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Probing finished surfaces

Chris Bernhardt

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Our Oregon wood destroying organism SOP states that finished surfaces are not probed. How can I say this… uh there’s this other inspector I know who does probe painted siding. I.., I mean, he uses a thin blade of a box cutter to do comparative probing because it causes the least amount of damage say compared to an ice pick or a screwdriver.

How many of the brethren probe painted siding with a tool?

If so how do you report areas soft to probing if your SOP and maybe even your contract said that you don’t probe painted surfaces?

When an area is soft to probing would you describe it as rot damage, moisture damage or just it’s soft to probing?

Would you describe what you used to probe the siding so that others could confirm your findings? For example a broad tip screwdriver might not detect softness that a thin blade box cutter will.

How do you identify in the report siding whose damage is only found thru comparative probing with a tool? For example T1-11 plywood and all of the composition siding products can appear solid and undamaged even to probing by thumb but yet yield under a tool. In order to demonstrate that the siding is damaged one has to probe it. For example “I found the siding under the window soft to probing. Siding soft to probing most probably will continue to deteriorate regardless of attempts to seal it. Have a siding contractor replace all siding soft to probing.â€

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I very gently probe siding with the tip of a screwdriver. When I find a soft spot, I use my fingers to probe further. About two weeks ago, I walked out onto a deck, pointed to a spot on the surface that probably would have looked fine to most folks and then pushed my finger right through it up to the second knuckle. The client's eye's went wide and the agent stepped back inside off the deck.

Here's the bottom line; what homeowner can rightly argue that a hole put through a wood component with one's fingertip is the result of an inspector's negligence and not a result of the homeowner's negligence? I assure you; Bruce Lee I'm not. I don't have fists of fury or fingers of steel. If I can shove one of my arthritis-ridden fingers through it, it's rotten,...period. We're required to probe here and I'm not shy about aggressively probing anything that's in the second stage of rot or better. If it's to that point, it should have been repaired long ago.



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Do you differentiate between siding soft to probing on the basis of decay fungi or moisture swelling?

I know that surfaces sunken are likely due to decay fungi and surfaces raised are likely irreversibly damaged from moisture.

How do you report on siding that is soft to probing with a tool but not necessarily soft to probing by your fingers?

I am convinced from my experience probing siding that if the siding is soft to probing with a tool even though it's not quite detectable by finger pressure that it will worsen.

Chris, Oregon

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The first thing you need to come to terms with is that you cannot find all rot. It's impossible.

There are three stages of rot; incipient, intermediate, and advanced. When you find soft wood, you're finding either intermediate or advanced rot. For every little bit of that you find, there's going to be even more incipient rot and the only way that you can detect that without bore holes and extensive scientific analysis is with a pick test. Search the site for 'rot' and 'woeste' together and you'll pull up Prof. Woeste's article about detecting rot with a pick.

All we can do in this business is point people to the intermediate or advanced rot and make them wise to the fact that what they're seeing is not the early stages, that there's more where that came from, and tell them to deal with it.

OT - OF!!!


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It has never posed a problem with me. A trained eye should be able to distinguish between solid wood and wood that has moisture damage. Yes, you will have the occasional "hard to tell" areas and this is when I probe.

I do not probe just to probe. The best probes that I have found are on my hands. I push with my fingers. If the wood is soft I can tell very quickly. If I'm in a crawl space I will use a screwdriver or pocket knife.

I always try to look for other signs of water damage. Look for stains, ripples, blisters or bubbles in the paint, etc. Uneven or rough areas are usually a sign of patching.

As for hidden or camouflaged damage, this I cover in my contract. It is also covered under several state home inspector laws. We simply can not be liable for hidden, latent defects or camouflaged damage. Be sure that this is in your contract and that you explain it to your client. I tell my clients (in my contract) that I'm not "Superman" and I can't see through walls, underground, etc. This gets the point across without any misunderstandings.

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Usually there are visual signs that lead you to probe. If it's visible and finished I use my homemade straightened and sharpened paint roller probe to touch and gently push. Once on some puffy LP siding I made my buyer begin to twitch and squirm because I kept poking and pushing, so I eased off.

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Tap first, if soft lightly probe, if still weak, try your finger. It is a bit moveable, try a pick, xacto knife or other small ended probe.

Some times I tap the wood or composite siding with the soft edge of my shoe, it may or may not be enough to determine wood rot and resistance to pressure. Often moisture damage happens at the bottom most areas nearest to the grading.

Some moisture damage / decayed wood based material can crumble much larger than the area being probed so be careful and use common sense.

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