u/DSGNjunkie

Hey all — looking for some real-world, long-term feedback on under-deck drainage systems before I lock in a plan.

I’m building a new deck in the Pacific Northwest (so lots of rain, moisture, pollen, etc.) and want to create a dry, usable space underneath where there’s a flat cement slab. The deck will be \~15’ deep x 32’ wide, with joists at 16” OC, draining over the 15’ run (short direction).

**Goals:**
\- Reliable dry space underneath (ideally usable year-round)
\- Long-term durability (not something that fails in a few years)
\- Low maintenance / easy to access if something goes wrong

**Options I’ve looked at so far:**

**Over-joist systems (like Trex RainEscape)**
\- Pros: Keeps framing dry, “best practice” from a building science perspective
\- Cons: Hidden under deck boards → harder to repair if something fails; reviews seem mixed depending on install quality

**Under-joist systems (like TimberTech DrySpace)**
\- Pros: Can install after deck is built, easy to access/repair, doubles as finished ceiling
\- Cons: Joists still get wet (planning to use joist tape on top to help mitigate this)

**Between-board systems (like Dexerdry)**
\- Pros: More “engineered” solution, keeps water above framing
\- Cons: Seems more complex to install and requires more planning/slope adjustments than I’m hoping for

Right now I’m leaning toward an **under-deck system + joist tape + good ventilation**, mainly because I like the idea of being able to access and fix things easily over time… but I’m still concerned about pests getting in and overall longevity.

**Questions for the group:**
\- What system have you used, and how has it held up over 5+ years?
\- Any regrets or things you’d do differently?
\- Have under-deck systems caused any long-term issues with joist rot/mold in your experience?
\- For those with over-joist systems, have you had to repair them—and how painful was it?

Anything I’m not thinking about that I should be?

Appreciate any insight—especially from folks in wet climates.

Hey all — looking for some real-world, long-term feedback on under-deck drainage systems before I lock in a plan.

I’m building a new deck in the Pacific Northwest (so lots of rain, moisture, pollen, etc.) and want to create a dry, usable space underneath where there’s a flat cement slab. The deck will be ~15’ deep x 32’ wide, with joists at 16” OC, draining over the 15’ run (short direction).

Goals:
- Reliable dry space underneath (ideally usable year-round)
- Long-term durability (not something that fails in a few years)
- Low maintenance / easy to access if something goes wrong

Options I’ve looked at so far:

Over-joist systems (like Trex RainEscape)
- Pros: Keeps framing dry, “best practice” from a building science perspective
- Cons: Hidden under deck boards → harder to repair if something fails; reviews seem mixed depending on install quality

Under-joist systems (like TimberTech DrySpace)
- Pros: Can install after deck is built, easy to access/repair, doubles as finished ceiling
- Cons: Joists still get wet (planning to use joist tape on top to help mitigate this)

Between-board systems (like Dexerdry)
- Pros: More “engineered” solution, keeps water above framing
- Cons: Seems more complex to install and requires more planning/slope adjustments than I’m hoping for

Right now I’m leaning toward an under-deck system + joist tape + good ventilation, mainly because I like the idea of being able to access and fix things easily over time… but I’m still concerned about pests getting in and overall longevity.

Questions for the sub:
- What system have you used, and how has it held up over 5+ years?
- Any regrets or things you’d do differently?
- Have under-deck systems caused any long-term issues with joist rot/mold in your experience?
- For those with over-joist systems, have you had to repair them—and how painful was it?

Anything I’m not thinking about that I should be?Appreciate any insight—especially from folks in wet climates.

Hey all — looking for some real-world, long-term feedback on under-deck drainage systems before I lock in a plan.

I’m building a new deck in the Pacific Northwest (so lots of rain, moisture, pollen, etc.) and want to create a dry, usable space underneath where there’s a flat cement slab. The deck will be ~15’ deep x 32’ wide, with joists at 16” OC, draining over the 15’ run (short direction).

Goals:
- Reliable dry space underneath (ideally usable year-round)
- Long-term durability (not something that fails in a few years)
- Low maintenance / easy to access if something goes wrong

Options I’ve looked at so far:

Over-joist systems (like Trex RainEscape)
- Pros: Keeps framing dry, “best practice” from a building science perspective
- Cons: Hidden under deck boards → harder to repair if something fails; reviews seem mixed depending on install quality

Under-joist systems (like TimberTech DrySpace)
- Pros: Can install after deck is built, easy to access/repair, doubles as finished ceiling
- Cons: Joists still get wet (planning to use joist tape on top to help mitigate this)

Between-board systems (like Dexerdry)
- Pros: More “engineered” solution, keeps water above framing
- Cons: Seems more complex to install and requires more planning/slope adjustments than I’m hoping for

Right now I’m leaning toward an under-deck system + joist tape + good ventilation, mainly because I like the idea of being able to access and fix things easily over time… but I’m still concerned about pests getting in and overall longevity.

Questions for the group:
- What system have you used, and how has it held up over 5+ years?
- Any regrets or things you’d do differently?
- Have under-deck systems caused any long-term issues with joist rot/mold in your experience?
- For those with over-joist systems, have you had to repair them—and how painful was it?

Anything I’m not thinking about that I should be?

Appreciate any insight—especially from folks in wet climates.