I'd like to eventually build a deck for my new house. There will be a 20'L x 8'W screened porch on the back, on a brick/concrete foundation, so I'm hoping to do a detached deck off of that, and to match the length (from the corner of the house/porch). The porch lies within the outline of the house, so it's not sticking out past the back of the house.

I've glanced through NC code and have a decent handle on it; however, I'm still not sure of many things in the code. I was hoping to do this work myself.

Can anyone with experience/contractors answer some questions?

The highest part of the deck will be 30" or so (match elevation of the porch). I'd also like to do a 1 step down section, and then a section 1 step above grade. I'll do railings along all sections, except the one that is 1 step above grade.

My initial planning had 4x4 posts @ 6' OC with 8"W x 16"L x 6"T buried CIP footers.

Girders and joists are 2x8s.

Q1: Lateral support. The code reads (to me) that all decks have to have lateral supports, either by knee bracing or burying the posts 2'-6" (for a 4x4 post). However, that section of the code says the concrete footer must be 1' in diameter... so it a 8x16x6 block footer or a round footer? Or is this referring to embedding the post in 1' diameter x 2'-6"H of concrete on top of the footer? Do all sections need lateral bracing (30" above grade, ~20" above grade, and ~ 8" above grade)? If so, it seems like knee bracing is the way to go, though I don't care for the look of this. And do these go between each pair of exterior posts (all 4 sides)?

Q2: Girders. Are they supposed to be doubled (e.g. 2 2x8s)? I was going to use exterior posts as rail posts as well and dropped joists with joist hangers (so the entire substructure is flush). If girders are to be doubled, is it best to place both on the same side of posts, or split over posts (would this require blocking between girders to support decking above?)?

Q3: Blocking. Do I need to provide blocking between joists? Was doing 16" OC joists.

Q4: Spans. The code refers to joist and girder spans. I guess I'm not sure what this really refers to.

Q5: Angled corners. What's the best way to construct angled corners? I don't really know how to explain my question without drawing something up. I assume just angle cut the ends of the girders to attach to the posts and still bolt them? Since I'm using joist hangers (I assume I need to use hangers and not just nail through girder), how does that work on an angled girder?

I'm sure I have more questions and I'm working on some drawings as well.

Thanks.

[Edited on June 6, 2012 at 10:02 AM. Reason : .]

6/6/2012 10:00:16 AM

This thread is now about Magic: The Gathering

6/6/2012 10:07:21 AM

I've never played Magic so I doubt I'll ever open this thread again.

However, I DO like gatherings. Gatherings are fun, and if we talk about them I will be sure to come back. What do you do at gatherings? I like outdoor cooking (IE Grilling!), hanging with the pals (and drinking a few brewskis!), watching sports, and the like.

[Edited on June 6, 2012 at 11:16 AM. Reason : ]

6/6/2012 11:02:04 AM

Going to assume this is for raleigh area

Quote :

"Q1: Lateral support. The code reads (to me) that all decks have to have lateral supports, either by knee bracing or burying the posts 2'-6" (for a 4x4 post). However, that section of the code says the concrete footer must be 1' in diameter... so it a 8x16x6 block footer or a round footer? Or is this referring to embedding the post in 1' diameter x 2'-6"H of concrete on top of the footer? Do all sections need lateral bracing (30" above grade, ~20" above grade, and ~ 8" above grade)? If so, it seems like knee bracing is the way to go, though I don't care for the look of this. And do these go between each pair of exterior posts (all 4 sides)?"

little confused by terminology, but hopefully this answers:
To meet frost depth you have to bury footings at least 12"
Typical footing sizes are 16"x16"x8" that have been buried 4" deep

Not sure if required, but lateral bracing is rarely required if under 2'-6" to grade.
May want to consider bracing in the areas that are 30" above grade if it is detached.

Quote :

"Q2: Girders. Are they supposed to be doubled (e.g. 2 2x8s)? I was going to use exterior posts as rail posts as well and dropped joists with joist hangers (so the entire substructure is flush). If girders are to be doubled, is it best to place both on the same side of posts, or split over posts (would this require blocking between girders to support decking above?)?"

Yes, double the girders.
Would have to see a plan view to get a better idea of your spacings.

Quote :

"Q3: Blocking. Do I need to provide blocking between joists? Was doing 16" OC joists."

Not required

Quote :

"Q4: Spans. The code refers to joist and girder spans. I guess I'm not sure what this really refers to."

The joist span is the distance the floor joist is spanning between girders.
The girder span is the distance the girder is spanning between posts.

Quote :

"Q5: Angled corners. What's the best way to construct angled corners? I don't really know how to explain my question without drawing something up. I assume just angle cut the ends of the girders to attach to the posts and still bolt them? Since I'm using joist hangers (I assume I need to use hangers and not just nail through girder), how does that work on an angled girder?"

Again, not sure without a drawing, but maybe this will make sense: Cantilever your joists to different lengths and attach an upside down skewed hanger to your band board.


Make sure you won't be in violation of setback lines on the property as well.

If you get a drawing put together I can try to answer a little better.

6/6/2012 11:21:46 AM

Sorry, yes Wake County.

Quote :

"little confused by terminology, but hopefully this answers: To meet frost depth you have to bury footings at least 12" Typical footing sizes are 16"x16"x8" that have been buried 4" deep Not sure if required, but lateral bracing is rarely required if under 2'-6" to grade. May want to consider bracing in the areas that are 30" above grade if it is detached."

Code has 8x16x6, which is where that came from (for 6' max post spacing; or 12x12x8 for 8' max spacing). And I meant that burying posts 2'-6" in the ground is one way to achieve the lateral bracing, per the code. However, I don't see anything that fully explains deck height and lateral bracing, for my scenario (is there a lateral bracing requirement for decks <30" in height above grade? Is it required for decks at 30" above grade?).

Quote :

"The joist span is the distance the floor joist is spanning between girders. The girder span is the distance the girder is spanning between posts."

Thanks. Aren't these already set by the post spacing? Just duplicate terminology? I'm confused because 6' post span is fine, but I saw in one table for girder spans, something like 5' for 2x8s and in another place, 6'-10" for 2x8s. So does that mean the post spacing now has to be 5'?

[Edited on June 6, 2012 at 1:01 PM. Reason : .]

6/6/2012 12:54:42 PM

LOL... Ernie just threw down a different color UNO card

6/6/2012 1:31:55 PM

Not duplicate terminology, just not very easy to explain I suppose.
Both spans depend on how much area they are supporting.

For instance:

Say you wanted to make a deck 8'x14'.

You can run your floor joists the 14' length and have a dropped girder 1' from each end.
This gives you a floor joist max span of 12' long.

Your girders are going to be 8' long, and you can cantilever them 1' from each end also. So your posts can be 6' o.c.

Your joist span would be 12'-0"
Your girder span would be 6'-0"

As far as footings go, those will typically depend on just how much of a load is being carried.
You're probably right about the size of footings, although I haven't seen many 8x16x6 with deck design as people tend to not want to dig the holes out and opt for designing a deck out for less footings.

I'll check on lateral bracing

6/6/2012 1:40:13 PM

^ok, I see what you're saying now. I was working differently in my head. I'm looking at something like 20'x12' for the primary deck/level and then adding some smaller/lower portions to that.

Quote :

""little confused by terminology, but hopefully this answers: To meet frost depth you have to bury footings at least 12" Typical footing sizes are 16"x16"x8" that have been buried 4" deep Not sure if required, but lateral bracing is rarely required if under 2'-6" to grade. May want to consider bracing in the areas that are 30" above grade if it is detached.""

Also, the code refers to footings in one section (8x16x6) then in the lateral bracing it references 1' diameter concrete 2.5' deep. So is this referring to placing the 8x16x6 footer 3' below grade, then encasing the post for the remaining 2.5' to grade?

[Edited on June 6, 2012 at 1:43 PM. Reason : .]

6/6/2012 1:40:31 PM

essentially.

if you ever hope to remove/replace/add-on to it then it becomes a nightmare to work with though.

are you looking at doing the installation on your own? or having a GC do the install?

6/6/2012 1:50:15 PM

me

I'm much more capable with most of the actual work; however, I'm not familiar with the code and entire design process, so between googling and the code, different answers were throwing me off. I've helped build piers before so it's pretty much a lot of the same work (however, there was no code/permit for that and it was just simple/straight stuff).

^so it sounds like knee bracing is the way to go then. Does that go between each pair of exterior posts?

[Edited on June 6, 2012 at 1:58 PM. Reason : .]

6/6/2012 1:56:37 PM

let me still check and make sure you would need it at that height.

i always hate to put bracing on something that short because it seems like overkill.

6/6/2012 2:10:46 PM

Agreed. I mean, to me 30" is getting close to needing it and as you said, wouldn't be a bad idea, but probably overkill.

I just got my area's inspector's phone number... time to bug him

I've got the feeling that most of my questions are probably answered within the flooring code... I've just been looking in the decking code. I glanced through the flooring code and sighed. Time to get familiar I guess.

[Edited on June 6, 2012 at 2:22 PM. Reason : .]

6/6/2012 2:21:35 PM

When I was building houses a couple of years ago, the inspectors never required me to put any knee bracing if the deck was lower than 48"

I have no idea what the code book says about it. All I know (and all that really matters) is what the inspectors wanted.

6/6/2012 4:31:22 PM

truf

6/6/2012 4:43:16 PM

If I were to do joists on top of the girders with a 1' overhang on all sides, what do I do wear the 2 exterior joists are each 2 separate boards (if the length is longer than 1 board length, thus needing 2 exterior joists per side)?

Here's my flush substructure plan. Doable, but the dimensions are goofy (post spacing). I could do an over hang to get better dimensions/post spacing, but I'm not sure I can do a flush substructure + overhang... (well, the sides seem plausible, just extend the girders out; however, I'm not sure what to do for the side opposite of the house - would it be acceptable to extend the 2 exterior joists, add a girder to the outside on the ends of those and put short joists between the girder attached to the posts and the overhung girder that is only attached to the 2 exterior joists?)

Also, the split girders make me concerned about the 3.5" gap between them and the decking crossing over those gaps. I guess I could just fill in with a 2x4 or something?



[Edited on June 7, 2012 at 11:14 AM. Reason : .]

6/7/2012 10:48:36 AM

that's a lot of posts...

are there no stairs on that section?

6/8/2012 10:11:58 AM

haha, no stairs shown.

I thought it was a lot of posts as well, but the way I read it, my max girder span is 6'-1", so I just made the post spacing equal within the ~20' width. Now that I think about it, I think I was supposed to remove 1 column of posts since I went to 2x10s (I think that shows the spacing for 2x8s which have a max span of 5'

6/8/2012 10:22:30 AM

based on the way that is drawn it looks like the max girder span is about 5'-0"

if you kept that layout you could probably drop to 2x6 floor joists and 2x8 girders

6/8/2012 10:29:06 AM

Correct, which is what I had originally drawn, then change to 2x10 girders to eliminate a column of posts, which I forgot to do. So yeh, as is, could be 2x6 & 2x8

6/8/2012 11:03:28 AM

only problem i could foresee with the design is the row of posts against the house.

are you going to try and tie them in with the house footing?

[Edited on June 8, 2012 at 11:48 AM. Reason : edit]

6/8/2012 11:41:36 AM

Not sure on those yet. I'll have to wait to see what the house footing will be (how far out from the house it comes and how deep). I currently have it planned so that the deck footers are 4" from the house and using an extra girder or two on between the house and posts to build out the deck.

If I can't do that, I guess I'll just switch to joists going over the girders and have a 12' or 16' overhang, so that the house foundation doesn't interfere with the deck footers.

6/8/2012 1:30:35 PM

you could probably dig down to the existing foundation and tie into that

or do the dropped girder like you're talking about.

or just attach a ledgerboard to the house and avoid the posts against the house altogether.

6/8/2012 4:27:41 PM

I could do a ledger. The house foundation is a crawl space on cinder blocks, so I wasn't too thrilled about connecting to that.

Oh yeh, if I can use the house footer as a post footer, that'd be great; just have to wait and see.

6/8/2012 5:00:55 PM

First, drop the rear posts and thru-bolt your rear band to the house band. No need for posts and footings back there unless you can't thru-bolt.

Second, I would drop the 4x4 posts and go with 6x6. You up your span and gain strength. 4x4s will start twisting also. You notch them around a double band and then thru-bolt or use brackets to attach to the band.

Third, forget the flooring section of the code as it's not applicable. Floor load is 20 lbs./sq.ft. and decks are 40lbs./sq.ft. You want Appendix M of the Code.

Fourth, I've never seen a deck with 2x6 joists that was not spongy within 5 years. 2x8s are the minimum I'd go with. It's above code but remember that code is basically bare minimum.

Fifth, lateral bracing is not needed below 4' with 4x4s ore 6' with 6x6x. The exception would be if the inspector comes out and says that you've cut corners.

If you'd like, I can give you some engineering that will fly through inspections and hold anything you want to throw at it. It's what I use for both decks and floor systems for sunrooms (including full glass conservatories). It'll be very overbuilt (2x10 joists, 2x12 bands, 20" sq. footings) but you can use it as an idea.

Also, you have pm.

[Edited on June 8, 2012 at 8:03 PM. Reason : y-bracing]

6/8/2012 7:50:40 PM

Where do you work Dave?

[Edited on June 8, 2012 at 8:43 PM. Reason : Ahsd]

6/8/2012 8:42:50 PM

^ My family and I run a Four Seasons Sunrooms dealer in the western part of the state. We cover NC from Greensboro west and upstate SC. Actually we're a specialty retailer that do "home leisure" (anything from hot tubs to grills) but we specialize in sunrooms. That's the side I work in and since I'm one of the 2 license holders, I handle the engineering, inspections, plans, etc.

6/8/2012 8:53:17 PM

^^^thanks. I just read some reports about 4x4s twisting on people. I've also upped girders/joists to 2x10s. As far as bolting the rear band to the house, I'm fairly sure the foundation will be concrete and cinder blocks, with a brick top border, so I'm not sure I want to go through that for attaching the deck. I guess I could rent a hammer drill and do it, but my last experiences with drilling through concrete weren't too fun, nor were the results useable

And if you've got some plans, I'd love to have them!

[Edited on June 9, 2012 at 9:44 AM. Reason : .]

6/9/2012 9:43:02 AM

I don't think he was advocating going through the foundation to bolt the deck to the house, but the 2x10 band that sits on top of the foundation.

6/9/2012 10:12:26 AM

^ This. You won't be attaching to the block unless you're doing a step down from the house or the band is just inaccessible (which does happen but typically only with full basements with finished ceilings or overly filled crawlspace.

Also you have pm again.

6/9/2012 10:51:04 AM

your beams are longer than your girders. Al though there are a lot of them. Serviceability concerns?

I'm not familiar with wood design though, but this seems off.

6/9/2012 2:12:16 PM

^ Not sure what you're referencing but the girders are the 3 double bands running parallel to the house and the joists are running perpendicular between the girders. A girder IS a beam.

6/9/2012 3:51:41 PM

^^^no, I'm pretty sure it will be block. The deck is going behind the part of the house where a screened patio will be located. The screened patio is within the footprint of the house (not sticking out beyond the house) and shares the concrete/block/brick foundation. The floor of the patio is concrete, level with the top of the house foundation.

6/9/2012 6:00:15 PM

ah yeah sounds like you're dealing with a suspended slab then. Definitely more of a PITA. Probably would be easier to just do rear posts/footings.

6/9/2012 7:25:06 PM

Quote :

"I've never seen a deck with 2x6 joists that was not spongy within 5 1 year"

agreed

6/9/2012 8:46:31 PM

I'm looking to add about 12 ft length to my existing deck? anyone had any experience doing anything like this?

I'm in the granville(Oxford)/vance county area if you know anyone great to recommend? help please.

5/29/2013 1:56:16 PM

http://www.thewolfweb.com/message_topic.aspx?topic=613272

And don't worry about code

[Edited on May 29, 2013 at 3:05 PM. Reason : a]

5/29/2013 3:05:05 PM

^i wish i had the time to knock it out myself.

5/29/2013 3:30:56 PM

lol, yeah, that was my unemployment project.

5/29/2013 3:54:59 PM

what was the cost of your second kit?

5/29/2013 3:57:58 PM

I had about $1k into it when it was all said and done. I have tons of leftovers though

5/29/2013 4:01:47 PM

not bad at all. I'm looking for 600-700 range. cant see it being more than that just to add 12X10. hardly any cutting.

5/29/2013 4:03:28 PM

check out the packages at BDC, and they would probably deliver the whole package to you. If you have friends that know what they are doing you could get it done in a weekend.

For that price range, you are definitely looking at DIY.


[Edited on May 29, 2013 at 4:09 PM. Reason : a]

5/29/2013 4:05:32 PM

Nice. Thanks, they have a store in Henderson so even better. I have a friend that is a contractor so hopefully i can feed him beer to get it done.

5/29/2013 4:09:35 PM

If you do buy from BDC I recommend going and picking out the wood yourself. They have some pretty wonky ass lumber, and if you have it delivered you can guarantee you will get all of it.

5/29/2013 5:57:56 PM

do you know off the top the price comparison between Lowes and BDC?

5/30/2013 12:31:12 AM

My experience has been that Lowe's is a good bit cheaper than BDC (though, I don't know how the packages compare to Lowe's) and that BDC does not allow you to pick through lumber. At least not the one in Wendell.

5/30/2013 8:26:41 AM

^ They let me pick through mine (In Graham). In fact, the dude working out in the yard was pretty fucking lazy. I pretty much loaded my truck myself. That was when I got my first deck package. When I bought the second one I had it delivered, and the wood actually looked pretty decent. Probably because they were a day late so they figured they'd better give me the good shit.

I have actually found it to be considerably cheaper than Lowe's if you need a lot of lumber. If you just need a few pieces, it's probably apples to apples.

The 2 pieces of advice I can give are pretty much no-brainers: Don't bury your posts, pour footers and secure the posts to the top of them. And use screws, not nails. The downside to the deck packages at BDC is that they come with nails, so plan on the extra expense of buying screws. Fortunately I was able to get Lowe's to take the nails and give me store credit for them.

[Edited on May 30, 2013 at 9:50 AM. Reason : a]

5/30/2013 9:45:27 AM

^ so you are saying pour the footer and then secure with a bracket to the footer, then fill with dirt.

5/30/2013 9:58:20 AM

No. I poured the concrete all the way to the grass line and secured the deck post to it with a bracket. I guess you could leave it a couple inches below the grass line and cover it with dirt, if you just don't like the look of the bare concrete. It's mainly just future proofing. If one of the posts warps or I hit it with the mower and break it, it's easy to remove/replace it. If you bury the posts, it's a huge pain in the ass to replace them if you need to. Here's a pic of one of my posts:

5/30/2013 10:07:23 AM

If you don't stop your footer below grade, at least plan on covering it with mulch/pine needles.

Otherwise it just looks sloppy.

5/30/2013 10:13:31 AM