Building Regulations for external frameless glass balustrade fixing detail (into oak)

[sean1933]

Evening all.

 

Short story is our balcony frames on the gables is made of 250 x 225 oak. The intention being to fit frameless glass balustrades (21.5mm lam/tough) in the associated channel. I have the glass and Posiglaze channels on site but when revisiting my building regulations i note the following condition 'Provide full balcony guarding details i.e. glazing and support posts and fixing 'details. 0.74 KN/m at 1100mm height not 1m.'

 

I'm yet to speak with building control as I don't want to set hares running just yet, but all the fixing details/deflection test data I can find are into solid concrete or steel. Speaking to the manufacturer they agree 200mm M12 coach bolts at 200c (as per concrete detail) will be fine, but obviously don't have certificates to back this up. They do however now have certificates for their timber fixing plates which can be used on much smaller 100x150 timbers... but at £12.50+vat each at 200mm centres I'll need something like 116 so its going to cost a small fortune.

 

I'm interested in others experience of such fixing scenarios - do I get into it with building control and hope they agree the coach bolt concrete fixing spec is fine, or just suck-up the extra £1500 and move on with my life?

Edited February 19 by sean1933

[Russell griffiths]

Are you mixing up names. 
coach bolts- these would go through the timber and out the other side with a nut and washer. 
coach screws these go in to a set depth and are held in by the physical grab of the screw against the timber. 
 

Coach bolts- you would need to drive a tank against that glass to get it to fail, then the glass would fail first, so this method would pass any spec it needs to. 
 

coachscrews- driving one of these 200mm into oak, you will need to do some rigorous testing to get this right, you won’t drive them in without a pilot hole, hole too tight you risk sheering of the head of the bolt, hole too big and you comprise the pull out strength. 
I believe they will need to be stainless going into oak, you will also have to spec the strength of them, some stainless can have the strength of firm cheese. 
if you get the spec right, the coach screws will take a huge amount of pressure to pull them up enough to get any movement in the bottom glass channel. 
 

have you looked at drilling a larger hole and resin fixing in a stainless stud with a nut on the top, there are particular resins that work on timber not concrete. 
 

having done a fair amount of demolition I would be happy using any fixing into oak as it has good pull out strength. 
 

but all this might need passing by a structural engineer. 

[markc]

Will the glass be bottom fix only or if fitting between frames are they in side channels? A sketch of your intended install would help a lot.

[sean1933]

Thanks for your responses both.

To confirm - its bottom fix channel only, and yes I meant coach screws sorry. Coach bolts would be simple but look awful from below as obviously visible from the underside.

 

Russell sadly you appear to confirm my secondary worry in that without testing the pull out strength is unknown, not to mention my (probably overthinking mind) worry about splitting / weakening the beam with so many big holes in close succession. The need for a structural engineer would probably negate the cost of the already tested method, especially as I'd need to find a new one as mine has retired and emigrated. 

 

This is the alternative that I was trying to avoid purely due to cost - expensive but tested and avoids the need for deep holes. https://pure-vista.com/product/timber-fixing-plate/

I've managed to get a bit of discount due to quantity but still eye watering for what it is.