# Building Pergola : questions about wood



## mbrittb00 (Apr 26, 2016)

We are wanting to build a pergola over our existing patio. The construction is simple enough for us to do the work ourselves. However I have some questions about the size and type of wood to use. 

The following website shows the general design idea 
http://www.doityourself.com/forum/l...47-building-pergola-questions-about-wood.html


The pergola is going to be roughly 13' wide (rafters) by 10' deep (beams). The plan is to attach a ledger board to the house and use 4"x4" posts to support the front end beams (2 sandwiched around the posts). There would be three pairs (3" spaced) of main beams connecting the ledger to the end beams (one pair sandwiched around each post and one pair in the center. Finally the rafters would be on top of the main beams.

I was originally thinking 2"x6" would would be sufficient, but was wondering if 2"x8" would be better, especially for the end beams (13' span). 

Also I've read mixed opinions on treated vs untreated wood. Treated wood has the advantage of being more resistant to the elements, but as a result of the treatment process is heaver and needs time to dry before finishing. Untreated would be nicer looking and some think it would be as resilient to elements if sealed and finished (stain). The 3rd options that is generally considered better would be more durable wood like cedar or redwood. Unfortunately I'm not sure where to look for those (Lowe's and Home Depot only carry the pine (treated and untreated).


Thanks in advance for your feedback.


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## bud16415 (Apr 26, 2016)

I built mine all from PT and used a red stain on it. I wouldn&#8217;t use untreated anyplace outside.


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## nealtw (Apr 26, 2016)

If you build it now with treated wood, it will be dry enough toward the end of summer to stain.
Rough cedar would give a much niicer look and can be found or ordered from a regular lumber yard but it will cost more.


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## mbrittb00 (Apr 26, 2016)

Thanks.

"regular lumber yard"  : Would this be something like 84 Lumber, or do need to find a more local / less national place.

Also, what about the size of the boards 2"x6" or 2"x8".  I'm a little concerned by the 13' span on the front end beam without a support in the middle.  Should I add a temporary support during the summer while it dries, or would that even make a difference (this was a suggestion I had seen elsewhere).


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## Snoonyb (Apr 26, 2016)

Use the 2X8.

Here is a resource that can be used to find wholesale as well as retail lumber vendors in you area;http://www.thebluebook.com

While the big boxes do not carry much other than standard material, the special order desk can get you an estimate.


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## nealtw (Apr 26, 2016)

For the beams I would go up to 2x10


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## mbrittb00 (Apr 28, 2016)

nealtw said:


> For the beams I would go up to 2x10


 
I was planning to use 2"x6" for the rafters and main beams (10' direction), so I'd be a little afraid that 2"x10" for the end beams would stand out a bit.  If I added angle braces for the end beams reducing the unsupported span from 13' to 9' (or 8') do you think I could get away with using 2"x8" for the end beams?


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## Snoonyb (Apr 28, 2016)

If your lumber is S4S and you're talking 24" OC, thats only 8 rafters, and you crown the support, 2x8 should be fine.

Keep in mind, there are two other milled surfaces for the lumber, Re=sawn and Rough sawn. Both have a rough texture and are a thicker milled product.


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## nealtw (Apr 28, 2016)

mbrittb00 said:


> I was planning to use 2"x6" for the rafters and main beams (10' direction), so I'd be a little afraid that 2"x10" for the end beams would stand out a bit.  If I added angle braces for the end beams reducing the unsupported span from 13' to 9' (or 8') do you think I could get away with using 2"x8" for the end beams?



The 2x8 will work fine, I like the look of more substantial. And in a few years will it have a roof and a snow load.


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## slownsteady (Apr 28, 2016)

Part of the charm of a pergola is the shadows it casts - and the shade it can create. The bigger boards create bigger shadows (more shade when needed).
Previous discussions here have pointed out that a freestanding pergola may have advantages over one that is attached to the house. (debate will no doubt start again )
Both redwood & cedar come up on the Home Depot site, available for special order. I imagine Lowes has the same capability.


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## bud16415 (Apr 29, 2016)

I built something I roughly called a pergola over my hot tub last fall. but the intent was to put a tin roof on it from the onset. I&#8217;m no SW designer by any means but was hoping for that look and needing a cover of some kind for the 100&#8221; of snow that was coming. Sizing the lumber for casting a shadow and carrying a snow load are two different things. If it is never to be covered then wind is the only concern plus the little bit of weight of the beams.


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## mbrittb00 (Apr 29, 2016)

Snoonyb said:


> If your lumber is S4S and you're talking 24" OC, thats only 8 rafters,


 
The 8 rafters will be at 14" OC.  



Snoonyb said:


> ...crown the support...


 
I know what crowing is, but not sure I understand it in this context.

Thanks


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## Snoonyb (Apr 29, 2016)

mbrittb00 said:


> The 8 rafters will be at 14" OC.



Is that an aesthetic, or a mathematical spacing, because at 16"oc 2x6 span 16ft, and at that spacing you'll have 13.



mbrittb00 said:


> I know what crowing is, but not sure I understand it in this context.



Just a reminder, crown up.


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## mbrittb00 (Apr 29, 2016)

slownsteady said:


> Previous discussions here have pointed out that a freestanding pergola may have advantages over one that is attached to the house. (debate will no doubt start again )


 
While I'm not necessarily interested in starting a lengthy discussion, would you mind giving what are considered the main advantages of a freestanding as opposed to attached to the house.



slownsteady said:


> Both redwood & cedar come up on the Home Depot site, available for special order. I imagine Lowes has the same capability.


 
I may be looking in the wrong place, but the only dimensions I can find for cedar are 1x sizes.  I know I can just go in and talk to them, but I prefer to do as much research remotely as possible.


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## Snoonyb (Apr 29, 2016)

Do you have their phone #?

Are you aware that when you place an order,"remotely", the vendor assembles the load and ships it, and you get what they load.

If you don't like the appearance of some of what you ordered, "remotely", guess who gets to return it, and wait for a replacement to arrive, [CLUE] It ain't HD or L.

While instead, were you to purchase at a lumber yard you can select the lumber, have the load built and delivered.


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## bud16415 (Apr 29, 2016)

mbrittb00 said:


> While I'm not necessarily interested in starting a lengthy discussion, would you mind giving what are considered the main advantages of a freestanding as opposed to attached to the house.



I dont know what SnS is thinking but I would say the biggest advantage to freestanding is you dont have to violate the seal of the house siding system.


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## mbrittb00 (Apr 29, 2016)

bud16415 said:


> I dont know what SnS is thinking but I would say the biggest advantage to freestanding is you dont have to violate the seal of the house siding system.


 
I would likely be attaching the ledger into brick.


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## mbrittb00 (Apr 29, 2016)

Snoonyb said:


> Is that an aesthetic, or a mathematical spacing, because at 16"oc 2x6 span 16ft, and at that spacing you'll have 13.


 
OC in an abbreviation for "On Center" correct.
 Also, the rafters would be running in the 15' direction with their spacing in the 10' direction.  



Snoonyb said:


> Just a reminder, crown up.


 
Still confused on this.  How do you crown up a 2"x8"?  What specifically are you talking about crowing up?


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## bud16415 (Apr 29, 2016)

OC is on center CL is centerline 

When you sight down any long dimensional lumber on the width the piece may have a slight bend. You want the bend or crown up kind of like you would have camber in a beam and let gravity pull against the arch. I always lay all the material out flat and sort them according to crown and put the straightest two on the outside ends and gradually space them so the ones with the greatest crown is in the center. If it gets decked it is strongest this way and if it is something like you are building it will look straighter. 

The counterpart to crown is cup and cupping and that is when doing plank flooring like in a deck. You want to then look at the end grain and put the cup up so the screws will pull it flat and it will then stay flat. Most people select the best looking side to go up and then have half the planks cup.


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## bud16415 (Apr 29, 2016)

mbrittb00 said:


> I would likely be attaching the ledger into brick.



I dont have a lot of experience hanging a ledger off brick work. old brick work is structural and with proper anchors I would think could support a great deal of weight. New brick work is mostly for looks and the wood structure is behind it holding the house up. Im sure you can attach your ledger to it and be ok, but if it was to be load bearing I think you would have to study it carefully.


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## Snoonyb (Apr 29, 2016)

bud16415 said:


> I dont know what SnS is thinking but I would say the biggest advantage to freestanding is you dont have to violate the seal of the house siding system.



From the msg;"If your lumber is S4S", not SnS.

Explained, it's "surfaced 4 sides".


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## Snoonyb (Apr 29, 2016)

mbrittb00 said:


> I would likely be attaching the ledger into brick.



Bricks, because of their composition, are a very weak element to attach to, unless you are penetrating and actually attaching the the structure.


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## mbrittb00 (Apr 29, 2016)

bud16415 said:


> I dont have a lot of experience hanging a ledger off brick work. old brick work is structural and with proper anchors I would think could support a great deal of weight. New brick work is mostly for looks and the wood structure is behind it holding the house up. Im sure you can attach your ledger to it and be ok, but if it was to be load bearing I think you would have to study it carefully.


 
It's standard 4"x4"x8" brick, not the thin façade brick they use sometimes.


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## nealtw (Apr 29, 2016)

Just some thoughts, not recommendations.
Cedar is a nice looking wood, does not do all that well underground, and fades fairly fast to a grey color unless treated early and often.
Treated lumber is most often really wet and when drying may warp, cup, twist and crack and is best stained after it is dry.
Only wood treated for underground use should touch the dirt.
Any would will do better if it is sealed with a peel and stick just at ground level.
A pergola will need bracing of some kind as you don't have benefit of sheeting holding things square.
A pergola built with 12' 6x6 post with 4 ft in concrete and corner braces will still move a little in the wind.
Attaching to the house will give it much stability.
I think you are fine anchoring to a brick structure but if it is brick over wood you must drill thru and bolt to structure.
Any time you bolt a ledger on a house you would like to have flashing above the ledger and behind the siding behind the house. As that will not happen, add some kind of spacer so water can run between ledger and brick.
In a perfect world it would be nice if a the all the timber open to weather had a roof cut on top so water would not pool on top.


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## bud16415 (Apr 29, 2016)

Snoonyb said:


> From the msg;"If your lumber is S4S", not SnS.
> 
> Explained, it's "surfaced 4 sides".



SnS = Slow n Steady


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## nealtw (Apr 29, 2016)

bud16415 said:


> SnS = Slow n Steady



Not soft and soggy?


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## bud16415 (Apr 29, 2016)

mbrittb00 said:


> It's standard 4"x4"x8" brick, not the thin façade brick they use sometimes.



I understood that but the brickwork is still just a finishing element. In an old brick building the walls were over a foot thick and made of solid bricks with bricks turning back into the wall for strength. Now they tack a little metal tab ever few rows to the house and then mud it into the bricks for support. As mentioned above the bricks are more designed for weathering abilities and look and less as a structural element of the home.


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## Snoonyb (Apr 29, 2016)

Structural brick, when referring to an unreinforced masonry structure are several courses thick, unlike the brick exterior finish on building which is a single course, were the structure supporting the b rick fail, the brick would crumble like a house of cards.

Were you to drill into a brick the residue is a fine powder, not dissimilar from the same process in concrete, however, when you insert the anchor and tighten the lag bolt causing the anchor to expand creating the "grip", the brick will split, the concrete will not.


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## bud16415 (Apr 29, 2016)

nealtw said:


> Not soft and soggy?



We use nicknames and short cuts to save time I often use SnS and sometimes use Neal for nealtw, I also shorten Snoonyb to sob on occasion.


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## nealtw (Apr 29, 2016)

bud16415 said:


> We use nicknames and short cuts to save time I often use SnS and sometimes use Neal for nealtw, I also shorten Snoonyb to sob on occasion.



So can be shorten Bud to *A*


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## nealtw (Apr 29, 2016)

mbrittb00 said:


> It's standard 4"x4"x8" brick, not the thin façade brick they use sometimes.



The other consideration with this brick, is there is a gap between the brick and substructure to allow water to run down behind so over tightening could damage the brick.


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## bud16415 (Apr 29, 2016)

nealtw said:


> So can be shorten Bud to *A*



In Canada they call me Eh Bud or Eh Bub.


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## nealtw (Apr 29, 2016)

bud16415 said:


> In Canada they call me Eh Bud or Eh Bub.



That's not the A I was thinking about eh.


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## slownsteady (Apr 29, 2016)

nealtw said:


> Not soft and soggy?


Studly -n- Sexy   :


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## nealtw (Apr 29, 2016)

slownsteady said:


> Studly -n- Sexy   :



Slow and sloppy.


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## slownsteady (Apr 29, 2016)

mbrittb00 said:


> While I'm not necessarily interested in starting a lengthy discussion, would you mind giving what are considered the main advantages of a freestanding as opposed to attached to the house.


 
As Bud mentioned, there is the issue of weather protection for the house, and also I remember talk about difference in seasonal movement between the the freestanding portion and the attached portion. You can search the site for other threads about pergolas; and perhaps some threads on deck construction may be helpful.



> I may be looking in the wrong place, but the only dimensions I can find for cedar are 1x sizes.  I know I can just go in and talk to them, but I prefer to do as much research remotely as possible.



To be honest, i would prefer a lumber yard to a big box store in a project like this. I just got curious about what can be ordered at HD, so I looked and found material available. I did not go as far as to check specifics.


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## slownsteady (Apr 29, 2016)

nealtw said:


> Slow and sloppy.



Some things _*need*_ to be done that way. But it has nothing to do with this site


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## mbrittb00 (Apr 29, 2016)

bud16415 said:


> I understood that but the brickwork is still just a finishing element. In an old brick building the walls were over a foot thick and made of solid bricks with bricks turning back into the wall for strength. Now they tack a little metal tab ever few rows to the house and then mud it into the bricks for support. As mentioned above the bricks are more designed for weathering abilities and look and less as a structural element of the home.


 
So not only would I need to drill all the way through the brick but hope that I found a stud on the back side to mount the ledger to?  

If that's true then free standing may be the way to go.  

FWIW, I did some calculations and using PT Pine wood the hole thing (w/o posts) would weight around 1000 lbs.


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## bud16415 (Apr 29, 2016)

As far as the weight that sounds correct. Weights add up pretty fast my 10x16 deck where I built my pergola over I&#8217;m sure weighs a couple ton and then I have a 6000 pound hot tub sitting on it plus the pergola and I made it all free standing and it rests on 12 4x4 posts. 

Around here the building code is even different when it is attached to your house as opposed to just an inch away as I did the deck. 

From an aesthetic point of view I like the look of a free standing pergola better than attached with ledger but that&#8217;s my tastes is all.

When you don&#8217;t attach it to the structure you do loose stability of the building.


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## Snoonyb (Apr 29, 2016)

mbrittb00 said:


> So not only would I need to drill all the way through the brick but hope that I found a stud on the back side to mount the ledger to?



From a specific reference, use a studfinder and transfer the measurements to the outside.

Corbels act as a stabilizing element.


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## mbrittb00 (May 1, 2016)

bud16415 said:


> From an aesthetic point of view I like the look of a free standing pergola better than attached with ledger but thats my tastes is all.
> 
> When you dont attach it to the structure you do loose stability of the building.



After giving this some thought, I planning to do it as a free standing using 6"x6" posts.  Since it isn't attached to a structure, then stability is something I'm going to have to sure up.  My thought was to put angle braces in the each of the corners (both directions for a total of 8) from about the 2' mark on both the vertical and horizontal.  The only problem is with my design (partially for aesthetic reasons) is that both the end beams and the outer main beams will be sandwiched around the posts (not on top of it), so there is not direct angle from the post to the beams.  I have a couple of thoughts on how to resolve this, and am interested in any feedback or other ideas.

Idea 1: Make a compound miter cut (45deg and ??) in 2"x4"s? so that the braces would angle out slightly from the posts and come directly under the beams.  This would have the advantage of the braces attaching to the bottom of the beams giving them direct support.  This would also be helpful on the 13' span.

Idea 2: Make simple 45deg miter cuts on the 2"x4", and attach them to the beam with a bolt.  This is the simpler solution, but also won't provide as much support under the 13' span.

Also, I decided to add up the wight (using PT as a worst case) of the rafters (528 lbs) and the center beams (97 lbs) to see how much weight is actually going to be on the center of the 13' end beam span.  The one place I wasn't sure is weight distribution.  For instance, each rafter sits on top of 6 main beams.  Do each of those main beams get 1/6th of the weight or do the center beams get significantly more.  I'm going on the theory that it is evenly distributed.  With that assumption the two center main beams together would be supporting ~210 lbs.  Again assuming even distribution, the end beams and beams near the house would each (pair) be supporting 105 lbs, and thus each of individual beams would have to support ~52 lbs at the center.

I'll be honest that doesn't sound like a lot, but then again, I'm not sure how to make the deflection calculations in order to determine if that is acceptable.  

Thanks again for all your feedback so far.


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## bud16415 (May 1, 2016)

mbrittb00 said:


> After giving this some thought, I planning to do it as a free standing using 6"x6" posts.  Since it isn't attached to a structure, then stability is something I'm going to have to sure up.  My thought was to put angle braces in the each of the corners (both directions for a total of 8) from about the 2' mark on both the vertical and horizontal.  The only problem is with my design (partially for aesthetic reasons) is that both the end beams and the outer main beams will be sandwiched around the posts (not on top of it), so there is not direct angle from the post to the beams.  I have a couple of thoughts on how to resolve this, and am interested in any feedback or other ideas.
> 
> Idea 1: Make a compound miter cut (45deg and ??) in 2"x4"s? so that the braces would angle out slightly from the posts and come directly under the beams.  This would have the advantage of the braces attaching to the bottom of the beams giving them direct support.  This would also be helpful on the 13' span.
> 
> ...


I think I would sink the 6x6 posts in the ground for footing and added stability. I placed a 6x6 PT post 4 deep and mounted a large farm bell on it well over 20 years ago and it still looks like the day I put it in. I didnt add concrete into the hole but doing that makes for a very good anchor. On the top I would notch and make a ledge for the beam to sit on and then any angle braces I used would be inline with the post and the beam. They would add support but I would also cut them to be a design element. 

As to the span and the weight, without a deck or roof on top I wouldnt even be slightly concerned with the weight of the rafters beams. If you really want to calculate the weight distribution or look at some charts, search on rafter span tables and you will find many tables and calculators to help you figure that out. If you need help finding one you like just ask and we will help. 

The design possibilities are endless from quite simple to quite ornate. I would just start with a photo search and find a look you like and then plan from there. 

https://www.google.com/search?q=per...KEwjrgKeZ6rjMAhUEGD4KHRU2Cn8Q_AUIBigB&dpr=0.9


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## Snoonyb (May 1, 2016)

Beside which, it then becomes an individual, freestanding, architectural element.

Adding corbels, ordered from a lumber yard, are milled to your specifications, fitting your choice of aesthetics.


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## nealtw (May 3, 2016)

..................


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