Seed Home 2 Design Log

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Sep 23, 2020 - Wall Interface

Hi Elijah,

After more debate, we are leaning towards going with your option 1 and modifying it a bit like this on pages 3-5:

The main differences are: - We can't actually use tongue and groove (or shiplap), so the panels would just sit side by side - We'd cover the seam between the panels with SAWP tape - and then cover the tape with a (ripped plywood) board (a spin on board and batten finish) - We would add another top plate because the plywood is not connecting adjacent panels.

So, we wanted to ask you:

- What do you think? Can this work? - Is it ok that our panels are not tongue and groove (as long as we connect/lap them with a structural board)? - What kind of SAWP tape should we use? I'm sort of imagining something like Self-Adhesive Waterproof Flashing that we use on windows. But I'm not sure if that's the right stuff. - Will the SAWP tape work on rough sawn panels? I'm pretty sure the butyl-based window flashing stuff will stick to anything... But what do you think?

Thank you so much for all your help, you've been a rock star!

Marcin + Catarina

Sep 1, 2020

Hi Elijah,

We are taking the Seed Eco-Home to product release next year. We are doing a major campaign with a goal of getting 2000 built over 2 years. The promise is a 1000 sf home for $50k that you can build with a friend in one week. That's a significant offer, and we think we can do it. The trick is: people build and stash modules, then have a week-long build with, at minimum, one other person.

There is one outstanding issue that we are negotiating: the joint between panels. It is critical - as it's what allows all the walls to be done, from prepared panels - in about 4 hours for a 1000 sf house. We used tongue-and groove exterior panels in our last build, and build the walls in less than a day, including building panels. You can see more pictures of the stellar product after 4 years at

That is 1400 sf. We're planning on 1000 sf and flat roof for the product release.

For the product release, we'll use plain exterior treated plywood panels to simplify the joint. Please take a look at the doc and comment on - whether the 2 routes proposed can be negotiated through codes and existing inspection schedules. Which one would you suggest? Do you have another solution? Would love your insight, and also your help in the product release. We're planning a large scale collaborative design where we publish an open enterprise model. We plan on training 100 entrepreneurs to do the builds, and a number of one week on-site training for owner-builders where we build an entire house in each event. So essentially, really taking it to prime time - it's all working and we want to solve housing as promised.

Thanks, Marcin

Jessica Leete

Marcin, This is exciting... I can imagine this system developed with different materials for application in different contexts.

On the wall module interface, in the second image it should show exterior sheathing, then weather barrier, then siding. The weather barrier goes outside of the sheathing. It could be that the module does not include the weather barrier and siding- this would be a more historic approach. Similar to stress skin panels that are plywood and insulation- no studs thus decreased temperature bridge issues. See attached images. The blk and wh from one of Harry's first projects. The first solution could be useful for improved structure. How are the panels and framing connected? Would be interesting if these 1000sqft house modules could be joined in a larger structure. The second likely would not work with building codes but there is a newer system that uses a ceramic coating on the plywood sheathing as the weather barrier and a tape at the joints. I am sure they had to go through all kinds of testing to get this to pass codes.

What are the goals of the prefabrication part other than for a handful of people to be able to raise it in a week?


See Feedback on Inspection Schedule