caulking beams?

In the book I have it suggests caulking joints between the 2x's if doubling then up for a beam. Should I? I live in Florida so melting and freezing snow isn't an issue, but we do get lots of warm rain. Should I bother, cause I'm not sure I will see much benefit?

 

Never heard of anyone doing that.
Once or twice I've seen a strip of roofing felt used.

 

I'd be afraid it would do as much to trap water as it would to keep it out.
Sometimes those books are written by those that have never actually done the work more than once

 

That's what I was thinking. Even if I caulked the beams what about every little check mark and Knot hole.......

 

IMHO, use some Grace I&W on the beam tops, helps seal the nail holes also. Any water gets in can still drain out...seen it on joist tops too. Builders paper would just hold the water there- 5-30 perms. Research it for your hot climate.

Gary

 

Where are these beams located? Inside or outside? Are they "beams" (horizontal) or "posts", vertical?

 

They are beams. If by outside you mean in the yard, then yes.

 

If they are outside but under cover (eg a roof) they would not need caulking.
It certainly would not add anything to the strength of the combined beam.

 

There is no roof, it is just a ground level deck in the yard.

 

We're gonna get there......what is the purpose of these beams?? Does it hold your deck up?

 

Hows about I just post a picture?

 

There ya go. Pix is worth 4 words, or more. Trying to seal the tops of these joists will drive you crazy. Build it, the partiers will come.

How long are these joists?

 

The joists are, if memory serves, around 8 1/2'. Everything I looked up said the max span was 9'9" so I wanted at least a 1' safety factor.

 

That's great. Just looked longer in the pix, and I wanted to make sure it was within parameters.

 

It feels pretty solid, I went with 16" OC, except the 2 nearest the rim joists are more like 14". I'm decking next week with 5/4" premium PT boards from home depot.

 

Doesn't look right to me. A doubled 2x carrying 8' of joist (on each side, combined) should be 4'8" max. between piers/bearing. http://www.awc.org/Publications/DCA/DCA6/DCA6-09.pdf

What does the center doubler measure between piers? How far apart are the beams (joist length, exactly)?

Gary

 

Gary, the reference didn't stipulate a "both sides" parameter, and the 4'8" measurement was for 14' joisting on single side. Can you direct to the right part? I would want additional piers at each end of the cantilever, too, but it isn't absolutely necessary.

 

Yes, I don't care about the cantilever as you are allowed /4 length of joist. I am looking at the total deck beam length = 12' minus 1' at each end cant. = 10' span with one pier in middle at 5'. With SYP (pp.5, Table 3) for 9' span = 5'10" (between 8' and 10') for one side. Because the center beam is loaded from both sides, I doubled the 9' span to 18' span in table = 4'1".

Another way; the total load on a SYP beam (850fb for a doubler) at 5' span equals 1428# but multiply 9' span times 5' beam span times 40# per sq.ft. = 1800# per minimum deck code, you would be 372# overloaded. It appears to be the same 3 pier configuration under the center beam which is carrying twice the weight as the outside piers.
What did the Inspector say, if permit required?

Gary

 

I suppose if you really wanted to, you could run a bead of caulk down the joint. Another option to help seal out the rain over your doubled 2x's is to use a product like this:
Shop Vycor 50'L x 9"W Rubberized Asphalt Flashing at Lowes.com

 

Didn't go with any caulking.

I submitted a rough layout to the permitting office, they said it looked fine, but because it's a ground level deck less then 12" off grade it doesn't require a permit. I built everything according to the charts I found in the book and also confirmed by other sites like deck.com. Monday morning internet quarterbacking is fine, but I posted up my plans and asked a lot of questions before I started building.

Unless I read these charts wrong I should have been ok up to at least a 6' span on the footers and 9'9" on the joists. Either way it doesn't matter, I'm half done with the decking and don't intend to rip the whole thing out to build it all over.

Beam Span Chart Table - Decks.com
Deck Joist Span Calculator