Existential roof deck question

11 years ago

I recently purchased a house with a large complicated roof,
that includes a two-level deck on the back of the house. This deck sits on top of some of the first
floor rooms (dining, family). The upper
level of the deck is probably 15’x30’, then there are 4 steps down to a smaller
deck area that is 10’x10’. The deck is
made of some sort of poly wood material, on top of 2x6 stringers, on top of
some sort of membrane. I’m no expert but
I believe the deck construction is wrong, in that the stringers are run across
(perpendicular to) the limited pitch of the roof. There is an upper normally-pitched roof area
that sheds water down onto the deck.
What happens is the water goes through the deck seams, and basically
forms pools behind the stringers. The
water then slowly works its way out and off the edge of the roof, but mainly it
pools. After a rainstorm I will have 1
to 2 inches of standing water below the deck, on top of the membrane, for
weeks. Absent a dry spell, I basically
have standing water 24/7 under the deck.
When I have unscrewed and lifted the deck boards I see mosquito larvae
etc swimming around. So I have known all
along I will need to do something with this deck, because constant standing
water will eventually find a way in.

Sure enough, this winter (the house is in the NorthEast - LOTS
of snow, lots of freeze, thaw cycles), the lower deck area had some sort of
failure and I ended up with water coming through the ceiling below. I stapled a tarp over the deck, redirected
some drains, and the water stopped.

This week I had what I genuinely consider to be a very
quality roofing company come out and give me a quote to remove both decks
(upper and lower), remove the existing membrane, check for pitch, install new
membrane, flashing, and trim. Not
including replacing the deck, and not including any carpentry to re-pitch the
roof should it need it, the estimate was $25k.
This is considerably more than I was hoping to spend. And yes, the roofer agreed the deck was constructed wrong (perpendicular stringers).

Going back to the drawing board, I am considering not
replacing the membrane on the larger upper deck area (since it has not leaked), just having the upper
deck removed and rebuilt, and then also having the lower deck area and the
underlying roof membrane replaced, since that is where there was actual
failure.

My question is this – should I be talking to a roofing
company about all the deck work (removal, replacement), or talking to someone
else (a “deck specialist”?) about the deck work, and just have the roofing
company do the actual roof work? Or are
roof decks actually best handled by roofing specialists, because they are also,
well, roofs?

Yes, this is my first house…

Thanks for any advice

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Comments (5)

klem1
11 years ago
You are getting off on the right foot by thinking this through before starting construction. Good roofers are hard enough to find when buying 3 tab composition,and even good composition roofers seldom understand membrane so stick with factory authorized membrane contractors. Call manufactures for lists of factory authorized installers. I would probibly remove the lower deck then have roofer inspect it to see if it can be repaired or needs replacement. Ask roofer for a referral to a deck installer who understands membrane. I would be inclined to have deck installer follow roofer's reccomendations but would put little stock in what most deck guys have to say about roofing. I'm not even sure the manufacture will warranty their product with a deck installed over it so better ask. Naturally,you want the roofer to take a look at upper deck while there for the lower so ask if the upper deck should be removed. I can't believe anyone would sit sleepers directly on the roof rather than blocking them to allow water to drain. Are you certain leaves and dirt havn't clogged drains beneath sleepers and need cleaning?
aztec123
Original Author
11 years ago
Well, thanks for the answers. I had pulled up about an eight foot width of the deck boards and there was no visible drainage mechanism. I don't think it's denial so much as a reconsideration of what genuinely needs to be done, now that I have an idea of how much it may cost. I really had no idea before. To the extent I move forward with getting an additional quote, I'm wondering if I should change what I am having quoted. What I think would be optimal is to have someone (deck guys?) carefully remove both decks. Then have the roofer inspect both roofs. Since the upper (larger) roof has not leaked, and has actually not leaked despite having several inches of standing water on it 24/7, I'm thinking it may be OK. If the roofer thinks it looks OK, then have the deck guys install a new deck on the upper roof with proper drainage. On the lower deck, I guess I can have the roof guy opine on 'fixabiity' (he actually raised that as a possible, cheaper, path for me when he was inspecting the roof), but if I want real peace of mind - then have the lower roof replaced. And then have a new, properly drained deck installed on the lower roof as well.

By (potentially) eliminating the replacement of the larger roof, maybe I get the cost down a bit. I guess my question is - am I thinking about this right? Is it reasonable to expect roofing / deck specialists to work like this, or is it not economical for them?

The only additional factor would be that the remaining roof on the house (asphalt shingle) is in its last few years of life (based on surveys of house, and general appearance). The prior homeowners passed along several estimates they had done on replacement (including one from my quality guys - that's how I found them), and I had an additional 'ballpark estimate' done by another firm that was doing some work on adding a dryer vent, and it looks to be a $35k to $45k job (based on the estimates). I'm hoping to put this off for 1-2 more years for cash flow reasons. Is there any benefit to hiring one firm to do both, though not at the same time.

Thanks so much for any thoughts or guidance. I'm really not trying to pinch every penny here; just want to spend $ efficiently.
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PRO
Joseph Corlett, LLC
11 years ago
No standing water on any roof, leaking or not, especially in a freeze-thaw climate.
PRO
Sombreuil
11 years ago
We redid one of these a few years ago, made the walking deck in 4x4ft panels (mahogany) so they could be removed to clean underneath. The sleepers also need rubber pads where they sit on the membrane so they do not abrade through.
Casey
aztec123
Original Author
11 years ago
Great idea. I was thinking of asking to have access panels or ports built in for cleaning, but making it so the whole thing can be taken up every few years for cleaning is even better.