Or 66 Posts For Porch Roof
Building a porch roof is great to expand a home or businesss outdoor living space. But it can be difficult to ensure that it is sturdy and structurally fit off the ground. Because its frequently a question of 4×4 or 6×6 deck posts.
Choosing the wrong one would not be good for you. But then again it is tough to choose ideally!
So, your concern is, should I use 4×4 or 6×6 posts for porch roof?
Well, you need to consider a few factors to choose one. First, differentiate their capacity and spacing. Then you need to consider their weather resistance. Finally, see if their cost is fine for you or not.
You are just at the beginning of the main part. So, keep on reading to get to the main part to know about it in detail.
Sounds just about right? Lets get started!
Calculating Tributary Size For A Deck
The first thing you will need to do before tiring to figure out what size posts you need is to determine the tributary area.
The tributary area is deemed to be the area that will cause load on a particular structural element .
To calculate the maximum load of your deck, you will take the total area and multiply it by 50psf . For example, if you have a deck that is 100 sqft, the deck would only be able to support 5,000 lbs.
The 50psf is a safe value that structural engineers have deemed fit to be used in most applications for deck building.
Going forward with this example, we will consider that your deck is attached to the adjoining house by a ledger board. This means that the ledger board will be supporting approximately 50% of the load. Thus, you will halve the total area of the deck, with the initial half not needing any posts.
Should I Replace Existing 4×4 Posts
I currently have a high 20×14 deck attached to the back of my house on a very sloped yard. It is 13 ft off the ground and in great shape. However, It is currently supported by 4×4 posts that are in the ground and notched at the top where it is attached to a 2×8 and 2×10 ledger support.
We want to eventually close in half of the deck and make it a 3-seasons room. Should I replace these 4×4 posts with 6×6 posts? Or could I just add the 6×6 posts directly right next to the existing 4×4 posts, so I don’t have to jack up deck/remove 4x4s? I would dig new holes for the 6×6 posts, with poured concrete and use post base to attach them above ground and use post caps to attach to the existing support ledgers.
I am looking for the safest, most efficient way a DIYer can achieve this herself. We are located in Georgia, so we really don’t get snow, but we do get a little ice here and there.
BTW One of the posts is shredding at the ground level and the corner posts looks like it is cracking.
- 1I’m having a hard time knowing what I’m seeing in that extreme closeup. Maybe back out a bit and show a couple angles. isherwoodSep 8, 2021 at 15:28
- I’m sure you’ll have this conversation with the building inspection/permits people, but I’d be concerned about how appropriate the floor structure is for your 3 season room plan.
If the 4×4 posts were up to code for when the deck was built then your proposal would be considered a repair and repairs usually have looser guidelines.
Sunroom
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Calculating Deck Post Spacing
You will need to place your posts in the second half of the deck . Consider that the maximum spacing for 4X4 deck posts should be no further than 6 feet apart. Then 6X6 deck posts should have a spacing of 8 feet. Note that the measurement is obtained from center to center and not the outer edges of the posts.
Take note that, typically, you will start by placing posts in the corners of your deck to provide the most support. There are cases where you will want to distribute the posts, but more than likely, if you are building a deck and have to consider load and area beforehand, you would have approximated to place the posts as close to the corner as possible.
Depending on your decks size and where you have theoretically placed your posts, you will need to calculate the tributary area for those.
To obtain the area each post will support, you will have them placed with the appropriate distance apart and divide the distance from post to post. This will be the width of each post. The length will be the distance from the end of the deck to the midpoint.
What Is Better 44 Or 66 For Deck Railing Posts
A 6×6 will work as a railing post too but is over-kill unless there are other aesthetic or structural reasons for the heavier posts. The 6×6 is larger and checks and cracks will be more visible, however, it may not twist or bend like a 4×4. It can be notched by up to 2-inches to sit on the deck and fasten to the rim board.
The style of railing or desired look may require a different post, but for most deck railings 4×4 posts work well. Once they are tied in with the top and bottom rails and the railing cap board attached, theyll resist twisting and bending.
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Maximum Allowable Height For A 44 Deck Support Post
The maximum allowable 4×4 deck support post height under the 2015 IRC is 8-feet. The longer a post, the more likely it is to bend under load than shorter posts, thus the limit set on the height of 4×4 posts. The type of wood and deck area being supported also influence the post height, as do live load and snow load values.
The 2018 IRC altered the allowable height of a 4×4 post yet again. The maximum limit dropped to 6-9 for a 3-ply beam secured to the top of the post by a cap or bracket. A 1 or 2-ply beam, or equivalent, can still mount atop an 8-foot 4×4 post.
Choosing The Right Post For The Job
While there may be a handful of circumstances that only require the minimum 4×4 deck post, you will more than likely want to choose a 6×6 post for the deck. It provides more stability for larger decks, the ability to hold a heavier load, and more room for notching. Given that the price difference tends to be minimal, the choice between these two post sizes is clear.
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Stacking Two 6×6 Posts For Two Story Deck
We are having our two story deck fixed. The deck is built on the downward sloping side of a hill and the footings were failing. The footings were replaced with much larger tube-formed footings.
When the contractor installed the new posts, he actually cut off the old posts at the halfway point and put new posts under the old/existing posts. So now we have a two story deck that is supported by six 6×6″ posts, stacked on top of six 6×6″ posts. This just looks wrong and dangerous.
Is it acceptable to stack posts on top of one another to create a total height of 20’+ for the purposes of deck construction and support? If so, how should the posts be secured to one another?
- Welcome to Stack Exchange. You should take our tour so you know how to participate here with upvotes on helpful answers and check marks for accepted answers. HoneyDoApr 10, 2020 at 19:41
- You say “two-story deck”, but I suspect you actually mean a deck at the second story height. Which is it? Are there two levels to the deck?Apr 10, 2020 at 20:01
- You are correct. It is a deck at the second story height above a carport. TBelenApr 11, 2020 at 2:24
- How much new post is on the bottom of this 20+ foot tall stack, and how much old post is on top? In either case, you’ve still got a hinge-point or slipping point, but how the joint is reinforced and how that reinforcement looks , my depend on where the splice is.
How Much Weight Can A 66 Post Support
The actual dimensions of a 6×6 are 5-1/2 x 5-1/2, giving it a cross-sectional surface area of 30.25 square inches. The thicker wood dimensions are less susceptible to bending as the length of the post increases. As a result, a 6×6 will support a greater tributary surface.
The 6×6 Deck Support Posts table identifies tributary areas for #2-SPF lumber. High grades or stronger wood species support greater areas for similar lengths. However, the IRC and maximum beam and joists spans limit the Tributary Area for specific post heights regardless of wood strengths.
The Tributary Area is determined by the joist span between supports and beam span between posts. A center post carries 1/4 of four areas based on joist and beam span so essentially, its Tributary Area is defined by the joist span multiplied by the beam span. A corner post supports a 1/4 of the area defined by the joist and beam span, and an edge post supports 1/4 of two areas.
A post may be able to support more but the code sets the limits. The Tributary Area multiplied by the dead and live load rating, or the design load , identifies the weight the post may support.
The maximum Center Post Tributary Area based on an 18-foot joist span on a 3-ply 2×12 beam for #2 Grade SPF posts 7-11 apart is 141sq.ft. .
Multiply that area by the design load of 50psf and the load on the post is 7050-pounds.
Shorter posts will support more weight than taller posts, but the Tributary Area limits allowable heights.
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Will 4×4 Posts Carry A Patio Cover With A 12 Foot Span
I have a 10 ft tall 12 ft wide and 46 ft long patio cover that I’m adding to the back side of my house. I have it all supported by 4x4s. They are spaced at about 7 feet apart down the entire 46 ft length but the 12 ft wide from the edge of my house to the edge of the porch has nothing.
I’m going to be putting a metal roof on top of it. Are my 4x4s enough to safely hold this weight? I live in South Alabama so snow is not usually a problem and wind where I’m at is normally not a big problem either.
Also: I used 2×6’s for the entire rafter system as well as my main beams holding the weight. I feel like I screwed up on that one. I’m thinking about coming back in underneath the two by sixes and adding another one directly below the ones I already have, just for extra support, or take A 2×4 and lay it flat on my 4×4 and attaching that down the whole length of the 4×4 just so my 2×6’s have something to sit on top of in order to stop the shear weight from possibly snapping my screws.
Any info will be greatly appreciated thank you.
Post Requirements For Deck Stairs
Post requirements for deck stairs depend on the type and span of the stringer. A cut stringer must be supported every 6-feet and a solid stringer every 13¼-feet. A 4×4 post may be used to provide support up to 14-feet. The post must rest on a 10-inch square or 12-inch diameter footing at least 6-inches thick.
The 4×4 post must be notched to fit the stringer and bolted with 1/2 through-bolts with washers. There must be 3/4 or more of the stringer below the bottom bolt, and at least 2-inches of the stringer above the top bolt. The post should also be secured to the footing.
An intermediate landing must be built if the stairs exceed a vertical height of 12-0 but may be used to shorten smaller stringer spans. Intermediate rectangular landings must be built as ledger-free decks, wide enough to support stairs at least 36-inches wide, and a landing width of no less than 36-inches. Based on the dimensions of the landing, either 4×4 or 6×6 posts may be used.
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How To Support A Porch Roof
- Written by Tim Bossie on Nov 16, 2010To ensure our content is always up-to-date with current information, best practices, and professional advice, articles are routinely reviewed by industry experts with years of hands-on experience.Reviewed by
Adding a roof onto an existing porch can add a lot of character to the front of your home. Instead of just having an open porch, installing a porch roof will enable the homeowner to be able to use the space during times of rain or intense sun. One of the major considerations of the porch roof is the support that will keep it from falling down. Many homes use columns, while others use a simple post and beam type of construction. If you are looking at adding a porch roof, here is an easy way to support it.
Can I Use 4×4 Posts As The Primary Support For A Deck
I have an old cedar deck, and most of the decking and vertical support posts are rotted out. I’d like to rebuild the deck as-is, just replacing the rotting pieces.
The current design is as follows:
- 2×8 treated ledgers anchored to concrete foundation
- 2×8 treated joists coming off the ledgers
- 2×8 treated rim joists around the edges
- 4×4 cedar posts around the edges , sitting on concrete footings
- Posts are notched and are supporting the rim joists, attached with nails
- There are no other supporting posts or beams
My concern is that all the information I’ve found on decks shows people using 6×6 posts as the main supporting structure, with beams on top of those and joists on top of the beams. I only see 4×4 posts used to form the supports for the railings.
I’m hoping to use the current design, and replace all of the posts, decking, and railings. The only significant change I have planned is to attach the posts to the rim joists using carriage bolts instead of nails. Is it reasonable to have 4×4 posts as the primary support, or do I need to consider more significant design changes?
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Vs 66 Deck Post: Which Is Better
Building a deck is a great way to extend the outdoor living space of a home or business. Making sure it is solid and structurally sound from the ground up though, is often a matter of 4×4 vs 6×6 deck post. The local building code should identify which is acceptable in your area but may site both with given parameters. So, which is better?
The load capacity of a 3-foot #2 grade 4×4 is 17,426 pounds, and a similar 6×6 is 20,834 pounds or 16% better. However, an 8-foot 4×4 supports 6468-pounds and 2339-pounds at 14-feet, while a 6×6 is 18032 and 10550-pounds respectively or 64% and 78% more load capacity. So, for posts 3-feet and shorter, its a matter of preference, above 3-feet use 6×6.
In this article, well explain 4×4 and 6×6 posts, when and where to use them, how to secure them to a beam, and the spacing between post supports. Well also look at posts for deck stairs and deck railings. By the end of your read, youll be able to identify which post is better for your deck construction to ensure it is structurally sound and code compliant.
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A ballpark way is to figure out what wall would hold that floor up. For two story, this is typically a 2×6 wall 24OC. You then count how many studs that wall has, your posts need to roughly have the same amount of wood.
Overall, for something you walk on, it is 6×6 post, for roof 4×4 is fine. Working with 2x lumber is better as it won’t split as much as a solid post. If you cover it with house wrap and clad it with wood, it will last much longer as well.
If you want solid posts, best to do a cut on a hidden side down to about the center of the post , this will relieve the stress and less chance of splitting as it dries. Consult an engineer no matter which way you go though, this is not a DIY kindof design.
Columns like this usually fail by buckling , so bracing becomes important as the columns get tall. Long, slender structures aren’t particularly stable. Fatter columns can be longer before they start to fail for the same load, for example. All this means that what might be a safe for a 4×4 that is 2 feet high probably won’t be safe for that same 4×4 column that is 14 feet high.
An engineer can work this all out for you. I’d expect some kind of bracing to be required for a 2 story deck. You have similar forces to resist to what causes “racking” in a stud wall, but you probably can’t have shear panels to deal with that on a deck.
You don’t want to do this as a DIY project since you’re getting into a more complex structure than the typical ground-level deck.
Bill
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