Installing Trestles

[J Silverman]

Over the winter here in PA, I made about 30 wooden trestle bents, ranging from 8 to 40 inches in height. I'd like to install them soon, in a large loop. I'd like some advice on how to weatherproof, bury the bottoms, and connect bents together. Thanks!

[ttrigg]

J:
Any wood that I have in contact (i.e. buried or laying on top of) with dirt I treat with a wood preservative.  The one I use is called "Copper-Green" (brand name is Copper-Green) Wood Preservative and the UPC for the quart can is 7-35845-30004-5.  Here in San Diego it can be acquired at either Home Depot or Lowes.  I started using this stuff about 15 years ago, on some 2 inch dia by 6 ft long pine tree stakes, the wife wanted to use for the fruit trees.  Pulled the poles out of the ground last summer and rot was very small.  Poles were good enough to reuse for the tomato garden.  Before I put the poles into the ground I got a 4 ft piece of 4 inch PVC, and glued a cap on one end, put the poles into the tube (one at a time), filled the tube with preservative and let set overnight.  I have done the same thing with my timber trestle bridge (except in a smaller scale, I used a 3 pound coffee can).  It takes about a week and a half for the preservative to completely dry, then I applied a liberal coat of an oil based wood stain, the green color of the preservative is very hard to cover up.  In fact the wife prefers the green with a lite coat of stain.  After I pull the timber bents out of the preservative I just brush on some preservative on the upper portion, which will not be in contact with the dirt, for color continuity.

[markperr]

I've found that the 2 x 8 x 16 pavers found at home centers work really well as trestle footings.  I scored and split mine in half lengthwise with a brick chisel and hammer, then laid them in the dirt so that the long 2" side is facing upward.  Then I cut the bent to size and use a dab of liquid nails on each vertical post to secure it to the concrete footing.

Mark

 

 

[J Silverman]

Thanks. I like your suggestion of dunking in preservative, but my trestle bents are so big. I thought I would fill a sled with my favorite preservative (Helmsman Spar Urethane) but the bents didn't fit, and I would need so much preservative. I have heard about a product that allows you to spray paint on to surfaces with an air compressor or hand pump. Does anyone know anything about that?

[dwbeckett]

Try a FENCE stain .

[J Silverman]

What characterizes a fence stain?

[smcgill]

Ask the paint Dept. @ Lowes or Home Crapo

[smcgill]

I also used the pavers, on top of a bed of stone level and set the bents on it.

Drainage is important!

I then went and buried them all in stone .

 

[J Silverman]

Thanks everyone.

 

Today, I went out and bought a CO2 operated paint sprayer (for the urethane). Although it said oil-based paints could be used, I don't know how long he cartridge or my paint supply will last. I'll let everyone know my results.

[J Silverman]

Any advice on weatherproofing about 300 dowels? Each is 1/2x1/2x8 inches.

[dwbeckett]

Try using fence stain. The transllusent type ask at lowes or home depot paint department.

[ttrigg]

Any advice on weatherproofing about 300 dowels? Each is 1/2x1/2x8 inches.

Go to Wal~Mart and buy a $1.97 disposable aluminum turkey cooking pan and some rubber gloves, go to Home Depot (or Lowes) and get a quart of wood preservative for about $18.  Pour the preservative in the pan, drop in the dowles and let soak for an hour, take them out and put in another batch until complete.  They will come out green form all the copper in the preservative, but will turn a nice brown color in about a 2 months or so exposure to the weather.  A wood preservative is designed to soak deep into the wood and stop bugs from eating through and rot from contact from the dirt and water.  Fence stain will not soak as deep into the wood as a preservative and offers only limited protection from normal rot but does nothing to prevent bug damage.  Spar varnish will put a protective coat over the surface which will chip and peel over time thus granting full exposure to bugs and rot.  Standing them on bricks/stone gives great foundation but provides no protection from rot due to weather exposure, and it provides a direct path invitation for bugs to attack.  Placing small stones on top of the brick just provides a place for water and moisture to hide.  Take a look at the data available on the cans, spar varnish will tell you to sand and re-coat every 1-2 years, weather exposure dependent; fence stain gives 3-6 years worth of protection for the wood not in contact with the dirt, 2-3 years for wood in contact with rocks and dirt; preservative will give 8-15 years worth of protection for wood in contact with the dirt, and up to 30 years protection for wood not in contact with dirt.  Pay close attention to the periodic required maintenance, and then make your choice.

[J Silverman]

Thanks. What brands of wood preservative have you found to be the best?

[ttrigg]

At the risk of sounding rude, you want one that contains copper salts.  They are pretty well standardized, being very close to the same thing used for pressure treated lumber, in a not so deadly form.  The front face of the can should have words like; green, copper green, copper nitrates, copper salts, and the like, in the next to the largest print on the can.  Just ask your HD or Lowes paint person for "wood preservative".

[markperr]

Dowels are usually hardwood, I believe ash, and as such are tight grained.  Not too sure how deeply the wood preservative will soak in.  If you're going to bury a portion of the dowel, you may want to consider painting them with some sort of waterproofing agent like that black waterproofing stuff used on foundations or perhaps even DRY-LOK by UGL.

Mark