# Forum Home Renovation General Odds & Sods  Pre drill holes for coach screws?

## paddyjoy

I need to put some m10 coach screws into an lvl, is there a specified size I should predrill the holes or do I just need to try a few sizes until I don't get any splitting? 
Thanks

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## SilentButDeadly

It's quite easy to twist off the head of your average coach screw these days...I usually pre-drill to the size of the shank between the 'blades' of the screw.  And I've been known to use WD40 in the screw holes themselves..[hardly necessary for LVL]. 
So I'd go with 8mm holes or thereabouts.

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## phild01

Concerned that a coach screw is being used in line with the lvl layers.  I would check the manufacturers detail.  From what I have read, this is not recommended.

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## paddyjoy

> It's quite easy to twist off the head of your average coach screw these days...I usually pre-drill to the size of the shank between the 'blades' of the screw.  And I've been known to use WD40 in the screw holes themselves..[hardly necessary for LVL]. 
> So I'd go with 8mm holes or thereabouts.

  Thanks I'll try a test run with 8mm tonight and see how I go.   

> Concerned that a coach screw is being used in line with the lvl layers.  I would check the manufacturers detail.  From what I have read, this is not recommended.

  Thanks Phil I hadn't noticed that mentioned anywhere in the details but I'll double check before I use them.

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## GraemeCook

> Concerned that a coach screw is being used in line with the lvl layers.  I would check the manufacturers detail.  From what I have read, this is not recommended.

  
Good Morning Paddyjoy 
LVL has been around in the States since at least the seventies where I used it under the name of microlam.   My memorery is that you can screw into the face timber, but must bolt through the edge-grain.   Quite specific fastening rules were available, so I agree that you should check with the supplier, as Phil recommended.    

> ....I usually pre-drill to the size of the shank between the 'blades' of  the screw.  And I've been known to use WD40 in the screw holes  themselves.....

  Me too.   In fact, I grab the nearest available lubricant - CRC, oil, grease, lanolan, cooking oil, butter, soap, detergent, whatever ....   Lubrication is really necessary when I buy crap screws from BigChains!    
Fair Winds 
Graeme

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## woodchip

I think the guide is you need to go "through" 3 laminations, check tho' as suggested.

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## paddyjoy

Thanks guys, strangely I can't find anything in the hyspan LVL technical manuals however I feel safe doing this as I will be going into the face and will be going through about 10 laminations.

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## phild01

The smart frame have a very extensive literature set for their product and if it is anything to do with structural fixings, well anyway, it is worth reading about.  http://www.tilling.com.au/sites/defa...%20Details.pdf

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## paddyjoy

Thanks that's a really comprehensive document compared to the hyspan manual. 
Sent from my Nexus 5 using Tapatalk

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