Replacing Velux Glazing Unit

[Mark 9002]

I have to replace a GGL 606 glazing unit. Velux no longer do replacement glass for this window, nor do they longer do conversion kits for this. My local Glass shop have been able to supply me with a unit the correct size ( although the old unit is 3-9-3, I now have a 4-8-4 unit. I'm guessing that 1mm wont make any difference.. The guy in the shop advised that when they fit new glazing units to Velux they seal up with Silicon and don't use the Velux Butyl Seal as he said they've never had any issues just using LM/ Neutral cure Silicon. The Velux Butyl kit is upwards of £25. However, I have a good few rolls of Butyl tape (10mm x 3 mm) left over from a garage roofing replacement. If I double this Up to give 6mm thickness seal on Frame would this be ok ? The Velux supplied stuff comes in 2 thickness's 6.5mm and 4mm for the bottom cover. Any thoughts on this ??

 

[crank39]

From memory I don't think there is any butyl tape on the frame side only the glass, only torx screws hold the folded aluminium down

 

[Mark 9002]

Hi, Its the glass to aluminium profile side I was referring to. I think this is where the Butyl seal goes I think ?

 

[crank39]

( although the old unit is 3-9-3, I now have a 4-8-4 unit. I'm guessing that 1mm wont make any difference. If I double this Up to give 6mm thickness seal on Frame would this be ok ? Any thoughts on this ??

1mm won't make any difference. I thought you meant you were going to pack the aluminium section up off the timber using butyl tape to make up the discrepancy in unit thickness?