In this episode, we finally tackle the next massive milestone for our tiny house project: building, insulating, and sealing the main floor frame.
To start building up on our screwpiles, we had to ensure that our base frame is perfectly level and square. For this step, we started out by cutting our lumber to size, making sure our circular saw cuts were perfectly straight.
Our plan was to double up 2x6 boards to create the long, heavy-duty perimeter beams for the tiny house structure. This involved clamping the concaved sides of the timber together so they would pull straight, measuring out intervals of 60 centimeters, and securing them tightly. We used both new and old tools - some passed down by Frieda's grandpa - to attach the bolts.
After a bit of scratching our heads over whether the washers go on the top or the bottom of the bolts (thank goodness for smartphones on build sites!), and a bit of gentle hammering to dial in our diagonal measurements to a perfect 787.5 cm, our beams aligned beautifully with the foundation piles.
We then moved on to attaching the transversal beams and joists, making sure the joists are spaced 60cm on-centre.
With the main joists and transversal beams locked in, it was time to address a crucial piece of advice we received from experienced builders: installing a wire mesh to keep local rodents from chewing through our floor insulation.
Because we already had our structural support piles coming up through the center of the frame, we had to cut the wire mesh to fit around them. This left open gaps that needed to be bound back together. Frieda put her old kindergarten weaving skills to work, threading the mesh securely around the obstacles. To stay sustainable (read: we forgot to buy additional wire), we unwound and reused the packaging wire that came wrapped around the mesh roll itself.
Next came the actual weather protection. The very first layer inside the frame was made out of ISOplaat, special wood pulp and wax boards that serve a double purpose as both a wind barrier and foundational insulation. While we did have some problems setting up our newly acquired battery-operated plunge saw, the actual sawing of the boards to size was no issue. We made sure that the boards sat tightly and snuggly between each joist.
Then came the itchy part: Rockwool.
Suiting up in full protective gear - masks, long sleeves, and gloves - we broke open the tightly packed mattresses of rockwool. Watching them expand to full size is always a trip! For the areas where the factory measurements didn't perfectly align with our custom frame spacing, we found that an ordinary kitchen bread knife was the ultimate tool for slicing the rockwool neatly down to size.
To protect the rockwool from internal moisture, we rolled out a heavy-duty vapor barrier across the entire floor system. We kept the staples to a minimum - just enough to hold it steady - and relied on an incredibly sticky construction tape to seal every seam and staple hole completely airtight.
Nature decided to give our work an immediate quality assurance check with an overnight downpour. The good news? The vapour barrier held perfectly, and not a single drop reached our fresh insulation. The bad news? We had to spend the next morning playing squeegee tech to clear off the pooling water before moving on to the final layer.
To close out the floor, we laid down large sheets of 18mm OSB boards, staggering them neatly across the beams. Because we are pausing the build and leaving the site for the next six weeks, we didn't want to permanently pierce the vapour barrier underneath just yet, in case the Baltic rain swells the exposed OSB while we are gone. For now, they are secured just enough to keep them from catching flight in a summer storm.
If you want to see how our OSB floor holds up against the elements when we return in six weeks, make sure to hit that subscribe button over on YouTube. See you in the next episode!