2x8 tongue & groove flooring????

Started by williet, August 04, 2006, 03:53:03 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Print
Go Down Pages1
User actions

williet

August 04, 2006, 03:53:03 PM
If I use 2x8 t&g as flooring for the second floor, how far apart can I place the floor joists? Say we use a 2x4 sandwiched between two 2x6's for the joists ... would 48" be too far apart and make the floor "springy"?

williet

#1
August 04, 2006, 07:14:52 PM
I'm gettin lots of looks and no thoughts ..... was it a stupid question? :-/

Amanda_931

#2
August 04, 2006, 07:34:39 PM
Not really--it's Friday Night, not many of us here!

Although it kind of sounds like more than one question.

Joists?  Like this sandwich?

||=||

where || is a 2x6, and =, the 2x4?  (actually it might work better if the 2x4 were flush with the bottom--and you could run wiring through the space at the top (if you never ever had to change it out)?

Now the question is how far do these joists have to span--30 feet and it will almost certainly be springy, if not downright weak, no matter what you put on top.  And what these joists are made of is important too.

And there might also be questions about your 2x8 flooring--how thick is it really, what's it made of, etc.

I think somebody has posted--maybe even recently--span tables, probably in free stuff.

Amanda_931

#3
August 04, 2006, 07:36:54 PM
I was right.  Both Manhattan's and John's posts with links.

http://www.countryplans.com/cgi-bin/yabb2/YaBB.pl?num=1144980005/2#2

williet

#4
August 04, 2006, 07:57:40 PM
I had this in mind, ll ll ll ... 2x6, 2x4, 2x6. The distance will be either 16 or 18 feet. We should most likely use 2X10's on the outside. Yes the thought was to run wire in the cove and cap the bottom of the beams.
If we can come up with the right old beams, we will use them instead.

Looking throught the past threads, I saw one by Micky that covers the house we hope to have .... it's his! LOL ....

Daddymem

#5
August 05, 2006, 05:15:45 AM Last Edit: August 05, 2006, 05:17:41 AM by Daddymem
Check out the FirstDay Cottage website for pictures of the built-up beams like you are talking about.  We are building one and it uses 2x4 sandwiched between 2x8s.  We had stamped plans with 2'-8-13/16" between beams and 3' (code stairs) between beams when on of the beams had 2x4s top and bottom.  Our span was 12', they do 16 and 18 spans normal, but I imagine they use 2x10s on some of them.  our decking is 2x6 T&G Euro spruce and we have a very solid floor.

http://www.firstdaycottage.com/pictures/building/Building01.jpg

williet

#6
August 05, 2006, 06:58:07 PM
Yep, I know FirstDay .... I'm the same williet that's a member of your forum.

Daddymem

#7
August 06, 2006, 05:16:16 AM
K. Hard to keep track of who is who on here and there.  ;)

Doug Martin

#8
August 06, 2006, 09:45:10 PM
That is the first time I've seen 2x4's sandwiched between 2x10s/12s.  From what I know of structural engineering it doesn't seem to make sense at first glance.  I'm sure it works or they wouldn't be promoting it but how does that sandwiched member help with the tension or compression loads in the joist?  It is late for me so maybe I'm not seeing the obvious reason.

PEG688

#9
August 06, 2006, 10:27:56 PM Last Edit: August 06, 2006, 10:30:21 PM by peg_688
QuoteThat is the first time I've seen 2x4's sandwiched between 2x10s/12s.  From what I know of structural engineering it doesn't seem to make sense at first glance.  I'm sure it works or they wouldn't be promoting it but how does that sandwiched member help with the tension or compression loads in the joist?  It is late for me so maybe I'm not seeing the obvious reason.


IMO it , the 2x4 , is a spacer to form a chase / look of a beam. So the joist don't go fruit cake / warp / twist at the bottom when attached via the flooring / T&G 2x6 subfloor , at the top side of the joist.They would add nothing to the strenght of the joist in fact they would be added weight / load althought dead load.  

This thread / train of thought has been hard to follow / figure out from post #1 on. IMO.

That's my .02 on it anyway, for what it's worth. Oh ya two cents  ;D

G/L PEG

BTW I've never seen 2x8 T&G decking , does it exist? What type of wood is it made of? I'd think it would be pretty unstable / hard to straighten/ work with  , etc
When in doubt , build it stout with something you know about .

Rover

#10
August 07, 2006, 04:58:59 AM
I'm no structural engineer but the theory might be that with a 2x4 nailed in place flush to the bottom and flush with the top, would add more meat to the top and bottom.  This is where all the tension and compression happens in a joist.  It would have to be sercurely nailed & glued in place (not just as a spacer).  It follows the same concept as OWSJ or those factory made wood I's, made from 2x3 top and bottom members with waferboard panel between.

I would also be interested in more info re T&G 2x6 flooring.  I agree with Doug on the workability issues.

John Raabe

#11
August 07, 2006, 11:01:38 AM Last Edit: August 07, 2006, 11:03:49 AM by jraabe
I've done something similar to what you are asking about in several of the house plans where you want an exposed deck for the loft.



Here's the early morning Post-it sketch. It provides a built-up beam out of standard lumber - looks more substantial  :D and is more substantial! You have built-up a bit of an I-beam configuration and the interior 2x6 or 2x4 does put some meat into the bottom "flange" where the fiber stress in tension is doing the real work.

I go up to 48" on the spans for the decking in a loft load environment. Make sure it is T&G and is pulled together tight. I have more information on this in the 20' wide 1.5 story cottage plans.

Don't count the interior spacer in the calcs for span. Just use a span table for 24" o/c joist spacing and double it to go 48".
None of us are as smart as all of us.

williet

#12
August 07, 2006, 02:27:29 PM
We purchased the 1.5 20X30 plan yesterday. I was wondering about the pictures I saw of Micky's house. It looks as thought he's using a solid beam instead of a built-up beam. We like this and wanted something like it. Balloon framing and beams on about 4' centers with T&G flooring above .... maybe the plans will answer my questions when I see them in a few days ..... Do they give a 2X6 and a 2X4 wall framing plan?

As to the built-up beams, I know it can be done because the FirstDay plan uses them to span a pretty good distance without support walls.

John Raabe

#13
August 07, 2006, 03:53:30 PM
The 20' wide 1.5 story uses 2x6 framing.
None of us are as smart as all of us.

John_M

#14
August 07, 2006, 09:18:45 PM
In my cabnin, I have used 4 x 12 (true dimensions) hemlock beams  spaning 18 feet.  On top of this I have 2 x 8 tongue and groove flooring.

It seems pretty solid.  I will try and update my blog and give you some pics!  (See address below)
...life is short...enjoy the ride!!

williet

#15
August 07, 2006, 09:41:57 PM
Thanks John,

We'd love to see the updated pics.

PEG688

#16
August 07, 2006, 10:06:06 PM
QuoteIn my cabnin, I have used 4 x 12 (true dimensions) hemlock beams  spaning 18 feet.  On top of this I have 2 x 8 tongue and groove flooring.

It seems pretty solid.  I will try and update my blog and give you some pics!  (See address below)


What address :-/ :-/
When in doubt , build it stout with something you know about .
Print
Go Up Pages1
User actions