Mortar/sealant around uPVC DG units - best practice?

2 Dec 2009
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United Kingdom
A couple of my uPVC DG units are allowing the passage of air, noise and possibly insects. I'll start a different thread about building up the interior. as I'm waiting for application notes from the tape vendors, still vacuuming out insect detritus and waiting for ACDs from an architect friend.
Externally, some of the mortar is gone and some of the frame sealant expansion beads are gone too. I assume the mortar acts as an airtightness barrier and the frame sealant is to allow for expansion and contraction due to climatic conditions.

[Edit: Oh I see they have mortared right up to the frame, then applied a filleted bead of frame sealant around the interface perimeter. Is that correct? The sitting room window was a separate installation (Everest by the looks of it) and is intact].

What is the best way to *neatly* replace the ext seal ?

Mortar first then frame sealant?
Frame sealant first then mortar?

I was thinking of pulling, the frame sealant out, chipping the mortar out.
Placing a temporary bead (6mm strip of ply) against the frames, a strip of making tape further out to define the margins
Mortar between the tape and bead with a margin trowel.
Remove plywood bead. Remove masking tape
Allow mortar to dry.
Fill in the gap with frame sealant.

Many thanks.
I'll be out and about working so might not see responses promptly.
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