I am rebuilding the covered front porch deck and joist system on my
raised floor wood frame house. The new joists will be installed
between two sheathed walls, so I'll be using a ledger board on each
side. The span is only 6', so I'll be using 2x6s 24" o.c. A couple
questions on the ledgerboards:
1) Would 3 20d nails per stud 16" o.c. be sufficient to hold the
ledger board to the cripple wall, or should I use lag screws? If
lag screws, what size and spacing?
2) It seems like it would be simplest to set the ledger board just
below the bottom of the joists and just let the joists bear on the
top of the ledgerboard. Then I would toenail the joists to the
ledger. The alternative would be to use joist hangers and set the
ledgerboard at the same height as the joists. What are the pros
and cons of each method?
typically, deck ledgers are lagged. i like the fastenmaster ledgerlok
(google). without consulting an engineer, you could put two every 16"
and it would be more than plenty. if the deck is between two walls,
the nails would probably be OK (don't have to worry about it pulling
away from the house), but the fastenmasters are so slick that unless
you need to give your elbow a good workout, I would use them.
if you set the joists on a ledger, you will need to block between the
joists to prevent them from rolling over. also, in actual practice,
getting enough bearing on a 2x ledger is tough unless you are very anal
about your joist length. for that reason, when i have set joists on a
ledger, i have used 4 X material, per an engineer's instructions.
also, you have to prevent the deck from pulling away from the wall
somehow. so with all that in mind, joist hangaring into a ledger is
quicker and easier.
Indeed, I found section 1604.8.3 of the 2006 UBC, which states:
1604.8.3 Decks. Where supported by attachment to an exterior wall,
decks shall be positively anchored to the primary structure and
designed for both vertial and lateral loads as applicable. Such
attachment shall not be accomplished by the use of toenails or nails
subject to withdrawal. . . .
Thanks for the suggestion. Their flyer nicely quotes the NDS 2001
design values for 16d, 20d and 40d nails and 1/4", 3/8", and 1/2"
lags. Of course, assuming there may be a lateral load on the ledger,
using nails is out by the above requirement.
Obviously this is out now, because of the prohibition on toenails, but
that issue aside, if the joists are attached to the ledger at the
bottom and 3/4" T&G boards at the top, isn't that sufficient to
prevent rolling over?
the connection at the deck boards & the ledger actually give very
little resitance to the "parallelograming" of the entire deck / joist
blocks placed between the joists; on top of thel edger & under the deck
boards act like little "shearwalls" and prevent rolling
If you want to convince yourself nail up a small (2 joist) system (only
about foot long joists) w/o blocks & see how little "roll" resitance
exists...then add a block
3/4" deck boards are kinda thin even for 16" oc joists........a heavy
persons foot fall will flex them a fair amount.
I usually do a "reasonable" test before I settle on a design (unless
calcs or experience tell me things will perform)
Also T&G (IMO) is not a good choice. for deck boards
I'd use 2x material & allow side gap & end gaps such that water &
debris can easily clear / dry.
Ahh, of course, I was only thinking of a single joist turning over,
not the whole system.
Well, this is a covered front porch, it seems like individual boards
with gaps would be too informal a look. The original deck was T&G,
and it was nice being able to sweep/vacuum it. I am planning to pitch
the porch 1/8" per foot to allow for drainage. Perhaps I should look
for or make nominal 5/4 T&G deck boards for 16" o.c. joists.
Thanks for all the advice.
I'd use 1/2" lags ......one per stud just make sure you hit them.
I'd also agree with Marson...joist hangers are probably faster & easier
than toenailing & blocking.
Pro....less headroom used up with joist hangers Only an issue where
impostant) , no blocking to cut / install
Con...cost of hanges in installation hardware....I use SS square drive
I think I'd but the joists closer than 24" o/c...more like 16"
24" o/c might allow the deck boards too much flex for human perception
1/2" lags in 0.5 SG wood are good for 200 lbs in single shear
according to the 2001 NDS as quoted by fastenmaster. My 6' span porch
deck is subject to a design live load of 40 psf and a dead load of say
10 psf (probably less), which gives 150 plf on the ledger, or 200
pounds per 16" segment. So looks like your suggestion is right on the
Good point, what is the allowed span of 3/4" T&G redwood boards? Or
where can I find this information?
So actually I lied here a little. One side is an exterior wall of the
house, the other is the long side of an L-shaped wall defining the
porch and supporting the porch roof. That side need not be sheathed
on the porch side.
So what are the pros and cons of (a) using a ledger board with joist
hangers and (b) just running the joists past the studs in the wall and
securely fastening them (a la balloon framing)? This is assuming that
the joist spacing and placement would allow for (b).
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.