I've recently moved to a new home. This home had an addition that was built on top of a Crawlspace that is vented to the outside. Needless to say, the morning after the first cold night made me realize how much this affects the temperature in the main family room.
Before we move in an inspection also revealed a small mold problem on the joists in the crawl space. This was taken care of. While they were removing the mold they went ahead and added plastic to the floor and insulation to the walls. However, it's still vented to the outside and the plastic/insulation is doing next to nothing as there is no tape and there's gaps all over.
Also, there are some areas in the room above where I can feel air coming through.
So first thing I want to do is to seal any gaps between the crawl space and room above with caulk and expanding spray foam( not insulating the ceiling ).
Then comes the hard part. After doing some reading, it seems sealing the crawl space and doing some proper insulating/vapor barrier is the way to go.
How do I seal the vents? Next steps and order of importance is greatly appreciated. I'm fairly handy and have access to a family with plenty of experience, but I want to tackle as much if this as I can.
Here are some pics:
Best Answer
It is a good idea to seal any apertures between the crawlspace and the main house. If you have to rely on caulk and spray foam you're probably in a situation where the house has some weird structural problems - that is, you should not have giant gaps between the crawlspace and the floor above in any normal construction regimen.
It is not a good idea to seal off the crawlspace, ventilation is not only a good idea but it's required by code in locations where crawlspaces are an accepted norm (note that in places where winters are exceptionally cold the norm is finished and unfinished basements, not crawlspaces). The fact that you have had mold in the crawlspace is actually an indication that you might need MORE ventilation not less.
A proper insulation/vapor barrier installation at the level of the floor joists should solve any draft problems. Also, looking at your photos I would recommend that you insulate your ductwork/boots/wyes per local code.
So to reiterate, please do insulate and install a vapor barrier! Do not seal off the ventilation for the crawlspace - indeed look into your local code to see if you have enough ventilation.
As a side note - any issues of moisture (and therefore mold) in the crawlspace need to be addressed. Possible sources of moisture include but are not limited to: leaky plumbing supply or waste lines, inadequate drainage system at the perimeter of the house (undersized gutters/downspouts, poor grading, no storm drain, etc.), and a possible high water table.
Good luck staying warm this winter!