out door deck subframe spacing

[workinallthetime]

anyone have any specs on the subfloor spacing of a wooden out door deck? i plan on using 6x6 post along the outside for effect and 4x4 where you cant see them under the thing. i also plan on using 5/4 x 6 x 12 deck boards. the deck will be 12 x 43 and HAS to be off the gound about 24" in the highest part. what spacing should i use for the sub floor? would 16" centers work w/ 2x6 or should i do different?

 

[firefighter9208]

I always build a deck like I am building the subfloor in a house. I built a 16x40 deck on the back of our house and I used a 2x12 band with 2x10 floor joists on 16" centers. The deck is 4' off the ground. You'd be suprised how many people you can get on a deck that big and I don't think 2x6 floor joist would be big enough. JMHO

I built a 10x30 deck on my parents house and used a 2x10 band with 2x8 floor joists on 16" centers. The deck is 8' off the ground (above ground basement) and is solid as a rock. I bolted the band to the house with 3" x 3/8 galvenized lag bolts.


Chris

 

[EddieWalker]

16 inch centers would be the best, but allot of people build them on 24 inch centers to save a few bucks. I wont' go that far myself as the 5/4 decking will get bouncy over time and wear faster.

The same is true with using 2x6's for your joists. How far apart are your posts going to be? If more then four feet, I'd double up the 2x6's, or go up in size depending on your post spacings.

My last deck had 4x4 posts on 6 foot centers with 2x8's 12 feet long for joists. I like to overlap my joists to tie it all together. I also use screws and never nail a wood deck. The wood will shrink on you and the nails will work themselves loose over a short period of time. Two screws per joins on the decking. One will just cause the decking to curl.

Some people say to always lay the decking the the grain curled down, but each board will have it's own natrual cup to it. I always work with the board and take advantage of it's natural cup to shed water.

If you can, buy your material a month or two before you build. Preasrue treated wood will dry on you and shrink quite a bit. 5/4 inch decking is REALLY bad at shinking. If you can't wait for it to dry out, be sure to install it tight. Do not leave any spacing. It will shrink on you more then you want anyway.

Before you do anything, go to the magazine and book sections of Home Depot and Lowes. They both carries all sorts of information on deck building. Some of it is overkill, but if you follow the plans in those books, you won't go wrong. Mistakes happen when taking shortcuts and trying to save a buck with wider spacings and thinner lumber.

If you set your posts in concrete, be sure to build up the concrete above grade and slope it away from your posts. Posts always rot out at the level of the ground around them. If the cement comes above the ground and is sloped to shed water away from the posts, they will last much, much longer. Some instructions say to put a rock or something under the post to keep it off the bottom of the hole. I've removed my share of fence posts and have never seen the bottom of the posts rotted enough to make any difference. They will rot out at ground level decades before they will rot out from the bottom. I also wonder if the rock, or gravel at the bottom of a hole will actually hold water longer then just putting the post on the bottom of the hole and backfilling with dirt or concrete?? I never use gravel or a rock on the bottom of my posts.

One poster here suggested putting tar paper down on the top of the joist to shed water off of them. Then the decking goes on over the tar paper and the joists. You will never see the tar paper, but it will protect the tops of the joists from standing water. It sounds like a really good idea to me, and something I've started to do myself.

Eddie

 

[workinallthetime]

good ideas guys !!!
i like the tar paper and i like the 2 x 8 or double 2 x 6 ideas. this deck is in the very early stages of planning, the deck will serve as yet another seating place around the pool. i have not decided on post spacing yet only that i have to use 6x6 to match some existing work i did. the last deck i built was about 8 years ago and i ussed 2 x 8's for the decking. i pulled each board together with a clamp and a cleat before i screwed them down and ended up with about 1/16th to 1/8th gap over the years. i also have pulled lots of fence post and have yet to see one rotted at the bottom worse than the top. ever pulled a tie wall down and found the dead men ties to look brand new and the actual wall to be rotted away? i think the gound acts as some kind of insulator but who knows. agree on the dome top concrete also but using sonna tube is overkill for post only 2 feet in the ground. i dont like the method for setting post on top of blocks out of the ground, just looks wrong. next time im at the depot i will look at some books and post pics as the project gets under way.

 

[WayneB]

When we started our new porch at camp we went ahead and used 2x10 (16 on center). Support post were 6x6x16 and 6x6x12's a bear to handle. We sunk the 6x6 post 4 feet into the ground.

When we did the roof we selected 2x8x14 and the collar ties are 2x8x12, cut to fit! The location of the deck / porch faces north / northwest and we do get some pretty heavy winds and most of the storms come in from the northwest so we went a bit heavy on the structure.

We did the work this past fall right up into December and then it was just too cold and we were worried about the snow coming so we put the finish off until spring. Going up in two weeks to check thinks out and start working.

Prepare your BOM and do it with different lumber 2x8's and then with 2x10" so you can get a feel for what the over-all cost will be to increase the lumber size. The deck will be there a long time so it is worth putting in the extra lumber.

Just my thoughts

Wayne

 

[inveresk]

If you're going for permit, best check with your building inspector. Load/span tables might well be given in your local building code.

Otherwise, as a rough rule of thumb, you can work out joist size for a given span by halving the span and adding an inch. For example, a 14 foot span would work with 2 x 8" joists (14 divided by 2 plus 1). This assumes normal residential floor loading for live and dead loads and joists spacing of 16". If your joists are less deep you'll either get deflection or a good deal of bounce. If at times you're likely to load the deck over and above what could be considered normal, go up a joist size.

 

[Timber]

I am currently building a 16x52 deck with a pergola of the same size. I have built several Decks and I typically use 2x10 construction 16 in center for the deck and 24 on center for the pergola. I also prefer to set a deck on sauna tubes rather than planting the posts. You didn't mention it it is free standing or attached. Regardless you have to be sure the Rise and tread fall into code. That may determine the hight of your deck. How your deck is constructed is determined by your location,the style, weather it is free standing or attached with a ledger board to the sill plate or the foundation. You can cantilever 2 to 3 feet depending on you local codes. How you lay your decking will impact your framing as well. The first thing you do is draw it out to scale. I make blueprints my self but a scale drawing on graft paper is fine. If you buy your lumber ahead of time like Eddie suggested to dry be sure to stack it properly so it doesn't twist. I also suggest dimensions that eliminate waste. Lumber is sold buy the linear foot so if your cutting off 2 feet and tossing it away your wasting a lot of money. Proper planning is done in the drawing. 43 is a bad dimension keep to even numbers. If your set on 43 feet take the end decking boards and run the same direction as the stringers and you will take up that foot 6 inches on each end. How ever it will cost you 2 extra stringers. It will look nicer that way too just Miter the corners. At 24 inches off the ground that is 2 steps 3 rises to the deck at 8 inch rises standard code no Higher. That also gives you the option of no railings if you want to wrap the deck with steps. You also don't want to use all 12 foot planks, Use 12's, 10's, 16's, and 8's. You want to stager the joints. The rule is at least to rows before you repeat the pattern


This is a 24 inch deck I built that is a 10X12 landing that the steps to access the house and the main deck. The deck I am currently building is going to be of the same design

 

[RPK]

It is usually easiest to design a deck by starting with the deck boards. Exterior decks need to be designed to support a 40lb/sq.ft. load. When using 5/4 deck boards 16" on center joists are a must. Trex and most all of the types of high end decking need 12" on center joist spacing. 2x6 joists are only good for about 8 ft of clear span at 16" on center. 2x8's are good for 12 ft and 2x10's are good for 16 feet. Using that information and knowing the overall size of the deck you can determine how many carrying beams will be needed. The size of the carrying beam(s) are determined by the size and number of concrete piers. The more piers the smaller the carrying beams
RPK

 

[workinallthetime]

good points timber and all you guys.
i guess i should give you guys a little more detail about the site and my ideas
1st the site
the length is 43 aprox and the width is 12
12 foot width was determined for demensional lumber
the deck will sit slightly above an existing rock wall on the pool side and the back side will be tucked close to but not touching a hill that i will dry stack sandstone on before i start. under this deck water flows when we get alot of rain and the soil is pure clay and rocks. i dont get any kind of debris floating through this area just a little stream that is spread out.
the railing will be made of 4 x 8 sheets of lattice hung between 6x6 pt posts. ive had good luck with my design for that in the past. this deck will serve as a sun area and entertainment area for the pool and there will only be 2 places to step up to the deck which will probably be made from natural stone.

if it rains tomorrow i will not be able to do much so i can get some pics for you guys to see.

Yahoo! Photos - theglenlane_barn@sbcglobal.net's Photos - house work

here are some pics of before and after work and some unfinished work ive done around the place in the past couple years.

 

[EddieWalker]

Two things realy cought my attention.

First, the water flowing under the deck. I know it probably not feasable to change this, so it's very important that you ditch the ground to keep the water away from your posts. Also be sure to grade the slope to keep the water moving. Standing water will lead to mold and bugs. Is there anyway to catch the water before it gets to the deck and channel it through some sort of pipeing?

Second is the lattice. I understand it's fairly quick and easy to work with, but I've never seen it last more then a few years before starting to break. I've used it myself, and probably will again if a client insists, but I'd really try to find another material. Those books at Home Depot and Lowes will have all sorts of alternatives. One Idea I've been kicking around for an outdoor railing is rebar. I want to leave them unfinished and let them rust. I've seen copper pipe that had an amazing patina that was really nice that I'd love to try sometime.

Eddie