rudy558
Advanced Member
- Joined
- Oct 22, 2023
- Posts
- 49


We’ve been struggling with persistent condensation and airflow issues in our 337 RLS Reflection and could really use some advice from those who have tackled similar problems.
Temperature Conditions:
- The worst condensation happens during extreme cold (below 20°F with wind chill). We believe the temperature differential is a key factor.
Our Setup:
- RV Model: 337 RLS Reflection 5th Wheel
- Problem Areas:
- Hitch-Side Cold Draft – Cold air enters on the hitch side of the bed, leading to condensation between the bed and the slide-out wall.
- Moisture Under the Bed & Dog’s Sleeping Area – Condensation forms along the floor under our dog's bed in the closet alcove, leading to mold against the step-up.
- Hitch-Side Cold Draft – Cold air enters on the hitch side of the bed, leading to condensation between the bed and the slide-out wall.
What We Need Advice On:
1. Checking for Mold and Removing Carpet
- What We’re Planning to Do & Need Advice On:
- Remove the carpet between the outer wall of the slide-out and the bed support to inspect the wood underneath.
- Any tips for safely doing this in a slide-out?
- Remove the carpet between the outer wall of the slide-out and the bed support to inspect the wood underneath.
- What We Are Encountering:
- Moisture and mold on the wall and floor of the hitch side of the bedroom slide out between the bed and the slide out wall.
- What We’ve Done So Far Since Discovering the Mold Again:
- As a temporary fix before we start ripping things apart, we followed the instructions on Mold Control Fungicide.
- Moved one of the dehumidifiers into the slide-out corner.
- Attached a small fan to the legs of the homemade night stand (has space around the support for airflow and a damp rid container) between the bed and the slide out wall
- As a temporary fix before we start ripping things apart, we followed the instructions on Mold Control Fungicide.
- What We Tried Previously To Prevent Moisture (That Wasn’t Enough):
- The homemade nightstand that has been in that corner for a year has space around the support for airflow and we had a damp rid container in there
- There is a dehumidifier in the room
- The homemade nightstand that has been in that corner for a year has space around the support for airflow and we had a damp rid container in there
- For the general airflow situation: see Section 4. General Air Flow and Moisture Situation
2. Pulling Up Trim in the Closet Step Area
- What We’re Planning to Do & Need Advice On:
- Remove the trim to inspect for mold and moisture.
- Any advice on removing this without damaging the structure?
- Remove the trim to inspect for mold and moisture.
- What We Are Encountering:
- We found moisture buildup between the bottom of our dog’s bed and the floor as well as mold on the step in the closet alcove
- We suspect more mold behind the trim where the closet step meets the floor.
- We found moisture buildup between the bottom of our dog’s bed and the floor as well as mold on the step in the closet alcove
- What We’ve Done So Far Since Discovering the Mold Again:
- As a temporary fix before we start ripping things apart, we followed the instructions on Mold Control Fungicide.
- What We Are Now Doing to Prevent Future Issues:
- We have now placed her bed on a raised dog bed frame to maximize airflow even more than that provided by Dricore.
- Attached a small fan to the clothing rack in the closet to increase airflow further.
- We have now placed her bed on a raised dog bed frame to maximize airflow even more than that provided by Dricore.
- What We Tried Previously To Prevent Moisture (That Wasn’t Enough):
- Used Dricore Mattress Underlay between our dog’s bed and the floor and between the back of her bed and the closet step-up - moisture occurred where it was anyway
- Removed the closet doors (her bed wouldn’t fit otherwise).
- Used Dricore Mattress Underlay between our dog’s bed and the floor and between the back of her bed and the closet step-up - moisture occurred where it was anyway
- Notable: We didn’t find moisture in the rest of the closet—only between the dog bed and the floor/step.
- For the general airflow situation: see Section 4. General Air Flow and Moisture Situation
3. Improving Bed Airflow & Lowering Bed Height
- What We’re Planning to Do & Need Advice On:
- We are considering replacing the solid wooden support with a steel support that has lots of airflow and is shorter (bed frame)
- How might replacing the bed support affect the slide-out’s function?
- Any concerns about wiring, slide-out mechanisms, or movement?
- We are considering replacing the solid wooden support with a steel support that has lots of airflow and is shorter (bed frame)
- What We Are Encountering:
- We are not having mold between our bed and the bed support
- Our bed is just too high, we have to be careful not to hit our heads on the slide out ceiling
- Because of this and the general issue of airflow in other parts of the bedroom, we are thinking of changing things up.
- We are not having mold between our bed and the bed support
- What We Tried Previously To Prevent Moisture (That Wasn’t Enough):
- Installed a mattress underlay under the bed Dricore (in place for about a year).
- Painted the wood bed support with antifungal paint (in place for about a year).
- No issues with moisture/mold under the bed, only between the bed support and the outer slide-out wall.
- Installed a mattress underlay under the bed Dricore (in place for about a year).
4. General Air Flow and Moisture Situation
- Bedroom Door Removed – Since it’s just us, we keep the bedroom door off to allow maximum airflow
- Dehumidifiers – One in the bedroom, one in the living room, we had one in the bathroom but have moved it to between the bed and slide out for now.
- Ventilation
- Kitchen vent is always used when cooking.
- Showering is avoided in the RV whenever possible (alternative showering options used).
- When we do shower, we open the vent and run the fan to prevent condensation.
- Kitchen vent is always used when cooking.
5. Additional Thoughts & Photos
- We’ll include photos of what we’re dealing with. It’ll take a second because I’m going to post this first.
- Any suggestions on any section would be greatly appreciated!
- We’ll also update this thread with what we find and what ends up working (or not working) to help future forum members dealing with similar issues.
Edited because half the text ended up bolded for some reason.
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