any others ever deal with this?

Yup, many years ago.
Installed two of the fans you described and they helped a lot.
Don't remember the sq. footage of the crawlspace.

 

Particularly in Florida, I have my doubts that any reasonable venting would do a lot of good. You're drawing moist warm air into a cooler space, and that's going to give you condensation. Most bulletproof way would be to seal it and make it part of the conditioned space.

 

I forced myself to crawl on my back in a Florida crawlspace several years ago. I get the heebie jeebies just thinking about it sitting in my chair. Couldn't do the tunnels when I visited Vietnam last March either. Good on those of you who can.

 

Crawl space liner with a dehumidifier is the only way to beat it.

 

Yes we've put them in before. Did the janky single unit ones then came upon Atmox crawl space systems. We've put a couple in and they are awesome. It monitors the outside and crawl space temp/humidity/dew point and calculates when to exhaust air, intake air, and can connect a kick on a dehumidifier if connected. Crazy expensive IMO but if it's a nicer house well worth the money. We don't actively pitch them or crawl space encapsulation because my guys HATE it and I had one of my good guys quit on me over a big crawl space encap.

Crawl Space and Attic Solutions - You can reach out direct to them and setup an account for contractor pricing and training. Was always good guys when dealing with them, just expensive as hell product.

 

When the normal exhaust fans, stove vents, etc turn on in the main home, they are likely pulling air from the crawlspace slowly into the home.

If you can't stop dank and humid air in the crawlspace from occurring, have you considered better isolating the airflow from crawlspace to main home?

 

I would take a look at the crawl space floor and start there. If you've got dirt floors I would lay some sort of of class 1 vapor retardant across and continuous 8-10" up the foundation walls to prevent ground moisture from rising. Only way to deal with Vapor and water is to go directly to the source, mechanical venting will only mitigate the issue to a certain point

 

You have to seal the crawl space, insulate, install transfer grills & then install exhaust for it to work properly - exhaust only with open venting to outside only makes things worse especially with ducts in there. Calculations are in the IRC as I recall but like most ventilation items, no real field science or studies to back them up.

 

there are people who know more than you, just google crawl space remediation. Sounds like you're screwing around where you shouldn't and it is going to end up costing you time and money and you'll still have an unhappy customer. Find a guy you trust, give him the referral, and he'll have plenty of work in the neighborhood eventually and he'll refer work back to you. Half measures will do you no good here.

 

Relax dude. Why do you think he is asking.

 

i`m in south Florida. very humid
for years i`ve crawled under houses ( in the crawl spaces) and repaired rotted wood ( mainly floor joists , 2x10`s.) , mostly round the bathroom or a/c closet area.
sometimes having to shore the floor up with adjustable jacks.

worked on this house 2 years back, ( these are nice homes in expensive areas)
this house has continuous humidity. can smell it in the house.
it seems to have plenty of venting around the house, just might be a damper area than most
i purchase 2 exhaust fans , and installed them on one side of the house , so there is a constant airflow throughout.
we even crawled throughout and laid 6 mil plastic throughout to make some kind of a moisture barrier.

client is calling back , and asking me to install a couple more , saying she can still smell humidity.
just don`t know any calculation to know how much is enough. don`t know if i`m helping ,
manufacturer couldn`t tell me much about their own product.( they`re dual fans , on a timer , and also have a dial for humidity levels, fits right in the access holes)
don`t know any contractor , who knows more than myself about it . not saying i know the secrets.
it seems like we all kind of wing it.

any others ever deal with this?

This is a simple code question. Are you a licensed contractor?

If this is a high end home, recommend the owner to get ERVs installed

 

I wonder what code addresses that. Mechanical venting of a residential crawlspace by code. Never heard of it.

Spike, just admit it, you're new...🤣🤣🤣

i think 98%+ of members here are handymen or laborers for contractors. There is rarely competent responses if even on topic. You just gotta keep your fingers crossed here.

 

To answer your question, I would say if some helped, some more would help more. Hard to say without seeing firsthand.

 

Ed if you are being serious - See 408.3 CHAPTER 4 FOUNDATIONS - 2021 INTERNATIONAL RESIDENTIAL CODE (IRC) (iccsafe.org)
FirstOption --- ERV for a crawl, you need a sign especially for that area of the country... If you do anything like that it would be going with a ventilating dehumidifier

 

Mechanical venting of crawl spaces is not covered in the IRC. It is in the IBC.

 

Humidity in crawl spaces is tough, especially in South Florida. You’ve done a lot with venting, fans, and a moisture barrier. It might help to measure the humidity with a hygrometer; if it's still high, a crawl space dehumidifier could be a solution. Sometimes adding more fans isn’t enough, and active moisture control is needed. Hope this helps

 

In a humid climate, venting a crawl makes things worse. You need to seal it and bring it inside the conditioned envelope.