How to fix gaps under door jambs after new flooring
Removing old flooring or changing plank thickness often leaves exposed gaps and subfloors under door frames that are difficult to make look right without experience. Depending on the size of the gap, homeowners can either fill them using wood filler or Bondo, or glue in custom-carved wood inserts before painting or staining.
What the numbers show
Counted from the threads quoted below. How we count
- People have been saying this in most months since September 2026.
- This comes up 18.9× more often in r/Flooring than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
How to fix gaps under door jambs after new flooring
- 1Leaving the gaps alone and living with themDid this help you?
- 2Hiring a professional to redo the door casingDid this help you?
- 3Undercut the trim and jamb and get the flooring underDid this help you?
- 4Replace the bad cutsDid this help you?
- 5Use plinth blocks to cover gapsDid this help you?
- 6shoving backer rod into the gap and sealing it with siliconeDid this help you?
- 7Using caulkingDid this help you?
- 8Using groutDid this help you?
- 9using temporary removable products like spray sealants seen on TVDid this help you?
- 10adding weather stripping and corner sealsDid this help you?
- 11Using caulk or trim to cover the gapDid this help you?
- 12using sikaflex with backer rodDid this help you?
- 13cramming foam weatherstrip as a fillerDid this help you?
- 14Applying caulk to fill the spaceDid this help you?
- 15Installing a small shoe moldingDid this help you?
- 16Slipping the floor planks slightly under the threshold during installationDid this help you?
- 17reaching out to the builder to extend the weatherstrippingDid this help you?
- 18installing thicker weatherstripping that collapses when the door closesDid this help you?
- 19replacing old weatherstripping with a wider profileDid this help you?
- 20Use thicker 5/4 lumber for the casing to bridge the gap without installing jamb extensions.Did this help you?
- 21Cut back the old plaster, install new drywall, and use jamb extensions to make the surfaces flush.Did this help you?
- 22Trim the foam, tape the jamb, and build up the edge flush with 90-minute joint compound.Did this help you?
- 23Applying adhesive foam weatherstripping tape along the frame where the door meets it.Did this help you?
- 24Loosening the strike plate screws and shimming behind it with cardboard or thin wood so the latch catches.Did this help you?
- 25Filling the visible gaps with color-matched or white caulking.Did this help you?
- 26Using an oscillating multi-tool to undercut the door jambs before laying planks.Did this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“In a few spots around doors, there are gaps where you can see the subfloor.”source ↗
“I recently put down some new vinyl plank flooring, but I'm struggling with how to clean up the gaps around the door frames and jambs.”source ↗
“The door trim was reused and i just didn’t measure the plank to account for that piece correctly, leaving exposed subfloor.”source ↗
“I’m not sure what to ask my contractor for because I’m not sure what typically goes here but it seems like something should.”source ↗
“This is my interior engineered hardwood flooring meeting an exterior door and there’s what I would consider a notable gap between the two.”source ↗
“We have much worse at our home but we paid the guy so little + a few bottles of u know what so we never complained.”source ↗
“Had LVP pulled out to refinish hardwood underneath, which left us with a lot of doorjam gaps.”source ↗
“Would I just use wood filler/bondo here? Not being square seems like it would be tough to get them to look right, especially since I have no experience.”source ↗
“Or maybe have a woodworker carve some inserts, glue them in and paint over?”source ↗
“I've got a gap between my door seal and tile. It's about 1/4" or so. Just wondering what I can use to seal it.”source ↗
“I'm thinking caulking or grout, just wondering which is best (or if there's something else).”source ↗
“Just noticed today that the installer left a messy 1/2” jagged gap above the trim. What should I use to cover the space - caulk? Trim?”source ↗
“there's a gap in the upper right corner. The aluminum? flashing wasn't cut to length and I'm wondering if there's a good way to find more of the same stuff or a way to repair it all so that there are no gaps.”source ↗
“When I was sitting across the room on the sofa on the bottom left it was more than just a slit of daylight but when I approached the door on the bottom left I could have put my finger underneath it to the outside.”source ↗
“I'm not sure the landlord will be responsive to any kind of fix”source ↗
“They are not repair inclined at all but I just hate seeing them lose all their heat”source ↗
“wanted to get some advice for a gap under my door.”source ↗
“For some additional context, the concrete step is slanted towards the door which directs water to that area, thus why I want to cover it up.”source ↗
“I have this gap on both sides of the garage door and it seems like the weatherstripping doesn’t cover it all the way.”source ↗
“I’ve been having a cricket issue in the garage.”source ↗
“Is there anything I could use to temporarily fill in the gap? Or is the gap there for a reason?”source ↗
“It’s there. Just doesnt close super tight”source ↗