Backalong you gave me a suggestion that seemed eminently sensible
concerining the use of SBS on the roof of a shed attached to a garage.
Well, I spent the last month pretty much tearing down the shed and
rebuilding it and now it's ready for a roof, so I went out to get an
unsanded nonadhesive base ply for SBS and found that no such is sold
north of Baltimore, at least not under any brand name that I can
So, checking the GAF site I find that Liberty can be applied to ASTM
D226. The local code also requires that ice and water shield or an
equivalent be applied directly to the decking on a low slope roof
The local guys generally if they use Liberty apparently put Liberty
cap directly on Weather Watch.
Now, I have a roll of Deck Armor, which I was going to use for
underlayment on the main part of the roof. Deck Armor meets D226
structural requirements. What I'm thinking about doing is putting
Weather Watch down on the shed roof to meet code, then Deck Armor over
it and Liberty Base and Cap on top of that, using the Deck Armor as
the base layer instead of the StormSafe or Liberty Base MA products
that are purpose-made for that use but which are unavailable here.
Am I shooting myself in the foot to do that? The only real risk I can
see is if the Liberty Base doesn't stick to the Deck armor and if that
happens then I get to pull it off and replace it with somethine
else--if it's not stuck down then that shouldn't be all that horrible
a job. I wouldn't expect to be an issue though--the adhesive on
shingles will stick to it so I'd assume that the Liberty Base would as
The alternative is to have a friend in Atlanta get a roll of StormSafe
or Liberty Base MA and send it to me. I'd rather avoid that though.
I wondered if you changed it as you mentioned shingle in the second
Not at all. I had to take a moment and check on that as roofing
vendors sell materials that are engineered for different regions.
They blend the products they use differently to resist the problems of
the area (for example, it is already 100 degrees during the day here,
but it won't snow, and may never freeze this year) and sell the under
different product names.
The 3 ply roof you specified should work great if you install it
exactly as you described. Any experienced roofer would be pleased
with your detailing.
A couple of notes on the installation.
The ice&water shield/barrier around the perimeters directly adhered to
the deck is good. The Deck Armor is good (this appears to be a
treated polyester reinforced scrim as opposed to a cotton fiber
asphalt dipped product) but it will need help. As you build your
bases, it is just like building your house. The next layer up is only
as good as the layer below it.
Since this is a small roof, I would not go to the expense of the
plastic capped nails for the Deck Armor to secure it to the deck. But
it must be secured well as the "base" for the SBS base sheet. Buy a
box of 1 1/2" or 2" tin caps and nail off the roof with your nail gun
(or by hand) with your nails not being more than 16" inches apart. If
you have wind concerns, shorten that distance to no more than 12"
apart with tin caps under every nail. We usually staple the sheet
down with the tacker and then go back and tin cap the material.
Don't be stingy with your nails and tin caps as they will actually be
holding the roof in place. When you work your perimeters, put the
nail/tin caps no more than 8" apart to lock down the wind affected
We actually put small roofs on (less the ice&water which isn't needed
here) using 30# felt as the first base to dry it in, then a water
repellent polyester scrim sheet (from a lot of manufacturers) then the
cap sheet on top.
We have found a couple of things that really make the roofs last well,
and don't cost much to do. We double the base sheet. This provides a
little more roofing underlayment to move and work with the roof, and
it helps the surface weather better. I honestly don't know why, but I
got that detail from Allied Signal/Honeywell many years ago, and it
works great. We stagger the laps on the underlayment so that no
joints, horizontal or lateral, are ever in line or even close. We
nail the first layer lightly enough to hold it in place, then nail the
snot out of the second layer.
We also nail the lap edge of the cap sheet that is covered by the next
sheet. You will have a "selvedge" edge which is the top of the roll.
Nail this down (we use a gun) even though it is self adhered. Nails
go 6" (!) apart along the selvedge and are covered by the next sheet.
This is especially important when you have even a minor slope, but at
1 in 12, you could probably nail every 8".
Next, we don't use official/recommened SBS perimeter metal edge. We
had nothing but problems with it, so it isn't used unless specified.
We found that the SBS will shrink as it grows old and will recede from
the perimeter of the SBS edge, causing leaks. We use 2X2 drip edge (a
standard material), nailed every 16", each joint lapped 6" and sealed
with adhesive (NP1 or Sonneborn) before securing the lap joint.
This is actually a pretty standard commercial detail. Make sure you
prime all the metal or your SBS will come up in just a few months.
Run your cap and base out an inch from the metal.
Should you decide to add venting to this, if you use a turbine, prime
the metal and install the SBS on it. Then come back and caulk with
NP1 around the collar. Trust me on this one. If you add ridge vent,
lap all the way over the ridge to have a dry lap.
Cut your slot, and use shingles to finish it off, not SBS.
armor > and if that happens then I get to pull it off and replace it with
I wouldn't > expect to be an issue though--the adhesive on shingles will stick
to it so I'd > assume that the Liberty Base would as well.
Oh, don't worry about that. You will be surprised at how well it will
stick! If it is a warm day, you will think you are applying bubble
One more thing. When you are ready to start installing your base
sheets, take out the cap sheet and roll it out on the driveway (NOT
the yard - the moisture will screw it up) and leave it out in the sun
for an hour or a little more. Let it get good and warm, but not too
hot to handle. Rolling it out on the driveway allows it to relax from
being tightly wound on the core, and it will all but eliminate
wrinkles and seized spots.
When applied, you may have a spot that doesn't adhere for one reason
or another. Buy a tube of roofing tar in a tube, lift up what you can
in the offending spot and shoot it with the tar. Put a weight in the
spot and wait a week. It will be adhered.
SECRET ROOFER TRICK: If you get a bubble, don't worry. Make a tiny
hole in the bubble and try to step on it to make it adhere. The hole
will let out the air in the bubble, and then you can put a tiny spot
of sealer on the hole. But for a stubborn bubble, take a sharp blade
in your utility knife and cut a small slice into the bubble on one
side. This is a vent; cut a slice large enough to get your caulk gun
nozzle into it on the other side of the bubble. Squirt adhesive into
the hole, making sure the
vent is open. Work the adhesive across the bubble towards the vent
hole. That should take care of it.
Let me know how you do!
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