I need help on a somewhat strange problem. I have a deck which is almost level, but has a shallow low spot. The reason this is a problem is that water collects in the shallow spot and with winter coming, I don’t want to have a skating pond.
The deck is constructed of 2×6 joists hung on one side to a concrete wall using a 2×8 anchored to the wall with spacers for drainage. No problem on this side. There is a built up beam on posts based on piers supporting the joists mid-span (5 feet, total span 10 feet). There is a pony wall on the outside edge resting on a concrete footer which supports the outer end of the joists. The deck is surfaced with 2x6s screwed into the joists, running at a 45 degree angle to the joists. On top of the 2×6 decking is a layer of 1/2 inch ACX plywood glued and screwed down. Coating the plywood is a layer of BASF Sonoguard (a polyurethane water proofing). Around the edge of the deck galvinized flashing was inslalled, covered with fiberglass tape and Sonoguard before the entire deck was coated. 90% of the deck drains just fine. There is an area about 5×5 feet which ponds a thin layer (under 3/16ths of an inch) of water. What I’m looking for is advice on how to improve the drainage.
I need to either lower the edge to help drainage or raise the low spot. Is there a good (or al least less than awful) way to raise a portion of a deck like this? I’m considering using some all-thread rod and turnbuckles to locally warp the joists, does anyone have experience with that?
Any help would be appreciated. If there is a need for more information, please let me know.
Thanks in advance.
Replies
How about putting a drain smack dab in the middle of the pond? I think that would be easiest. I think your deck would be difficult to warp due to the rigidity of the surface. As an experiment you can try jacking up the low spot and see if it will even out. If so you'll have to figure out a permanent fix (perhaps sister new joists in place). You may have to cut some joists to be able to get it raised up. I'd go ahead and make that point a sligtly high spot on the deck before sistering joists in.
Strange method but not too awful
I have come up with a method that seems to be working. I took an old sawall blade and re-set the teeth to enlarge the kerf. I then ran the blade between the bottom of the joist and the top plate of the pony wall where I needed to lower the deck. The sawall with a bit of twisting and swearing, removed a small part of the underside of the joist where it bore on the top plate. I used a variety of means to keep the blade from being pinched in the cut. The result is that the outside edge of the deck can be lowered about a 1/16 of an inch at a time. When I'm satisfied with the draining, I'll reattach the joists to the top plate with some steel tie downs.
My dogs have learned a whole bunch of new words by being around me during this process.
For a 'spot' lift...
you could set up a jack to lift a small header like assembly to lift directly under the low apot. Being summertime helps so use a hot day to do the set up. Lift the jack to where the low spot actually becomes a high point. Once it's set like that for a few days with maybe a spritz of water on the substructure lumber each day, install new X bracing directly beneath the low spot in a couple rows and for several joist pockets each way past the affected area. Install it tight as you can with solid and dry lumber. Once you have the bracing installed and attached well, let off the jack and see if the spot has raised any. You can always cut all the screws between the joist and the backside of the decking to drive shims in for even more spot control.(do this before bracing) You'd be able to reattach by toenailing screws through the joist into the decking once you get everything to proper elevation.
Just get a cheap telescoping steel lolly column, put it under the low spot, and leave it there for a few months.
Or (probably better) drive plastic wedges between the joists and the planks in the area of the low spot.
I like Dan's idea of gently correcting the problem over time, but if you must install a drain, don't just drill a hole. Water will wick between layers and delaminate them and you'll have a much bigger problem than you started with. You'll need a proper drain assembly, preferably spec'd by the exposed surface manufacturer.
warp a deck
How about drilling a small hole in the middle of the pool?
If you want to try to warp the joists, you could anchor a cable at two points on opposite sides of the low point, then use a turnbuckle to tighten the cable against a 4x4 or some such placed just below the low spot, under the joist.