C-Purlin & Patio question

[Keithb]

We have poured a slab for a patio and now it seems I'm questioning myself like I normally do. I put 2 metal plates in the slab where column 1 and column 2 are shown. My initial thought was to suspend purlin 4 on column 1, and purlin 7 on column 2. These 2 purlins would carry a majority of the weight. My though was the purlin has to be more sturdy than the open c?

Is this plan going to crumble with just R-Panel as the roofing material? Should I run a pipe or square tubing from building 1 out beyond column 2 and just lay the purlins on that pipe or tubing? I may would need to anchor another column at bldg 1 if so. Or will the purlins bear the weight I put on them? Could I double 2 purlins back to back on purlin 4 and purlin 7?

Any comments or suggestions from self-proclaimed civil engineers? I'm a little nervous now I may have screwed the engineering pooch.

[Ouch]

It strikes me that you'd need something with some backbone running from Bldg 1 to Purlin 8, along and attached to the Columns for rigidity/stability.

ETA: I'm no metal expert, but that seems like a long run not to have another "joist" under your purlins...

[RatherBhuntin]

I would highly recommend running some square tubing from building one out to purlin 8. You would not need to put in another column depending on the exterior wall of building 1. Just anchor the end of the tubing to the wall of building 1 if possible. If you do not run this beam it will most likley sag.

Side note: How were you going to hold up the other purlins in your original design? Were you just going to attach the purlins to the beam you have at the ends of the purlin? This may be possible depending on the overhang from the columns. If that is the case I would do as you suggested and double purlin 4 and 7.

[Keithb]

Side note: How were you going to hold up the other purlins in your original design? Were you just going to attach the purlins to the beam you have at the ends of the purlin? This may be possible depending on the overhang from the columns. If that is the case I would do as you suggested and double purlin 4 and 7.

Yes, exactly. The beam on the far right is the open c that the c-purlins fit into. All purlins will tie into that, and the weight will be put on that, and then onto the 2 columns. A majority of the weight will be on purlin 4 I believe.

The reason for offsetting the columns in 2' is to allow for bricking and trim. We couldn't do that if they were on the edge.

[RatherBhuntin]

Yes, exactly. The beam on the far right is the open c that the c-purlins fit into. All purlins will tie into that, and the weight will be put on that, and then onto the 2 columns. A majority of the weight will be on purlin 4 I believe.

The reason for offsetting the columns in 2' is to allow for bricking and trim. We couldn't do that if they were on the edge.

I noticed you are using a heavier gauge for the open c, so I see no reason why it would not work. A 2' over hang is not to much for the load if you double it.

Granted it may not be to code but it will work.

[Keithb]

Luckily we are far from the city. I spoke to a builder who puts up metal buildings and he said it should work, but if it's flimsy to come back and double up the purlins. I may just double up on those 2 to be on the safe side. Hopefully that will be solid enough to hold the weight.

[Keithb]

I'm questioning myself again. I'm wondering if I can run a 6" or 8" purlin (instead of 3x3 box tubing) from bldg 1 across column 2 for a resting point for all the other purlins? That would spread the load across the whole length instead of on one 2-3' section of purlin.

Any suggestions?

[Palmetto]

I'm questioning myself again. I'm wondering if I can run a 6" or 8" purlin (instead of 3x3 box tubing) from bldg 1 across column 2 for a resting point for all the other purlins? That would spread the load across the whole length instead of on one 2-3' section of purlin.

Any suggestions?

Thats how I like to do it. If I have a freespan between posts, I run a stringer for the purlins to sit in. It just makes sense to me.

Here's a pic of a equipment shed I just got through building on my place. Spacing between the posts is 28'. I built a bar joist to span the between the posts, to hold up my purlins.

Also, at 25' span, the 8" purlin might try and torque on you. They did on the shed in pic. 2. I had to run a stringer on the bottom side of my purlins to keep them straight.

Different types of buildings, but kinda the same thought process. Hope this helps.

[Draco]

Use 2"x8"x14ga. or 3"x8"x14ga. rectangular tubing across your columns and you should have no problem.

[horns100]

they have receiving channel that purlin fits into. i build metal building for living

[Quackerbox]

My patio is made from 2x2 square tubing and 4" c-purlin. Its not designed like yours but trust me it aint going anywhere!!

I attached the tubing/posts to the slab with 5/16" quick bolts through some 2x2x1/4" angle iron brackets welded to the bottom. The posts are topped with more 2x2 tubing and the purlin is welded to that "c" side down. I know if would have been stronger with the perlin standing up but due to a miscalculation by my engineer it had to go down. R panel was screwed to the perlin after that. Its been up 6 years or more and taken its share of storms. Best investment Ive made on the house!!

[Grizzly1]

My patio is made from 2x2 square tubing and 4" c-purlin. Its not designed like yours but trust me it aint going anywhere!!

I attached the tubing/posts to the slab with 5/16" quick bolts through some 2x2x1/4" angle iron brackets welded to the bottom. The posts are topped with more 2x2 tubing and the purlin is welded to that "c" side down. I know if would have been stronger with the perlin standing up but due to a miscalculation by my engineer it had to go down. R panel was screwed to the perlin after that. Its been up 6 years or more and taken its share of storms. Best investment Ive made on the house!!

Do you have any pics of this patio, this sounds like what I'm looking into building. Thanks!

[Wampuscat]

I don't know where you are buying your steel, but if you go to "Shades and Shelter" they will check out your engineering for you for free. I took my drawing in with parts list... they checked it and showed me that I was way over-building my 34'x22' patio covering. They are located on SH-6 between Alvin and Manvel. They were formerly "The Tin Spot" off SH-35 between Alvin and Pearland. I highly recommend them to everybody in the Houston area.

[Quackerbox]

Do you have any pics of this patio, this sounds like what I'm looking into building. Thanks!

Not on the phone. Ill try and get some in the morning. If i forget shoot me a pm with an email and get ya some

[Keithb]

For those that were following along, this is what we got accomplished this weekend. The columns are 11 gauge 4x4 which will be bricked/stoned which is why they are moved into the slab. The purlins are 8". Overall it is 25x30 with an 8" drop. I think the single support purlins are enough but I left room on the plate on top of column to add another on each one. Hopefully we'll get to run tin this weekend. What do you guys think?