# 6x6 or 8x8x post?



## ricksample12 (Feb 6, 2015)

I'm still drawing up my gable roof over deck plans to submit to the building department. I was originally going to go with 8" posts... but they are hard to come by. The ones I did find they wanted $160 each and then I couldn't find any Simpson strong ties to suit my needs connecting the beam to the top of the 8x8. So I'm wondering if 6x6 would hold up the roof since they are only $30 each and the simpson strong ties are available. I know the building department will have the final say... I just wanted a general opinion based on what you guys have built in the past. We do get snow... but I can easily push it off thanks to windows on the back of my house if we get to much. Normally all winter we have 5-6" on the ground at all times. We rarely get anything more than that.

The roof is going to extend out from the house 12'
The roof is going to be 16' wide. 
Half of the roof will be connected to a ledger board which is then connected to the band joist of the house. The joists hangers I'm using are capable of supporting 6,000 pounds each. So I think that half of the roof will be well support... if I'm wrong please let me know :thumbsup:

I'm just wondering about the 6x6 posts... it would sure make my life easier rather than having to special order something and try to find something to attach it with.

Here's what I have figured out weight wise (I could be wrong I've never done this before)

Trusses 400LBS
OSB 450LBS
Shingles 300LBS
Beams 300 LBS
Hardware 50 LBS
Snow load 3000LBS ????? Does that seem to high? 
4,500 LBS total. I have 2 beams and 2 joists hangers... so... 4,500/4 = 1,125 LBS per 6x6 post? Is my math correct? Can a 6x6 hold 1,125 LBS? The 6x6 will extend almost 11.5' from the cement to the beam. I was reading online from one person that a 6x6 can hold 6,000 lbs... if that's the case I"m sure I'll be fine.. but that seems to high.


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## Robpo (Mar 30, 2014)

I think 6x6 word work fine but not look as nice. It looks to me you need some sheer strength though if you get winds or are going to have any kind of weight up there.


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## ricksample12 (Feb 6, 2015)

Yeah I was looking for different ways to strengthen the top for winds... but not to sure how to go about it. The 6x6 posts will actually be wrapped with 10" pcv column wrap. So the posts themselves will look beefy. Then the simpson strong ties that connect the beam to post will be a T shape bracket. It will have a flat roof in it to so there will be 9 2x4's running from beam to beam


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## Robpo (Mar 30, 2014)

After rereading your post I see you are going to have a gable roof which will give it sheer strength.


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## ront02769 (Nov 28, 2008)

A six bye six hem-fir post is good to about 26,000 pounds compressive strength. Ron


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## concrete_joe (Oct 6, 2014)

ront02769 said:


> A six bye six hem-fir post is good to about 26,000 pounds compressive strength. Ron


is this linear across the bending modulus?? i suspect not.

the support equation (for vertical supports, ledger + posts) needs to accommodate dead load + live load + snow/water load. the wind load is typically used in a materials and fastening equation.

is it really flat roof? i would pitch it some so water can roll off.

the 2x10x12 dbl'd up everywhere? might be easier using glu-lam?


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## ricksample12 (Feb 6, 2015)

Thanks everyone, A lot of good information here. Just so we're on the same page... here's what it looks like with the engineered trusses. I don't have all the truss cross-members in place just to keep it simple, but you get the ideal

I've also included the 6,000 pound per side joist hanger that will attach both main beams to the ledger of the house. What are your thoughts on the overall strength of it? Do you think with the combination of these 2 joist hangers along with the (2) 6x6 posts will hold the roof? The post isn't going to be exactly 12' away from the house... there will be roughly a 11.5' span between each post and the house. 

As far as the wind... the fasteners I'm using at the posts say they have an uplift of 2500LBS and 1070 lateral I assume thats in pounds... not sure what type of wind speed would it take to exceed those. Then I'll use standard hurricane ties to connect the trusses to the beams.

I know it's possible... I've googled and it shows a lot of these types of gable roofs over a deck. I just don't know what the skeleton looks like... I could only find a couple small pictures and no pictures of the attachment at the house.


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## Robpo (Mar 30, 2014)

might want to include Simpson H1 for your trusses or something simular.


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## concrete_joe (Oct 6, 2014)

so, what you have listed looks plenty beefy.

i would however use a different style truss, one that has the cross member up higher so that you have what looks like a raised ceiling from the deck, then adding ceiling fan or something later can hang higher.

most std wood screw (sized per tie recommendations) that you would use on all the ties will have plenty of yield and shear strength.

if you plan to finish the ceiling then you could include a couple of cross braces (wood, or cable) in that "attic" space to help stiffen it, to help against twisting. from the pics, looks like the posts are just sitting on concrete pillar, thus you'll have little rigidity in that post (no match for torq), hence why i think you need some cross bracing in the "attic". or if you dont finish the ceiling then perhaps decorative style cable bracing.


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## ron45 (Feb 25, 2014)

Even a 4" x 4" would hold it.
Since your going wrap and brace it there's your look...

Here's the link for strength values.
https://courses.cit.cornell.edu/arch264/calculators/example7.1/index.html


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## Thurman (Feb 9, 2009)

IF I am looking at your drawing correctly, you have a "2x10x16 single" as the ledger against the house. Then you show a "2x10x12 double" as the outside beam. Is there some reason you are using two different lengths of ledger/beams running parallel to each other? I don't know where you are located but around here the 8x8 PT posts are located next to the 6x6 PT posts in all three building supply stores. The cost difference between the 6x6 and the 8x8 are minimal. What method are you using to connect the beams where they meet at each corner?


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## woodworkbykirk (Sep 25, 2011)

6x6 is perfectly fine. if you want beefier you can just build it up and clad it

as for 4x4.... not even a chance. pretty much all regions will no longer accept a 4x4 post for bearing purposes as they can and will break when under stress. in tornado zones they can even break under wind loads. the only time 4x4s are accepted as a post is for a hand rail post


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## ront02769 (Nov 28, 2008)

The thing as designed is fine and is not going anywhere. Posts are held to concrete footings with metal brackets, they are further supported 3' up by the floor framing and then again by the roof structure. There are a couple of types of hurricane ties that will work for the rafters with all of the Simpsons being adequate, nailing them on is also fine, no need for screws, as long as you use the nails specified on the simpson web site, fill every hole, and don't leave any just bent over. Have fun!! Ron. Ps. Change that front double two bye ten to read 16' before you show the thing to the town!!


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## Daniel Holzman (Mar 10, 2009)

There is no need to guess at loads. Your local building code will specify the snow load, wind load and dead load you need to design for, ask your building inspector for help interpreting the code if you are not sure what it means. Once you know the unit loads, multiply by the tributary area to each column to determine the load on each column.

Just for the record, post design for long posts (over say 6 feet long) is almost always controlled by buckling. You check for direct compression, but the allowable buckling load is almost always substantially less than the allowable compressive load, and the smaller allowable load always controls. Add in the required factor of safety, and you can determine the maximum load a column will handle. The equations are pretty complicated, the good news is that there is a nice on line calculator here that will give you the allowable load on a column, see https://courses.cit.cornell.edu/arch264/calculators/example7.1/index.html​


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## ricksample12 (Feb 6, 2015)

Thurman said:


> IF I am looking at your drawing correctly, you have a "2x10x16 single" as the ledger against the house. Then you show a "2x10x12 double" as the outside beam. Is there some reason you are using two different lengths of ledger/beams running parallel to each other? I don't know where you are located but around here the 8x8 PT posts are located next to the 6x6 PT posts in all three building supply stores. The cost difference between the 6x6 and the 8x8 are minimal. What method are you using to connect the beams where they meet at each corner?


I'll get that fixed, I just copied the 12' beam and turned it... but I forgot to change the size :thumbsup:

I checked with a few places on the 8" post... couldn't find it anywhere in stock. I found it at one lumber yard but it was a special order item for $160. The 6x6 posts are only $35. Then I couldn't find any simpson strong ties to connect the top of the post to the beam for the 8". I'm glad that so many have said the 6" post will work... total savings is around $300 for the smaller piece of lumber and the smaller post base and they actually make strong ties for the 6" post 

I'll be using a Simpson post cap for each of the main 12' beams. It'll surround half of the 6x6 post and it has a large plate to nail into the beam with a vertical uplift of 2500 LBS. The 16' beam in the front of the gable I'm just going to use standard simpson hurricane ties. 

Here's a picture of what it looks like from the top.


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## ricksample12 (Feb 6, 2015)

Daniel Holzman said:


> There is no need to guess at loads. Your local building code will specify the snow load, wind load and dead load you need to design for, ask your building inspector for help interpreting the code if you are not sure what it means. Once you know the unit loads, multiply by the tributary area to each column to determine the load on each column.
> 
> Just for the record, post design for long posts (over say 6 feet long) is almost always controlled by buckling. You check for direct compression, but the allowable buckling load is almost always substantially less than the allowable compressive load, and the smaller allowable load always controls. Add in the required factor of safety, and you can determine the maximum load a column will handle. The equations are pretty complicated, the good news is that there is a nice on line calculator here that will give you the allowable load on a column, see https://courses.cit.cornell.edu/arch264/calculators/example7.1/index.html​


Thanks for the site :thumbsup: It looks like the posts will hold a little over 11,000 lbs each @ 11.5' extended. So that's good to know... I definitely don't want to guess. My plan is just to build it as sturdy as possible with the strongest hardware/simpson ties and turn it in to the building department. Those 2 posts along with my simpson ties will put the max load at 34,000 LBS which I'm sure I'll never exceed if my math is correct.


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## ricksample12 (Feb 6, 2015)

concrete_joe said:


> so, what you have listed looks plenty beefy.
> 
> i would however use a different style truss, one that has the cross member up higher so that you have what looks like a raised ceiling from the deck, then adding ceiling fan or something later can hang higher.
> 
> ...


Thanks :thumbsup: It doesn't show it in the picture... but the ceiling height is a little over 9'. But a ceiling fan would be nice... I may have to use the savings from not buying the larger posts and put it towards a ceiling fan if I can get the ceiling high enough

I'm going to have all the wood capped with white fascia, the posts are going to be wrapped with 10" columns, and the inside ceiling I'm going to put the white PVC sheeting so there wont be any exposed wood.


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## Robpo (Mar 30, 2014)

Those H2.5a come in right side. Left side are different so watch what you are getting.


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## ricksample12 (Feb 6, 2015)

Now since we got the structural issues aside... but if anyone thinks of anything else please do let me know... What do you guys think of a black or maroon metal roof? I wasn't a fan... but after looking at multiple roofs I kind of like the look the house being shingled and the deck roof having metal. 

Just not sure what the installation would be like, cost, if it would be noisy or look good Thoughts?


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## Robpo (Mar 30, 2014)

How does that work? I hope there is some kind of cricket or something up there. 
You said "Thoughts?"


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## ron45 (Feb 25, 2014)

There's an echo in here..??????


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## concrete_joe (Oct 6, 2014)

the last few pics posted, doesnt show the post tie in to the ground.

my point earlier was, a 4x4 steel ibeam sitting on top of a concrete block can easily fall over (the bottom tie is no match for torq).

the design and materials chosen are plenty strong, but i am still questioning how the posts are just sitting on concrete with a "weak" connection.

there's no significant sheathing on the outside walls (this would typically provide stiffness from bending & twisting, etc).

so, everything else looks good, but re-check the post to concrete tie in, and perhaps you need some x-bracing in the "attic"?

think about how stiff the post would be if the post was 3ft in the ground and then concrete poured around it (pillar being say 5ft deep). this method not accepted in many locales, etc. i am not sure if a steel sleeve in pillar is accepted or not.


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## ront02769 (Nov 28, 2008)

First three pix in the thread show what I see as a post anchor in blac, bottom of the post closest to the front. Ron


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## ricksample12 (Feb 6, 2015)

Here's a picture of the footer I drew up today... not sure if I need fill at the bottom or not...

But I plan to insert the bolt into the wet concrete. After t dries attach the 6x6 post anchor to it. :thumbsup:


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## Robpo (Mar 30, 2014)

concrete_joe said:


> the last few pics posted, doesnt show the post tie in to the ground.
> 
> my point earlier was, a 4x4 steel ibeam sitting on top of a concrete block can easily fall over (the bottom tie is no match for torq).
> 
> ...


 I am not an engineer but I have been told by an engineer that the roof sheathing has the same effect of holding the ceiling square as long as the trusses are anchored to the beam.
It may move a little but there is no sheetrock to worry about cracking.


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## concrete_joe (Oct 6, 2014)

ricksample12 said:


> Here's a picture of the footer I drew up today... not sure if I need fill at the bottom or not...
> 
> But I plan to insert the bolt into the wet concrete. After t dries attach the 6x6 post anchor to it. :thumbsup:


post #24, no match for torq that can be generated at that junction point.

also, the more screws you put into that post via that tie, the easier it is for torq to simply cause the wood to split/crack at that joint.

its not the tie/anchor that i am questioning, its how the post just sits on top of the pillar. that bottom simpson post tie is an anchor, it provides little in the way of combating torq that is parallel to the ledger, etc.

since you are wrapping it, i would perhaps find some ~14-16ga galvanized rips (approx 4ft long x 6" wide) and set them in the wet concrete (2ft in, 2ft out) on the open ends of the simpson tie. when you set the post it will be held down by the anchored simpson, and then the rips (screwed to post) will provide some stiffness to combat any torq that will develop from wind and loads, etc. if you cant find galvazied rips you can find 4-6" wide 1/8"thick mild steel flat stock at almost any metals supplier, clean them and coat them with galvanized spray.

since the top of the post is tied to ledger there is little movement in that direction, thus, the open sides of the post simpson tie should be parallel to ledger (if you use the rips i speak of). if you elect to not use the rips then the open sides of the simpson tie should be parallel to your upper side beams.


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## Robpo (Mar 30, 2014)

concrete_joe said:


> post #24, no match for torq that can be generated at that junction point.
> 
> also, the more screws you put into that post via that tie, the easier it is for torq to simply cause the wood to split/crack at that joint.
> 
> ...


I have to agree. It seems like it would take pressure off the ledger and the framing of the roof caused by wind.


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## ricksample12 (Feb 6, 2015)

concrete_joe said:


> post #24, no match for torq that can be generated at that junction point.
> 
> also, the more screws you put into that post via that tie, the easier it is for torq to simply cause the wood to split/crack at that joint.
> 
> ...


I think I see what you are saying. I would rather it be to strong than to week. I updated the drawing below to reflect the steel. Wouldn't they make something just as strong out of the box? The only problem with the steel plates are trying to keep them in a vertical position without them sinking while trying to make sure they are plum with the house. But I do have a lot of steel plates I could get at work at no cost so this could be the best option. :thumbsup:

What about something like the below simpson tie? It sinks into the concrete 8" and has 8.25" above and made with 7 gauge steel held on with 5/8" bolts. Reading the chart it looks like each one of these would have a 4200LBS uplift. So that would be 8400 LBS up front. But two of the sides would still be open


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## ricksample12 (Feb 6, 2015)

Here's something else to I found for only $33 bucks each... anyone heard of them?

The uplift on these are 9,019 pounds per bracket... shear pounds (not sure what that is) is 6638. These brackets seem a lot heavier at 17 pounds with 1/4" steel. Would these keep the front end down? 

http://products.midwestpermacolumn....l-plus-wet-set-concrete-anchor-brackets/swp66


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## Robpo (Mar 30, 2014)

ricksample12 said:


> Here's something else to I found for only $33 bucks each... anyone heard of them?
> 
> The uplift on these are 9,019 pounds per bracket... shear pounds (not sure what that is) is 6638. These brackets seem a lot heavier at 17 pounds with 1/4" steel. Would these keep the front end down?
> 
> http://products.midwestpermacolumn....l-plus-wet-set-concrete-anchor-brackets/swp66


Sheer strength is the strength from the side to side like from wind.


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## concrete_joe (Oct 6, 2014)

the tie is plenty strong. its the bending in the direction that is open on the ties that is where i am looking. the ties are ANCHORS. 7ga metal is pretty beefy, might be ok with those if you keep the open ends parallel to your upper side beam.

the tie with single anchor can likely be rotated some if needed, that heavy one that looks like its using some rebar and cant really be rotated once set, so be sure its set exactly how its needed.

the method i said, the higher up on the post the metal reaches the more it will combat any torq, etc. the extra plate, really doestnt need to be in pillar more than 12".

i think you have enough info to keep your project moving along.


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## ricksample12 (Feb 6, 2015)

concrete_joe said:


> the tie is plenty strong. its the bending in the direction that is open on the ties that is where i am looking. the ties are ANCHORS. 7ga metal is pretty beefy, might be ok with those if you keep the open ends parallel to your upper side beam.
> 
> the tie with single anchor can likely be rotated some if needed, that heavy one that looks like its using some rebar and cant really be rotated once set, so be sure its set exactly how its needed.
> 
> ...


That sounds good... I'll add these heavy duty posts bases to my list instead of the Simpson ties. I'll also check to see if I can find a couple pieces of metal that I can bolt on the opposite ends so the entire post is closed. It could be a little tricky to assemble... but I think I can figure it out. 

I also need to make another structural change I think to the beam that sits on top of the 6x6. I noticed that bracket I listed should be installed in pairs (each side of the 6x6) to get the entire load rating of 2500 LBS uplift 1070 lateral and I can't do that because I have another beam that runs across. 

Which one should I use:

Just one of these at the end of each 12' beam, then the 16' beam will meet on the opposite side held on by hurricane ties.











Or this... Uplift 3640, doesn't give a lateral number but we could be have the same problem since the it looks like it could rotate on the open ends. I am going to have a 16' beam placed on the inside of this bracket to the post/other bracket on the opposite side.. I wonder if that would stop it from turning and give it some lateral support.


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## Robpo (Mar 30, 2014)

ricksample12 said:


> That sounds good... I'll add these heavy duty posts bases to my list instead of the Simpson ties. I'll also check to see if I can find a couple pieces of metal that I can bolt on the opposite ends so the entire post is closed. It could be a little tricky to assemble... but I think I can figure it out.
> 
> I also need to make another structural change I think to the beam that sits on top of the 6x6. I noticed that bracket I listed should be installed in pairs (each side of the 6x6) to get the entire load rating of 2500 LBS uplift 1070 lateral and I can't do that because I have another beam that runs across.
> 
> ...


I think either way. It is up to you or the building inspector. I would probably go with the first way because it is probably less expensive but then my wife would make me do it the second way. That one is for a center post. They make those for corners but I don't know if you can find one in your size.


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## ricksample12 (Feb 6, 2015)

Lol that sounds about right... my wife is the same way. I prefer the cheaper stuff and she likes the more expensive stuff. I tried to find a corner piece and the dont make them to fit a 6" post and a 3" beam. I will go with the first way for now and see what the building department says. Best case they will aprove it worst case they may offer an alternative bracket of some sort. I have everything almost finalized. Ill post the final drawings later tonight of what i plan to turn in with my permit showing the osb, shingles, etc


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## ricksample12 (Feb 6, 2015)

Alright... here they are pretty close to being completed. I still need to add a few measurements and touch it up a bit... but it's 99% done. I didn't use the plate in the footer yet... I'll wait to see what the building department says... the posts are going through my deck which sits 3' off the ground... I figured I could brace the 6x6 post inside the deck with a few 2x12's to give it lateral support.


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## Robpo (Mar 30, 2014)

I would run the side beams out another 2' to catch the outside trusses.


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## ron45 (Feb 25, 2014)

This thread reminds me of Hyperinflation.


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## concrete_joe (Oct 6, 2014)

i suspect your inspector guy wont even 2nd think that post bottom tie, bet ya they are looking at anchor, but if they dont mention it you should pose the question. the last pic you show looks like it should be strong where all you get is bending of the post across its whole length (bending modulus of the lumber, which is minimal, etc) vs pivoting at the tie point. just be sure the closed ends are parallel to house (open end points to house), etc.

do you have many wood bugs there? be sure to treat the lumber that is closer to ground. since you are boxing in the post i would use some bug powder around base of post (deck side) before enclosing, this helps keep bugs from crawling up, etc.



Robpo said:


> I would run the side beams out another 2' to catch the outside trusses.


its only one "truss" past the end (pic doesnt show actual truss, etc). the extended facia and added cats should suffice.


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## ricksample12 (Feb 6, 2015)

Robpo said:


> I would run the side beams out another 2' to catch the outside trusses.


Yeah I was thinking about that and I've decided to put it in my design. It should add a lot of character.

I was originally going to cap all the beams with white aluminum... but I think if I run the beams out to the edge of the flying truss I'll make a pergola beam design at the end. Then I'll leave all the beams exposed and stained Espresso color. I think with the white vinyl ceiling and the exposed dark colored beams it would really add something to the design. 

My beam placement will look almost like this with the longer side beams that extend out and the other beam even with the posts. 

I've been thinking about this today... would anyone recommend 3 2x10's on each side or should I just stick with 2? I can't find/read any beam span tables.. so I'm not sure if 2 on each side would hold or if I should stick 3 in there. From what I'm estimating with snow load I may have around 6K pounds on there... that means if I had 4 beams each one would have to take 1500 LBS. If I added an extra beam on each side each one would have to take 1000 LBS. Does anyone know how much a 2x10 with a span of 12' could hold?


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