Is Mold Under a House Normal? (Solved & Explained!)

Having mold beneath your house is a common problem, but I wouldn’t describe it as “normal”. Mould can cause a range of problems related not only to the structural integrity of your home but also to your health. 

Mould can cause respiratory illnesses in humans when left untreated for long periods of time in areas that aren’t well ventilated.

In this article, we’re going to look at what the causes – and solutions – are for having mold underneath your house.

So let’s get started.

What happens if there is mold under your house?

Mold is a microorganism that simply wants to survive and reproduce. To do so, it will rot away your possessions and make parts of your home smelly and dangerous for your health.

If you have mold in your house, it’s because the conditions exist in your home that allows mold to grow – but what exactly are these conditions?

  • Dampness and humidity in the air
  • Poor ventilation (causes humidity)
  • Some kind of nutrient source that it can rot away – for example, old wallpaper, rags, cardboard, neglected books, etc., etc.
  • Mold ideally grows in temperatures between 32 and 120 degrees Fahrenheit 

The main things you want to avoid are stagnant air and a humidity level that raises above 50% – if you can control these factors, you simply won’t get mold, even if the other factors are present.

What does mold smell like in a house?  

Aside from seeing mold with your eyes, the easiest way to identify a problem is by using your nose.  

Mold has a very distinctive smell and should be immediately identifiable to somebody who has had the experience of it before. The smell is musty, earthy, and vaguely fungal, like gone-off mushrooms.

Should I worry about mold in the crawl space?

Mold left untreated can rot away the timbers and wood that support your house, and if the conditions are right it could even spread into the interior structure of your home. This means that given enough time the whole structure of your house could be compromised, leading to the lowering in value of your property on the market.

As well as this, mold smells terrible and can leave ugly marks on your walls, even after it’s gone.

This is before we even start talking about the health effects for people who are exposed to mold in the long term!

How long does it take for mold to grow in a crawl space?  

Mold can grow extremely quickly, with the beginnings of an infestation taking root within 48 hours. 

It takes just as quick for it to spread all over the infected area

What does mold in a crawl space look like?

Mold is very distinctive-looking – black, yellow, or white patches with a sort of white or yellow fuzz. Like any bacterial growth, its shape is irregular and blotchy, like a rash on your wall.

How do I prevent mold in my crawl space?

 As we mentioned above, there are a certain number of things that mold needs to survive – if you have an infestation underneath your house, the best way to kill it is to change the conditions that gave rise to it in the first place. For each requirement the mold has, you need to starve it.

  • Dampness – Look for any water sources that should be there, i.e., leaky pipes, cracks, puddles where moisture gathers.
  • Ventilation – Depending on your crawl space you might have more or less ventilation – try to create a kind of through breeze if you can by having an opening on either end. 
  • Nutrients – unfortunately, the crawl space under your house will always have some kind of nutrient source, as it is right adjacent to the soil. You can help, however, by removing any trash or debris that might provide a base for mold. Cardboard, newspaper, anything paper or fabric.

Changing the temperature under your house is obviously not an option, however, if you deal with the above you’ll have the best chance of prevention and the temperature won’t be as big a factor.

What kills mold under a house, or in the crawl space?

Prevention is the best cure, but if you want to kill the mold that’s growing under your house the best option is to use 1 part bleach, three parts water and to scrub the affected area using a clean sponge and bucket. There are commercially available DIY treatments for mold that use variations on the bleach and water mixture

When doing this, be sure to wear the appropriate PPE, meaning a mask and gloves at least for your own safety.

What can I spray on floor joists for mold?

 Similar to what we specified above, a water and bleach mixture should be fine to spray and wipe away. As well as this there are sprays that can be bought from your local hardware shop that claim to have preventative properties. As well as this, there are some specific paints you can buy to help with the process.

Can you Do it yourself to get rid of mold in your house?

 To an extent, but it is a dirty, smelly, time-consuming job. You have to be prepared to spend a long time looking for the source and scrubbing. If you find a leak, crack, or another moisture source you also have to know the safest way to fix it.

A DIY job of this kind will always be more unreliable than an expert

How much does it cost to remove mold from a crawl space professionally?  

This, of course, depends on the contractor that you hire and the quality of the work done, as well as the size of your crawl space and the severity of your problem.

In general, however, you can expect to be paying somewhere in the region between $500-$3500, with the national average being somewhere around $2500.

Not an insignificant expenditure for your average family!

How long can you live in a house with mold in the crawl space?

That depends on your definition of ‘live’ – it’s possible to live in a home that has mold in the crawl space, but over time the mold will spread and possibly start causing damage to peoples’ health. 

The longer it’s ignored the problem will only become more severe and costly to deal with, ultimately ending in a scenario that requires major refurbishment of your home.

It’s possible to ‘live’ with mold in your crawl space, but it would be irresponsible to give a specific time frame as a response to that question – get rid of it as soon after you notice it as you possibly can.