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building deck, 2x8 or 2x10?, need help

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Newbie
Dec 28, 2007
85 posts
7 upvotes

building deck, 2x8 or 2x10?, need help

I am planning to build a PT deck like this:
14(w) by 16(L) feet , 18 inches from ground level, attached to house one side.
Want to use pier in-ground footings using sono tubes and attaching 2 beams on top of in, (no posts).
Will be using Cantilevered post types with joists hanging about 2 feet past beam.

My questions are:
1) since my deck is not too high (only 18 inches), can I use 2x8 for beams and joists? 16 feet length total can be ok to use 3 footings? or how many footings?
2) will 2x8 joist sitting on top of 2x8 beams are ok with spacing of 16 feets? or I can use 12 feet spacing? I just don't want to use 2x10 due to only 18 inches max height of deck, which leaves me with 3.5 inches pier above ground, 7.25 inches for beam, 7.25 inches for joists for a total of 18 inches and I have to figure out for water drainage also.

3)Will using 12 feet spacing makes it better vs 16 with 2x8 beams and joists?

If I have little bit more room above ground I would have no problem using 2x10.

4) what size of sono tubes I should be using? 6" or 8" diameter?

Any sugessions will be greately appreciated.

I am in Toronto area.
30 replies
Member
User avatar
Dec 13, 2003
446 posts
18 upvotes
2x8 for joists will be fine, with 16" OC. Should use 2x10 for beams but 2x8 will be fine as well. If you are worried you can triple the 2x8 for the beams but double will be sufficient. You should put the beams at 7 and 14 feet out from the house, with the piers you should do 3 per beam with spacing of 1, 7, 13. This will be very sturdy.

Go with an 8" sonotube, and make sure you put post anchors in them.
[OP]
Newbie
Dec 28, 2007
85 posts
7 upvotes
mystical2003 wrote:
Jun 20th, 2008 12:23 am
2x8 for joists will be fine, with 16" OC. Should use 2x10 for beams but 2x8 will be fine as well. If you are worried you can triple the 2x8 for the beams but double will be sufficient. You should put the beams at 7 and 14 feet out from the house, with the piers you should do 3 per beam with spacing of 1, 7, 13. This will be very sturdy.

Go with an 8" sonotube, and make sure you put post anchors in them.
Thanks Mystical.
I am thinking of using 2 2x8 laminated for outer beams at 12 feet from house. At house will be 2x8 ledger bolted and will be using joist hangers for joists. Do I need another beam (2x8) between ledger and outer beam?
Thanks again for all your inputs.
Member
Oct 20, 2003
364 posts
1 upvote
Waterloo
If your first beam is 12' out from your house, you definitely will have a "bouncy" deck with 2x8 joists. I would go with what the previous poster said, have 2 beams.
Deal Addict
Nov 18, 2005
4037 posts
598 upvotes
Kitchener
these are the Kitchener deck building codes, I would think other citys are similar
maximum 2 X 8 span 12" on centre is 12'-6" with a 20" cantilever
maximum 2 X 8 span 16" on centre is 11'-9" with a 16" cantilever
maximum distance between post holes for 2 ply 2 x 8 beam is 8'-7"
Deal Addict
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Dec 2, 2002
1233 posts
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How big is your backyard?

Because 14 x 16 is an odd size, nearly a complete square.
[OP]
Newbie
Dec 28, 2007
85 posts
7 upvotes
Kenneth wrote:
Jun 20th, 2008 12:43 pm
How big is your backyard?

Because 14 x 16 is an odd size, nearly a complete square.
Thanks everyone who have answered. My yard is 45 W by 40 Deep. I chose this size because of basement windows. can not go wider than 16 feet. This is top level 14x16 plus I am building a lower deck beside it 7x10 so that window will not be covered plus no need for steps and railings.
Member
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Dec 13, 2003
446 posts
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bangan wrote:
Jun 20th, 2008 7:26 am
Thanks Mystical.
I am thinking of using 2 2x8 laminated for outer beams at 12 feet from house. At house will be 2x8 ledger bolted and will be using joist hangers for joists. Do I need another beam (2x8) between ledger and outer beam?
Thanks again for all your inputs.
Your Ledger at the house should be 2x10, should always go at least one size larger. As for the Beam I would 100% put two of them. The added cost and labour on the overall project is minimal and you can be sure the deck is solid.
[OP]
Newbie
Dec 28, 2007
85 posts
7 upvotes
mystical2003 wrote:
Jun 21st, 2008 1:49 am
Your Ledger at the house should be 2x10, should always go at least one size larger. As for the Beam I would 100% put two of them. The added cost and labour on the overall project is minimal and you can be sure the deck is solid.
Thanks Mystival. I will go with 2 beams of 2x8 laminated at maybe 6feet and 13 feet from house, I want some hang out. Also will go with 2x10 for ledger. Few more Q if U can help with:

How to attach ledger to brick siding of house, HD guy sugested using bolts that you drill, push in with glue then insert bolt and they expang inside brick/concreet?. Or you just drill and hammer bolts straight on snugg fit and tight nuts?

What kind of footing anchot to use to attach 2x8 beams to the cement piers? set in wet concrete the ones with rod welded at bottom? or some sort of J type at HD that can be adjusted up or dowm? or there are other better and eassy kinds?

Thanks.
Member
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Dec 13, 2003
446 posts
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bangan wrote:
Jun 21st, 2008 10:02 am
Thanks Mystival. I will go with 2 beams of 2x8 laminated at maybe 6feet and 13 feet from house, I want some hang out. Also will go with 2x10 for ledger. Few more Q if U can help with:

How to attach ledger to brick siding of house, HD guy sugested using bolts that you drill, push in with glue then insert bolt and they expang inside brick/concreet?. Or you just drill and hammer bolts straight on snugg fit and tight nuts?

What kind of footing anchot to use to attach 2x8 beams to the cement piers? set in wet concrete the ones with rod welded at bottom? or some sort of J type at HD that can be adjusted up or dowm? or there are other better and eassy kinds?

Thanks.
Anchoring just to the brick will give minimal strength. It is not recommended at all for the amount of weight you will have. Can pull the brick right out. You should go right into the actual foundation. Hard to tell you what you need without a picture and measurements. If you can go right into the foundation (assuming it is poured concrete) then I would use 1/2" wedge anchors. Just need to drill the hole then hammer them in. As you tighten up the nut they will get tighter in the hole and will not come lose ever.

Use the 4x4 post holder set into the wet cement. Just make sure you have your piers at the right height. This would be the easiest. If you are worried about this then you can get the adjustable ones.

Proper measurement and placement of the piers will make the rest very easy.
Sr. Member
Oct 8, 2002
604 posts
15 upvotes
Mississauga
Or if the foundation is too low, you can go through the brick and attach to the wood frame of the house with lag bolts/washer
Deal Addict
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Apr 14, 2005
1584 posts
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I just built a 12x15' deck. 12 attached to the house and 15' out. I have one beam at 13'.

joists are 2x10's @ 16 inches.. beam is also made of 2x10's. Decking is 5/4x6.

Have I built this thing wrong..? This was sort of scribbled out with the guy at a local lumber yard where I purchased the lumber.. he seemed to know what he was talking about.

I have notice a bit of "bounce", but it isn't so bad that I care.. but would I be shortening the life of the deck in any way with having just the 1 beam? I could probably raise another beam midway under the joists as well..
Deal Addict
Nov 18, 2005
4037 posts
598 upvotes
Kitchener
maximum span for 2 x 10 16"oc is 13'-8" with a 24" cantilever... but this is minimum building code and sometimes minimum code is not good enough. Did you attach cross members between the joists, this prevents them from twisting and helps stiffen up the deck so it doesn't feel bouncy
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Dec 13, 2003
446 posts
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mork wrote:
Jun 22nd, 2008 12:19 pm
I just built a 12x15' deck. 12 attached to the house and 15' out. I have one beam at 13'.

joists are 2x10's @ 16 inches.. beam is also made of 2x10's. Decking is 5/4x6.

Have I built this thing wrong..? This was sort of scribbled out with the guy at a local lumber yard where I purchased the lumber.. he seemed to know what he was talking about.

I have notice a bit of "bounce", but it isn't so bad that I care.. but would I be shortening the life of the deck in any way with having just the 1 beam? I could probably raise another beam midway under the joists as well..
You have what would be minimum required and as DrThorne said, minimum is often not good enough. If you already feel a bounce in the deck then you will notice it to get worse over time. The above posters mention of cross bracing is also important. You should have done atleast two cross braces per joist to tie everything together.

Depending on the height of your deck putting in another beam would be a good idea. Especially if it is high enough to do so, remembering that the footings for the beams should be below the frost line, if they are not you may just be causing yourself more problems. Also the higher the deck the more secure you have to make it. It is one thing to have a problem with a deck a foot off the ground, another to have one 8 feet of the ground.

A neighbour a few houses down built a deck 16x16 attached to his house about 8 feet above ground. All they have supporting it is a double 2x8 beam all the way out at the 16 foot mark supported by a 4x4 on each corner. I will go nowhere near that deck. It is a disaster waiting to happen. He just built it this year and I guarantee it will not last. I also guarantee no permit was obtained and he better hope no neighbours get a permit for something they do and have an inspector come out.
Deal Addict
Nov 18, 2005
4037 posts
598 upvotes
Kitchener
mystical2003 wrote:
Jun 22nd, 2008 9:11 pm
A neighbour a few houses down built a deck 16x16 attached to his house about 8 feet above ground. All they have supporting it is a double 2x8 beam all the way out at the 16 foot mark supported by a 4x4 on each corner. I will go nowhere near that deck. It is a disaster waiting to happen. He just built it this year and I guarantee it will not last. I also guarantee no permit was obtained and he better hope no neighbours get a permit for something they do and have an inspector come out.
holy smokes, he's asking for trouble or even a law suite if that collapses. Anything over 24" above grade requires a permit and anything over 4' requires 6" x 6" posts. Has his deck seen snow loading yet?
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