Window extend to french doors - how tall for doors?

[Rugby rich]

Hi All,

I'm normally quite DIY savy, but never had this situation before, so after some opinions... I'm opening an existing window downwards, and replacing with french doors. My question is regarding how low should this go for the doors?
Normally I'd have thought it wants to stop at floor level (so the whole door is essentially sat on the floor, and this would then be the measurement given to the door supplier), however due to the frame thickness etc, I was wondering if you could/should extend it slightly lower, so there is a smaller step over the door (it's already a reasonable sized step to the garden, so minimising the up & down would be good).

The considerations I've already made are:
Joist direction - they're going parallel to the wall the door will be in, so no issue in joists being supported here.
Damp proof course - is ~ 2 brick courses down from floor level
Walls are solid double brick
Doors will be opening outwards

I've noticed some suppliers do different height thresholds. From looking at it, I think I'm best ensuring the total height of the door, will place the threshold finishing just above the floor height to minimise the step (and therefore the threshold & sill are recessed downwards into the wall). This would mean the total height would be (distance from top of current window to floor) + (1/2 threshold height + sill height). Does that sound reasonable, or is this a really bad idea?

 

[Notch7]

Measure from head of window down to finished floor level, deduct say 15mm, then add on cill thickness.

You will need to remove brickwork below underside of door frame threshold and then make good with a split cours or mortar.

 

[Rugby rich]

That would essentially put the bottom of the threshold at floor level, with the cill below, so the step over would just be the threshold height, correct?

 

[Notch7]

That would essentially put the bottom of the threshold at floor level, with the cill below, so the step over would just be the threshold height, correct?

Sorry I should've given more detail as it depends where you measure from as a upvc door set will have a rebated frame and a cill below

As it's open out, I would say aim to have 15 to 20mm of the frame showing on the inside only -although bear in mind if you need to trim between floor finish and door frame -you might need enough for a trim to fit. 15 to 20 will roughly make the door frame rebate flush with the floor finish.

Don't forget if you are measuring with the window in place, you need to measure up to the lintel, not the internal plaster.

 

[Rugby rich]

Great stuff, all makes sense now I think. Cheers.

 

[Diver Fred]

If you are using a 'local' supplier why don't you measure from floor to top of window reveal (ideally outside - rough guestimate - an inch more than inside measurement) or underside of lintel and then ask their advice for how much lower than floor level you have to go (probably one course of brick).