Estate Gates

[Harlan Barnhart]

A customer recently asked if I could make a set of heavy wooden gates for his driveway. By heavy I mean a finished thickness of three to four inches spanning a 20' drive. It's still early in the planning stage but I would appreciate your thoughts. I am posting here rather than the general woodworking because I imagine I'll be doing a lot of the joinery by hand.

(1) Will white oak hold up to constant exterior exposure? I would like to use a native wood if possible. Also white oak in that thickness will certainly be more available and affordable than an imported variety.

(2) Should I show any preference for riftsawn versus plainsawn? Will a rift sawn face weather any better than a plainsawn face?

(3) I am planning pinned mortise and tenon joinery. Should I bother with glue?

(4) What moisture content should I aim for? Is kiln dried too dry for an exterior application?

(5) Tung oil or BLO? Should I oil the insides of the joints (assuming no glue)?

(6) Any tips for weatherizing exterior structures? Copper caps for upright end grain?

Thanks for your thoughts.
Peace,
Harlan Barnhart

[Frank Drew]

Harlan,

I'd probably go for a lighter weight wood than oak, maybe fir, cypress or redwood; I'd definitely use mortise and tenon joinery, and I'd use glue in addition to pinning the joints, just because.

With heavy gates, with any gates, really, the posts are as important as the making of the gates themselves; if they stay straight and plumb for the long term you're already in good shape.

I don't have much experience with clear outdoor finishes, so can't help there. UV resistance, though, has to be in the mix, in addition to resistance to water. Capping any vertical pieces is probably a good idea, although if the clients nix metal you could also fashion the tops of any of those pieces to shed water, at least to some extent.

[James Taglienti]

I'd suggest cypress too- white oak might be too heavy.

If it was my job, I'd be pushing hard for something painted. If I did wind up using a clear finish, I wouldn't put longer than a 6 month guarantee on it. (the finish.)

I've done a couple front doors with spar urethane that lost their finish in about a year, and those were shadowed for half the day, and didn't take a lot of rain. A gate is pretty much in the elements constantly. I'd paint that sucker brown.

But thats just me.

[Jamie Buxton]

I watched a pro gate company put in a gate pair like that down the street a couple years ago. As Frank said, they invested a lot in the posts. Big gates try really hard to overturn the posts. They started by making a foundation. They ran a trench from post to post. They also put trenches under where the gates would stand when open. They put lots of rebar and concrete in the trenches. Where the posts would be, they formed up about 8" above grade, and had heavy J-bolts sticking out the concrete. After the concrete cured, they brought in two pieces of steel pipe, maybe 10" in diameter, that bolted to the J-bolts. The pipe had bosses on the side which was where the gate hinges would eventually bolt. Then the stone masons spent days surrounding the pipe with rock work. Eventually the gates arrived. Structurally they were steel, with wood draped over it. That is, they looked like they were wood, but the wood was really just for show.

[george wilson]

Definitely do not use a simple oil finish. Cypress will age to a gray color,and last quite a long time. I made a box for parcels to mount beneath my mail box many years ago,from cypress. It actually lasted longer than the strap hinges' screws that I put on the lid.

I'd opt for no finish at all,because the cypress will outlast the finish,unless the finish is maintained.

Hanging a 3"-4" thick gate 10' wide is going to be a HUGE strain on whatever hinges you hang it on. What are you going to mount the hinges to? Stone work?

The hinges should probably be made very heavy,and forged out by a blacksmith. Probably 1/2" thick,and 4" wide at the hinge line,tapering to something like a leaf shaped point,or whatever shape he wants,and probably 3' long. They need to be very sturdy. If they are hinged on pintles,I'd say that the pintles need to have vertical "hinge bars" maybe 1 1/2" in diameter. The iron work will blacken the wood near them. This should be expected,and the owner should understand that it will add to the massive effect of the gates,and agree to it. Even if the iron work is painted,it will eventually stain the wood. I'd get long,hand forged nails with rose heads made to fasten the planks together. There's a company who makes them,but I can't think of the name right now. What they are is boat nails with rose heads forged on their heads. Fulton nails??? The nails need to be LONGER than the thickness of the gates,and CLENCHED over on the opposite sides. If they are not,they WILL work loose from the wood swelling and shrinking over the seasons. I'm thinking at least 5 1/2" long. They will probably have to be custom forged. I doubt that factory rose head nails come that big. Google it and find out. They kept these commercial nails in the main warehouse in Williamsburg,but I never saw them over 4" long.

Is there any way you could have some type of wheel on the swinging edges of the gates? It would help an awful lot with the extreme strain on the hinges.

Whatever you decide to do,THINK BIG on those hinges,or you may find yourself in big trouble when the gates tear themselves off the hinges,and the owner demands them to be repaired. Think in terms of the gates on a castle,because that is what they will be equivalent to.

[Jonathan McCullough]

Twenty feet!?! Time to call in a structural engineer. Depending on how you make them and what you make them out of, the torque at the end of the gates would be enormous. Another thing to consider is what would happen in a wind storm. There's a reason these are usually made out of wrought iron.

[Stanley Covington]

I built something similar many years ago in Utah. Oak is not the best choice unless you need tons of extra mass, but the extra mass makes it hard to open and close the thing. I used cedar. Strong, light, rot resistant. Cypress would probably be even better.

See the two gates at the links below. Notice how the top hinge is high to deal with the overturning moment. The further the top and bottom hinges are separated, the better they can resist the push-pull forces acting on them.The post supporting the hinges must be very strong and able to handle the moment caused by the deadload (weight) of the gate plus the weight of as many adults as can manage to climb onto the gate. That's a lot of weight. Unless you have structural engineering training, you should have an engineer take a look. Failure to do so can get people hurt. I kid you not.

Also notice the timber gate uses triangulation. The other gate uses a tension rod to the same effect. This is the surest way to make a heavy gate work in the long term. Maybe not as pretty, but effective.

When you have a choice, use steel to deal with tension. Not too hard to hide inside a timber, and welds or bolt nicely to a hinge.

http://www.google.co.jp/imgres?imgurl=http://www.ranchdrivewaygates.com/images/ranch-gates/ranch-gate-1g.jpg&imgrefurl=http://www.ranchdrivewaygates.com/ranch-gate-1.htm&h=332&w=650&sz=48&tbnid=pDzzdmiLPaIDYM:&tbnh=70&tbnw=137&prev=/images%3Fq%3Dranch%2Bgate%2Bimages&hl=en&usg=__lj7EIPH0A7NjCH_9Q1yEYrhA_s0=&sa=X&ei=-K1bTPPAKoeEvAPMl5CeCQ&ved=0CBcQ9QEwAA

http://www.google.co.jp/imgres?imgurl=http://www.photoseek.com/07SAW-Idaho/bin/images/large/07SAW_1156_57_Sawtooth_Mountains_horse_ranch.jpg&imgrefurl=http://www.photoseek.com/IDusa.html&h=460&w=1149&sz=169&tbnid=47b8Rddr44cqHM:&tbnh=60&tbnw=150&prev=/images%3Fq%3Dranch%2Bgate%2Bimages&hl=en&usg=__nYlC1x6FiqITJwZlXSA3W2HtyAg=&sa=X&ei=-K1bTPPAKoeEvAPMl5CeCQ&ved=0CB8Q9QEwBQ

[Frank Drew]

Very interesting information, Jamie; I didn't know all that goes into the job these days.

[James Taglienti]

harlan, how will the gates be opening? on a track or on hinges? will they be motorized?

[Jon van der Linden]

As Jamie said, most commonly wood drive gates have a steel structural frame. When the gate is wide it puts a LOT of stress on the gate itself. Then you get into the problem of the hinges and post.

As was mentioned, you also need to take into account more than just the weight of the gate. If someone hangs from it and that pull the hinges even slightly out of alignment, that can be a huge problem over 10'. You'll need a wheel or really strong hardware. One other option is to have the gate on rollers so it rolls to the side. This is a fairly common solution in drive gates.

Most of drive gates of this size use commercial automated gate hardware. I would look there first and build the structure around that. Either way it's going to be quite a bit of work just to figure this out.

[Mitchell Andrus]

Most of drive gates of this size use commercial automated gate hardware. I would look there first and build the structure around that. Either way it's going to be quite a bit of work just to figure this out.

Agreed. The hardware will drive the design. Start with what you can buy or have fabricated. I'd make 20' gates out of steel then design the wood 'skin' to fit onto it. It'll be lighter overall and less dependant on wood joinery.
.

[Herbert Mulqueen]

I have built many , many timber trusses. These are what you see in churches, high end restaurants, county clubs and municipal buildings.

In the past customers and architects would request wood other than Southern Yellow pine or Douglas fir. It was always denied. A gate is structurally different that church trusses. The risk is great with a church roof.

It is very difficult to get engineering sealed for anything but those species.

Wood sizes could run from 3 x 6 to 12 x 12 , remember that a railroad tie is 6 x 8 and I believe 7-6 long and a switch tie is 7 x 9. So if your handling 20 foot stuff make sure you can handle it.

Another option is to use laminated wood.

I really like the idea to use a rolling fence gate. The forces on such a gate with one leaf using one post are huge and require a lot of post and foundation design. There is a movie series on cable called" pillars of god ".
In the book I believe they cited numerous occasions of Cathedrals roofs killing a lot of people. Thus the flying buttress. Lots of forces at work, one does not realize.

Some thoughts-----

Try not to have any splices on the top or bottom. These member should be one piece.

A local structural engineer would be nice to give you advice. Probably the cost would be reasonable. Foundation, post requirement , gate span ---most structural engineers are fine with concrete and steel---but do not have a clue on lumber trusses. Wood trusses are both engineering and art and lots of time in serving that marketplace.

What you might want to do is build a mock gate out of 2 by material and get the proportions of bottom chord, top chord and webs. For example --8 inch top chord 12 inch bottom chord and 6 inch webs---the customer might decide on 8 inch top 10 inch bottom and 6 inch webs. It needs to be studied, remember most customers have no idea what they want---but know it when they see it.

Always have your bottom and top chords in the same plane as the webs.

That is use the same thickness wood.

So that would translate into a 3x8 or 4x8 top chord---3x6 webs and 3x12 bottom chord.

Proportion sizes are very important for balance and what the customer desires.

I ramble as usual..

Herb

[Harlan Barnhart]

Hmmm... now I have even more to think about. I agree oak is excessively heavy but I got started in that direction by looking at Large outdoor gates in England which seemed to be made of oak. Cypress or Redwood are definitely lighter but may be hard find that thick.

The drive is roughly 20' feet so each gate will be only 10', actually a little less since some of the 20' will be occupied by the posts.

I was planing on using commercially available closing hardware. Google "large wooden gates" and you can see some installed.

Mr. Wilson, I was planing to use bolts to attach the hinges. I imagine the hinges will have to be custom made. Large pins in the 1 1/2" range seem like a good idea.

For posts, I was planing steel in concrete with a stone cladding. This is surely one place where excess is in order.

Thanks for the ideas,
Harlan

[steven c newman]

Since concrete things are my kind of thingy, a few tips here is in order;
Use the anchor bolts that can be tied into the footer/pier's rebar, not just a few "Redhead' bolts.
Use an "H" shaped column, with four holes for the anchor bolts. You can then attach any hardware to either flat side of the "H".

When digging for the pier footers, also dig a trench between the two. Use a rebar "cage" to bridge between the two piers. This tie-beam will keep the posts vertical, simply by not allowing the piers themselves to "tip over".

You can then add whatever covering you like over the "red-iron" core. But it is in the base that all things start. A good,firm base is needed.:cool:
If there is any other concrete questions, send them my way.