How To Build An Underground 

Hobbit House

That You Can Live In, That Will
Last 100's Of Years
Master Masonry Results for the Unskilled Mason
masonry formwork concrete shotcrete hobbit house construction
Any self performed project must self appraise ones own skill for carrying out the project.   What skills must I learn and at what price? Rework, unacceptable finished product? Masonry skills are being lost because of the high cost of the labor component and competing lower cost alternatives such as glued on veneer stone. Stone has wonderful earth energy and will give any structure and space a unique special connection with the earth. Concrete is also a special material similar to natural stone. Concrete is a man made conglomeration of many stones bound with cooked limestone (cement). My approach to building with stones is whenever possible use natural full size pieces, not veneer, combined with concrete to create a less skill required finished result. Laying loose pieces of stone on concrete formwork and backfilling with concrete creates a strong monolithic composite structure with the look of pure stone. Concrete backfill can be accomplished with traditional casting or shotcrete (gunite) methods. In the Hobbit house I used mostly shotcrete sprayed directly on the stones to create a thickness of 4-6".
Excellent bond is easily achieved between well consolidated concrete and clean stones. In building structures like the hobbit house I have found this procedure to be fast and always excellent aesthetically when the forms are striped and the joints are pointed with mortar. The only masonry skill required is choosing a stone and placing it on the the formwork. On vertical surfaces the stones are held in place with tie wire. The tie wire is placed around the stone and through small holes drilled in the form work. In earlier projects I used dirt or sand placed between the stones prior to placement of the concrete backfill. This prevents the concrete backfill from coming through the joints between the stones and filling in front of the stones. This method works well on horizontal surfaces but not so well on vertical surfaces such as walls. I have found using spray foam out of an aerosol can with a tube works excellent. After concrete backfill and formwork striping, the foam is present in the exposed stone joints. The foam is dug out with a screw driver. In the case of overhead work I would still recommend sand or dirt. Once the joint is cleaned of foam or dirt a masonry mortar is tooled into the joint similar to a repointing procedure. Repointing procedure involves mixing standard masonry cement and mason sand in a stiff consistency and packing the mortar into the joint openings. The key to professional looking joints is to allow the mortar to stiffen, which may take a few hours and then with a jointing tool finish off the joint. When complete a muriatic acid ( home depot) wash cleans up the stone
of any smeared mortar on the stones.

Entrance way from the interior after formwork has been removed and prior to removal of spray foam

 hobbit house construction formwork concrete dome masonry

Tool List

Tie Wire

Drill and bit

Spray Foam

Completed masonry entrance after repointing of joints

After foam is scraped out of the joints masonry mortar is tooled into the joint . When complete looks like hand layed wall. Fast and efficient !

Stacking of stone on skylight formwork
note the that each stone is placed and held in place with tie wire. 
Entrance stones after completion
hobbit house construction formwork concrete dome entrance masonry wall
Note the edge stones on the entrance arch. These stones were placed on the formwork and are held in place by the bond achieved by the gunite placement
Skylight interior view
hobbit house construction formwork concrete dome skylight masonry wall
Note the finished masonry look of the exposed portion of the masonry. After formwork is striped and foam is removed,  mortar is pointed into the joints
Placement of Center Masonry Core
To conserve the amount of stones required on this project only one layer of face stone is used. To accomplish this a form is placed on the interior surface. The form is made from 4x4 WWF wrapped with geotextile cloth. Easy to make a curved form this way. Mortar is packed between the form and face stone. The core becomes the basement of the Hobbit House
Masonry core ties to Block wall
Masonry Chimney built on around cast in Flue liner
hobbit house construction formwork concrete dome masonry chimney
The chimney is built to create adequate draft. The chimney is 13 feet in total length from the wood burning stove outlet duct to the duct outlet on top of the chimney
Entrance wall construction
hobbit house construction formwork concrete dome masonry entrance wall
Face stones are laid with mortar and backup wall on the interior to conserve use of stones. The door way is held to tolerance with a wooden template. The curved wood is saw cut to allow for even bending and radius
Entrance walls 
Stones are laid as face stones backed up by reinforcing bars and concrete.
Entrance walls under construction
hobbit house construction formwork concrete dome entrance walls
Masonry stairs between the two levels
hobbit house construction formwork concrete dome masonry stairs
Same stones used as are used to create rustic floors. Masonry blocks are used to support the face stone on the stairs