Anyone dealt with crawl space encapsulation??

[GrassNole]

Not sure if anyone has encapsulated their crawl or know anything about dealing with high humidity crawls. Having issues, figured I would lob this out there.....

I'm having some issues with my crawl space and wrapping my brain around a few things, so I was hoping someone could help. I recently moved in with my wife (just married) and we live in an older home built in 1952. It sits on a crawl space, air handler is in attic, and we have a furnace in a closet. I have never owned a furnace and only used heat pumps.

I noticed we had humidity issues in the crawl space so I decided to pull a few quotes to correct the issues.

I ended up hiring a company to come out and partially encapsulate my crawl and install a Aprilair 100E dehumidifier. All vents were sealed and 12mm barrier put down on the floor.

Now here comes the fun part. The house is single story brick ranch and in the 80's had a sunroom added. This sunroom is 13x17. There is roughly 2 6" holes allowing air flow between the main crawl (where dehumidifier is installed) and this sunroom addition. The dehumidifier is working great for my main crawl but after sealing the vents, the sunroom humidity has started to rise. I assume not enough air flow through the two 6" holes between the spaces. In my attempt to get more airflow between the spaces, I purchased a 4" inline fan and installed so it was sucking humid air from the sunroom crawl and dumping into the main crawl space. This actually made it worse. So, this AM I changed the airflow direction--the inline fan is now blowing dehumidified air from the main into the sunroom crawl. This has seemed to help but time will tell.

My questions:
--Does the plan using an inline fan make sense? Should I purchase another and use one for intake and the other for exhaust? Is dumping dehumidified air from the main to the sunroom crawl enough to take care of the humidity issues--- Issue like high moisture content in the wood??


Back to the furnace-- I know nothing about them except they get hot . While in the furnace closet, I noticed an air vent in the floor. Roughly 10x18. My wife had this covered over and I never noticed it was there. What is vent for? My first thought was this was sucking air from the crawl through AC and keeping crawl space dehumidified--which I was going to be pissed if this was the case and buying a crawl space dehumidifier was a waste.....But I don't see any way that air is being sucked from this closet...

Any help or thoughts would be greatly appreciated.

 

[fitter30]

Furnace room has a solid or louver door? Vent in floor might be for combustion air. Rh flows from hi to low and will pull from the whole space including walls and wood floors unless there is a easier place to pull from. Call or look on their web site your electric company ask if they offer a energy audit that includes a blower door test ( tells how tight the house is)( youtube). Crawlspace and attic has all penetrations to the house been caulked. Sun room why is there two 6" holes to crawl space?

 

[billconner]

I would seal vents between house crawl and sunroom crawl OR encapsulate sunroom crawl.

Furnace should have a supply and return. Are there grills that allow crawl to be return plenum?

 

[Ak Jim]

Now that the crawl space is sealed up you might need to provide a make up air supply to the furnace closet. Do you have a co detector? If not you should probably get one asap.

 

[My Old Tools]

Some older homes used the crawl space as a return air plenum. It was a bad idea with unsealed crawl spaces, but I have seen it done.

 

[slowtwitch73]

I wouldn't want crawl space air being pumped into living space.

A radon mitigation system works really well for dirt floor crawl spaces. The barrier they put down and seal does a way better job than a 12 mil just laid down loose at controlling moisture.. so you kill two birds... radon (and other ground gases + smells) and moisture being controlled. I'd keep the dehumid, as moisture control is a fringe benefit of a radon system.

 

[Snip's]

Check your gutters... If they are overflowing when it rains you could have water pooling by the foundation that could be entering into the dirt floor crawl space.

 

[FlamingoLover]

Interested in possibly encapsulating my crawl space but worried that huge roots form maple tree have damaged the foundation wall. Not sure how to proceed. Any suggestions???

 

[Chuckster in NJ]

A crawl space needs ventilation. (1 square foot of screened vent for every 150 square feet is code) A "rat slab" or vapor barrier would be helpful. Take a step back on radon until you test for it.

TIP! Install a carbon monoxide detector near your bedroom until you get the make up air situation take care of………. I highly suggest calling a HVAC contractor to help you out.