Frequently Asked Questions

Below is a compliment of some of the most asked questions. If you do not find your answer, please contact us directly.

What is the difference between Cobra™ Rod and Postguard?

In Canada Do-It-Yourself sized packages of the rods are sold under the Postguard label while industrial customers use the Cobra™Rod product. Simply put, while both products are the same legislation requires that commercial and domestic (home use) products require different labels.
In the United States all customers, from home owners to utilities, use the Cobra™Rod labelled product.

How do I apply the liquid products?

Products such as GenBor RTU-2 and Genics CuB 2-20 can be used by brushing or spraying. Coverage varies based on the type and dryness of the wood but typical coverage is about 200sq ft per gallon (18.6m3). Since these are water based products and contain no oil-based solvents or carriers the water can both freeze in the cold and flash off on hot, sunny days. Care should be taken to avoid both extremes during product application. Also, since these are very mobile in water it is important to cover with a water resistant sealer when applied in areas exposed to the weather.

What sizes of rods are available?

Rods are currently available in 1/3×1″, 1/2×2″, 1/2×4″ and 3/4×3″ sizes..

How do I choose the right size of rod?

The first consideration is the size of the lumber. Brickmolding and other smaller dimensional lumber would require the 1″ or 2″ long rods, fence posts normally take  2″ or 4″ rods and large logs require the 4″ or 3″ rods.

The second consideration is the volume of wood to be treated. Each rod contains a certain amount of material and has a Boric Acid Equivalent (BAE). In order to effectively protect wood, a loading of at least 2.0 Kg/m3 (2oz/cu ft) is recommended. The simplest way is to first calculate the the volume of wood you wish to protect. Then using the chart below divide by the appropriate size’s treatable wood volume to find the total number of rods required. In cases where existing decay is present the load rate should be tripled.

Rod Size

BAE

Volume of Wood Treatable

1″ – 1/3×1″

3.80g / 0.134oz

0.00141 m3 / 0.0498 ft3

2″ – 1/2×2″

13.83g / 0.488oz

0.00631 m3 / 0.223 ft3

3″ – 3/4×3″

53.30g / 1.880oz

0.0214 m3 / 0.754 ft3

4″ – 1/2×4″

26.93g / 0.950oz

0.0127 m3 / 0.447 ft3

i.e. To treat 3′ of a 4″ x 12″ beam with 2″ rods (4x12x36=1 cu ft / .223 = 4.48) would require 5 rods minimum.

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Where do I place the rods?

The rods work by diffusion. What this means is that the moisture present in the wood (the same moisture which allows the fungi to destroy your lumber) will drag the copper-boron complex with it. In order to best protect the wood the rods should be installed so that:
They are spread out evenly in all three dimensions
Spaced 7″ (18cm) to 14″ (36cm) apart
Installed cross-grain

Do I need to use Cobra Plug with the rods?

While treatment holes need to be plugged to keep out excess moisture, insects and fungal spores the method of sealing these holes varies. The advantage of the Cobra Plugs is their quick release threads which can be removed for future inspection and retreatment. However, in highly visible areas it may be preferential to plug the holes with wood dowel or other wood filler. Other times a small amount of caulking or wood filler is applied over the Cobra Plug just to hide it.

What size of hole do I need to drill?

The optimal treatment hole is just larger than the rod itself, keeping the rod in close proximity to the hole surface while maintaining easy installation. When using the Genics Cobra Plugs the treatment hole should be 1/16″ smaller than the plug size being used. Refer to the chart below when selecting the best drill size.

Rod/Plug Size

Actual Diameter

Suggested Hole Size

1″ Rod

8.5mm / 1/3″

10mm / 3/8″

2″ Rod

11mm / 7/16″

12mm / 1/2″

3″ Rod

19mm / 3/4″

21mm / 13/16″

4″ Rod

11mm / 7/16″

12mm / 1/2″

9/16″ Plug

14.3mm / 9/16″

12mm / 1/2″

11/16″ Plug

17.5mm / 11/16″

19mm / 3/4″

How do I install the rods?

The rods are installed by drilling a hole, inserting one or more rods and plugging with a reusable plug, caulking or wood dowel. The treatment holes should be slightly larger than the rod and long enough to allow for plug. Drill holes cross-grain for best diffusion.

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