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6 x 6 or three 2 x 6's ?

6 x 6 or three 2 x 6's ?

6 x 6 or three 2 x 6's ?

I am building a new workshop .... 3500 sq ft ... 1000 sq ft attic ... doing everything myself.

I am a very conservative builder.

For example, I am using 16" TJI's for the attic floor to get a 125 psf rating. I don't think I could ever possible put that much "stuff" up there but I know I have a lot of heavy items and wanted to be safe.

So, I have a problem.

The way it worked out, I have limited head space on the stairway leading to the attic.

In order to get even a standard doorway, I need to reduce the header size.

The opening is 48 " ... minus 3" on one side for a double jack stud ... and 1 1/2" on the other side ( there is actually a pocket in the wall with 3 jack studs ) so 43 1/2" opening.

I only have 5 1/2" for the header.

I was about to use just three 2 x 6's nailed together with two 1/2" spacers (so I would have 5 1/2" x 5 1/2" since I am using 2 x 6 stud walls).

Then I started thinking maybe I should use a 6 x 6 ?

I just keep thinking I was told at some time in my past that individual pieces were stronger as if there is defect, it would not be through as it is in a single piece.

As another possible solution, I could use a piece of 4 x 4 steel tubing (say 3/16 or 1/4 wall) ... if I can find some (local metal yard only likes to sell complete 20 ft sticks).

This opening has a roof truss sitting on it directly in the center (roof trusses are spaced at 24" and this is an intermediate support wall).

Any advice would be greatly appreciated.

Thanks .... Mike

PS ... my wife has been putting up videos of the build ... they are a month or so behind but it gives a food picture of what I am doing Link

RE: 6 x 6 or three 2 x 6's ?

Almost forgot .... you probably need more information ...

So, the bays on each side are 20 ft wide .... I assume this means the supporting wall will support half the load ... so 10 ft on each side (11'-6" if you take the distance along the slope).

Since the rafters are spaced at 24" (they are an engineered product) .... they support 12" each side ... 24" total.

So the roof are is 46 sq ft.

If I am correct, they figure on 10 lb's per sq ft for the roof itself.

Snow load in our area (Jericho, Vermont) is 50 lbs per sq ft.

I think that puts a maximum point load of 2,760 lbs on the header ... with a safety factor of 1.25, that is 3,450 lbs.

Thanks .... Mike

RE: 6 x 6 or three 2 x 6's ?

It really depends on your wood source and grade. More connections with the 3-2x6 would also affect the comparison. I would be tempted to shim it with plywood on each outside face rather than the spacers you're suggesting. But, it's your build bud.

RE: 6 x 6 or three 2 x 6's ?

Thanks ...

That makes sense ... shim on the outside.

I was just playing with the Weyerhaeuser software (Forte) .... interesting, it lets me try LVL's down to 5 1/2" (as far as I know, 11 7/8 is as small as you can buy).

It seems even just two LVL's at 5 1/2" will easily pass! Three is way over kill but I minimal cost for piece of mind.

It looks like # 2 lumber will fail but #1 would pass. Looking at the lumber I have been getting, not sure if #1 is really #1 ... all looks very rough.

Thanks ... Mike

RE: 6 x 6 or three 2 x 6's ?

We get 5 1/2" 7 1/4" 9 1/2" deep LVL here all the time. So I wouldn't be concerned about availability. If you just need something slightly stronger than standard lumber, most places also stock LSL studs in 1 1/2"x5 1/2", would likely fit the bill and be a bit cheaper.

RE: 6 x 6 or three 2 x 6's ?

Tripled up 2x6's are fine. That's probably what I would do. You'll want to have some "field" nails to connect them together so that act as a single unit.

Why would I prefer tripled up 2x6's:
1) More available than 6x6's.
2) Easier to handle if you're doing the work yourself.
3) I like that I can see any flaws that exist when I buy them at the lumber yard. For 6x6's it's harder to tell... you only see what's on the outside faces of the lumber.

RE: 6 x 6 or three 2 x 6's ?

Thanks guys!

I am a machinist ... not an engineer or builder.

Like I said, rather than engineer every piece, I when very very conservative on my build.

When two 16" LVL's would handle the load according to the span charts, I used three.

Since there is no labor cost .. just me, myself and I .... I don't mind putting extra money in material.

The biggest problem on this project is me over thinking every part ... plus I try to build with wood the same as I would metat.

My walls are all within a 1/32 of an inch .... way to accurate. I just worry if I don't them right, things like the roof trusses will not fit.

Even something simple like this one door opening ... I have looked at it .. thought about it .... and now posted about it.

Still, when it is done, I am hoping to have a decent workshop.

Thanks again!

PS ... overkill .... I am using galvanized ring shank nails for all the framing and sheathing

RE: 6 x 6 or three 2 x 6's ?

I think if you use 3 or more layers, you can use the repetitive member factor of 1.15 increase.

RE: 6 x 6 or three 2 x 6's ?

Hopefully an unnecessary reminder: Make sure the triple 2x6 has the 6 dimensions in the vertical direction.


RE: 6 x 6 or three 2 x 6's ?

I did not know there was a 1.15 factor

Yes ... but I do understand having seen a lot of obvious mistakes out there ... they are vertical.

I really think I might go with 5 1/2" LVL's

I call the manufacturer ... they said no problem cutting down a 16" LVL (I have a few spare pieces that are long enough).

According tot he software, even at worst case I am only loading them to 50% of their capacity.

I will be sure and paint my end cuts (well any cut) since I am building very slowly and they do see weather for now.

My wife just put up another video ... number 11 ...

Thanks again !!!!!!!!


RE: 6 x 6 or three 2 x 6's ?

xtal - my gut says any of the 4 options will be fine. 6X6, (3) 2X6, (3) 1.5"X5.5" LVL, or steel. my gut says you should not buy the cheapest grade in the yard if you go with a sawn lumber option. I do the same thing as you on my home projects and spend more time than necessary thinking, but I enjoy thinking it thru and I learn more that way.

Ron - you are correct according to US code, the 6x6 option does not get a 1.15 "repetitive member" bonus. However, it is 1.22 times bigger.

RE: 6 x 6 or three 2 x 6's ?


I decided to go with the LVL's.

I didn't realize the online software allows you to enter a custom depth.

With 3 LVL's, I a wayyyyyyyy over rating this opening ... which is fine with me. Everything in the place is done this way.

Thanks again ...

PS ... outside right now framing the last two walls ... first frost was on the ground this morning ... winter is coming

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