Advise installing fiberglass door in concrete

[Grubs]

I need to replace an entry door in our basement. This is at ground level in an old stone and concrete foundation. The existing door is wood with wood jam. I want to replace it with a ThermaTru or Jeldwyn Pre-hung Fiberglass door.

What I hope to do is take out old door and jam (leaving only the bare concrete, no wood frame) and install the new fiberglass pre-hung in that opening. (The rough opening is 35 x 82.5” btw)

So the question is, can I do this, or do I need to frame it out and custom order a smaller size door?
Thanks

 

[Snoonyb]

Welcome.

A 35" ro will require a special order door, allowing 1-1/2" for the jamb.

The height can be fairly easily adjusted at the threshold or the header, your choice.

 

[Sparky617]

I would pad it out and use a 32" door rather than going custom.

 

[nealtw]

I agree with the 32" door and the height might be good but if needed an outswing door needs less height than a inswing. Sometimes more than an inch shorter.

 

[Grubs]

Thanks. I’ll double check my measurements and the specs from the manufacturer. Appreciation for the quick response!

 

[nealtw]

Thanks. I’ll double check my measurements and the specs from the manufacturer. Appreciation for the quick response!

Normally the door frame is 1 1/2" wider than the door it self and you want another 1/2" for leveling it up. And standard doors come in 2" increments.
So if you measurements are right you would start with a 32" pre hung. Add 1/2" to each side and then shim it to level and plumb.
Your height is very close so you want to make sure you check that for top level and measure from the low side. Check the floor for level and measure from the high side.

 

[Grubs]

I would pad it out and use a 32" door rather than going custom.

That’s what I was hoping for, but I haven’t installed many doors before into concrete. Does the pre-hung unit’s jamb act just like the wooden jamb in the pics? OR do I need to install a wooden frame to accommodate the pre-hung? Also what do you mean by ‘pad it out’? Pack any gaps with concrete? Thanks.

 

[Grubs]

Normally the door frame is 1 1/2" wider than the door it self and you want another 1/2" for leveling it up. And standard doors come in 2" increments.
So if you measurements are right you would start with a 32" pre hung. Add 1/2" to each side and then shim it to level and plumb.
Your height is very close so you want to make sure you check that for top level and measure from the low side. Check the floor for level and measure from the high side.

Ah, will do. The height is no problem but it is a pretty solid 35 wide. However... the old concrete could be chiseled out at the tight spots I guess, as the original stonework is more like 37” wide.

 

[nealtw]

Ah, will do. The height is no problem but it is a pretty solid 35 wide. However... the old concrete could be chiseled out at the tight spots I guess, as the original stonework is more like 37” wide.

I wouldn't touch the old masonry, stay out of trouble. 32" is standard for basement doors.

 

[Grubs]

I wouldn't touch the old masonry, stay out of trouble. 32" is standard for basement doors.

Ok, thanks for your help!