
If it were me, I'd redo any water system piping so that it is just under the floor and put a good layer of rigid insulation below that. Use heating blankets under the tanks and heat tape where needed. (Except if you dry camp in below freezing temps, not a solution.) Spray foam would work really well but you'd have a mmajor problem getting at things to repair them if ever needed. Expensive too. You should be able to install rigid foam so that it surrounds the tanks. In fact, it might be possible to put a rigid foam layer immediately under the sub-floor and immediately above the coroplast layer so that there is a totally insulated cavity under there. You *might* even be able to reduce the heated air CFM into the cavity that way? I'd maybe look at bolstering the tank supports as they can sag a fair bit when full.
I think the ONLY reason manufacturers install enclosed underbellies is to hide all the substandard work. Also, IMO batt insulation is a poor choice under a TT. Anyone who takes down the coroplast should be ready for a big shock - wires and pipes thrown in there, bad insulation work, etc. I plan to re & re ours to address any issues that are in there, and there will be some.
If using rigid foam, I'd look at using polyisocyanurate type as it has a much higher R-value per inch. It's what's used in freezer walls and garage doors for ex.
If upgrading insulation, also look at adding some under the bed where the pass-through storage is.
It would be nice to see some photos of the work in progress.
On top of that, you need to ventilate the interior, esp. during cold weather so you are pumping heated air outside. Heated underbellies are very inefficient because the heated air in the cavity also ends up outdoors. The furnace can run almost non-stop in cold weather.
IMO, insulating the floor will still help, mostly for in the heating season and esp. if doing cold weather camping. I come from a building construction background and have been involved with heating system design and I know insulating floors helps a lot and it's required by code anyway. Upgrading insulation under the floor will make it feel much warmer to your feet if you're not wearing slippers or shoes and will also make your lower legs warmer.
If it were me, I'd redo any water system piping so that it is just under the floor and put a good layer of rigid insulation below that. Use heating blankets under the tanks and heat tape where needed. (Except if you dry camp in below freezing temps, not a solution.) Spray foam would work really well but you'd have a mmajor problem getting at things to repair them if ever needed. Expensive too. You should be able to install rigid foam so that it surrounds the tanks. In fact, it might be possible to put a rigid foam layer immediately under the sub-floor and immediately above the coroplast layer so that there is a totally insulated cavity under there. You *might* even be able to reduce the heated air CFM into the cavity that way? I'd maybe look at bolstering the tank supports as they can sag a fair bit when full.
I think the ONLY reason manufacturers install enclosed underbellies is to hide all the substandard work. Also, IMO batt insulation is a poor choice under a TT. Anyone who takes down the coroplast should be ready for a big shock - wires and pipes thrown in there, bad insulation work, etc. I plan to re & re ours to address any issues that are in there, and there will be some.
If using rigid foam, I'd look at using polyisocyanurate type as it has a much higher R-value per inch. It's what's used in freezer walls and garage doors for ex.
If upgrading insulation, also look at adding some under the bed where the pass-through storage is.
It would be nice to see some photos of the work in progress.
