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interior door installation

factotam's picture

i am installing 17 interior doors in new residentual construction, the doors are knock down pre-hung, there is 1/2 inch clearance from the bottom of the door jamb and the bottom of the door, part of the house will have 3/4" hardwood flooring, and the bedrooms will have pad and carpet, if i set the jambs on a 3/4" spacer i will have 1/2" clearance at the bottom of the door and the top of the finished hardwood floor and will be able to slide the floor under the door jamb and door caseing, i was wondering if the 3/4" space under the jamb will work with the carpet, will the pad and carpet slide under the jamb ok, is 3/4" too much space for carpet-thanks for your advice

Probably to much, depends on (post #182451, reply #1 of 8)

Probably to much, depends on the carpet I guess. For comparison we usually set baseboard 3/8" off of the unfinished floor for carpet. Some carpets it needs to be tighter or there can be a gap. Don't think I ever set it more than 1/2" for carpet

Barry E-Remodeler  

with having only one half (post #182451, reply #2 of 8)

with having only one half inch from the bottom of the door to the jamb isn't very much for carpet but it will be ok for wood. the pre-hung interior doors that i use usually use have 1 1/4" then i can cut off the bottom of the jamb depending what type of flooring i am allowing for.
i usually leave my jambs up about 1/2" for carpet and then the carpet layers chisel the carpet in around the jamb.i think you will be ok to leave them up 3/4 if you leave them down any lower you might halve to cut off the bottom of the door if it rubs on the carpet. good luck ..........nicko

Yes a 3/4" gap under the door (post #182451, reply #3 of 8)

Yes a 3/4" gap under the door jamb will be way to high for the carpet. I have have most carpet installers request a maximum of 3/8" gap for them to tuck their carpet under (some were even fine with 1/4" but I think that that is a little too tight). Install the jamb according to the finish flooring. If you require to set it lower for carpet for one half of the jamb and notch it for the hardwood then that is what has to be done. Once the flooring is completed, adjust the bottom of the door to match the flooring once the transition strips are installed.

thanks for the replies and (post #182451, reply #4 of 8)

thanks for the replies and comments and advice, my thinking is that since i have doors that only have an existing gap of 1/2" between the bottom of the door and the bottom of the door jamb that if i held the door jamb up 3/4" the hardwood flooring installer would not have to undercut the door jambs and the bottom of the doors would not have to be cut, also since i want all the headjamb door caseing to line up i thought that i might be able to get away with the 3/4 under the jamb for the carpet if the installer slides the pad and the carpet under the jamb instead of installing the capret tack strip next to the jamb and tucking only the carpet under the jamb, now i am begining to have second thoughts

find out how thick your (post #182451, reply #5 of 8)

find out how thick your carpet and pad are i just cut some carpet on my job the other day to install a peice of wood to support sliding closet door track. i cut out a two inch wide strip between the jambs and measured the carpet and pad thickness to make my wood strip flush with top of the carpet and it was 5/8" and that was old beat down pad and berber carpet. i have left doors up 1 1/4" off the floor allready and after the carpet is laid the doors still brush the carpet in some spots. depending on your carpet thickness with pad i think you will be fine to leave them up 3/4" and run the carpet under the jamb.then fluff the carpet up around the jamb. talk to your carpet layer good luck.....nicko-- by the way i just looked at my carpet where it meets my 3/4" hardwood floor and it is a good 3/8" above my hard wood and it is a low tight knap carpert with pad

i am going to keep all the (post #182451, reply #7 of 8)

i am going to keep all the jambs 3/4" off the sub-floor, this will allow the hardwood flooring to slide under the jamb with no undercutting and leave a 1/2" space between the finished floor and the bottom of the door, this way all the door caseing with be at the same elevation, a thicker carpet pad will be used if necessary to take up any extra space

3/4" for carpet will work. (post #182451, reply #8 of 8)

3/4" for carpet will work. Carpet guys like 3/8" for baseboard tuck-under, but that is carpet only, not pad & carpet.

Any good pad will be at least 3/8" and even low nap carpet will be at least that much.

Don't forget that unevenness of subfloor can result in one side of a jamb being higher than the other. If you just shim 3/4" under each leg of the jamb you might end up with an un-level head jamb.


The space under the door is (post #182451, reply #6 of 8)

The space under the door is also for the cold air return in the case of a forced air system in a room with out a dedicated return air outlet
This becomes a issue often up here in canuckistan when people complain of cold bed rooms due often to pressure build up in the rooms with the door closed
If there are teen agers in the house they sometimes will block off the bottom of the door so no one can hear them talking on the phone ( seen it been there )