Why repair cracks in wood
Cracks in timber beams need not affect the overall
integrity of the structure. Indeed, cracks in timber beams can be taken
as a positive visual feature of the timber, which, in conjunction with
the timber grain, distinguish timber from the more uniform man-made
materials such as steel and concrete.
In spite of this, there is a steady demand amongst
specifiers for crack-injection of beams for the following reasons:
- To improve fire resistance
- To improve resistance to weathering
- To improve mechanical performance
- To prevent wood rot and insect attack
Repair Methods
Cracks, shakes, warps and fissures are formed as
a result of the timber giving up moisture and shrinking. This may occur
as part of initial drying or subsequent changes, during service, in
the Equilibrium Moisture Content. The EMC of timbers inside buildings
can range from 9% to 14%. Fibre saturation is reached in constructional
softwoods at about 28%.
For cracks and splits that are greater than 5mm
wide the void can be filled with our Mouldable
Epoxy Putty, but if the crack penetrates more than 30% through the
timber it will be necessary to provide dowels across the filled section
in order to 'stitch' the two halves together. The advice of a Structural
Engineer should be taken with regards to the number, diameter, length
and spacing of the dowels. The dowels can be made of glassfibre, carbonfibre,
steel or stainless steel. We normally recommend the use of epoxy/glass
or epoxy coated steel, set in our epoxy adhesive, Thixotropic
Epoxy Injection Resin.
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Step 1 - clean out cracks with a saw blade and vacuum
clean. Fill cracks with Mouldable
Epoxy Putty, using our Epoxy
Primer for hardwoods.
Step 2 - drill holes across the filled crack into
sound timber on the opposite side. Blow out or vacuum out the wood dust.
Step 3 - inject Thixotropic
Epoxy Injection Resin from the hole base outwards using an extension
tube.
Step 4 - fit dowels (into the Thixotropic
Epoxy Injection Resin) at 100-150mm intervals, to act as connectors.
Cap off holes with Mouldable
Epoxy Putty
Timber
Beam Repairs
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Repair Systems
T: 01626 872886
E: Mail us help@propertyrepairsystems.co.uk
Site written by: David
Moore
David Moore, B.A. (Hons.),
C.T.I.S., C.R.D.S. Technical Author
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Sites:
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www.drywallandfloor.co.uk
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www.fire-door-paint.co.uk
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www.joist-repair.co.uk
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www.propertyrepairsystems.co.uk
- our Home Site
www.steel-fire-paint.co.uk
- treat steel with Intumescent Paint to provide fire protection
www.timber-repair.co.uk
- how to repair timber beams
www.woodworm-info.co.uk
- how to kill and prevent woodworm and death watch beetle
www.woodworm-expert-advice-forum.org.uk
- all your questions and our answers about woodworm treatment DIY
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