10 BULLETIN 894, TJ. S. DEPARTMENT OF AGRICULTURE. 
KILN CONSTRUCTION MATERIAL. 
The selection or choice of building material depends largely upon 
the first cost, depreciation, upkeep, and fire hazard. The materials 
which may be used are: 
Wood: Studs sheathed on both sides or sheathed inside and plastered outside. 
Crib or laminated construction. 
Brick: Solid brick, brick and tile, brick with air space. 
, Tile: Hollow tile walls, plastered outside and inside. 
Concrete: Solid concrete or hollow concrete blocks. 
The depreciation in kilns, of whatever material they may be built, 
is much higher than in ordinary buildings, on account of the excessive 
heat and moisture. In wood kilns the alternate moist and dry con- 
ditions swell and shrink the boards, causing more or less working 
of the frame, loosening of nails, etc. Brick, tile, and concrete walls 
expand unequally with the heat, causing cracks, through which heat 
can escape and moisture enter. 
Where fire risk is not a consideration and insurance rates will per- 
mit, a well-built wood kiln is very satisfactory, wood being a very 
good insulator, easily repaired, and costing less at first than other 
materials. Where available, fir, Douglas fir, yellow pine, redwood, 
cypress, and similar woods with low shrinkage rates should be used 
for sheathing and sills. Studs, roof timbers, etc., can be of any good 
straight-grained material. All wood should be thoroughly air dry. 
Sheathing should be shiplap laid horizontally and nailed twice at 
each stud, in the middle and at the bottom of the board. Outside 
walls should be insulated with a good moisture-proof, heat-resistant 
insulator. The ordinary quilt insulations sewed between so-called 
waterproof paper have not proved satisfactory in dry kiln construc- 
tion. The inside walls should be painted with a good moisture and 
heat resistant asphaltic paint. 
Where lumber is relatively plentiful and cheap, as at or near a 
sawmill, crib, or laminated construction is frequently adopted, the 
walls being built of 2 by 4 inch or 2 by 6 inch planks laid flat, and 
the roof of similar material laid tight together. When the kiln is 
properly built of well-seasoned, well-manufactured stock, this form 
of construction is slow burning and resistant to heat loss. Inasmuch 
however, as the material is usually low grade and knotty stock, 
tight, weather-resistant construction is extremely difficult to obtain. 
The shrinkage of the walls is excessive, and causes considerable 
trouble at door jambs and where pipes pass through walls. Figure 1 
shows a kiln built of wood, illustrating stud and sheathing and also 
crib construction. 
Brick or hollow tile is available almost everywhere and makes a 
very satisfactory fire-resistant construction; and where permanency 
is desired is usually more satisfactory than wood. The brick or tile 
