The author may be confusing two similar terms

Tuff = Tuffstein is a rock consisting of consolidated volcanic ash

Tufa = Kalktuffe is a variety of limestone, formed by the precipitation of carbonate minerals from running water, often seen on the ledges of waterfalls in limestone/Karst areas

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Note added at 39 mins (2013-10-28 15:20:05 GMT)
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The Tuffstein = tuff you are looking for is the volcanic ash rock and is quarried for building in volcanic (or formerly volcanic) areas around the world.
In Germany, many houses in the Eifel region are built from tuff

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Note added at 1 hr (2013-10-28 16:01:11 GMT)
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Here's a German reference:
http://www.geodienst.de/tuffstein.htm

BTW: tightly consolidated Tufa = Kalktuff is better known under the name of Travertine and is a highly-valued building material


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Note added at 3 hrs (2013-10-28 18:15:00 GMT)
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A couple of quotes and references:

Ancient Rome
Travertine was used to build the Colosseum and other buildings. It is a kind of yellowish or grayish white limestone formed by mineral springs, especially hot springs, and can form stalactites and stalagmites, but is also a worthy building material as the Colosseum testifies. To the untrained eye ivory-colored travertine can pass as marble. Much of it was mined near Rome in Tivoli.

Many of the buildings that were constructed during the classical period of Rome were made of soft, porous local volcanic rock called tuff that was then faced with marble. The Romans were well aware that tuff was weak especially when soaked with water or soaked with water and subjected to freezing temperatures that occasionally hit Rome. The construction method made sense in that the tuff was cheap, available, close, relatively lightweight and easy to shape. Much of it was extracted in Rome itself and covering it with sheaths marble, which was much easier and cheaper than using heavy, expensive marble blocks.

The earliest buildings built in and around Rome were made of tuff, a type of volcanic rock of varying hardness, which could be worked mostly with bronze tools. Later, harder stones were used, like peperino and local albani stone from the Alban hills. During the empire, the most common stone used for building was travertine, a form of limestone quarried in Tivoli, as used on the exterior of the Colosseum in Rome.

http://tinyurl.com/mt7nwxj


The German Mining Museum in Bochum
http://www.bergbaumuseum.de/web/doktoranden-pohl_meinrad

BEAMIS HALL -COLORADO COLLEGE
BEMIS HALL

ADDRESS: 920 N. Cascade (1988); 938 N. Cascade Ave.
AREA: 65,662
BUILT: 1908
MATERIAL: Ignimbrite or Welded Tuff
COST: $100,000
ARCHITECT: Maurice B. Biscoe of New York & Denver
DEDICATED: October 1908
DONOR: Judson M. Bemis & General William Jackson Palmer provided most of the funds

AUSTRALIA
In the geological literature of Queensland it
is described as a Tuff—the Brisbane Tuff. In the quarry and
stonemasons' trade it is called "Porphyry."
It is a rock which was formed by the deposition of fine
fragmental hot ash material violently erupted on to the then
old Palaeozoic land surface.

The fair county of Somerset - UK
Cockercombe Tuff
The very distinctive Cockercombe Tuff is a fine-grained, grey-green volcanic lithic tuff, confined to a small outcrop area in the northern Quantock Hills around Cockercombe, Keepers Coombe and Plainsfield. It was mainly used for local ashlar and rubblestone, notably for the construction of Quantock Lodge and Plainsfield Gatehouse.

Tuscany - Italy
The Tuff Area is named after tufo, a volcanic, porous rock commonly used as a building material.