Concrete patio deck over – sleeper protection?
I’ve read most of past threads on sleeper protection but I’m still not settled on which way to go. The concrete patio was put in when the house was built. It sits 3 3/4″ below the the thresholds of the patio doors. House has a slab on grade foundation and the door thresholds are mounted directly to the house slab.
The patio is uncovered and “U” shaped with roof drainage to the patio surface. The patio is sloped to direct rainwater to a channel in the concrete next to a house wall and then out to the back yard. The concrete patio was originally decked over when the house was built but was removed before I bought it.
Since 3 3/4″ vertical space is all that’s available to make the deck surface flush with the door sills, horizantal sleepers were the first thing that came to mind. Even though we don’t get a lot of rain here (20″ avg), the next thought was how do I protect the sleepers from getting soaked and rotting out like they apparently had before. With the sleepers horizontal and 5/4 deck boards, that leaves about 1 to 1 1/4″ for sleeper protection under each sleeper. My WAG is that 1/2″ of rain water would be the max depth for a hundred year rain and that the normal depth would be less than 1/4″.
EPDM is a great water barrier but as far as I know, the thickest comes at 90 mil which is .09″ and would take 3 layers cut to width & length to fit under each sleeper to keep the sleepers 1/4″ off the concrete.
I also thought of simpson like post raisers, but then you have the problem of rust even with galvanized.
At the moment I’m stuck with no simple but effective protection other than going with a total plastic sleeper system (Trex,etc.). I’m aware of PT, redwood, cedar, cypress, IPE, etc for sleepers, but the problem is the “protecter” would lie face down on the concrete surface and stay wet for a long time.
Any thoughts would be appreciated,
Ken
Replies
Whatever you use doesn't need to be exceptionally strong, just water-resistant and reasonably incompressible. I recall in the past seeing plastic decking that's intended to go over existing decking. It's 1/2 to 3/4" thick, and should do just fine under your sleepers.
Another option would be to get rubber matting (eg, playground matting), cut that into strips, and place it under the sleepers. You may even be able to find some that's perforated, for better drainage.
Roofing Membrane Solution?
How about using ice and water barrier? I use roofing membrane cut into strips to cover the ends of deck joists at connection points with hangers, etc to further prevent any reaction of the galvanized hardware with PT preservatives. Up here in New England the snow and damp weather is nasty on most materials . I would think that this technique should protect the sleepers for a good long time - if not forever. It would be a bit costly, but considering the material options you have to true long-term rot protection it probably will be comparable. Just cut the membrane into strips wide enough to cover the bottoms of the sleeper and wrap up a couple of inches (to take care of any standing water that might accumulate). Because its self-sealing you can throw a few staples in there towards the top end - it doesn't like to stick to wet PT.
Use PVC blocks under the sleepers. Use 3/4 x 1 1/2 x (width of sleeper). Place them every 12 inches.
Yeah, you probably DON'T want something like roofing membrane, as it sticks so tightly to the surfaces that it will trap water. And ideally you'd want something that's "interrupted" at regularly intervals, to allow water and air to flow sideways.
I figure the PVC would be easier to get and work with than anything else I could think of. I don't know if the dampness and humidity would still be a problem with that low of a deck. It could still be a moisture trap.
Yeah, chunks of PVC should be fairly good. The only question is how big and how close together they need to be to adequately support the stringers. And I guess there's also a question of how to anchor them.
Guys,
Thanks to all for the replies. Everyone had something good to contribute.
Based primarily on comments by Mark & Dan I searched for "PVC blocks" with little sucess. When I changed the search to "Mats" I found some very expensive PVC mats. Removing the PVC designator finally brought me to rubber mats and Global Industries ( http://www.globalindustrial.com/p/work-benches/mats-carpets/drainage-kitchen/grease-resistant-3x5-drainage-mat-black ).
Being rubber in this case, meant affordable. Based on the deck dimensions, I calculated the surface area for all the horizontal sleepers to be a little less than 70 square feet. The mats I stumbled on were on clearance at 1/2 price which made total cost $100 (without shipping). Attached are some pictures of what they look like and some of their features.
The mats come in 36"w rolls either 5' long or 10" long. When I did my calculations, I assumed the surface was stable enough to not sink measureably with weight on it (it's made to hold a number of kitchen workers at the same time) and decided that since the mat was 1/2" thick it would at least not compress below the normal 1/4" rain I guessed at and could then be cut to a 3" width instead of the full 3.5" width of the sleepers.
I like the fact that there are many holes and that both the top & bottom have "mini" standoffsthat might promote better drying & drainage.
Pvc would be easy to cut on a table saw and I don't know how a saw will get along with the rubber, but if I have to, I assume I can always borrow Occams razor while he's not using it. ;-)
Ken
Guys,
Thanks for the replies. Everyone had good points to share.
Based primarily on Dan & Mark's comments, I searchd the net for PVC Blocks but didn't have much sucess. When I modifed the search to Mats I found some very expensive PVC mats. When I searched for just mats without "PVC" I came up with several hits that looked better. It turns out in this instance that rubber mats are much cheaper than PVC mats. I'm attaching 2 pix from the website of Global industries ( http://www.globalindustrial.com/p/work-benches/mats-carpets/drainage-kitchen/grease-resistant-3x5-drainage-mat-black ) that show the mats that I think will work well.
The mats have drainage holes and are 1/2" thick. Since they are for several food service people standing on them, I'm assuming that they won't permanently compress below the 1/4" normal rain max depth I assumed. I decided that the mats would be cut in 3" wide strips to be placed under each hoizontal sleeper for the full length of the sleeper (nominal 10'). It would be possible to fasten the mat strips to the bottom of the sleeper stainless nails/brads or staples or even adhesive of some sort.
The area under the individual sleepers to be matted came out to a little less than 70 square feet. The mats come 36" wide and either 60" or 120" long. It would take 1 roll of 60" & 2 rolls of 120" (total of 75 Sq ft). They are made for either indoor or outdoor use in commercial kitchens and will withstand harsh clean up chemicals.
These mats are now on close out at half price so the cost would be ~$160 plus shipping which is OK all things considered.
The only unknown (I think) will be ripping them 3" wide. My intent would be to put them on a table saw, but they could also lay stationery on a sacrifical bed and cut with a circ saw. If neither of those work well I assume I could always borrow Ocamm's razor when he's not using it. ;-)
Ken
I don't know how or why it happened but the fact that 2 posts of mine above were both delayed by several days is beyond my comprehension. As you can see, they were written on the 22nd & 23rd but not posted until today.
Anybody know why that happened?
Ken
Dunno why it happened (other than due to some very strange software), but the same happened to some of my posts.
sure
Taunton prefers software that is terrible
The PVC blocks I was talking about you would have to cut from pieces of PVC trim, such as AZEK or Royal Moulding products.
Mark, That clears it up. I did look at some of thr PVC trim available at Home Depot but felt it was too expensive.
I think the rubber matts with the drainage holes are the way to go.
Piffin, I'd like to stay with a material (like wood) that is softer underfoot. I've had stone patios before and have been using this concrete one for several years and I just prefer a softer material, but thanks for the suggestion.
Same on the pavers & pedestals.
Ken
Mud and pavers or quarry tiles, maybe buestone
Sleepers
Have you consisdered pavers on pedastals? These are usually seen on roof decks but would work for your application.
Little if any maintenence. Here's a link.
http://www.appianconstruction.com/aws.htm
Harry