Sealing exterior door frame

[Clive George]

The builders have failed on this twice now, so I thought I'd ask around :

There's a gap between the back door frame and the stone wall. About 1/2", filled with cement, foam, plastic in various places.

Originally that gap was covered by a cement (sand/cement?) fillet/wedge. That fell off.

Next try was some soft putty-type stuff. It's still quite soft after several months, it looks somewhat like yellow sand apart from being obviously puttyish. Applied in the same fillet/wedge as the cement, it lasted a little longer, but now it's falling off.

Neither of these have managed to adhere to either the stone or the wood sufficiently.

So, my question is what to try next?

People mention mastics - unfortunately a) I don't know how big a gap they'll cover and b) what mastic actually is. So can you aim your answers at a fairly low level of knowledge :-)

TIA, clive

[Cicero]

========================== If the door frame is wood you could attach a wood beading to the frame to cover most of the gap and then complete the seal with silicone sealant where the new wooden beading meets the wall.

Cic.

[Clive George]

What sort of gap size should I be aiming for?

cheers, clive

[Cicero]

============================ Fix the wooden beading to the door frame so that it is touching the brickwork (covering as much as possible of the gap) and then use the silicone to seal the irregular edge where the beading meets the brickwork.

Cic.

[Clive George]

That'll be 'none' then :-)

Thing is, it isn't brickwork, it's stone, and hence a bit more irregular - I was wondering how much gap I could get away with before having to cut the wood to shape.

cheers, clive

[Cicero]

========================== For the best appearance I would suggest that you limit the silicone filled gap to 1/4" (6mm) or less.

Cic.

[Clive George]

Thanks. Looks like I'll be playing with templates then...

cheers, clive