Hi, I have a brick opening of 2270 wide and two side hinged wood garage
doors 1070 wide (total width 2140, no rebate) to fit. The height is not
a problem.
If I use treated 3 x 4 for the frame this adds 152 to the width which
is now 2140 + 152 = 2292.
So I need to shave off 11mm from each door width, plus some more for
clearance.

Questions.
How much do I need to remove for the clearance?
There is no rebate but I plan to add a plank down where the doors close
together to stop the wind whistling through. Are there any better
methods?

If I use 2x4 instead for the frame I am left with a gap of 28mm. Is
28mm enough for the clearance and perhaps a small strip of rebate wood?
Is 2 x4 strong enough to use as a frame?

Thank you

You don't say how accurately the doors are hung (door hinges, gate
hinges?) or how accurate/rigid the joinery.

I'd choose the heavier 75 * 100 frame, as you will no doubt need some
substantial fixings for the doors (and the frames to masonry). Hang the
doors, close them against each other, mark the overlap and take off and
trim one of the doors (remember they may sag a little bit so the shut
line may not be quite parallel with the door edge). A cut rebate offers
slightly better security than an applied one. I guess you've already
figured your solution for bolts & locks?

wrote:
You don't say how accurately the doors are hung (door hinges, gate
hinges?) or how accurate/rigid the joinery.

I'd choose the heavier 75 * 100 frame, as you will no doubt need some
substantial fixings for the doors (and the frames to masonry). Hang the
doors, close them against each other, mark the overlap and take off and
trim one of the doors (remember they may sag a little bit so the shut
line may not be quite parallel with the door edge). A cut rebate offers
slightly better security than an applied one. I guess you've already
figured your solution for bolts & locks?

Hi, thank you for your helpful reply. The doors are old second hand and
well made, but not excessively heavy. I'm planning on using 3 gate
hinges per door.
Do you know what clearance I should leave between the doors and frame?
Thank you

Hinge side, I'd go for about 5mm - assuming these are fully framed and
boarded doors that will only sag to a minute extent. Bit more if
they're ledged and braced doors (which are more likely to sag a bit as
they get older).