# Considerations when replacing interior 1 3/8" doors with 1 3/7" doors?



## peinal (12 mo ago)

I am wanting to replace my hollow-core 1 3/8" thick doors with solid Cherry doors. They are $$$$--so I want to ensure I dont screw-up the order and create a lot of fit-headaches for myself. My question is-- the lockset bore is currently centered in the 1 3/8" door. Should the lockset bore also be centered on the new 1.75" thick door? or should it be offset such that the edge of the bore is the same distance as the original door? ie offset 3/16" toward the edge of the door which will hit the jamb's door stop? Are there other potential gotchas I should be aware of? Thanks!!


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## Jar944_2 (Oct 30, 2020)

You will need new jambs, or at the least to move the stops if they are nailed on and not integral. The locksets are always centered.

Hollow core jambs are usually barely adequate for hollow core doors.


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## swp (Dec 17, 2021)

Yep, plan on replacing the jambs. Unless they are perfectly installed already, they will not be plumb, the stops will have to be moved to accommodate a thicker door, the hinge mortises will need to be set back a bit, the 3-1/2 inch hinges should be replaced with something designed to carry some weight; at least a 4 inch, probably a 5 inch hinge. A new solid cherry door, 36x80 might be about 70 pounds, the hollow core less than half that. You will probably want a new lockset made for the thicker door. Some locksets will work with both thicknesses; some won't. 
All this is easier than you might think. Watch a few youtubes first. Just go slow, use a good 6 foot level and enough shims in the right places to keep the jams straight, so buy a big pack of shims. Back when I started we nailed the jambs to the stud; now I use trim head screws exclusively. They leave a bigger hole to fill than a nail, but a nail in the wrong place is a lot harder to move than a screw. And when you do fill the holes, don't use caulk; it never looks right. I use water putty. It's cheap, hardens fast, and can be pared flush with a chisel before it turns solid, so no sanding.


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## JohnGi (May 9, 2019)

When you say "solid cherry doors" do you mean stile and rail doors or solid core, cherry veneered flush doors? There are big differences in how these are intended to take locksets. 1 3/4" doors are typically exterior doors and are mostly intended to take 2 3/4" backset locks. This means a 6" stile with 1/2" sticking leaving a 5 1/2" face which the lockset is centered in. Interior doors are commonly 2 3/8" backset and have narrower stiles. With flush doors, there is frequently internal engineered construction that is designed around a specific backset. Boring for the wrong backset can disrupt the structural integrity of this internal construction. 
Most common bored locks are intended to be centered in the door. I've seen some that could be adjusted for off center installation, generally for asymmetric construction in a flush door. American style mortise lock cases are so wide they need to be centered in a 1 3/4" door. Narrow European style mortise locks can be set off center in doors with rabbeted edges.
Stile and rail doors are rarely "solid lumber". Especially doors intended for exterior use more commonly have elaborate laminated construction in the stiles to keep them straight when exposed to different conditions of temperature and humidity on the opposite sides.

There are a lot of pitfalls to this. The best way to avoid them is to have an approved installation drawing from the manufacturer. I know there were times I came across as a real jerk when I had to tell people they had voided the warranty on an expensive door.


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## FirebirdHank (Jan 25, 2021)

I can see no up-side to using 1 3/4" doors for interior use. If you are trying to get away from hollow core doors that can be easily done with 1 3/8 units and avoid any issues with the jambs. One thing to consider is the increased weight of the new units. If a heavy door gets slammed, either on purpose or because of air movement, it can do serious damage to standard frame. Plus 1 3/4" doors are generally considered to be exterior doors and look out of place when used for interior use (at least to me).


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## Jar944_2 (Oct 30, 2020)

FirebirdHank said:


> I can see no up-side to using 1 3/4" doors for interior use. If you are trying to get away from hollow core doors that can be easily done with 1 3/8 units and avoid any issues with the jambs. One thing to consider is the increased weight of the new units. If a heavy door gets slammed, either on purpose or because of air movement, it can do serious damage to standard frame. Plus 1 3/4" doors are generally considered to be exterior doors and look out of place when used for interior use (at least to me).


1.75" doors are considered upgrades for interior doors. Not common on most residential homes but certainly not unheard-of for custom high end work. Similar to 2.25 to 3" exterior doors or 1.25" cabinet doors. Obviously jambs and hinges need to be appropriate.


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## TimPa (Jan 27, 2010)

^ ^ ^ what he said. there are many thicker doors in the houses in my town. as said, the jambs/hinges are as important to match up. also, fwiw, i always upgrade the lockset as well.


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## GCTony (Apr 5, 2018)

We've installed hundreds of 1.75" doors in commercial buildings so just food for thought:

Most times the frames are metal but when we make wood frames, they are always 1" stock, casing well attached to the jambs and wall. 
Most of our solid core flush doors weigh about 120 pounds.
6/8 and 7/0 door are always 3 hinges, 4.5" ball bearing. 8/0 doors are 4 hinges.
The 2-1/8" bore is 2.75 back set, 1" latch is centered in the edge of the door.
A lot of residential hardware doesn't work with 1.75" doors. 

I personally wouldn't use 1.75" doors in my home (the scale would look "off) but I have been changing out my cheep hollow core flush doors from the 70's with shop built 1-3/8" shaker, rail/stile 2- panel doors. (poplar frames & 3/8" mdf flat panels) They aren't overly heavy, maybe 60 lbs but I did cut in a third 3-1/2" hinge. Looking back, I wouldn't build them again. I would order them from a factory simply because 1) There's no saving with the material cost and my labor to shop build them and 2) building 30 doors takes more free weekends than I have so it's slow going.


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## B Coll (Nov 2, 2019)

peinal said:


> I am wanting to replace my hollow-core 1 3/8" thick doors with solid Cherry doors. They are $$$$--so I want to ensure I dont screw-up the order and create a lot of fit-headaches for myself. My question is-- the lockset bore is currently centered in the 1 3/8" door. Should the lockset bore also be centered on the new 1.75" thick door? or should it be offset such that the edge of the bore is the same distance as the original door? ie offset 3/16" toward the edge of the door which will hit the jamb's door stop? Are there other potential gotchas I should be aware of? Thanks!!


I would not use the stock jams. Make new jams with 5/4" stock. If your framing is wide enough 1-1/8" is what we always did, but you can get away with a full 1" jam. The benefit if doing the jams is you can mortise the jam and doors as a set. You can do it by hand if you wish, we used a door mortising setup, not worth the price if you are only doing a few doors. On exterior standard (1 5/8") and thicker we always used ball bearing hinges. For your door you could get away with 3-4" hinges. Baldwin makes a very nice ball bearing hinge. When installing the jam make sure the jam is secured to the jack studs at all hinge points, behind the strike, and top and bottom of the strike side.


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