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Rafter Scanners, Bosch D-Tect 150?

jmoles

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Nov 15, 2023
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52
Location
Maryland
Anyone have a scanner they could recommend for use on an asphalt roof to locate rafters?

How accurate are the Bosch D-Tect series, the Hilti PS 38, or other scanners on a single layer asphalt roof?
 
Don’t know.
The method I have used is to drive a nail or screw from below the roof sheathing to identify the edge of a rafter or truss chord and then use a tape measure from there. Alternatively, depending on what purpose finding a rafter is, pulling a couple shingles to reveal the roof deck/sheathing has been done.

At prices ranging from $600-$1300 I’d spend a little time in the attic space LONG before I’d ever buy this!!!

It says in its specs it will detect wood mass to 40cm so about 1-1/2” and some reviewers say it works well on shingles but even if locating a starting point takes a half hour - buying this tool is probably more expensive per hour than trump’s lawyers imho
 
Second hand they seem more reasonable $300 - $400. If they save me a ton of time then buying second hand and re-selling when I finish would be worth it.

I‘ve got 3 roof sections. Two of those roofs are closed, no attic access.
 
Second hand they seem more reasonable $300 - $400. If they save me a ton of time then buying second hand and re-selling when I finish would be worth it.
If that works for you - great!

YMMV but I’ve been building/remodeling or selling building materials since ~1985 and I’m telling you that it’s not hard to determine rafter placement in 10 minutes, 1/2 hour if you over-think like me. Any “testing” nail holes you create can be sealed with polyurethane caulking that will outlast the 25-30 year lifespan of composite shingles anyway.
$400 buys a lot of groceries.
 
You'd be amazed by how well you can zero in on a rafter using a rubber mallet. You won't miss the first one more than an inch. You can correct and zero in from there.
X2!!! No worries if you miss if you're using a quality roof mount system with large flashing mounts, they will cover any holes. something like this:
 
X2!!! No worries if you miss if you're using a quality roof mount system with large flashing mounts, they will cover any holes. something like this:
That reminds me. IR actually addresses this.

Straight from Ironridge installer videos.

"If a missed pilot hole is more than 2" from the edge of the flashing seal it with approved sealant and move on."
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