The Home Inspector Logo


The Home Inspector

Like boot camp for homeowners.

Mold testing vs. Moisture Testing

This week's blog post topic comes from a potential client who was doing some research to decide on which home inspection company to hire. He wrote the following question to us:

One part of your website says you do Mold testing and another part says you do Moisture testing (and the Moisture testing page does not mention mold). This is confusing to me because these two things go hand in hand. Can you help me understand these two tests better and why they are separate?

That's a great question. While the two go hand in hand, mold and moisture are not synonymous, and we typically talk our clients out of mold testing.

Moisture Testing

Moisture testing

Moisture testing is done on exterior walls to determine if there are moisture problems behind the siding. The vast majority of moisture problems in walls are the result of bulk water intrusion, which typically results from water getting into the wall sheathing around windows, or through improper flashing at other penetrations such as roof ends and deck ledgerboards. Water intrusion at exterior walls typically involves expensive repairs, with stucco and stone veneer siding being the most expensive types, and the most notorious for leaks. These wall coverings are expensive to install, they're difficult to take apart, and hold a lot of water. For a few examples of stucco repairs, check out these blog posts below:

Vinyl siding is the easiest siding to repair; it comes off quite easily, the damage caused by water intrusion on vinyl siding takes a longer time to get really nasty because vinyl "breathes", and the same pieces of matching vinyl siding can be put right back up on the wall after repairs have been completed. Don't get me wrong, I'm not saying the repairs are inexpensive, but they're far less expensive than stucco repairs. Here's a blog post from last year about vinyl siding repairs: Moisture Testing Homes with Vinyl Siding.

Mold Testing

Mold and Mushrooms

Mold testing can be done by air sampling or swab testing. Swab testing is typically done to surfaces that already appear to have a problem; in those cases, what's the point?

Air sampling is done to find hidden mold. If there is moisture in the walls but no mold growth in the walls, air sampling for mold testing will not help. If there is mold in the wall but the wall is completely airtight, air sampling for mold won't find the mold. Conversely, air testing for mold can also produce false positives; more on that topic here: To Test or not to Test: That is the Question.

My knee-jerk reaction to mold testing is "don't bother". The situations where mold testing may have some value are few and far between. For an in-depth discussion of why there is little value in hiring your home inspector to test for mold, check out this article that appeared in the ASHI Reporter in November of 2010: Home Inspectors and Mold Sampling - Hype or Help?

For the record, the Minnesota Department of Health does not recommend mold testing, and neither does the EPA.

Author: Reuben Saltzman, Structure Tech Home Inspections


The best of the worst home inspection photos of 2015: Amen to duct tape!

This is always my favorite blog post of the year, featuring our best home inspection photos from the past 12 months.  Click on any of the photos for a large version.  Enjoy!

Planning for emergencies

Bathroom fan 3-way switch

Flat roof / chimney combo Chimneys and flat roofs are notorious for leaks. Someone managed to combine the two here. While this image looks photoshopped, it's not. I just blurred out the surrounding scenery to keep the location anonymous.

Chimney _ flat roof combo

Roof Mullet Again, no editing was done here.  I just blurred out the surrounding scenery.

Roof Mullet

Hack wiring, right out in the open

Crazy light

Who needs beams?

Cut beam for garage door opener track

Dr. Seuss's handiwork

Dr. Seuss Water Heater Vent


Duct tape drains

More duct tape repairs.

Duct tape wall

Those paint cans better come with the house.

Ladder too short

I have no idea...

Ball Washer

Backboard magnifying glass Check out what the backboard did to the shingles right behind it.  Crazy, right?

Magnifying glass basketball hoop

Bad planning. This microwave door is open as wide as it will go because it binds on the wall. Yes, this was a flipped house.

Microwave won't open

More home flipper stuff (zero pride)

Nice Paint Job

More bad planning

Poor planning

I've got a fever...

More saddlevalves

Plumbing vent flashing used inside the attic Someone didn't know how to connect the corrugated duct for a bathroom exhaust fan to the roof cap, so they used a piece of flashing for a plumbing vent.

plumbing vent flashing inside attic

Don't worry.  It was toe-nailed on the other side too ;-)

Toe-nailed newel post

Valley trees (like, omg!)

Valley Trees

Re-purposed shower rods

Sink supports

The multi-tasker's dream bathroom 

Tight toilet and sink

You don't need to know what nice work looks like to know that this ain't it.

Mortar at chimney

Tuckcaulking Every mortar joint is filled with caulk.


Perfect fit.

Water Heater Drain Capped

Ok, that makes twenty three.  Close enough.  If you enjoy these types of photos, please visit our Facebook page, where we keep 'em coming.  Also, be sure to check out our top photos from previous years:

Happy New Year!

Author: Reuben SaltzmanStructure Tech Home Inspections


Latest Home & Garden Blogs

Poll: Is it ever OK to snitch food from someone else's plate?

See more polls