The "L" in L girder is created by attaching a piece of 1 x 2 (any length) horizontally onto a piece of 1 x 4 there by creating an "L" shape.  The purpose is so that one may screw boards, tops surfaces, etc. from underneath the layout making it easy to undo if future adjustments become necessary. 

I highly recommend buying this book:

How to Build Model Railroad Bench-work.  "L" girder is absolutely the best way to construct bench-work that requires much more than just a few simple flat oval(s) of track.

There are some photos of my lgirder construction in this thread and this thread.

If you know how to use sketchup I can send you the drawing file. You don't have to do things how I did, but my benchwork is right out of the book mentioned above (though in some short lengths I undersized the lumber). In most places I used 3/4 inch plywood ripped to match a 1x4. It was cheaper and stronger, but not everyone has tablesaw to do that with. 

Don't get too caught up in the passionate debate on the forum. I'm a beginner compared to many here. But you can't go wrong either way. Both have their merits. My opinion is lgirder has great strength with less and lighter materials, but with my inexperience, I wasted a lot of materials. Simple square 2x4 box construction is easy and cheap and very strong. And 2x4's are much cheaper than 1X4s. I didn't want legs on the floor so I could store things easily under the layout. And I was personally curious to build lgirder cause it's fun to try new things. I could have been up and running much sooner without lgirder, but for me the hobby is more fun to experiment with stuff I've never done before.

2 x 4 bench work construction is overkill.

AMEN!

When I had a basement layout, I used 1x4's for the vertical section of the L-Girder and 1x3's for the top. Used 2x2's for legs. I could walk on it with no issues at all.

I'll have to try and dig out the old video segment that George Seil and I did on the construction of L-Girder benchwork. It's in the stack of old 1-inch videotape masters from the 90's.

Would like to see that too, Rich!!  Thank you.

     Hoppy

Hey Matt,

Since you're just starting out, pick up the Book (you'll keep it and re-read it for reference), go ahead and give the L-girder a try. 

As mentioned above, there is no good or bad way, but L-girder is more flexible, lighter weight, just as strong(if not stronger) and adapts to many different scenarios. You'll find that over time you might end up using different methods for different circumstances, but for now it's worth it to give it a try. Because it is unfamiliar to you, be patient, in the end you'll be proud of what you built.

Me too!

Like Tim said, don't get hung up on the passion here. There are people who make the "L" out of 2x4's rather than 1x2/1x4's simply because of cost. Yes, it's overkill and weighs too much, but some of us do pinch pennies, so to speak, even though we know this is not an inexpensive hobby, and not everyone plans on ever moving their layout. L-girder has a lot of advantages; easier to change things, add rivers/valleys, doesn't need as many legs over a given span, etc. Linn Westcott designed it back in the day when lumber costs were much different and he was designing HO layouts. Many of us played with O gauge on nothing but floors. I once had a grade supported by books, magazines and anything else I could get my hands on as a kid.

ALL things considered though (time, money, materials), some variation of it is probably still one of the best methods, but it's definitely not the only method to create a great layout. A lot of people find deals on materials, so that is what they use. For example, Tim cuts strips of plywood rather than purchase expensive 1x lumber. My problem with that is the "L" has to be screwed into the "ply" and that doesn't seem as strong as screwing into 1x wood. However, it works for him and that's all that matters. Mianne uses an I-beam system and Woodland Scenics uses a lot of foam.

The one thing that is selling me on L-girder is the ability to screw the tabletop from underneath so no screws are showing and they don't interfere with landscaping. I also recommend buying the book mentioned above, but don't expect it to be cheap, so I'd check out the local library first. Or, you can check out some You Tube videos, there are many:

Don't get weirded out by some of the guys who do the videos, just watch what they do and how. Search Google too for "l-girder benchwork" and check out some of the links.

FROM THE WEBMASTER...

Embedding videos is MUCH better than just lasting the web addresses here. PLEASE learn how to do that!

I embedded these for you. Not too sure about the host in the first one...

Just a Note on that Book. "How to Build Model Railroad Bench-work"

Check out your local Library First! To see if they even have it already.  I was able to find a copy at a Library right down the street fro my work.

Because the cheapest price I found it on Amazon for was $40, which I think is a little steep for a book that came out almost 20 years ago...

Glad I saw this topic.  I'm also in the design phase and I must say, you guys made it a little easier to understand.

I have a good copy of Linn Westcott's 1979 Edition of "How to build Model Railroad Benchwork" which is the infamous "L-Girder" cookbook.

For $5 which should cover a mailer and postage I will mail it to the first one that e-mails me.

Michael Rodgers was the first to mail me. If you want the book I need your postal address.

having built, l GIRDER T GIRDER AND PLAIN OLD FRAME IT TO h3## sections, I offer the following observations.

L girder is a huge plus for screwing into, or rather from, it has a larger accessible flange.

 in lynn westcott's day screws were flat blade. counter sink, drill and twist that screw driver...  with the Phillip's head and myriad other drive choices in screws today and the large range of very stable glues... this is all much easier than ever before.

secure you top to the bottom with finishing screws if you are using plywood use fine tooth screws for dimensional lumber pre-drill and use course screws. glue both assemblies if using plywood or dimensional material

if you use plywood for your cross braces you can shape the contour of the cross braces as you go, hence removing the need for risers.

it is best to use square drive or regular head screws for mounting your uprights and cross members, that way they are easily discerned if you have to re-located material

 the need to cross brace your legs with long runs of strip is not essential but use at least a 6"X 6" diagonal plywood brace in all corners

I like to 'box" my l girder with a solid section the same height  as the "riser" of the L girder.

 before you start doing a lot of
wet work" cut and install a fascia board contoured to match your terrain, you can trim it down to contour after you finish roughing out your scenery but it will provide stability, if you use masonits for this you can also get gentle curves along the front of the layout.

I always lean towards ripping furniture grade ply for my structural members, dimensional lumber varies so much these days that it is a crap shoot of you try and match up what you  already have.

"L" girder is simply the best method period...because it is designed to be undone and revised.  Sooner rather than later you'll be glad that you did...

I have that video and have watched it many times. Very good visual on how to build L girder.

There seems to be another opinion in the O-Gauge camp on the best way... if you are following Jim Barretts series on building his layout in run 269 he uses a framework method that looks really interesting..

Any comments from Jim on the difference??

I like the 1"x3" & 1"x4" L-girder theory and believe that it would produce a sufficiently strong platform for a layout.  However, the difficulty associated with finding straight 1x3's and 1x4'x in my local market would prohibit me from going that route as compared to the 2x4" stock.  Not that you don't also have to sort through the 2x4" stock, but it is much easier and quicker to find straighter lumber in the larger size.  Probably due to the speed drying and new growth/green wood often used today.