Hemlock Beams... What do I seal them with?

[JP11]

Building a snowmobile/tractor bridge. Smallest beam is 8x8. largest is 8x5.

They will be joined 4 or 5 beams wide into two bridges, and set about a foot apart from each other. Threaded rod thru a few holes drilled horizontal across the beam.

My question... It's a lot of effort to build. What should I seal the beam with for help with rot? I'm planning to build a footer with some crushed stone, and set a 6x6 under the end.. so that piece is the sacrificial one touching ground.

Linseed oil? Or some other thing like thompsons? Figuring a bug sprayer and a peavey to turn them (got them stacked on pallets now in the yard.

Would appreciate any ideas or experience.

JP

 

[JustWood]

Foudation coating. I might even be tempted to seal between the beams before bolting together.
Hemlock wouldnt be my first choice for bridge making though. I've built quite a few crane mats and skidder bridges with white oak.

 

[JP11]

Really.. that gooey tar stuff?

I know it's not ideal.. But I couldn't stomach giving up some of my big veneer logs for a bridge. I've got red oaks.

Usage won't be too much. The span is probably 10 on the short side, and 14 on the longer one. Beams are all 16 to 18.. so plenty on dry land. I'm figuring each will be close to 40 inches wide. Tractor footprint is only 5' or so. I may deck the top with what's piled up from my rough cut 2x6 and house trailer frame bridge that was there last year. Figure the crossways 2x6s will help for wear, and keep a ski on the sleds from falling down in the middle. Was planning 6 inches to a foot gap between the two mats.

JP

 

[JustWood]

It drys hard and soaks into the wood.
Hemlocks pretty soft and doesn't stand up to traffic. Especially picked sleds. The local snowmobile club decked an abandoned railroad bridge down the road from me with 2x12 hemlock planks and they were wore through in 2 seasons.
Oaks hard as a rock , lasts forever and you can buy 8x8 cants at about any mill now for around 50 cents/BF.

 

[JP11]

Only two sleds will go over it.. Both mine. The Skandic WT is un studded.. and the 800 Switchback 144 is no studs as well.

Just my tractor too. Really just want to be able to log over there.. it's always dry. Of course.. this year.. I can drive the kubota about anywhere.

So foundation coating.. and it's thin enough as is to soak in?

I can't beat the hemlock for price, mine, free to cut. I had about a dozen logs. Ended up with 10 beams and a pile of boards. It was a buddy's saw rig. 300 bucks. He and I did it all in about 6 hours with the mill. I spent a few more getting everything back to my house.

JP

 

[Backwoods Savage]

JP, I'd guess you should get at least 10 years from the hemlock but those 10 years seem to go by pretty darned fast.

 

[basod]

JP, I'd guess you should get at least 10 years from the hemlock but those 10 years seem to go by pretty darned fast.

And your ten years older
Wiser but kicking yourself for not doing it right the first time

 

[JP11]

JP, I'd guess you should get at least 10 years from the hemlock but those 10 years seem to go by pretty darned fast.

In 10 years I should have the runway up there, and will want a real ROAD up there, since the hangar will go by the house. That's pretty far down the "want" list... but it's there.

JP

 

[ScotO]

I'd consider letting them go untreated, especially if they are green right now. Hemlock is highly bug resistant, and gets a beautiful patina to it over the years, from grey to brown. If its going to be sitting on stone, maybe let it be. Just my .02 cents.

 

[nrford]

The hemlock will outlast the oak!

 

[firefighterjake]

Based on what you're using this for . . . as long as the hemlock is not directly on the ground and has good drainage I would bet you would get many, many years out of this bridge.

 

[JP11]

Based on what you're using this for . . . as long as the hemlock is not directly on the ground and has good drainage I would bet you would get many, many years out of this bridge.

Hope so.

Just ordered the threaded rod to hold em all together.

 

[JP11]

Each mat took me 3 hours. Burned up a 6.5 amp 1/2" drill. Thought I was taking it slow enough. Bit was only 16" but it all worked. Finished off the last two holes in the last beam with the cordless!

 

[jharkin]

If you did use something like Linseed oil, dont use it straight. A trick historic preservation contractors and old window restorers use is to mix a 2-2-1 batch of Boiled Linseed Oil, Penetrol and Turpentine. This penetrates and seals even heavily weathered wood (restorers use it as a pretreatment for painting worn exterior wood that was previously bare).

The restoration types also use preservatives from outfits like http://www.ewoodcare.com/ They have coatings similar to Thompsons but with more preservatives blended in.

 

[JP11]

I managed to get them built and in. I may seal them in place. HEAVY!

They held up the excavator.. which is about 15k... so my little kubota shouldn't pose a problem.

The woods road is pretty much done. I have one more load of gravel to haul in a few bumpy spots. Back 40 (much drier) I now have pickup and tractor access too. WOO HOO.. Fresh ground to cut on.

JP

 

[Hogwildz]

I'd consider letting them go untreated, especially if they are green right now. Hemlock is highly bug resistant, and gets a beautiful patina to it over the years, from grey to brown. If its going to be sitting on stone, maybe let it be. Just my .02 cents.

X2 most of the old barns round here from the 1700's were built out of hemlock, lasts forever. My parents have an old grist mill and still ahve some of the old wooden gears and such. Barn still standing in great shape. A few beams replaced over the years, but other than that, just like way back when.

 

[Danno77]

I would have the ends on sacrificial railroad ties.

 

[firefighterjake]

I would have the ends on sacrificial railroad ties.

I was thinking the same thing . . .

 

[JP11]

I was thinking the same thing . . .

I don't get what you are both saying.

I did set the ends on a sacrificial 8x8. I ran the tractor across it yesterday morning before I left for work. Got a WHOLE LOT of woods roads now to make better. I drove along with the loader down low so I didn't get surprised by stumps. On the way back I just dragged the logging winch. It did a fair job of clearing out the pucker brush.

 

[Danno77]

That was just such nice wood, I was thinking a pretreated railroad tie (or more) would last a little longer and not hurt your feelings as much when they die. just keep on top of making sure rot doesn't travel through the sacrificial 8x8 to the bridge.

 

[firefighterjake]

That was just such nice wood, I was thinking a pretreated railroad tie (or more) would last a little longer and not hurt your feelings as much when they die. just keep on top of making sure rot doesn't travel through the sacrificial 8x8 to the bridge.

My thinking as well . . . longer lasting . . . but it would have been more of an expense.

 

[JP11]

My thinking as well . . . longer lasting . . . but it would have been more of an expense.

The 8x8s were pretty much free. I think once they dry a bitt.. they will be light enough for me to be able to lift the ends with the kubota to replace the "footer" I've got one 18' 8x8 left.. and a few 10 foot 6x6s. I can't decide if I want to "deck" it with the 2x6 rough cut that made up the old bridge. It would help on the skeg wear.. so I guess I'll do it.