Building an upside down boat as temporary construction, then tearing it down and burning the unusable curved pieces is in itself a little strange. But, Formwork yields a result that is unique and special. Stripping the formwork and beholding the resultant structure makes all the labor of building worth it.
Organic Shapes made with green oak boards
1x6" fresh cut green oak boards are bendable and form the natural curved shape of the dome. 1/2" sawcuts help with sharp bends. Most of the fastening was done with drywall screws for ease of removal
dry wall screw , the most used fastener on the project
Tool List
Radial Arm Saw
Screw Gun
Finish Nail Gun
Grinder
Metal Strapping Used to strengthen the curved 1x6 oak boards
Materials Used
Home Depot (Simpson Strong Tie)
Purchased in coils. Cut with tin snips or grinder. Fasten with drywall screws to the wood
1/2" PVC pipe helps determine layout of dome
Sheathing of dome roof , Like building a boat upside down
Sheathing is attached to the curved 1x6 with finish nails( nail gun). easy to remove after concrete is placed on the formwork
Entrance arch is made with curved 1x6
Note the sheet metal banding strap material (available from homedepot) Simpson Strong Tie product. helps reinforce the bent board prevents cracking at saw curfs.
Shoring support of roof structure
The timber roof structure requires additional support with shoring towers to handle the placement of wet concrete.
Vertical walls are made of 1x6 boards laid horizontally.
Shoring tower is placed to stabilize the curved support members
Formwork ready for welded wire fabric reinforcement
boards are sealed with spray foam (available in cans at homedepot. Some mortar is placed on the form between the entrance and the dome to form a gentle curve.
4x4 Welded wire fabric is placed on the dome formwork
Blue electrical duct is placed first to provide electrical service to light fixtures in ceiling of dome. Yellow spaces support the WWF. note the masonry block wall is flush with the formwork
Ready for concrete
View at entrance. Concrete will be placed in the coming day.
Skylight opening and shaft
1x6 boards are placed vertically at the shaft opening. Stones are layed up against the form work held in place with tie wire. Foam is placed between the stones to prevent shotcrete penetration to the finished interior.
Chimney flue liner cut and placed on formwork
The clay tile flue liner is cut with masonry grinding wheel to fit the contour of the roof. Nails are placed on the form boards so flue liner fits securely
PVC 4" Pipe Vent Placed
Underground structures need ventilation. Two PVC pipes are placed on opposite sides of the structure to provide fresh air ventilation.
Note the 3 cable strands wrapping around the formwork. These strands are continuous around the dome providing tension constraint for the dome. Sometimes called the tension ring.
All Stone is placed prior to concrete placement
Stone placement as a form liner is an easy way to place stones. Not a lot of skill required. Looks great when completed
Sawcuts in curved 1x6 allows for bending of boards without breaking
Entrance to Hobbit House
Stone placed on form boards. White material between stones is spray foam to prevent gunite material penetration to interior finish surface
Chain saw grinding wheel
The best way to smooth out the formwork around curves is to grind with this tool. Amazing and very dangerous, makes quick work of removing uneven surfaces
