November, 1917 
37 
A TEST of STUCCO BASES 
How Uncle Sam Is Trying to Determine the Best Values for the Construction 
of the American Home—The Story of a Government Progress Report. 
C . O . POWELL 
H ALF the world was at war. We had 
taken our stand as neutrals, you will 
remember, and the efforts of government offi¬ 
cials were directed to maintaining that stand. 
This was the background of 1915. It was a 
background of threatening war clouds. One 
would think that in those days Uncle Sam 
had enough on his hands. Yet he still had 
the time to study out what were the best ingre¬ 
dients to go into the construction of the 
American home. 
This story is only a page torn out of the 
romance of our government, to show how' 
varied are its endeavors for its citizens. 
The prospective builder who decides to 
make his home of stucco often finds it difficult 
to decide which of several construction meth¬ 
ods will result in a permanent and satisfactory 
job. Each has its special talking points. 
In almost every type of construction there 
are certain definite methods, well known 
to all builders, which must be followed 
if satisfactory results are to be secured. 
Stucco construction has, because of its 
newness, been handicapped through 
lack of such definite standards. The 
builder of stucco houses has not had the 
benefit of centuries of experience as 
have the artisans who use older mate¬ 
rials and methods. 
The standards formulated and pub¬ 
lished by manufacturers of various 
materials used in stucco construction 
have done much to establish good 
methods, but the government took the 
Missouri stand and wanted to be shown. 
The Question of Stucco Bases 
One part of stucco construction 
which has caused more discussion than 
any other is the kind of material which 
should be used as a base for support¬ 
ing the stucco. The composition of the 
stucco has been pretty well determined 
by well-known authorities, but the mass 
of conflicting claims regarding the dif¬ 
ferent types of bases has led many a 
builder to choose some other type of 
construction rather than run the risk 
of selecting the wrong stucco base. 
Recognizing the value to builders in 
having definitely established the results 
which may be obtained by the use of 
various stucco bases, and being re¬ 
quested by a group of manufacturers 
to make such tests of stucco construc¬ 
tion as would determine the efficiency 
of these bases, the Bureau of Stand¬ 
ards of the United States Government 
arranged a series of complete and com¬ 
prehensive tests. These tests were 
planned to cover all the elements enter¬ 
ing into stucco construction. 
To preclude subsequent criticism of 
materials, mixtures, construction and 
workmanship, the Bureau of Standards 
placed the entire program in the hands 
of a committee invited to act in an ad¬ 
visory capacity. 
The committee chose about fifty of 
the most common types of stucco construction 
to be tested and sixteen different stucco mix¬ 
tures. Fifty-six panels, each 15' long and 10' 
high were then constructed, using the various 
types chosen. 
Each test panel contained either a door or 
window and all were embodied into the wall 
construction of a test building erected in a 
manner to compare favorably with good resi¬ 
dent construction. 
The Test Panels 
bhe bases for the fifty-six panels comprised 
nineteen of metal lath, nine of terra cotta tile, 
eight of wood lath, six of monolithic concrete, 
four of plaster board, three of brick, three of 
gypsum block, two of a stucco which has a 
heavy fiber backing covered with asphalt, in 
which are imbedded dove-tailed wooden lath, 
one of concrete block and one of a special pat¬ 
'Ttathod of usiti^ M.etal l^olK. to -prevent Plaster craoKiug at Corners 
ented base of wire lath and building paper. 
The number of panels of each base were 
roughly proportioned to the probable extent of 
their general use throughout the United States. 
The metal lath panels included three types of 
construction commonly used. The first type 
was that in which the stucco was applied over 
metal lath furred out to provide an air space 
between the stucco and the paper covering the 
sheathing. The second type was only furred 
enough to allow for a key or clinch between 
the lath and the paper over the sheathing. In 
the third no sheathing was used and the lath 
was applied over furring strips placed directly 
on the face of wood studs. The face of these 
studs was waterproofed so that the wood could 
not absorb the water from the wet stucco, and 
thereby prevent the proper setting of the stucco 
The metal lath used was all painted lath. 
In constructing the panels having a base of 
wood lath, three were lathed horizon¬ 
tally in the usual manner over sheath¬ 
ing and building paper. The remaining 
five were counterlathed, the lath being 
placed diagonally over the sheathing 
and building paper. 
The construction of the balance of 
the test panels was carried out in 
accordance with the established meth¬ 
ods of construction for those materiaL 
No sheathing was used back of the pan 
els of stucco board and plaster board 
The plastering for all panels was 
applied between October 19 and 
November 24, 1915. The stucco was 
kept well wet down after applying and 
during the latter two weeks was well 
protected from frost. 
Two inspections of these panels have 
been made; one in April, 1916, and 
another in December, 1916. 
The method of inspecting is particu 
larly interesting and should be remem 
bered to secure the full value of the 
reports on the various types of con 
struction. The same plan was fol¬ 
lowed in making both inspections, first 
(Continued on page 64) 
To prevent cracking at 
the corners metal lath is 
often applied over wood 
lath. The illustration 
above shows the wall 
construction 
An exterior wall finished 
on metal lath and a 
cross-section of a wall 
construction. Both show 
how the walls are finally 
built up 
TWO METHODS OF USING EXPANDED METAL LATH FOR. 
EXTERIOR STUCCO -FINISH 
Figure 1 
No Sheathing. Studs 
spaced n“oc. braced by 
2 bridging, faced by 
bimetal furring to which 
lace of Studs, and/or 
one inch back, offace 
on each side, thoroughly 
waterproofed with tar or 
asphalt 
Figure 2 
Sheathing laid diagonally 
across Studs and coher¬ 
ed with a substantial, 
thoroughly waterproofed 
paper laid horizontally. 
Furring firms an in¬ 
tegral part of the 
Metal firth 
Figure 1 
Figure 2 
