Redoing a bathroom using natural building and mushrooms

Aug 02, 2025 16:34:29

You can build a door using wood and mushroom insulation so why not a bathroom shower?
Beau built a door it at Wheaton Labs and made a webinar. So how about a bath that uses wood to replace the existing old plastic and mushroom insulation behind to help keep the bathroom at a good temperature.

Outline of idea

Bath has three walls and one is an outer wall of the home. Both inner walls will have mushroom insulation used and if outer wall's insulation is not good it will be replaced with mushroom insulation. After insulation is in place wood would then be put on top. Wood needs to have water proof surface and last a for years with little maintenance aside from cleaning. Total area to be done is about 50 square feet or 4.6 square meters.

Issues that would need to be solved

Water proofing both wood and insulation. Prevent build up of unwanted mold, bugs and etc.

Shou Sugi Ban or Yakisugi be used on pine or other woods and stand up to daily use of shower?

What other ways could one waterproof wood that are nontoxic?

Does there need to be a layer water proofing layer between the insulation and wood and/or between drywall?

Could the mushroom insulation be grown in place and would the drywall need protection?

What other issues do you think I have missed?

Aug 03, 2025 15:41:58

This sounds intriguing! I don't see why it shouldn't work....Sauna's often have wood finish interiors don't they? What sort of wood or protection do those use?

Aug 03, 2025 15:54:01

Nancy Reading wrote:This sounds intriguing! I don't see why it shouldn't work....Sauna's often have wood finish interiors don't they? What sort of wood or protection do those use?

I think cedar is the wood that is used in sauna. I do not know how cedar would stand up to a cool wet area. I would need to experiment with this idea and talk to my lumberyard about what type of cedar to use.

Aug 03, 2025 16:10:55

Cedar is used to make sheds and upmarket greenhouses in the UK (pretty wet and cool!) so stands a good chance of being reasonably durable I think.

Aug 16, 2025 16:03:33

So need to change a few items on this project

Mushroom Insulation: I am growing a test using Ganoderma lucidum and old Azure Standard flyers, random copy paper, and junk mail. I will put this in another thread and will not be using it in this project.

Water proofing: I was talking to my local lumberyard about this project. I said that at Wheaton Lab old billboards are used for water proofing and he found a product that is like the stuff that billboards are made out of to water proof the wall. I was reading Permaculture Magazine I cannot remember the issue but long story short. Osmo Oil looks like it could be a water proofing for wood. Also I need to see if one could use Osmo and Shou Sugi Ban to treat the wood. In Shou Sugi Ban linseed oil and turpentine (1:1) is used as a sealant for the wood. See https://www.shizenstyle.com/post/the-complete-guide-to-yakisugi-shou-sugi-ban-1 for more on information.

Sourcing wood: I was again in my local lumberyard and when I walked in and man who mills his own wood was talking to the owner. After they finished I asked if he could get cedar. He has some cut up and ready to go I just need to get him the square feet.

Flooring: So what happens when a pallet of slate hits the ground? Some broken slate and the owner asking if I want to use some of it in my project. Answer is yes and I am thinking about using it as trim and flooring.

What is next? Getting all needed measurements and a good cleaning. Then planning out the order of events and making sure supplies are in place.

Sep 01, 2025 13:20:50

Removed old shower insert and found more surprises on the walls. I knew most likely an issue would come, I just hoped it was not very big. The issues wear the bath and wall met water had deteriorated the dry wall, about a 3 to 4 inch strip was no more and light water damage was seen on the walls. The corners of the bath tub was fixed by putting plumbers putty into the corners to try and make a waterproof area between the tub and wall.

So I put up an PVC liner that is 40 mil (about 1 mm) then adding the Shou Sugi Ban on top. The liner is in and looks to be protecting the wall. Now I am trying to find a way to attach wood to the walls. Saunas use tongue and groove on the edge of the wood to join them together. I do not know how to fasten the wood to the wall. What type of fastener would work? That is a question I need to answer.

Update on mushroom insulation, not good. The test has gone bad due to what I think is bacteria contamination. Smells like ammonia and therefore I will not be making another thread or using it. I have a new batch of Ganoderma lucidum growing now and after I have the bathroom done using the mushroom insulation under and/or above the room.

Jan 05, 2026 16:50:10

How's this coming along, T?

Jan 08, 2026 08:33:12

Beau M. Davidson wrote:How's this coming along, T?

I have a plan for how I am going to get the wood up. Now I am stuck on how to waterproof the wood.

Carnauba wax looked like it could work so I tried it. Since the melting point is 180F that is higher than what a person would take a shower or bath. After doing a test on wood the wax did not do well. When applied as a light layer it did protect the wood from water but solidified fast. Also if not done well the wax would crack.

Linseed oil and Turpentine (1:1) I do not know if this mix would do well in a bathroom. If you have used it please let me know the details. Thanks.

Any other ways to waterproof wood please post!

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