FAQ about the RE1 Rafter Center Locator

The RafterEye RE1 is able to read through up to 9″ of material. Precision diminishes above 5″. In this image, the paint stick at bottom is a stand-in for the 1.5″ thick roof deck.

How does it work?
Does it work on any kind of roof?
Is the RE1 capable of reading through insulated roof decks?
How does penetrationless rafter center location avoid structural damage?
And cosmetic damage?
Does the RE1 use electrical energy?
What applications does the RE1 have outside of rooftop rafter center location?
Will it work on log rafters?
Is the RE1 patented?
Where can the RE1 be purchased?
Is Clampster another name for the RE1?


How does it work?
The RE1 forms a magnetic field around and through a roof’s structural member (rafter, truss, TJI, etc.) that can be read with a magnetic compass from the rooftop, directly indicating the center of the structural member. 

Does it work on any kind of roof?
The RE1 works on any non-steel roof whose structural members are exposed or accessible. Steel roofs block its magnetic field.

Is the RE1 capable of reading through insulated roof decks?
The magnetic field of the RE1 has been read through over 9” of substrate, but accuracy begins to diminish typically at distances greater than 5-7 inches.

How does penetrationless rafter center location avoid structural damage?
It does so in several ways. 

First, the traditional method of drilling probing holes weakens the rafter by removing bulk from the top of the rafter.  The resulting voids allow compression stresses to cause greater downward flexion of the rafter under dead, live and snow loads precisely at the location where the attached hardware will concentrate those loads.

Second, as all rooftop installers are aware, it is not uncommon, even after painstaking probing or using other methods of rafter center location, to have a lag screw split a rafter and/or exit through the side due to being even just slightly off center.

Finally, while the attachment hole will be both caulked and filled by a lag screw, each probing hole is a potential route for water leakage.  How reliable is the seal below the top layer of roof membrane?  Any leak, detected or undetected, is likely to eventually result in structural damage.  Given the 20-40 year lifetime of solar and other rooftop installations, it’s a risk that should not be discounted.  Accurate centering and minimizing the use of probing holes mitigates these serious threats to a roof’s structural integrity.

And cosmetic damage?
Rafters that are exposed, whether indoors or out, present a special challenge to rooftop installations.  Accurate center location with traditional methods almost requires creating at least one visible hole through the roof.  Lag screw “blowouts” through the sides of rafters can actually become more common due to guesswork following efforts to avoid leaving visible probing holes.  Even after these lags are removed and relocated, scars remain, whether in a porch roof or above a living room.  Beyond these forms of cosmetic damage, expanding foam or caulk-type sealants used to fill holes resulting from probing, measurement reference drilling, blowouts, or above-deck insulation removal, can fall onto and damage or ruin antique collectibles, artwork, musical instruments, furniture, carpeting and other finished surfaces located underneath attachment points.

Does the RE1 use electrical energy?
No.  The RE1 requires no battery and no household current to operate.

What applications does the RE1 have outside of rooftop rafter center location?
The RafterEye RE1 can be used to identify a location through other non-steel surfaces such as floors or walls, as long as there is something to clamp to, or a person to hold the magnet blocks on the other side.

Will it work on log rafters?
The RE1 can be used to locate the “center” (deck contact point) of a log rafter.   Because most logs are too large to accommodate the clamp, the Magnet blocks are manually held against the top of the log on both sides.  A second person reading from the roof can then locate center normally.  This method can also be used on oversized rafters.

Is the RE1 patented?
The primary operative features of the RE1 are patent pending.

Where can the RE1 be purchased?
The RafterEye RE1 is available at this time exclusively through raftereye.com.

Is “Clampster ” another name for the RE1?
“Clampster” was a working name for the RE1 Rafter Center Locator that appeared in some publications.