Timber Bridge Preservation 1

[PhDE]

What is the best way of treating timber decking for a pedestrian bridge. Power wash the decking and then treat it with a water proofing agent or just use something like linseed oil and let it soak in? Stiff brushes and wash the decking then treat it?

 

[Sawbux]

The best way is to use treated lumber or naturally resistant wood like cedar for the decking material.

Sounds like the bridge is already built so you will have to use a brush on treatment. You can pressure wash, but then it is best to let it dry out again to allow the preservative or stain, which is usually oil based to soak in. I would recommend a solid stain to give some UV protection also to the wood. Most of the wood preservatives use a mixture of petroleum oils with wax added for repellant. Depending on your climate, you might be able to make it last for 10 to 15 years.

Another option would be to put "roll roofing" over it. The granular surfacing would also make it slip resistant.

 

[jheidt2543]

I would agree with Sawbux's first suggestion, but I would really think hard about the second. I would be afraid that water could be trapped under the roofing material, either from condensation or leaking through the roofing material. It would take a VERY long time to dry out, thus a possible source of decay. At least the wood exposed to the elements has a chance to dry out periodically.

Just my two cents!

 

[RockEngineer]

Some of your best preservatives if you are not able to pressure treat the woods are the borates like "TimBor". These give you protection against the bacteria that cause wood decay and some have additives that cause them to be sucked deeper into the wood than most of your surface treatments. There are several web sites which will give you information on borates for use in wood preservation. Here's one.

http://www.environmentsensitive.com/usingtimbortocontrol.htm

 

[dpa]

Check with your fisheries and ecology depts before painting over water. We built a pier with a floating dock at the end and the fisheries dept permit had 34 paragraphs of restrictions. The permit very pointedly mentioned fines and jail time.

 

[pug]

I would not use untreateded wood in structural elements period. As a wearing surface, use untreated wood and replace every ten years. The fisheries followup is essential as mentioned earlier.