|
|
Re: Deck strength for a hot tub?From: info@builderswebsource.com
Category: Decks
Remote Name: 63.198.181.43
Date: 01 Sep 2002
Time: 05:01 PM
CommentsYou are installing a hot tub and want to know whether your deck framing is sufficient. The hot tub measures: 93" x 93" x 40"D with a 1,200 lb dry weight, and 500 gallon water capacity. Your proposed deck specs are: 16' x 16' overall size with 6" x 6" Posts on 8' centers (6 of them located in the middle and outside edge of the deck); (2)2x12 beams (on middle and outside edge). The part that is fixed to the house is hung with joist hangers only (2x10" joists on 16" centers). The tub is located near the house (the part that's supported by joist hangers). Based on our understanding of your description, the hot tub dead weight equals the dry weight plus the loaded weight (assuming 500 gallons of water). Since water weighs roughly 8.33 lbs/gallon, this gives you a water weight of 4,165 lbs. Adding the dry tub weigth of 1,200 yields 5,365 lbs. Since the area of the tub is 60 square feet, this amounts to 89 psf of dead weight. The minimum live load is 40 psf, and doesn't account for other loads, such as snow or wind loads. Assuming these loads are evenly distributed over one corner of the deck and you have 2x10 joists @ 16" centers spanning 8' without intermediate supports, your proposed deck specifications check out fine (assuming Douglas fir or equivalent). Other woods will yield different results. We do recommend using at least a 3x12 pressure-treated ledger against the house, anchored into the wall (into a solid ridge board behind the wall or into the foundation) at 16" centers with heavy-duty galvanized or stainless steel lag bolts. The method and size of lab bolt installation should be computed by a licensed structural engineer based on the proposed embedment and material. We also recommend using heavy-duty joist hangers, such as Simpson HU210TF (which have a top flange and face-mount flange) or HUS210 (face mount only). Don't take a chance with less expensive, lightweight joist hangers. If the top surface of the deck is more than a couple of feet off the ground, you'll probably need additional lateral bracing to prevent racking. Furthermore, make sure your cement pads are designed properly to withstand the weight of the deck without settling. Overall, it sounds like you're on the right path and have a conservative design. Pay particular attention to the ledger, however, as if this fails due to insufficient anchorage, you'll have a mess on your hands, not to mention a potential safety hazard. Good luck with your project. Builders Websource.
|
|
