When
faced with a decayed structural timber in a building Architects and Engineers
tend to specify complete replacement with steel, or in a few cases they may opt
for an epoxy resin repair, cast in-situ, as a solid block. The
Timber-Resin Splice (TRS) was invented in the early 1990's with the intention
of reducing the volume of expensive, petrochemical based resin required to repair
large timbers in buildings and to offer an economically viable alternative to
complete replacement with steel. It is an economic method of repairing structural
timber beams in buildings without large scale opening up or destruction of sound
building materials. The
concept of the TRS is simple - replace the rotted end or midsection of a structural
timber beam with a renewable resource - timber - and use as little resin and steel
as possible, both in the manufacture and the installation of the repair unit. As
the sole UK Manufacture since its inception, Property Repair Systems has taken
its responsibility to develop the product seriously. In
common with most forward thinking Manufacturers it has a Policy of Continuous
Product Development, aiming to fulfil three criteria; 1.
Minimise the consumption of non-renewable materials - resins, composites,
steel, pre-glued timbers 2.
Reduce the Heath and Safety risks - in production, installation and disposal 3.
Reduce the whole life cycle costs of timber repair - labour, resins, composites
and steel
To
meet these criteria Property Repair Systems has undertaken a program of technical
improvement, backed by testing, to try to eliminate the problems of using bulk
epoxy resin as a repair material;
1.
Minimise the consumption of non-renewable materials - resins, composites,
steel, pre-glued reconstituted timbers. A.
Timber components - the smaller the timber section that we start manufacturing
from, the more machining, laminating and resin that is required. By sourcing the
largest kiln dried timbers available and machining with greater precision, we
have been able to considerably reduce laminating energy and resin consumption.
What little sawdust waste that is created is recycled as animal bedding. B.
Resin components - epoxy resins were originally used in laminating, bonding-in
the steel connectors and in the on-site connection process carried out by the
Client's Technicians. We firstly eliminated the epoxy from the laminating process,
using a less expensive high strength, waterproof single pack glue, and then from
the rod bonding process. Epoxy remains the resin of choice for on-site connection,
but we minimise its use through computer-based design of the connecting slots
and hope to find a more ecologically friendly material in the near future. C.
Composites - originally the TRS and most other site resin repairs incorporated
small diameter (5mm) composite Epoxy-Glass Bars, in bundles, for connection purposes.
This is wasteful, but it was also discovered that full wetting out of multiple
bars in a hole or slot could not be guaranteed, leading to weakness in the repair.
We therefore substituted larger diameter Epoxy Coated Steel Rebar, one per hole.
However, the epoxy coating was expensive and not reliable, so a further move was
made to Zinc Plated High Tensile Allthread. This has proved to be reliable and
economic, but with the rising cost of metals we must again move forward and a
number of 'greener' materials are in prospect. D.
Pre-glued Timbers - we have experimented with a variety of reconstituted
timbers, but the energy equation for renewable virgin timber is still considered
to be more favourable and because of the stock sizes we found that these man-made
timbers required either more expensive lamination or more waste in cutting than
locally available stock kiln dried lumber.
2.
Reduce the Heath and Safety risks - in production, installation and disposal A.
Manufacturing environment - despite rigid adherence to the manufacturer's
safety instructions all our workshop staff have eventually become highly
sensitised to epoxy and cannot even stay in a room with an opened pot. They have
worked with epoxy in well ventilated spaces, wearing long arm gloves, plastic
aprons and masks, but have still been affected by the vapour, eventually becoming
physically sick, dizzy and suffering from skin rashes and blisters. We therefore
had to remove all epoxy from our manufacturing processes and since then there
have been no new outbreaks of illness. We cannot emphasise too much the need for
great care in handling epoxies - I am one of the affected ones and I can vouch
for the effects. B. On
Site environment - we strive to minimise the use of epoxies in the installation
process. The use of paddle mixed products keeps the Technician further away from
the vapour than when using small pack, hand mixed products and Technicians generally
have short, intermittent exposure compared with Manufacturing Staff. Nevertheless,
we continue to seek alternative formulations so that one day we can further reduce
the health risks. C. Disposal
- we had great difficulty in storing and disposing of uncured epoxy residues in
pots left over from hand mixing. In the Workshop we have eliminated this process
and the products. To reduce this problem on Sites during the TRS installation
we mainly specify a paddle mixed, bulk resin product, so that only cured resin
remains in the bulk pot. Small residues of liquid epoxies still remain in the
component liquid containers - until we can eliminate the epoxy from the TRS Kits
this remains as a waste disposal problem.
3.
Reduce the whole life cycle costs of timber repair - labour, resins, composites,
steel, disposal A.
Labour - minimum machining, minimum lamination, simplified bar bonding B.
Resins - eliminate epoxies wherever possible, minimise their use where essential C.
Composites - eliminate if possible D.
Steel - minimise for now, seek to eliminate in the future E.
Disposal - eliminate the liquid epoxy residues
Obviously,
'whole life costing' is a complicated business and we need to balance our consumption
of a small amount of epoxy and steel against the vast amount of labour, energy,
steel and other building materials that are routinely thrown away when building
timbers are scrapped. There is still a substantial amount of Research and Development
to carry out in order to reach our goal - zero scrapping of structural timbers.
We have already made a considerable investment over the last 12 years and we hope
to continue to develop this excellent concept.
David
Moore Partner, Property
Repair Systems 2013
SHOPS
Repairs
| Beams | Privacy
Policy | Returns Policy
Contact
| About Us
|
About the Author
Property
Repair Systems
T: 01626 872886
E:
Mail us help@propertyrepairsystems.co.uk
Other Property Repair Systems
Sites:
www.drywallandfloor.co.uk
- membranes for lining damp walls, floors, basements and cellars
www.epoxy-info.co.uk
- epoxy resins for repairing wood, concrete, brick and stone
www.fire-door-paint.co.uk
- upgrade doors to 30 minutes fire resistance
www.joist-repair.co.uk
- how to quickly repair joists and beams of any size
www.propertyrepairsystems.co.uk
- our Home Site
www.steel-fire-paint.co.uk
- treat steel with Intumescent Paint to provide fire protection
www.timber.org.uk
- systems of repair, with step by step methods
Site written by: David
Moore
David Moore, B.A. (Hons.),
C.T.I.S., C.R.D.S. Technical Author
Google+
|