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Home Improvement--General/Sealing off the tub from the crawl space.


We had a jetted tub installed years ago. Where the tub drain goes to the piping in the crawl space below the floor - there is an open hole I'd say about 1' x 1'. I've recently had a problem with drain flies getting into the space around the tub. I could tell as when I opened the plastic side panel they were all over the place in there. I suspect they're coming up from the crawl space below and I need to find out what's going on down there. But in the meantime - do you have advice on how I could seal off the tub area from the crawl space? Some kind of foam of other material that I could shape around the vertical drain pipes?? Thank you.

Hi Michael,

Normally when I answer questions that people send in dealing with problems they have concerning something done by a contractor, subcontractor, tradesman, craftsman, handyman, etc. I diligently try to refrain from making critical comments about the individual that did the work.  But, when I hear something like your story I can't resist!  Whoever did this job doesn't belong in any aspect of the construction business. Even though it appears this job was done some time ago I'd be tempted to see if I could contact this incompetent, corner cutting disgrace to all tradesmen, contractors, etc. and ask him to come back and finish the job and if he doesn't know how to do it correctly ask him to pay the bill you get from a competent tradesman who does it right.

Building codes require penetrations from a basement or crawl space, or from one floor to another to sealed with a fire stop caulk.  Good workmanlike practices dictate that you don't leave gaping holes from living space to a crawl space.

I don't know what skills, tools, or access you have to the 1'x1' hole in the subfloor, but if you do have access and some basic tools and are confident you won't cut your fingers off here's a simple  approach.

You could take a piece of plywood a little bigger than the 1'x1' hole, cut it in half then cut half of a round hole in each half of the plywood near the center about the size of the pipe.  Then slide each half around the pipe so they encircle it, place a screw or nail in each corner, or if you can't get to it to use tools just put a bead of construction adhesive or Elmer's wood glue all around the edges of the hole in the subfloor and place the two halves on top of the glue.  After it hardens get a can of "Great Stuff" low expansion foam and foam all around the pipe and where the edges of the two halves are resting on the subfloor decking.

You could use hardware cloth instead of plywood and cut a slot with a hole at the end of the slot about the size of the pipe (like a key hole), tack it down with u-nails then spray the foam all over it to seal the 1'x1' hole.  You can get hardware cloth at any Ace Hardware store or probably any of the big box stores.  Be sure the mesh is small enough that the foam doesn't just fall right through it but stiff enough so it doesn't sag badly.  There are a half dozen other ways to seal the hole.  Good luck.

Len Kroll
Wood House Log Homes LLC

Home Improvement--General

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Len Kroll


I can provide advice on the proper design, construction, maintenance, restoration, preservation, cleaning and waterproofing of log homes. Questions concerning proper cleaning, sealing, staining and waterproofing are within my area of expertise. My expertise includes new construction and existing log structures. Chinking application or restoration, log replacement and repair are also in my area of expertise.


40 years experience in the log home and construction industries, 10 years in specialty contracting, 30 years in the log home field. We have designed, produced, supplied and built over 3,000 log homes and restored/repaired over 600 log homes. See more information at our web site:

Authored a monthly column expressing the Vice President and General Manager's "Observations and Insights" distributed to 300 employees and management.

BS degree in accounting, University of Illinois, 1963. Master of Business Administration degree, University of Chicago Graduate School of Business. Numerous relevant seminars including an intense two week business administration seminar, University of Pennsylvania Wharton School of Business, 1978. National Home Builders Association Graduate Builders education program.

Awards and Honors
National Honor Society Student, Illinois State Academic Scholarship, Dean's List.

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