How to protect and preserve wooden beams



Special properties

  • Highly concentrated wood preservative implants
  • Convenient to handle.
  • Full cross-section protection in damp wood
  • Wide range of applications


Wykamol Boron Rods are cylindrical implants composed entirely of anhydrous boric oxide. They contain the maximum level of borate preservative available in rod form (1kg of Boron Rods yields 1.7kg boric acid when dissolved).

For use as a wood preservative to control wood rotting fungi and wood boring beetles in new and existing structural and joinery timbers. The preservative is mobilised when exposed to dampness (wood moisture content greater than 35% w/w).

Suitable for use in timbers already at risk of or showing signs of decay (see also Wykabor 10 and Wykabor 40 data sheets) or as a preventative treatment in sound dry timbers which may be exposed to wetting in service (e.g.window, door frames).

Note: For full protection against wood boring beetles where the timbers may remain relatively dry in service, and/or protection against fungal decay due to surface wetting which does not mobilise the protective agent in Wykamol boron rods, a surface application of a suitable liquid preservative as an adjunct to rod installation is recommended (see separate data sheets).

How to protect and preserve wooden beams

Site work


All bats are protected under the Wildlife and Countryside Act 1981. Before treating any structure used by bats, consult English Nature (etc). Before deciding on an appropriate preservative treatment, carefully evaluate the structural integrity of timbers and/or replace those considered unsound (isolating from masonry where possible). Locate and rectify sources of moisture and improve ventilation as appropriate.

Following assessments by a qualified surveyor sound and/or slightly decayed timbers left in contact with masonry or soil below DPC level, or in other situations where there is a continuous source of moisture, may be treated with Wykamol Boron Rods (possibly together with other boron products – see separate data sheets). However, the full extent of eradication or protection cannot be predicted generally. Re-inspection at least every 5 years is therefore recommended under these circum­stances.

Timbers treated with Wykamol Boron Rods may exhibit surface crystal­lisa­tion of boric acid under certain circumstance and this should be taken account of when considering their use for the protection of internal (uncoated) decorative timbers. Wykamol Boron Rods are compatible with all conventional wood primers and exterior wood coatings, and will have no adverse effects on paint adhesion.


Drill holes in the timbers to be treated approximately 12mm greater in diameter and at least 10mm longer than the rod to be used. The hole should be drilled to a depth not more than 20mm from the rear of each section. Once inserted (pushed firmly to the bottom of the hole) the rods are sealed in position with a suitable filler or plastic cap/timber dowling.

How to protect and preserve wooden beams

The number and configuration of the holes/rods will depend on the type and use of timber and the area considered at risk of wetting. For window frames, in most situations, rods (of a suitable diameter/­length) should be inserted at 100mm intervals along the grain (e.g. sills) and at 50mm across the grain. In vertical elements the first rod should be placed no more than 50mm from any end grain/joints. Overall coverage of ca. 6-7kg Wykamol Boron Rods per m³ should be achieved in vulnerable areas.

In joists, a similar pattern is recommended but special care should be taken to ensure protection of concealed (built-in) sections in contact with masonry. The first holes should be as close to the masonry as possible and drilled downwards at an angle to finish not more than 30mm from the joist end.

For fence posts drill a hole at 45˚ to the groundline to a depth at least equal to 110% of the post diameter (see diagram below) and insert a rod of appropriate size.

It may be considered advantageous to apply Wykamol Boron Rods in conjunction with Wykamol 40 – a boron gel product (see separate data sheet) in order to provide a ‘fast’ and ‘slow’ distribution of the preservative material into the surrounding timber (especially if  some decay is already established or the wood moisture content  at the time of treatment is below 35% w/w). 

Finishing work

When desired, paint finishes can be applied to dry timbers surfaces without delay.

How to protect and preserve wooden beams


Size: 8 x 65mm (Each rod weighs approx. 6g. Other sizes available by order (e.g. 12 x 50mm, 8 x 24mm)
Appearance: Semi-transparent, colourless rods (‘glass-like’)
Storage: Keep in original container, tightly closed, in a safe, dry place
Shelf life: Indefinitely in dry conditions (sealed bags)
Odour: None
Safety: Wykabor Boron Rods are classified Reproductive Toxicant Category 2 (R60-61) under the Biocidal Products Directive (98/8/EC). Read the label before use. More detailed information is available in the Wykamol Boron Rods Material Safety Data Sheet.

Technical information

The information contained in this data sheet is for professional preservation specialists and is compiled accordingly.

Further information and advice is freely Available from the Wykamol Technical Department. For general guidance consult The HSE Guidance Note “Remedial Timber Treatment in Buildings” (HSE Books, ISBN 0-11885987-0).

The Company warrants this product to be of merchantable quality and fit for the purpose designed, providing that any instructions relating to use, handling and storage are duly observed. All transactions subject to our standard conditions of sale, copies available on request.


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