Answers to all your questions about Safety and Construction
How and Why was the Treefort constructed?
We have little flat space our two boys can use as a play area, so making a place for them that was their own, was the goal. In my own childhood the neighbor children and myself all built forts. The land was flat and so we dug trenches and tunnels and made walls.
It made a lot of sense to design a tree fort. It started out with several drawings in a CAD program to get the kids on board and make decisions on style and location. We had a deck that was pre-existing and was really not in great shape. On the uphill side of the deck is a Redwood tree stump approximately 4 feet in diameter and 7 feet above the existing deck. On the downhill side of the tree fort there is another smaller redwood tree stump about 3 feet in diameter. And 1 foot below the existing deck floor.
Both stumps have new little starter trees growing from the bases. The existing deck was built on trapezoidal ground piers that were placed on gravel. The deck approx. 7’ x 9’.
So we started by using some of the extra lumber I had from the foundation project we did 8 years ago. We had two PT 4'x6’ beams laid across the upper stump radiating out as an ‘A’ to meet PT 4’x6’ (one on the lower stump and the other over the down hill side pier. From there we made a floor joist grid at 24” center and blocked it. I noticed we needed some shear boards because everything was built at 90°. So We bolted a 45° 2x6 to the two downhill side PT 4x6 vertical beams. I also noticed when I was under the existing floor that the piers were not designed well. Instead of placing the floor joists atop of the pier beams, they nailed the floor joists to the side of the pier beams. So I poured two new piers 36” deep and 18” diameter and put 6x6 brackets in them. Then I put two new PT 6x6 pier beams and jacked up the old floor and rested it on a a new beam that spanned the front edge of the existing floor and tied into each 6x6.
Under the new floor and atop of the old deck we made studded walls with the idea of using the underside of the tree fort as storage. The walls also served as added support and mostly when complete would help with the shear strength. Then the tree fort floor was paneled with ⅝” ply and surfaces with storm guard. We built a rail around the edge with style that matches our home deck rails. We made walls on the tree fort floor that were designed around old factory wire glass windows we found. Then we skinned the walls with old redwood fencing at a 45° angle for a little more shear strength and for aesthetic reasons.
It is currently red tagged in an unfinished state. The tree fort roof is just storm guard atop of plywood. The walls are redwood fencing facing and nail gun nailed on at a 45° angle.
1. What about the tree fort is not to code?
It is a tree fort, and not to sound disgruntled, but 'built to code tree fort' feels oxymoronic. Is it safe? Yes and it will be more safe when completed. The railing is not to code for an adult because it falls below the hip and is too low. But there is going to be a cable screen that will prevent any kid from going over the ‘big edge’ sides. I believe the framing at 24” would pass as code for a small structure. I was in the process of adding a second over all shear board on the north side as precautionary measures to reduce any wear from kids running side to side above. Again it’d a tree fort so, there is no wall insulation and the windows are 1940s factory wire glass steal frame built into the walls and clipped from the inside. The roof has a pitch fall of 1’ over 7’5”. It is slight but the down side will have a gutter and line to remove water from the piers. Building on stumps for residential most likely not code. For tree fort kind of the point. The size for Marin may be too tall. But low tree forts are, well, called sheds.
2. How is the tree fort reinforced for safety? This is still an ongoing process. Shear boards and piers that tie into main structure to prevent any shift or lateral movement. We were always going to hire a professional engineer to assess safety revisions. This was a tree fort built as we went along and as we found materials. It has been ongoing for a year mostly on the weekends and one two week vacation. There are still unfinished railings that will add to the safety.
3. What is the state of the tree fort now and what were the next steps of construction?
The tree fort is 75% complete. We have extra oak flooring from the floors we put into our home. So we were going to floor the inside with oak and the exterior tree fort deck with reclaimed redwood possibly from our front deck which needs to be rebuilt. It needs two shear boards installed and the lower storage area tar papered and skinned with reclaimed redwood fencing to match top. The railings need to tie into the walls and gates installed. Spiral staircase around the upper stump to top of stump landing and railed in. Any pier reinforcements suggested by engineer.
4. if we hire a structural engineer what would the next steps of construction be? Have the engineer assess the possibility of making this tree fort a plausible permitted project. Develop drawings that support the idea of making this fort finalized with codes met. Create a planning department presentation with all engineered revisions to adhere to County Codes and build to pass inspections.