Home Improvement--General/cutting a hollow core door


QUESTION: I need to replace a hollow core door in a cement block doorway between the basement and living area six steps up from it.  (The door is at the foot of the stairs.) The entire door unit was removed after it was damaged by flooding and the contractor applied a waterproofing product to the cement block area under the door (and stairs) where water had seeped in.  The original door was a prehung unit and the door itself was shorter than usual--78" when new.  It had been cut to 77" to fit.  I purchased the same thing with the intention of cutting it to 77" also.  The work on the floor beneath the door is rough and irregular from the waterproofing work and the door may not fit.  How do I move the frame inside the bottom of the door if it needs to be cut shorter because of the repair?  Is there a way to eventually seal the crack under the door with weatherstripping if it's so uneven?  I'm not a carpenter, but might have to fix this whole thing myself and would like to know how it should be handled for the best result.  Thank you for any help.

ANSWER: Hi Carol,

I hope I correctly interpreted your questions .  If I don't properly address them, feel free to send me a follow-up question and perhaps a photograph or two of the repaired areas and the new door.

It seems you need to saw a door and perhaps the door jamb to length and install a threshold and sweep to seal the bottom of the door.

Read sawing a hollow core door to length for detailed instructions on sawing and repairing the door. You will need to install a threshold under the door so take the thickness of the threshold into account when calculating the amount that needs sawing off the door.  A simple aluminum threshold with no door gasket will likely work best. The gap between the door bottom and threshold should be sealed by adding an adjustable sweep to the bottom of the door.  If the gap is uneven the sweep can be adjusted up or down on each end to achieve the proper seal.  

If the threshold is mounted to a concrete floor the installation of plastic anchors into the floor will be required.  Cut the threshold to length and with it positioned in place mark the location of the plastic anchors by inserting a nail or punch through the existing mounting holes and tapping lightly with a hammer until all holes are marked.  Remove the threshold and using a masonry drill bit, of the size recommended on the plastic anchor package, drill a hole at each marked location that is slightly longer than the depth required by the screws supplied with the threshold.  The threshold may now be secured in place. Applying caulking under the threshold is optional but may result in a tighter seal to the floor.

I hope I have been of some service and wish you good luck with your project.


---------- FOLLOW-UP ----------


Thank you for taking the time to reply.  You sound very meticulous, which I really appreciate.  The ordeal with moving the rail in the bottom of the door (if necessary) sounds straightforward.  As far as the threshhold goes, there's a problem I didn't mention earlier.  The part of the area with the stairs and door (where the floor was treated with waterproofing and now is lumpy and irregular) is about 3" higher than the rest of the basement floor it leads to.  The lower floor is vertically flush with the basement side of the door.  In other words, there isn't room for a threshhold beyond the bottom of the door itself.  I'd also be very reluctant to drill into the concrete floor, since the openings in the cement blocks are there (although filled with the waterproofing material now) and it's the main area where water was entering.  I was hoping there's some kind of weatherstrip that could be applied to the bottom of the door that could magically conform to the gaps, but I realize it's unlikely.  Another possibility might be to apply a layer of concrete to the entire floor area from the base of the stairs to the edge of the concrete (which includes the floor under the door), so a better weatherstrip can be installed on the bottom of the door. Any thoughts?

basement door drawing ?
basement door drawing  
Hi Carol,

Still not sure if I have the proper image in mind of what you are describing.  Based on your description, I made a drawing as I visualize the door configuration.  If I am close to the way it actually is, and based on the limitations on drilling I can only think of a couple of things that might work.  Let me know if I was close with the drawing and if it was of any help.


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Tony Wood


I can answer a wide range of home improvement and maintenance questions. My expertise is in carpentry, painting, framing, siding/boxing, doors, windows, decks and screen and glass enclosures. Wood's Home Maintenance Service


I am a life time resident of North Carolina with over 30 years experience in multiple facets of the industrial, commercial and residential construction industry. For the past 23 years I have owned and operated Wood's Home Maintenance Service , providing services primarily in Johnston, Wake and Sampson Counties of North Carolina.


Several Home improvement articles published on Angie's List and other online forums.

High School graduate ~ proficient in CAD (computer aided design), Open Office program suite.

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