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Community and Q&A

Recommendations for a small bathroom reno

philray | Posted in Energy Efficiency and Durability on

We live in Zone 5 (Ann Arbor) and will be doing a small bathroom renovation in our 1957-built home. Mainly addressing functionality and water management (lousy amateur shower tile from previous owners), but I would welcome advice on expectations or direction we should set with our contractor for insulation, air sealing, and other energy priorities. The bathroom is 7″6″l x 7’w (external wall) x 7″6″h. We are planning for a Panasonic exhaust fan and LED lighting (avoiding cans). We will be replacing most drywall in this bathroom, including ceiling, as we replace the tub and wall tile.

This is a second floor, so we could consider a drain heat recovery pipe, but we don’t currently have that in scope, due to project budget and need to open then patch a finished wall on the lower level. The tub is used daily for both baths and showers. Domestic water heater is with a natural gas tank, conventional atmospheric venting.

It may not matter for such a small project, but here’s some additional info. I am not sure of the current exterior wall stack-up but believe it is along the lines of 1/2″ drywall with skim coat plaster, conventional conventional 2×4 (3.5″) framing and loose fill cellulose, asphalt-impregnated fiber board, paper or felt unknown, plywood T1-11 siding; no plans to touch the exterior of the house in the near future. Heat in the house is via baseboard hot water (80-85% gas boiler). The narrow end of the tub (not the plumbing end) will be against the exterior wall.

Recommendations on what to prioritize for air sealing and insulation or other measures?

Thanks – love the site and paid my membership in January. Appreciate the existing content on renovations, in addition to new building, and hope to see more content on renovation of existing buildings in the future.

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  1. GBA Editor
    Martin Holladay | | #1

    If you are working from the interior, the usual way to pay attention to airtightness is to follow the Airtight Drywall Approach. This method requires you to purchase airtight electrical boxes.

    I don't know what to recommend for insulation measures, since your walls are already insulated. The answer depends on your expectations and your budget. If you want, you can install interior rigid foam; here is a link to an article with more information: Walls With Interior Rigid Foam.

    Other tips? It all depends on your budget.

    A drainwater heat recovery device would have been a good idea, but that's evidently a budget-buster.

    Install a high-quality exhaust fan -- I'm partial to Panasonic fans -- controlled by a programmable time-delay switch.

    Pay close attention to lighting; more lumens are better than fewer lumens.

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