I would imagine the first thing would be to see if there is something dead under there and remove it.Lime,the powdered stuff from the garden store not the little green things,will help to remove the odor if it is a dead animal once it has been removed.

It sounds to me like you need someone to help you remove the dead animal first, then work on the odor (there are enzyme products for this).

My first concern is that it's not something like a gas leak but I'm pretty sure you're aware of gas smell. As long as that's not an issue then unfortunately there's not much to do until you eliminate the cause of the odor, assuming it's a dead creature, either by physically removing it or it rotting away over time. I'm sure you would prefer a quick cleanup. Once the problem is removed, the smell should dissipate fairly rapidly outdoors naturally or remove (and possibly replace) some dirt, or treat with something.

Could you pull up a deck board or two in the middle and get a view under the deck? Depending on the shape maybe you'd have to do it in more than one spot.

That's about all I can think of right now.

No, it's definitely not a gas leak.

The deck is large -- the main part of it is over 500 sq.ft. And we can't just pull up a deck board or two because of the way it was constructed. There isn't a single nail showing from the top. I don't even have any photos to show how it was done... but the nails are in the sides of the boards. We'd have to pretty much destroy it to take a few boards out.

We're in a suburb of Sacramento, and it's been in the 90s for the past several days, and is expected to be in the 90s for the rest of the week. So, I guess all I can hope for is that the heat will make the dang thing disintigrate more quickly...

Liquid live bacteria. Sold at Janitorial Supply companies or Restoration companies. It will digest the bad bacteria and solids that cause the odor. Where I work it is sold to control Skunk odors, mice odors etc. as well as for septics etc. It would have to be sprayed over the area so if you don't have access I don't know how you'll treat it.

I believe Mush is on to something...gonna keep this info if it ever happens around here...

I know EXACTLY the smell you're probably smelling...we had a dead mouse in our garage...We couldn't find it and the smell was sickening...we lived with that smell for about six months and after continual spraying it went away...I guess it finally withered up...cause we still haven't found the BIG OLE SMELLY STINKER...

I hope you find a remedy soon...it sure makes for not wanting to sit on your deck doesn't it!

Living near Sacramento, where it is hot, you might want to call in a professional. I can't begin to imagine living with that smell for a few weeks. I once had a mouse in a wall in my house and after it stopped scratching to get out, the smell was offensive for about 3 weeks.

I'm trying to picture a deck that isn't accessible from underneath, guess I've never seen one like that.

I just opened the hall closet to get out the fish food and was nearly knocked over by a huge whiff of decomp. Yep, dead mouse, pretty squishy, rigor was over, been dead a while. (Hey, I don't watch all those shows for nothing!) Scraped him up and disposed of him outside, pee-ew!

An outside dead critter- yeah, figure a couple of weeks, longer if there's little air flow. It's an eternity if it's IN the house somewhere!

Doesn't your deck have an access door, something like they often have for crawl spaces?

If not ... maybe you'll want to make one, if there's a location available where it could be placed.

ole joyful

Thank you, Mush, for that suggestion! We will definitely look into getting some of that stuff.

"I hope you find a remedy soon...it sure makes for not wanting to sit on your deck doesn't it!" Oh, Liz, you're so right!! We have incredibly comfortable furniture on the deck (it's by O.W.Lee - the Montrachet wrought aluminum collection), and I would so dearly love to be sitting out there reading good book on my Kindle, sipping a glass of wine and listening to the watefall into the pool...

I know that when the words "redwood deck" or just the word "deck" is used, most folks envision something elevated. But our redwood deck is ground level. Because of the way the yard has to be graded (for the water runoff swale), we couldn't do a concrete patio. Well, we could, but in some places it would have to be three feet (or more) thick. So, we opted for a redwood deck (which I prefer, anyway). Here's a photo of what we refer to as the "east wing" of the deck. (It's so named because it's on the east side of the house.) There is a walkway that connects it to the large main deck, but it's all on the same level. This photo was taken in 2004, when the yard was torn up because we were putting in a pool. All that dirt that you see heaped up in the upper left of the pic is part of what came out of the hole that was created to become the pool -- that area of the yard is actually the side yard on the east side of the house. Our lot is sort of pie-shaped so the side fences really angle away from the house rather than run parallel to it. Anyway, hopefully this will help you folks to understand how our deck is constructed and why we can't just get under there to find out what's going on. If you look closely at the photo, you can see that there aren't any nails or screws showing, which is why we can't just pull up a few boards to look underneath. Each board is nailed to the board next to it by nails that are in the sides of the boards...

Beautiful deck. I knew what you meant! lol

how much room did they leave between the boards? Doesn't look like much! Not as much as they leave between the boards up here. Have you been able to pinpoint the stink? I was thinking you could spray something down under the deck between the boards, but there's not much space.
the only thing I can suggest it to dig down below the fascia board so you can peek under the deck and take a look with a high powered flash light.

The only suggestion I have is to use a saw to cut the nails, so you can remove some boards to look. You will have to pin point where the smell is strongest, tho. Something has been able to get under it and die. Look for holes in the dirt around it, any tiny gaps, ect, where mice or moles could squeeze thru, stuff like that.

Wishing you lots of luck.

If you can't do this yourself, I'd call around and find someone who builds decks and ask them to remove a board or two and then fix it back.

I know what you're talking about on the construction, it's called blind nailing. They toenail it. You couldn't just saw off the nails easily. You *could* pull up a couple boards but it would be a shame to damage that beautiful deck. Essentially you'd cut a hole in it.

Other than wait it out, my only thought right now is if you could call a sewer outfit or some place that has one of those cameras that they put down sewers to probe around under the deck and look for the cause. Then decide what to do. Knowing the exact location you could cut a small hole, OUCH, I know, but it could be repaired to look pretty good. If it bothered you, build a matching planter, birdbath or something to cover it up.

If it wasn't so big I'd suggest jacking it up for access, but that would be quite a project in this case too. Have to go slowly, block it as you go, and possibly it's attached to the house and if so, you wouldn't want to do this.

Hope you find a solution... quickly! :)

Hey, I posted to this last night and now it's not here, crud!

Beautiful deck, Lindsey, I've never seen one like that. Good luck with the smell, I hope whatever died under there was tiny!

wait it out :o) Sooner or later it will stop smelling

There was a terrible odor in our den near the fireplace and a window- we took up part of the carpet and the flooring to try to find the source- didn't. A critter company came out and dusted lime as far under the floor as he could and we just had to wait it out. In the spring we were pruning a holly bush that was just outside the window and found a cat that had died right next to the foundation. We never once thought to look on the outside.

The source of the smell is definitely outside the house, thank goodness!!

Hubs and I are both strongly opposed to cutting any holes in the deck. If we can find somewhere around here where we can buy some of the liquid live bacteria that Mush suggested, we could easily apply it because the deck boards are not so tight that water won't go through them. After all, when it rains we don't get a pool of water on the desk and we can hose it off easily, too.

When the deck was constructed, some of that special black fabric was put down first, to keep weeds and any other vegetation from growing under there. There are concrete piers that are cemented to the ground to which the joists are attached. So jacking it up wouldn't be easy at all. (Even though the deck is actually not attached to the house itself.)

So, I'm thinking that if we can't find any of the liquid live bacteria, we'll just have to do as Maybee says and wait it out! Yuck!

When you mentioned "black fabric" it struck a bell. A friend used to put this stuff down in flower beds to kill weeds, then pile mulch on top. One time she told me she wanted to tear it up in this particular area, but when she went to lift it, it "smelled like a sewer under there" (under fabric).