THE
USE OF GLUE IN THE BUILDING INDUSTRY
What kind of wood joint is the strong- 'hardener' is used to accelerate the setting the main roof design involves the use of
make, the most per- or, est, the easiest to
more correctly, 'curing of the resin. seven trusses covering an area within the manent? Indeed, is there any one type Heat also accelerates curing and a com- walls of 112 ft x 48 ft, each truss having of joint which combines these three bination of heat and hardener can effect a span of 50 ft. with a 31 it. 9 in. rise qualities? The answer is 'yes' and the a cure within a very few minutes, even and a pitch of 50°. type of joint is a glued one an answer seconds. Heat, however, is dispensable.
other
which may surprise those builders who There are types of hardener capable of Another recently completed example of have always looked upon glue as a ma- providing curing times to suit most re- glued timber roof trusses is to be found terial totally unsuitable for use in primary quirements.
Hardener can be used in in a school in Yorkshire, England. This structures and in any building where the two ways: by the
mixed application is a single storey building consisting of an woodwork is likely to be subjected to the method in which it is mixed in with assembly hall, six classrooms and
of climate, ravages
attack by fungi, the resin before use, or the separate ap- accommodation. Both lattice girders and moulds and small insects.
plication method in which it is applied plywood box beams are incorporated to one of the surfaces to be joined and the roof design, means
the resin is applied to the other surface,
The box beams are made up of small With the latter method curing commences sections of European redwood with 6ma immediately the two surfaces are brought AX.100 plywood. Their overall span is
approximately 24 ft.
In this instance, however, glue synthetic resin glue, and particularly the gap-filling types known as 'Aerolite and Aerodux'. For these glues possess most of the virtues and few of the disadvan- tages of natural glues.
Synthetic resin glues are a type of plastic and, when set, are very similar to the material of such everyday products as telephones, radio cabinets, car facia pan- els and electric light fittings. Just these products are perfectly stable so, too, are good synthetic resin adhesives.
into contact.
in
In the building industry the separate The lattice girders, which are use 1 application method is that most frequent- need not be immediately joined. ly used, as waste is avoided and the parts mainly over the assembly hall, bridge a clear span of 42 ft 3 in. They consist for the greater part of short lengths of Select The statement has already been made Merchantable Douglas fir in sizes not ex- that good synthetic resin glues are 25
very coeding 6 in. x 2 in. and often as small suitable for use where climatic conditions
as 3
in. x 1 in. Similar girders are em- adversely affect ordinary glues and 'Aero- lite' and 'Aerodux' quoted as examples. and
lintels over the assembly hall ployed as The initial manufacturing processes are Independent tests provide the answer
elsewhere. During setting of the similar to those for plastic moulding pow- why these two glues have been singled out
'Aerolite' glue nails, in pre-bored holes, ders. For example, 'Aerolite' is made by for mention.
provided light clamping. reacting under carefully controlled condi-
These two examples of roof construction tions two materials called urea and for- Tropical exposure tests made by the
have been mentioned because they provide maldehyde and arresting the reaction be- British Royal Aircraft Establishment unusual testimony to the strength and fore they have fused to a solid plastic. have shown these glues to be markedly versatility of Aerolite". It should not. This statement must be qualified. The superior and we shall quote from their however, be concluded that the glue is reaction cannot be completely halted. It findings in a later issue.
suitable only for similar ambitious uses. continues. though slowly, until after about three months the resin (as it is
In building work, 'Aerolite' can be used It is equally successful for the smallest termed) becomes rubbery and finally а
for every job in which a permanent joint repair or joinery job. solid. It is for this reason that the is required. This even includes large roof To sum up, wherever a permanent bond liquid resin is powderised. In this form structures, because, as already indicated, is required between wood 'Aerolite' is it has a storage life of at least two years 'Aerolite' gives a much stronger joint superior to conventional glues and also to and is readily prepared for use simply by than any other known method.
nails, screws etc. It is, of course, unsuit- mixing with water.
For example, in the elaborate roof able for joints not intended to be per- or structure of St. David's Cathedral, Cardiff, manent.
A material known as a 'catalyst'
(Alone) Both lattice girders and plywood box beams glued with "Aerolite' were used in the construction of a school in England. In this picture the lattice gird- ers are shown in position over the main assembly Irall.
(Right) Four of the seven "Merohte" glued trusses for the main roof of St. David's Cathedral, Cardiff, ure shown erected, while the fifth lies on trestles in The foreground.
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