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Forum topic by Kilo19 posted 08-29-2018 03:47 PM 375 views 0 times favorited 6 replies Add to Favorites Watch
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Kilo19

104 posts in 705 days


08-29-2018 03:47 PM

All,

I have a question about using a laminated beam for a project. Actually it’ll be a total of 3 beams.

I am rebuilding an add-on bathroom that was poorly put together when we got the house. Now…3 yrs later I have finally tore down the “shack” and am in the process of doing some site work to get ready for concreting piers to be ready for beams to have the bathroom and back porch built. I’ll try to get a drawing/picture uploaded…I haven’t made any other than on AutoCad but the basic design is 14’ deep (going away from the house), and 25’-10” long (side to side), 13’ will be for a back porch (covered) and the rest will be for a master bathroom.

My plan is to drill piers to set metal brackets to hold the beams on to, and set floor joists on top of that. The beams will be +/- 25’-10” lets say 26’, to span the total distence. One idea is to use PT, (I also have multiple 2×6/2×8 old growth pine boards at my disposal to use) 2×6/2×8 for the beam, doubled up and lap jointed for this, the other is to make a beam to span. I like the later because I have many many 100 yr 2×4’s at my disposal to use. My biggest concern is protecting these beams. They will not be touching the ground at all/at any point in its lifetime. They will also be covered except on the ends where they may be slightly exposed. Should I be concerned with this, can I paint, stain, fiberglass cover this? I’ve considered buying epoxy to completely cover the beam to weather resist it, ( i know nothing is truly weatherproof)

Thoughts, or other ideas, I’m completely open, even if it means me making it.

Before you go off on a tangent, The cost of buying a gluelam beam is out of the question as I do not have the funds to spend 400$+ per beam (need 3 total) or replace with metal I beam. So making the beam, or using 2x’s doubled up (mentioned above) is what I’m looking at. How to protect them is my concern.

Thanks for the help. And may the grain be with you.

-- Justin


6 replies so far

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Kilo19

104 posts in 705 days


#1 posted 08-29-2018 03:58 PM

I probably should’ve added that the piers will be spaced accordingly:
on the beams spaced about 6-7 feet, like 6’ plus change
between each beam about 6’ (i’m coming in 1’ on the ends, the 14’ dimension) so the total distance for the beams would be placed at 1’ mark, then 7’, then 13’, +1’ takes you to the end of the joist. (hope that makes sense)

I’ll add that this may or may seem like over kill. I tell everyone I’m an engineer at heart but didn’t have the money to prove it, LOL.

-- Justin

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ArtMann

1425 posts in 1296 days


#2 posted 08-30-2018 05:21 PM

I’m having trouble visualizing the situation.

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Kilo19

104 posts in 705 days


#3 posted 08-30-2018 06:23 PM

And cancel the thought I had on having a cantilever on the outer most side of the frame (floor) The outer most beam from the house will sit flush with the edge of the wall. But my question about the beam part still stands.

-- Justin

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DBDesigns

230 posts in 477 days


#4 posted 08-30-2018 06:48 PM

Justin,
I’m not sure about your actual span but it sounds like you are spacing supports every 6’. If that is the case, let me make two suggestions. 8’ span would be better because it puts you into the natural dimension of most lumber and I would consider laminating plywood to make your beams. For example; if you face glue 3/4’ plywood you can cut it to whatever width is appropriate for the load, and laminate it as thick as you want. It will be stronger and stiffer than just regular dimensional lumber.

If, on the other hand you are truly spanning 25’, you may have a building code issue if you don’t use pre-engineered I-joists. https://en.wikipedia.org/wiki/I-joist Here is a link for the Wikipedia info on I-joists. They are way cheaper than glue-lam beams and they may save your project.

-- I remember when Grateful wasn't Dead

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Kilo19

104 posts in 705 days


#5 posted 08-30-2018 06:58 PM


Justin,
I m not sure about your actual span but it sounds like you are spacing supports every 6 . If that is the case, let me make two suggestions. 8 span would be better because it puts you into the natural dimension of most lumber and I would consider laminating plywood to make your beams. For example; if you face glue 3/4 plywood you can cut it to whatever width is appropriate for the load, and laminate it as thick as you want. It will be stronger and stiffer than just regular dimensional lumber.

If, on the other hand you are truly spanning 25 , you may have a building code issue if you don t use pre-engineered I-joists. https://en.wikipedia.org/wiki/I-joist Here is a link for the Wikipedia info on I-joists. They are way cheaper than glue-lam beams and they may save your project.

- DBDesigns

Yes the spacing would be about (starting from the house side) 1’ then 13’ left to split. One beam in the middle then one at the end (farest away from the house). How would 8’ be any different the 6’. The floor joist would sit perpendicular to the beams on top, then the subfloor then the finish floor. Span table says 2×6 beam can span 8-9’ (something like that) so if I space the beam pretty close to even, that gets me about 6’ ish.

I thought about using plywood, or osb, but this will be close to ground, not touching, but the beam I estimated would be about 4×6? At a 25’ long beam.. thats alot of plywood. The idea of using 2x’s with an epoxy glue, or titebond III, seemed slightly faster/cheaper as I have the 2x’s on hand.

On the span of the beam there will be a pier about every 6.5’ That beam should be plenty supported, I’ll use beam brackets that set in concrete upon pouring.

Where I live they have no code to enforce except my own…IRC is what I’ll follow.

Don’t take any of my comments/replys as rude (sorry if they seem that way). Thank you for everyones help/response.

-- Justin

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DBDesigns

230 posts in 477 days


#6 posted 08-30-2018 08:03 PM

Justin,
Not rude at all. I was actually not getting your design until I looked at your drawing a second time. If I get this, you are asking about the end beam. The end beam could be double 2×10 pressure treated pine and last for the life of the structure. If it is PT and it is out of the rain, you will not need to worry about rot either.

I would suggest that your height dimension be no less than 10”. (2×8 is under designed.) I would also suggest that you cantilever the joists across the beam and have a minimum overhang of 16”. This is counter-intuitive but the load on the end of the joists actually helps support the span of the joists because of the bending. (Downward force on a cantilever causes an upward moment in the span of the same beam.)
Good luck with your project.
Regards,
Tim

-- I remember when Grateful wasn't Dead

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