Built up Beams

[redwood]

In the latest mag., there is a article concerning code violations.

It specifies that beams must be built up, rather then solid. Why is that and when did this come into place? Is this universal accross the country?

Does Simpson even make column caps to handle double 2x's?

[Bobby Parks]

I believe what they're saying here is that although timbers such as 4x4s , 4x6s, and 6x6s have significant structural capacity when used vertically as columns within certain limits, they lack the abilty to handle vertical downloads created by the floor structure when these pieces are used as a horizontal beam or girder. Technically they could work but the span from column to column would have to be pretty short and its hard to say who would do this right.

Doubled 2x8s, 2x10s, 2x12s etc have more backbone when used as a beam than a 6x6 would have as this would be the equivialant of 4 2x6s attached together. A 6x6 if spanned very far would probably sag of its own weight. Solid beams such as treated gluelams would still be fine to use. Anyway this is what I think this is about.
Bobby

[redwood]

Most of my decks are not that high off of the ground and and tend to be anything but square. # of columns (posts) is not a issue.

My most common framing design uses 4x6 PT beams and 2x6 PT joists, with a 2x12 redwood fascia (rim joist). I use this combo as the 2x12 hides all of the framing. No spans are more then 6' in any direction. Solid blocking over all posts.

I've been doing it this way for 30 years with no complaints from the Building departments. Why the change?

[Bobby Parks]

Mark, it sounds like you've utilized or engineered your structures in way that 4x6s have worked without creating issues. You've minimized column spacing and kept the framing deadloads down by using 2x6 joist and controling the joist spans. Your building dept has apparently been comfortable with what you do. You've got more years in this business than most of us do and obviously you know what you've done in the past ahs worked.

Again it's my quess that there's been enough built out there by others that did not realize that overspaning such items created problems, therefore bringing attention to the usage. You can ask the author who I'm sure knows more about the details, in the comment section online with the article. Andy the editor knows more about this stuff as well and will probably shed more light on the topic. She's written a good piece here and it is an everchanging world and deck building is simply getting more attention.

I notice you're in California and I've often wondered what you guys have to do different that the rest of us who don't live in earth quake zones. The structural engineer that I use on occasion is from California Is there anything you incorporate into the structure thats significantly different than us in Georgia? Also it seems like you guys need to come up with some flameproof material because it seems as though you guys are often on fire.

Bobby
Alpharetta Georgia

[DeckCreations]

Bobby, similar to Mark I build the substructure for most all my decks with 4x6 PT beams and 2x6 PT joists using span charts as a guide for appropriate spacing. As long as one does not exceed the deflection limits with a particular construct, I am uncertain as to why they are now advocating joining 2x dimensioned material together... given moisture entrapment issues, more fasteners, etc???

I am not aware of any specific code requirements for decks built in high seismic prone areas other the the obvious of making certain that there is a positive attachment of the substructure to the footing so the deck doesn't start dancing across the yard after a trembler. I have seen some decks just resting on a footing without any positive attachment... makes me a little nervous.

High fire issues are a big deal out West. Depending on the local ordinances regarding High Fire Hazard Areas there are several construct options that can be considered in addition to clearing nearby brush and potential fuel sources. Here anyway there are at least three options to choose from. 1.) One can either build the structure using heavy timber construct. 2). Build a one-hour fire resistive enclosure around the perimeter from deck surface to ground level. or 3). More recently they have allowed the installation of an approved sprinkler system as a method to meet High Fire Hazard area requirements. There are some new flame retardant building materials on the market but I don't know if the verdict is in on them quite yet.

[redwood]

Thanks for the backup Bill.

For higher decks, really anything higher then 3', we normally need some sort of lateral bracing. I'm not sure if that would be a requirement in Georgia.

Like elsewhere in the country, decks have been off of the radar as per specific code requirements. Often time it is up to the particular municipality that you are working in. Requirements can be very different from city to city..

In my area, there are no fire hazard requirements in regards to decks that I am aware of.

[Bobby Parks]

Bill and Mark, its interesting for me to talk to you guys and others from different parts of the country. I've always given you the California boys credit for helping shape and develop our decking industry to a large degree in terms of design and custom looks. I remember seeing photos 12-15 years ago of some fantastic looking projects that were built out there. I remember customers showing me pictures in magazines or books and asking if I could do this? I also remember thinking I wished the California guys would slow down because they're making my job more difficult. Someone once asked me if I've ever seen a deck that I could'nt build. I told them only one and it was the Trex deck that was used as a marketing piece that looked to be built on the cliff on the Pacific coast. All kinds of curves and steel columns anchored into the rocky bluff. I was glad to find out it was at least partly computer generated. Now we see this type of work all over the country and I never cease to be amazed at what others are creating.

Just to touch base back on the original subject. It may be even though code is changing that with a structural enginneers letter you can continue to build as you have. Not sure about the feasibilty or cost etc to do it. I had the same thought about why are we messing with certain aspects of the code when things and techniques we used for years have not been a real problem. The rail 200 vs 500 lb side resisitance or whatever it was discussed recently is another example. I'm for always improving what we need to improve. I'm not into creating additional cost for no good reason. Bobby

[Andy Engel]

Folks, there's a clarification of this in the letter to the editor of the March issue.