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Bathroom remodel — multiple questions

Cougar86 | Posted in General Questions on

Don in Marine Zone 4c. Salem Oregon.
I am remodeling my 1965 Ranch style home. Best as I can tell its a “California Deck house”. My ventilated crawl space is about 20″, mud sill not bolted to foundation and 4×6 doug fir beams on 4′ centers supporting 2×6 T&G.
The space being remodeled has no underfloor insulation of any kind.
Questions I have are:
1. I want to put tile on the floor, concerned about deflection and sealing the floor. Insulating the crawlspace or the floor? best method to stiffen floor?
2. Selecting the proper size bath fan for a soaking tub, walk in shower and toilet, space is 80 sq ft, but there is no bathroom door as it attaches to the master bathroom with a 4′ opening. Humidity sensing, occupancy sensing?
Have a 4′ sq opening available to access crawlspace, until plumbing completed.

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  1. GBA Editor
    Martin Holladay | | #1

    You need to check two things to make sure that your floor doesn't have too much deflection for a tile job: (1) You need to make sure that the joists are adequate for the span, and (2) You need to make sure that the subfloor is adequately thick. We can't tell if your 4x6 joists are properly sized because you didn't tell us the span.

    The easiest solution for you is to hire an engineer to examine your floor and suggest remedies. You might need to sister new joists on to your 4x6s (or between your 4x6s), and you also might need a layer of plywood above the existing tongue-and-groove subfloor.

    Bathroom exhaust fans need to be effective, but they also need to be energy-efficient. If a bathroom exhaust fan is oversized, it wastes energy, because all of the conditioned air that is exhausted from the house is replaced by outdoor air that is cold in the winter and hot in the summer.

    I usually advise homeowners that it's better to have a small bathroom exhaust fan that runs for 10 minutes that a big bathroom exhaust fan that runs for 3 minutes.

    Codes require a bathroom exhaust fan to be capable of exhausting 50 cfm. This usually requires a fan that is rated at more than 50 cfm, because of the static pressure of the ducts connected to the fan. Whatever type of fan you decide to install, have it tested after installation to make sure that it is moving at least 50 cfm.

    For more information, see these two articles:

    "Bathroom Exhaust Fans"

    "Does a Home with an HRV Also Need Bath Fans?"

    One final note: You might want to insulate your crawlspace walls. For more information, see "Building an Unvented Crawl Space"

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