Which Bit To Use Through....

Warmsmeallup

We have to drill 16 holes, 1" x 16" deep. It a roof that is (2) 3/4" ply's, then 10" of air then 4" of concrete over corregated metal. A total of 16". How would you guys best accomplish this ?

We have 22" concrete bits for our Milwaukee demo hammer drill but I'm afraid to destroy the bit when we hit the metal.

CypertJ

start out with your 1" spade for the wood, drill the concrete with the 1" sds, you should be able to hear the difference when you first hit metal, stop there and move to the next hole, repeat until you have all 10 hole punched in the concrete, then come back with something more appropriate for the metal

neolitic

If the "concrete" was always
a roof deck, it's most likely
light weight.
You might just get away
with a couple of cheap
twist bits.
It's not like drilling a slab
with regular aggregate.

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Warmsmeallup

Good point. It's new home, new pour as well so I'll check with the GC to be sure and try the twist first. Thanks!

Darwin

I would use the longest, strongest bit money can buy. The 10" of air will be your hardest part to drill through. Good luck

steves

Your hammer drill bits will go thru that no problem no dammage.
We do it all the time on elevated slabs

TxElectrician

At the least it will be the hardest part to keep the bit straight in.

KyleVH

A Hilti SDS or SDS max bit can handle rebar. They have a full carbide head and last forever.