QUESTION & ANSWER
Q How can I mount newel posts to a deck on
a flat roof without cutting into the roof?
Paul Nichter, a contractor in
Islesboro, Maine, responds: I’ve been building wood decks
with safe railings over flat EPDM roofs on the rainy coast of Maine
for over 15 years without compromising the waterproofing. I avoid
the traditional method of bolting a 4x4 post deep into the framing,
as it penetrates roof surfaces and increases the possibility of a
leak long before either the decking or the roof membrane is worn
out from age.
My approach to keeping water out while achieving good resistance to
lateral forces is two pronged and is based on the deck being built
on sleepers above the roof. First, I design rooftop decks with
corners every 6 feet to 12 feet. Corners stabilize the railing, as
lateral loads aren’t borne by just one post; rather, the
loads are shared with adjacent posts.
Second, I mount the posts with hardware that bolts to the top of
the deck (Figure 1). Each post is a hollow box that fits over a
vertical threaded rod. The rod threads into a 3/4-inch nut welded
to the center of a 1/4-inch-thick steel plate. I secure the plate
to the deck with four 2 1/2-inch RSS Structural Screws (GRK
Fasteners; 800/263-0463, grkfasteners.com), but galvanized
lags would work too. The screws or lags should be as long as
possible without protruding from the bottom of the sleepers and
putting holes in the roof membrane. It is essential to place 2x12
blocking on the flat between the sleepers at post locations so the
lags will have something solid to bite into.
Figure 1. A threaded rod between one plate
screwed to the framing and another plate at the top of the post
firmly connects a hollow newel to a rooftop deck.
Once the plate and rod are installed, I stand the post in place.
Usually, some scribing and fitting are needed to make it stand
plumb without wobble or lean. Then I run a bead of construction
adhesive on the bottom of the post and seat it on the deck
A second piece of 1/4-inch plate fits at the top of the post in a
rabbet cut for that purpose. The threaded rod runs through a hole
drilled in the plate, and the assembly is drawn tight with a nut.
The nut tensions the threaded rod, compressing the post and
creating a solid connection.
I’ve also used manufactured posts from Fypon (800/446-3040,
fypon.com) and WeatherBest
(800/343-3651, weatherbest.com). One advantage of
using manufactured posts is that their makers have tested them for
Replace the Framing or Just
Q I’m getting a lot of requests for
deck remodels, and I’m not sure how to price the jobs, or
whether it’s a problem to reuse the existing frame. Do you
have any guidelines or points to consider?
Greg DiBernardo, a deck
builder in Waldwick, N.J., responds: At least half of my deck
projects are “re-skins,” where worn-out wood decking,
railings, and staircases are removed, but the existing joists are
left intact to be used as a base for new (usually synthetic)
decking and railing.
For obvious reasons, if the clients are willing to pay for a
complete demo and rebuild, the deck will be better for it. But a
re-skin can be a great lower-cost alternative, provided the
existing framing is up to the task. If the clients are satisfied
with the design of their existing deck, a re-skin can get them a
renewed look quickly. Plus, I’ll often change the shape by
clipping a corner, adding a new staircase, or extending the
While I’m taking measurements on the sales appointment, I
make a careful inspection, looking for obvious signs of rot,
mildew, or decay on the deck surface. More often than not, if the
deck boards have begun to rot, the framing beneath them is also
rotted. Simple things like a leaky gutter or downspout in a shady
corner of the deck can destroy an isolated section of an otherwise
structurally sound deck.
If I can access the underside of the deck, I’ll poke and prod
to identify framing that needs to be replaced. I’ll also note
the cause of the rot and add the cost of remediating it to my
proposal. If the root of the problem is not corrected, failure down
the road is guaranteed.
While I’m under there, I inspect the ledger to make sure
it’s flashed and fastened to the house properly; I make sure
all joists have hangers and that any hangers present are in good
condition; and I check for signs of rot between the layers of
built-up girders. I also check built-up girders to ensure
there’s no separation between the 2x10s or 2x12s. If there
is, I’ll draw the layers together using TimberLok screws
(FastenMaster; 800/518- 3569, fastenmaster.com).
It’s critical to have access under the deck to ascertain
whether the framing is worth reusing. My rule of thumb is if the
deck is too low for me to get underneath to inspect, the framing
has to be demolished and rebuilt. Generally, the low-to-ground
decks of yesteryear weren’t built with airflow in mind. Most
of such decks I’ve come across are examples of rot, mold, and
decay. There’s no point installing a modern synthetic decking
product with a 25-year warranty over a frame that’s past its
Although my inspection is thorough, some issues may remain hidden
until the decking and railings are removed. Therefore, I include a
clause in my contract permitting me to replace framing members at a
fixed cost as I deem necessary once I begin.
Another important consideration is how the existing decking is
attached to the joists. If the decking is nailed down perpendicular
to the joists, it can be pried up with little damage to the joists.
Removing diagonally installed nailed decking is usually as
harmless; it just takes a bit longer.
Screwed-down decking, though, can be difficult to remove — be
warned. Unscrewing each fastener usually doesn’t work because
the heads strip. Prying up the boards may or may not be possible
and usually damages the joists, anyway.
The fastest way to remove screwed-down deck boards is to cut them
on either side of the joists, letting the pieces of decking fall
between the joists. The 1 1/2-inch-long pieces of decking remaining
on the joists can be removed with a prybar, leaving the screws in
place. The fastest way to remove the screws themselves is to cut
them with a grinder equipped with a cut-off disk.
Most of the time, if a deck has screwed-down decking, I trash the
entire deck. I cut the decking with a chainsaw run in between the
joists; then I cut the joists, now with short pieces of decking
attached to them, into manageable pieces to cart to the trash
I always tear off existing staircases and rebuild them to my spec.
I have never encountered a staircase I couldn’t build
stronger and safer. Besides the safety issues a wobbly or rotted
staircase presents, most of the staircases I come across do not
have the proper tread width to accommodate typical 5 1/2-inch
synthetic deck boards, with a 1/2-inch-thick riser and a 1-inch
I also make sure the old stairs landed on a solid surface such as a
concrete slab or pavers. If the existing stairs land on the ground,
I include the cost for installing a 4-inch-thick concrete pad for
my new staircase to sit on.