Help with wood beam slice location

[crinkles]

do not splice at points of maximum bending moment, unless the splice is designed for it. so - on simple spans, don't splice in the middle of the span. on multi-span spans, e.g. 2 spans with a support in the centre, do not splice at the supports or mid span. It gets complex, and yes, you should see a licensed structural engineer or a builder. but someone's advice of splicing at 1/3 points is OK, i would probably splice at 1/4 points. came very close to being a structural engineer in an alternative life... but i chose the dirt...

 

[D189379]

 Originally Posted By: crinkles

on multi-span spans, e.g. 2 spans with a support in the centre, do not splice at the supports or mid span.

That's what I had stuck in my head when I asked the question.

 

[Gary Allan]

I'm trying to wrap around Crinkles direction here. The only thing I can see as a liability is that if you manage the splice like two independent beams (essentially two 10' spans with 10'+ beams) is that the potential for the center column to sink might have longer term inconveniences over the 20'+ span.

 

[D189379]

 Originally Posted By: Gary Allan

I'm trying to wrap around Crinkles direction here. The only thing I can see as a liability is that if you manage the splice like two independent beams (essentially two 10' spans with 10'+ beams) is that the potential for the center column to sink might have longer term inconveniences over the 20'+ span.

I think what he means is that the splice shouldn't be located where the bending of the beam is the greatest (Splice being the weak point) The beam wants to bend at the posts and at the midspan of the beam

 

[ksJoe]

Why not get 4 12' boards, cut a foot off all 4? Make two 11' beams an butt them together on your center post. Maybe get an extra large center post (4x6 instead of 4x4) so you have more room to set them on. Then you have no splices over any span. You'll spend just few extra $, but if you're posting about it you obviously care, so whats a few extra bucks to know its rock solid...

 

[Tempest]

I'm not sure why you wouldn't want the splices at the posts. The splice is the weakest point and is held up by the post. I understand that there may be some cantilevering going on but if the camber of the boards is put upwards it should solve that problem.

 

[crinkles]

 Originally Posted By: Tempest

I'm not sure why you wouldn't want the splices at the posts. The splice is the weakest point and is held up by the post. I understand that there may be some cantilevering going on but if the camber of the boards is put upwards it should solve that problem.

if the beam is to be continuous over the two spans, a splice at the centre post is going to be most expensive because you have a max bending moment there and centre spans. If you want 2 simple spans, no need to splice the beams if you have equal length spans/beams, just make sure they are adequately supported and braced on the top plane of the beam.

 

[D189379]

Figured I'd update you all with a picture. VOILA!!!

 

[Tempest]

Nice! It's still standing so it must have worked. LOL

 

[D189379]

 Originally Posted By: Tempest

Nice! It's still standing so it must have worked. LOL

Yup, it's very solid. And only 3mm out from being completely square!!

 

[Gary Allan]

 Quote:

And only 3mm out from being completely square!!

mori?

 

[D189379]

 Originally Posted By: Gary Allan

 Quote:

And only 3mm out from being completely square!!

mori?

Not sure what you mean?

 

[Gary Allan]

That's just the level of precision that I'd expect from mori. +/- 3mm from perfect over that scale.

 

[IndyIan]

Looks good! I don't think that will be too springy at all with normal use.

 

[D189379]

 Originally Posted By: Gary Allan

That's just the level of precision that I'd expect from mori. +/- 3mm from perfect over that scale.

Oh gotcha, don't worry that wasn't my aim. Just got lucky when we measured it all up.

 

[D189379]

 Originally Posted By: IndyIan

Looks good! I don't think that will be too springy at all with normal use.

There's no spring at all. I'm more confident in the deck than the rest of the house.

 

[IndyIan]

That's good! I guess two 2x10's on edge are pretty solid.

 

[crinkles]

i thin k it looks great! well doen

 

[Dupree]

I wouldn't splice unless It could happen at a bearing point. If having to splice adding a third piece and making a sandwich splice would be best. Also the screws wont work as the joining medium for the beam. Screws have no shear integrity as recognized by icc irc codes as well as many others. They just don't have near the shear load resistance as nails. You'll want to use nails, teaco nails would be ideal since they have the highest shear rating. Also note that if it is pressure treated lumber your using you'll want to use hot dipped galvanized as the treatment of that type of wood will rust out other nails. Hope this helps, oh yeah I am a Deputy Building Official for my job when not an oil lover (head building inspector).

 

[Dupree]

sweet talk about giving advice on a stale post