Sectional door too short, and render fell off!

[dobby1]

Hi Guys,

I have purchased a sectional door that will be installed on the inside of my garage. I took some measurements of the garage opening, and it is 20mm taller than the door. How can I "fill in" this gap? I tried to do a 3 coat (2 scratch) s/c render (+waterproofer) on the underside of the concrete lintel, but the render fell off about 40 hours after being applied; fortunately, no one was under it when that happened.

The lintel had an okayish key, I guess I could make some deeper gashes into it, use a 3:1 sand/cement mix instead of 4/5:1, but I'm not sure if that is the correct way to go about it, and I don't want another blunder as it can be very time consuming.
I did notice the first scratch dried out quite quickly (it has been quite hot the past few days).

I don't want to return the door either.

Please advise.

 

[^woody^]

Why don't you just fit a cover strip above the frame only. Like architrave, but in plastic.

 

[dobby1]

Thanks woody. That is a good suggestion, although I couldn't finding anything useful on "cover strips" when doing a quick google. Maybe they go by a different name?

 

[^woody^]

Cloak strip, cover strip, D mould, bull-nose strip, fillet.

Anyone that sells UPVC fascia and stuff will have this. It will be in various widths

You want the one that rounded on one edge and square on the other - bull-nosed.

Fix with silicone or external no-nails type adhesive, but you may need a couple of poly-top nails to secure it

 

[Alastairreid]

http://www.eurocell.co.uk/trims-and-cills/trims-quadrants-and-angles