Drilling through Eco joists

[Mark2spark]

Hi guys.

On new build site work, has anyone found a really good drill bit to drill out eco joists with please?

We seem to have had a batch come in over the last few months that are cardboard/hardboard material and the drill bits just bounce off once the pilot part has gone through.

It won't 'bite' with the blade I mean. That's using Bosch bits with the threaded starter. And the thread of the drill bit gets clogged up with this cardboard/hardboard matter.

Really frustrating taking so long to drill rows of holes through when first fixing 

 

[Geoff1946]

eco joists

Crikey!  Are we really building houses out of cardboard now?  I thought egg-carton doors were bad enough, but structural beams ??!!

Sorry, meant to add get some old fashioned "blacksmiths" twist drills. You can get quite large ones with a reduced shank which will go in a 12mm chuck, and you could always pilot with a smaller twist drill. They'll go though anything.

 

[ProDave]

What are these "ECO Joists" you talk of?

You need to be VERY careful here.  Some "Engineered" Joists have strict limits where and how big you can drill them.  And If these are I beams, with OSB type material forming a web with more solid bits of wood at the top and bottom, then you should never drill the top and bottom members under any circumstances only the OSB web and only in prescribed locations.

If these are metal web Posi Joists you should again never ever drill the top and bottom solid timber members.

But of course you also know if drilling plain ordinary timber joists there are prescribed zones where you can and cannot drill holes.

If your difficulty is using auger bits then they won't work well as there is not enough meat for the screw tread pilot to grip and pull the drill through.  Instead use flat bits.

 

[Fleeting]

A lot of these engineered I-Joists with the solid web have pre-formed knock-outs.

 

[Mark2spark]

Thanks for the answers Guys.

Flat bits are the only things that work, even they're a bit naff. It's the thread thing that pro dave mentions that's the issue. Not enough 'meat' in the carboard/hardboard centre part.

Auger bits tend to 'bite' and try and spin you off your steps 

Yes I know all about drilling zones, thanks for the re-education though.

FYI, we've actually had a tool box talk with the joist manufacturer on site, and he said that you can drill any hole less than 25mm, anywhere you like. Zones are out of the window to a certain extent. The one that surprises me the most is being able to drill a 125mm hole to take a soil/duct pipe (100mm nominal) through these joists.

Yes, you can't (not supposed to anyway) drill through the solid upper and lower timber sections.

 

[Sharpend]

You want the cheaper flat bits that don’t have the screw centre they also don’t have the tips on the wings so cutting edge is flat. 
 

It’s fine to drill through with large holes for ducting but you do have to keep the distances of centres apart from other holes.