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How to Remove Mold from the Crawl Space

I get it, no one wants to go crawling around under their house! Especially if you only have about 18 inches to work with. Someone should however, go under your house at least once a year to ensure that your crawl space is in good order. Too many crawl spaces are neglected and home owners are often then forced to be reactive instead of proactive.

So here we are, being reactive. Mold has started to grow on your floor joists and maybe also your sub floor. Let's first talk about how to handle your mold problem. Then we can go over why mold is growing under your house. Finally we will finish up with how to be proactive!

You can call most pest control companies and they have a ''mold killing'' process. This usually consists of spraying the mold with some kind of mold killing compound followed up by a mold prevention compound. Oftentimes though, they leave the compromised insulation in place and spray around it. There are many issues with this process, one being that you are only killing surface mold by spraying it with a compound and there is no guarantee you will kill the mold that has rooted deep into the wood. If you don't at least move the insulation, you won't get all the mold on the floor joist or any that has grown on the subfloor. Lastly, fiberglass insulation has been proven to hold moisture and mold can even grow on the back of the insulation. So without at least pulling down the insulation to inspect it when you are spraying for mold, you are risking doing all for nothing.

Now that you know what not to do, let's talk about the right way to tackle your mold problem through mold remediation. Starting first with removing all the insulation in the troubled areas and inspecting behind the rest of the insulated areas. Or more preferably, removing all fiberglass insulation and instead insulating the foundation walls when you're done. Now that you have assessed the situation, next comes the mold clean up phase by means of a soda blaster, an air powered pressure blaster using a baking soda media. Same concept as a sand blaster but with baking soda instead. This removes the mold from the wood all the way to the base of the mold and gets you back to square one. I also hook up an exhaust fan to one of the vents to help get the mold and dust to exit the crawl space when blasting. Once you are back to a nice clean wood finish again, I like to use Anabec, a mold killer, on the floor joists and subfloor.

There can be a lot of reasons why you have mold in your crawl space including poor gutter drainage, the property is sloping towards the house instead of away, a high water table, no vapor barrier, or leaving your vents open in a humid environment.

It is crucial to take all these factors into consideration to prevent mold from regrowing under your home. A vapor barrier is an absolute must for crawl spaces in humid climates. But it is also imperative to take all other factors into consideration in order to keep moisture out of your crawl space so that you do not allow the mold to return.

For a short video on how to remove mold from the floor joists and subfloor, click this link!

So we've finally peeked under the house after a good rain and what do we find? A little pond. So now it's time to ask, Mr.-know-all, Google who to call to handle this mess because the last thing you want to do is suit up and install a drainage system in your crawl space pond. You may not be sure what all issues could arise with having standing water in your crawl space, but deep down you know that it's not something you want to continue. The problem is, you can call five different companies that handle this kind of work and you might get five different answers on how to handle it. Along with five different price levels. So, let's find out why that is!

First, there are many reasons water can be entering your crawl space and we won't get into that but if you would like to know more about that, visit: That being said, if you can fix some of the issues leading to the water getting in to begin with, then you either can remove the need for a sump pump, or at least exponentially increase the life of the sump pump that is installed. You may have to take measures like installing exterior french drains, extending your gutter drainage away from the house, and improving the grade so that water moves away from the house instead of pooling near the foundation. These are all services that can increase the cost of a sump pump system, though not many companies that install sump pumps also offer these services. I do strongly suggest that they are at least considered though, since the number one goal should be to keep water out of the crawl space entirely or at the least limit the amount that is entering.

Now that we know we are ready to have a sump pump system installed in the crawl space, let talk about the differences in what companies offer. The most basic sump pump systems I find usually consist of a pump sitting in a five gallon bucket with holes drilled in the bucket. Sometimes rock is filled in around the bucket but not usually. This system usually ranges between about $700-$900. This is going to be your cheapest option. But, often times these guys are wiring the electricity themselves (probably not licensed electricians) and not to mention the pump will be running constantly since the bucket will only need about 2 gallons in it before the pump turns on. This in turn shortens the life of the pump. The other problem with this system is it doesn't include any drainage to the pump so you will most likely still have pools of water throughout the crawl space, since the water has no way to collectively get to the pump.

The best sump pump system you can have will include these three things; a quality sump pump, a basin that holds at least 15 gallons and is surrounded by drainage rock, and a drainage system around the whole perimeter of the crawl space that leads to the sump pump. For a system like this you will be looking at a cost of about $1,200-$1,600 for the installation of the pump and basin. Then you will need to add usually between $15-$30/foot for installing a drainage system around the perimeter of the crawl space. So if your crawl space is measured at 50'x30', on average you'd spend about $4,600 for a sump pump with drainage. Obviously this is going to fluctuate depending on what kind of materials the contractor is using. Most systems require drainage rock to be installed around the drain tile which is very labor intensive and time consuming. While others can be installed without adding drainage rock, saving on cost and time. 

A few other add-ons that can drive the price up are backup sump pumps, sump pump monitoring devices, and electrical fees. Also, in larger crawl spaces where a substantial amount of drainage is required, it may call for one or more sump pumps to be added to the system. I have also seen this in instances where a crawl space is split up into multiple sections and there is no other option than to add multiple sump pumps with their own drainage in each area. 

Keeping water out of your crawl space or removing it as quick as possible is essential to improving the structural health of the home. Wet and damp areas attract insects and rodents and creates a habitat where mold flourishes. Add to the fact that up to 40% of the air you breathe in your home comes from the crawl space and you have a recipe for disaster. A couple things to look at when comparing quotes are: what kind of drainage system are they using and how is it being routed? Are electrician fees included in the quote? What kind of sump pump is being installed and does it come with a warranty? And what kind of basin is being used? If you can compare those, then I am confident you can find the right company to complete your project correctly.


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