Best way to keep condensation under control

[Titotoby]

Starting to think through the insulation plan for my tiny home build later on, and I keep circling back to one major concern about condensation, with such a small interior volume and constant temperature swings coz I know moisture can become a real issue fast if I don't get the vapor barrier and ventilation right. I've seen a lot of conflicting advice about where to place the vapor barrier, some say warm side only, others suggest vapor open walls that can breathe both ways. I'm planning on spray foam in the roof and rigid or batt insulation in the walls, but I don't want to seal it up so tight that moisture has nowhere to go obviously. Am i asking for too much lol?
A lot of the plan has come together already, this is just but of few hurdles that are left
How should I go about this in the best way?

 

[radiogugu70]

Dont worry, its not much lol. Anyway, condensation can be a big problem in tiny homes for sure, yes, especially with temperature swings. Generally, it's best to put the vapor barrier on the warm side (inside) to keep moisture from getting into the walls. Spray foam in the roof is great, but for walls, using rigid or batt insulation with proper ventilation or a vapor-permeable barrier helps prevent trapping moisture. The key is balancing sealing with good airflow, so install vents or a small ventilation system to let moisture escape. Hope any of this helps. Good luck!

 

[Deleted member 45]

I love the idea of spray foam. But cost keeps pushing me back to foil radient barrier and fiberglass. My attic (vents location) is approx 6 inches in middle so that limits choices aside from cost. There need to be some space for air

 

[decluttered.dee]

Starting to think through the insulation plan for my tiny home build later on, and I keep circling back to one major concern about condensation, with such a small interior volume and constant temperature swings coz I know moisture can become a real issue fast if I don't get the vapor barrier and ventilation right. I've seen a lot of conflicting advice about where to place the vapor barrier, some say warm side only, others suggest vapor open walls that can breathe both ways. I'm planning on spray foam in the roof and rigid or batt insulation in the walls, but I don't want to seal it up so tight that moisture has nowhere to go obviously. Am i asking for too much lol?
A lot of the plan has come together already, this is just but of few hurdles that are left
How should I go about this in the best way?

For spray foam in the roof, a vapor barrier on the warm side is often inherent with closed-cell foam, as it acts as both insulation and a vapor retarder.
For your walls with rigid or batt, aiming for a vapor design that's open to the exterior is often a good strategy.
This means your primary vapor control layer, if needed, is on the warm side of the insulation, but the exterior sheathing and cladding allow any incidental moisture to escape outwards.
Good ventilation, perhaps an ERV/HRV, will also be critical for managing interior humidity from daily activities.
It's a balance, but entirely achievable!

 

[smallspaceBiglife]

Yeah for sure! Closed-cell foam makes putting roofs together way easier since it insulates and keeps moisture out. And going with walls that let vapor escape to the outside is a smart way to handle moisture. Plus, having an ERV or HRV is a must

 

[eDJ_]

A home has to "breathe" somewhat. It provides for some exchange of air which will help to evacuate a buildup of moist air in the home. People even give off vapor, so a home that is too tightly sealed may not be healthy for people or the building.

Some would purchase a de-humidifier if in a cooler (northern) area to condense the water from the air and drain it. A small window air conditioner could give both AC and de-humidification. There is also such a thing as an air to air exchanger. The EVR's in particular recover a significant amount of the energy used for heating or cooling while making the ventilation process highly energy-efficient. This system uses a special medium core that the air moves thru going out and fresh air moves thru coming in. The core retains most of the warmth or cool to impart back into the incoming air. There is some loss but by and large they are considered efficient.