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Cutting down metal exterior doors

rocketdog's picture

My son is installing 3/4" Brazilian cherry over 3/4" plywood glued and ramsetted over concrete.  What is the best way to cut down metal insulated exterior doors and build up thresholds to clear the added floor thickness.  Also any thoughts on handling transitions from new flooring to adjoining 1) carpet layed on concrete w/ pad and 2) ceramic tile (kitchen).


(post #59712, reply #1 of 7)

Raise the door and jamb or sub it to a door shop.


Who ever invented work didn't know how to fish....

"Some days it's just not worth chewing through the restraints"

(post #59712, reply #2 of 7)

Although I have cut metal doors, I do not recommend it.  There are other options but they are beyond the DIY.   I agree with the above post and would call a local door pro.

"One measurement is worth a thousand expert opinions"
"One measurement is worth a thousand expert opinions"

(post #59712, reply #3 of 7)

If you pop the door off and take off the sweep you will see the hole that the foam is put in the door by. ( the ones I have had to cut anyway.) This hole will let you measure the amount of wood frame there is and you can then determine how far you want to push the cut up. I have cut down doors for cold storage rooms and had to remove some of the foam coar so that a wooden block could be re installed for support. The block was held in place with steel stud screws that were later covered by the U shaped sweep once it was reinstalled.

That all said I would still think twice about cutting an exterior door exposed to the elements. Great way to have the door rust from the bottom over time since the metal on the door will heat when you cut it.

Scott T.

(post #59712, reply #4 of 7)

You can also get 'raise-ing hinges' the knuckles are angled, as the door opens it raises up..  

(post #59712, reply #5 of 7)

I had a similar situation last year and used a renovation-specific door. The door core and exterior case structure actually ended 1" from the bottom; the last inch was effectively just a pair of steel flanges. This was to allow adjustability. So it was an easy matter to put a steel cutting blade in a circ saw to cut off the required length and then clean up with grinder and file. Sorry, I don't know which manufacturer the door came from.

As for threshholds, I like to extend the flooring right into the door opening and apply the threshhold over it. Run another piece of flooring through the bandsaw to make a bevelled apron for the height transition on the exterior side. Ditto for transitions to other interior floors. Sill gasket underneath to keep out moisture when laid direct to concrete.

Lignum est bonum.

Buccaneer Contracting

Penticton, BC

(post #59712, reply #6 of 7)

Place door over a pair of horses, clamp staight edge to door leaving set back for saw base. Put carbarundum blade in saw. Cut each end of door with a hacksaw first, this prevents ends from folding up  and crimping. You only have to cut an inch or so from each end. Set blade depth to an inch deep, cut one side , flip and do other side. You will have a heavy burr and blackened edge, file burr off and repaint bottom of door.

If bottom of door has no support, cut piece to fit . Glue up with gorrilla glue and pin each end with 2d common nail ( underlayment nails or pin nails).Nail on edge of door and it will not be visible when door is closed.Do the cutting outside or in area that is not finished, throws sparks and metal dust. Where eye and ear protection. Do not try to cut thru both sides at once, you get a sloppy job. The cutting is easy, go slow and you will have no problems. When installing wood bottom ( if you need it ) temporarily drive a screw partly into each end, this gives you a grip to pull glued bottom out if you push it in too far.


(post #59712, reply #7 of 7)

pull the door/jamb ...

or start with new ...

and cut off the top.

Not that'd I'd consider this for a front entry .. without first deciding how goofy a top short door would look ... or a short entry door no matter where it was shortened ..

But we have lots short rear basement entries around here ...

easiest and most weather resistent fix is the standard Stanley metal door ...

I cut both the door and the jamb at the top .. leaving the factory sill intact.

Jamb is simply cut ... re-rabitted side jambs ... top jamb reattached.

Door ... I cut with an abrasive blade in the circular saw ..

usually about 3/4 inch "long" ... then lightly score the face with a utlilty blade ... and fold with my hand benders.

I foam the open top if need be ... but usually the insulation in there needs to be pusked down .. to fit in the new piece of 2x2 that I've cut to fit snug ... reinforcing the top ... stick it in ... gule .. and clamp.

When it's set up ... bend/fold/beat the flaps over tight. sometime an aluminum nail or two thru a predrilled pilot hole is needed to make for a near perfect fit.

Prime ... paint.

This makes for a cut that's well protected at the top of the door ...

and makes for a factory threshold at the bottom .. where it really counts.


Buck Construction   Pittsburgh,PA

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