How do I build a Freestanding Deck?

[Peter Stahl]

Any body build decks for a living? I want to build a small freestanding deck, main reason is the house is very old(100+ years). The old deck had 3 layers of decking on it, 1 2X4 and 2 5/4X6. Water damage rusted the old hangers badly. Deck size is aprox 8' X 7' and 44 inches high. The picture attached shows one beam, I want to use 2 so it stands on it's own supports not using a ledger on the house. Will most likely still lag bolt it to keep it from swaying. Questions:

What size beams would you use?

How many and what size post to hold the beams up?

What size Joist?

Do I need a double joist on the ends where the rim joist attaches with the joist?

Would you still use joist hanges or just nail through the ends?

Would you anchor bolt the post to the concrete piers?

Thanks, Pete

[David G Baker]

Peter,
Go to Home Depot and check out the concrete blocks that have the cross on the top of them. The blocks usually have an instruction sheet somewhere around where they are stacked. I used the cross blocks in California they are great and easy to use and held up well through a couple of earthquakes.

[Joe Pelonio]

I don't do it for a living, but have built several decks. Anything over a certain height (like yours) requires a permit. When I did one 72" up I had the requirements change regularly depending on which inspector came. One
thing they inspected was the attachment to the house, which was required by code. If you do go the permit route you will have to check the codes and do a drawing, it can vary by city/state.

[Garth Hulley]

A good reference source for building decks is the Fairfax County, Virginia, website.
http://www.fairfaxcounty.gov/dpwes/publications/decks/

It will give you most of the information and standards necessary for you to build a deck.

[Matt Meiser]

Unless things have changed, I think most home centers can quickly design a deck for you on the computer. When we built my parent's deck 11 years ago, we just gave the the dimensions we wanted and they spit out a drawing in about 1 minute. That gave the sizing for everything, post locations, etc and was good enough for the township for the permit.

[Peter Stahl]

Peter,
Go to Home Depot and check out the concrete blocks that have the cross on the top of them. The blocks usually have an instruction sheet somewhere around where they are stacked. I used the cross blocks in California they are great and easy to use and held up well through a couple of earthquakes.

David,

Living in NJ I need a pier about 30 inches deep need to anchor the deck to the piers. If it were a low deck I might consider them. Thanks for the reply.

[Peter Stahl]

I don't do it for a living, but have built several decks. Anything over a certain height (like yours) requires a permit. When I did one 72" up I had the requirements change regularly depending on which inspector came. One
thing they inspected was the attachment to the house, which was required by code. If you do go the permit route you will have to check the codes and do a drawing, it can vary by city/state.

Joe,

It will get attached but just to keep it from swaying not to hold it up. Thanks for the reply.

[Peter Stahl]

A good reference source for building decks is the Fairfax County, Virginia, website.
http://www.fairfaxcounty.gov/dpwes/publications/decks/

It will give you most of the information and standards necessary for you to build a deck.

Garth,

Thanks for the link, I'll check it out.

[Peter Stahl]

Unless things have changed, I think most home centers can quickly design a deck for you on the computer. When we built my parent's deck 11 years ago, we just gave the the dimensions we wanted and they spit out a drawing in about 1 minute. That gave the sizing for everything, post locations, etc and was good enough for the township for the permit.

Matt,

Thanks for the reply. I didn't know the big boxes offered that service. I thought they only did kitchen design. I'll have to check that out.

[Joe Tonich]

Best bet is to dig holes 18-20" deep (below the frostline) and cement the posts in. Guarantee it won't move. When I bought my house 18 years ago I put in a pool and built a freestanding deck (10'x14') for it. When the boys were born, got rid of the pool and used the deck as a fort. Boys got big and it's being used as a pool deck again, still as strong as when I put it up.

Heck....you can put in the posts and joists all at once, after you tamp down and water the cement, and it will hold everything square while the cement hardens. The decking can then be installed the next day.

'Least thats how I built em.

[Tim Morton]

Kelly Hanna builds decks for a living.

http://www.sawmillcreek.org/member.php?u=1800

[Joe Tonich]

ooops......forgot the questions......:o

What size beams would you use?

How many and what size post to hold the beams up?

4x4's......I'd use 9 total, equally spaced 4' on 8' sides, 3.5' on 7' sides and one in the center.

What size Joist?

I'd use 2x6's, and run a bearing joist underneath em in the middle. It will hold anything you put on it.

Do I need a double joist on the ends where the rim joist attaches with the joist?

Nope.

Would you still use joist hanges or just nail through the ends?

I'd just nail em.

Would you anchor bolt the post to the concrete piers?

I never used the piers, don't think they had em 20 years ago. I'd just cement em in. Level the posts while pouring the dry cement in...tamp it in good with a 2x4 or something, then water em. If your using a nailgun or screws, you can put up your joists while the cement hardens, guaranteeing it will stay square.

[Mike Hood]

I'm building one on the back of my house right now. It's 60' by 16'. I've learned a GREAT deal in this process. The first of which is get permit. :)

My deck is pretty large and 10' off the ground, but even with a $185 permit fee, it paid for a lot of good advice from the local planning official. He sat aside 30 minutes to go over my plans. He made some recommendations and signed them off. I learned a lot about the building codes and some designs that work better than others.

I'd suggest buying a good deck book at your local lumber yard and taking your time. Your tax dollars (and permit fees) keep these guys on staff in your local township... use them. They're very helpful.

Here's the 1 one the 4 drawings I was required to submit. I also had to calculate the impervious surface area and live loads before they'd approve it.

http://www.iboatnw.com/deck/Deck%20Scale%20DWG%201-12%20-%20Reduced%203.jpg

[Peter Stahl]

Everyone thanks for all the replies. Lots of good info there. Any more suggestion please post em.

[Peter Stahl]

I also had to calculate the impervious surface area and live loads before they'd approve it.



Mike, What is a impervious surface area and how you calculate that and the live loads? Thanks for the reply. Nice drawing, what did you do it with?

[Ben Grunow]

Here in Ct the footings go 42" deep and I am sure that is true for NJ.

I would avoid burying posts in concrete and use a post base (http://www.strongtie.com/products/connectors/AB-ABA-ABE-ABU.html) set over an anchor bolt cast in the concrete which keeps the wood away from the water. Local lumber yard in stock.

Joists could all be 2x8 and if you add a cross brace each way from each corner post (4x4 is fine) you might not need to attach to the house. I would make a perimeter of doubles that are bolted to the posts with 3/8" galv bolts and even notch one of the doubles into the post.

44" above ground requires a rail (anything over 30") so plan for one as a 44" fall is not fun.

[Peter Stahl]

Ben,

Thanks for the reply. We only have to go 30" in NJ. We don't get as cold down here.

[Rob Russell]

Mike, What is a impervious surface area and how you calculate that and the live loads? Thanks for the reply. Nice drawing, what did you do it with?

Impervious surface area is ground area that you cover with something that's impervious to rain and effectively creates run off. That increases the amount of water that other parts of the ground have to handle. For example, if you decided to add a large, 3-car parking area off of your driveway and that part of the yard has a gentle slope down to your neighbor's yard, you just sent that whole area's worth of rainwater down to their yard. I believe that the impervious area also figures into septic system leach field calculations.

Live load is the amount of weight you'd put on the deck per square foot. It's interesting that they want you to calculate the live load. In CT, the live load requirement for decks like Mike's building is 60 lbs/sq ft. As a comparison, standard house floors are typically framed to a 40 lb/sq ft live load standard. The reason for the additional weight-carrying requirement on decks is that people have outdoor parties and really pack decks with bodies. There have been deck failures in CT where people died, so they put in the more stringent load requirement.

[Peter Stahl]

Impervious surface area is ground area that you cover with something that's impervious to rain and effectively creates run off. That increases the amount of water that other parts of the ground have to handle. For example, if you decided to add a large, 3-car parking area off of your driveway and that part of the yard has a gentle slope down to your neighbor's yard, you just sent that whole area's worth of rainwater down to their yard. I believe that the impervious area also figures into septic system leach field calculations.

Live load is the amount of weight you'd put on the deck per square foot. It's interesting that they want you to calculate the live load. In CT, the live load requirement for decks like Mike's building is 60 lbs/sq ft. As a comparison, standard house floors are typically framed to a 40 lb/sq ft live load standard. The reason for the additional weight-carrying requirement on decks is that people have outdoor parties and really pack decks with bodies. There have been deck failures in CT where people died, so they put in the more stringent load requirement.

Thanks Rob. I would guess the higher it gets the tougher they are. I've seen several on the news that failed and the weren't attached to the build very well.