Frequently Asked Deck Buildings Questions (continued)

Joist Hangers

I am erecting a 12X14' deck and would like to know; if using 2X6 joist hangers spaced 16" on center with approx. a 5' span will it be strong enough to support the decking without too much bounce?

2x6 joists can adequately span 9 ft 9 inches without much bounce on 16 inch centers.  Take a look at the article on beck building on this site (Just click on articles and it is first in the article directory)

Beams on posts or attached

Can someone tell me which is structurally stronger, a) placing beams on top of posts or b) attaching beams to side of posts using bolts.  Any insight to each method would be appreciated.

Placing beams on top of posts is stronger.

Although for all intents and purposes, through bolts properly sized can carry the load placed on the posts with no problem. The weight bearing capacity of a bolted post is limited to the shear capacity (the point were the weight will 'shear' the bolt clean off) of the bolts.

Simpson makes special metal brackets for attaching posts to the underside of deck framing.

Deck pitch

How much pitch should a 10 x 15 deck have so the rain will run away from the house

Typically we don't put any pitch on a deck, since there are gaps between the deck boards to keep it from holding any water.

If you are building one with porch style, tongue and groove decking, then I think something on the order of 1/8" per feet is plenty.

Extending a deck

There is an existing free standing deck on the second floor of my house measuring five feet in width by 14 feet in length. I want to extend the deck by adding length to the existing joists (they are continuations from the interior floor set at 16"). Can 2x12 joists 16" on center be used to extend the deck another two feet in width without the need to add vertical supporting posts? What do you recommend to accomplish this goal?

I am not quite sure what you described. Is there any overhang now? If not, using 2x12's to extend two feet would be no problem. If you tie them in to the existing joists back about 4 ft, with the 2 ft extended out, you should have no trouble at all.

Freestanding deck

I'm going to help a friend construct a deck that needs to be removable. (It's a mobile home on a rented lot....)What the safest, most structurally sound way to do that??

How large do you intend to make it. Obviously you can't make it too large or it will be too heavy to be movable.Or you can make it in sections and bolt them together.

I would make it a freestanding deck supported on blocks. If you make individual sections of a manageable size(say 4x8 sections) and bolt them together underneath, you could make it moveable...

Building a deck over an existing concrete slab

Our house has a 8x20 ft. patio at the back. I would like to build a 16 in high deck over the slab, the same size as the patio. The patio is 4 in. thick floating slab. Can I anchor my support posts directly to the slab, or do I have to dig footings to below the frost line? If I can set the posts on the slab, should I build a completely free-standing deck, or can I build the deck attached to a ledger on the house If I do the latter, will frost heave pull the deck away from the ledger? Lastly, if I can set the posts on the slab, how deep into the 4 in. concrete slab should I drill to accommodate the anchor bolts?

If your patio is relatively stable, just rest the deck on the patio. No anchor bolts are necessary. But don't attach it to the house then. If you attach to the house, then you would want it on posts extended below the frostline. So assuming your patio is stable, build it as a free standing deck. Minor movement of the patio will not affect the deck.