2012年6月19日 星期二

Building Your First Deck For Your Home


This article will give you a good idea of what's involved in building a deck. There are always quicker ways to do things and you will learn them and invent some of your own as you proceed with your project. Always work safely and make sure you have a good firm footing underneath you. A trip or slip with a power tool can be dangerous. Let's get started with some of the tools you will need for your project.

TOOLS NEEDED- Electric saw, hand saw, hammer, 8,10 and 12 penny common galvanized nails, 4' level, string line, pencil, measuring tape, tripod and level gun (rent at your local rental store by the day), 5# sledge hammer, SAFETY GLASSES and a good pair of work gloves (your hands will love you for it).

LUMBER NEEDED-If you cannot figure out from your plans what lumber you need, most lumber stores will do a 'take-off" for you and sell you only what you need for your project. Many pre-made plans contain a lumber list right on them! Get some extra 2 " x 4" x 8' long lumber for temporary supports, etc.. If you buy pre-cuts studs, they are even cheaper. You buy the cheapest thing they have as it is only for temporary use. You can always use them for something. Framing anchors are needed for the post bottoms ledger joist connections and today they make many types of handrail anchors if you want to use them. Look at the anchor chart at the store and see what they have.

Building a deck isn't as hard as it may appear. All decks have the same basic components, just more or less of them. Posts, piers, floor joists, decking, handrails and stairs are the major pieces of any deck. Footing piers are covered in my e-Book footings so we will assume you already have footings in place and are ready to frame your deck. Building plans are available at most major hardware and lumber stores and give you tons of layout info even if the deck shown isn't exactly the size you want. Almost everywhere in the country today, building departments want your support posts to remain above grade. When you check with them as to whether you need a building permit or not, ask them. They will be glad to tell you what they expect to see. Remember, if you fail your inspection, they have to come back again and that is extra work for them. They want to pass you the first time!

The companies that provide pressure treatment to your posts have found the posts last a great deal longer if they are kept from having contact with the earth. I prefer this method as well and have found it to be true. Your pier footings or tubes should have been poured 2" above finished grade and this is where your new deck post will sit. You do not want to sit the post directly on top of the concrete without some type of anchor to hold it in place. Several brands of metal anchors are available at your lumber and hardware stores. If you are using a 6" x 6" pressure treated (PT) post, purchase the number of anchors you need, one for each post. One type is a flat plate with a center nail hole and 4 'feet" or points sticking out from the bottom in each corner. Place the anchor on the bottom of the plate with the "feet" or points facing downward, away from the post. Nail a 10 penny common nail through the plate into the post to hold it there while you work. Stand the post upright at the line marked for the corner of your framing. The "feet" will bite into the concrete footing pier from the weight of post and make it almost impossible to slide it around. Once the weight of the deck is on the post, it will not move. Repeat this work for each post for your deck. There are many types of post to footing anchors available. Some require a bolt be set in the concrete pier and the anchor then bolts to that and then nails to the post. All work equally well.

Now with all your posts ready, we'll assume you have 4 for this deck, you can either stand the posts into their exact positions as closely as possible and use some 2" x4"" lumber to brace them in an upright position until you complete the sub-floor framing for the deck or stand one post, frame to it, stand another post, frame to it, etc. I suggest you stand all the posts first to check your deck layout before you get half of it framed and find out you made a math mistake in your layout.

As you frame along to your plans, the old carpenters adage that measure twice, cut once, is still correct today. Lumber is expensive. Don't waste it and don't be in a rush! Wasted lumber costs money and a slip or fall with a saw or sledge hammer, can cause serious injury. Be careful while you work but enjoy it. Your plans show the size and number of post required. At this point they should all be standing, temporarily braced. The next item to be installed is the ledger board on the house if it is not already there. This board(s) will run the width of you deck minus 3". The exterior band joist nails to the ends of the ledger board for a neat finished look. The ledger board is always one size larger than your floor joists. 2 " x 8" floor joists, 2" x 10" ledger board. After removing the required siding to allow the ledger to be installed, nail the ledger with some 10 penny commons in a few places just to hold it there. Now a little math work. If you are using 2" x 6" decking lumber for your deck floor, set the top of the ledger board, 1 5/8" below the door sill to the deck. 2" lumber is actually 1 5/8" thick. If you want a 4" step out the door, set it 5 5/8" below the door sill and so on. With the ledger temporarily nailed in place, layout your joist locations on the ledger. Don't forget the exterior band joists on each end. Your plans will tell you if the joists are 16" on center (O.C.), 12" O.C. or whatever the design calls for them to be. Using your measuring tape, starting on one side of the deck and measuring from the outside of band joist, the next joist goes 16" ON CENTER, not the edge of the board. More than likely it will not come out even spaces. One space will be smaller. DO NOT MAKE THEM LARGER! The lumber is sized by design to carry a certain weight and making the joist spaces larger could cause a collapse of the deck.

With the joist layout complete, you can now see the spaces between the joists. Starting on the end bays or spaces, drill 2 holes, one above the other equally spaced in the ledger for lag bolts. Each bay after the end bays, gets one bolt not two. Stagger the bolts up and down from the top to the bottom so one bay the bolt is 2" down from the top in the center of the bay, the next is 2" up from the bottom in the center of the bay and so on. Pre-drill a pilot hole for each lag bolt. The lag bolt must be long enough to pass through the ledger and house plywood and into the house band joist behind. An example would be using a 2" ledger, ?" plywood on house, and a 2" band joist on the house, you would need a 4" lag bolt. Remember, lumber is 1 5/8" not actually 2". Here's where and electric impact socket gun comes in handy. You need to use a socket and ratchet for this work but it is possible with a plain old wrench. Either way, wrench or socket, your arms will be worn out when you have them all installed. The electric impact gun makes very short work of this task.

Ok we have the ledger installed, joists laid out on the ledger and it is time to build and set the beam across your piers or top of your support posts that will carry the outside end of the floor joists. The beam shown on the plans could be shown as 3- 2" x 10". You have to construct a beam from 2" x 10" lumber, three pieces thick, as long as your ledger board on the house. If your deck is 12' long, just nail 3-2" x 10" x 12' pieces together and your done. If your deck is 18' long this probably will not work. Some long length lumber is available but is very costly. It is cheaper to get 4- 2" x10" x 12' and 1- 2" x 10" x 8' piece. You cut one 2 " x 12" x 12' in half making two 6' pieces. Layout one 12' and one 6" piece end to end. Now layout another 12' piece over the 6' piece below and lap 6' onto the first 12' piece. Fill the 2nd layer with the other 6' piece you cut. Nail these together with 10 penny common nails. You now have two pieces 18' long, nailed together with the joints in the wood not lining up. NEVER line up the end joints. When nailed, place the last 12' piece over the 2nd layer starting from the 6' end and lapping over the joint. Fill in the last end with a cut 8' piece 6'. You have only 2' of wasted wood so far.! When nailed with 12 penny commons to the first two layers, you have an 18' long beam, securely nailed together with NO joints lining up. This is very important if the beam is constructed from pieces. Last note, every board has tree growth rings showing on the ends. Place your first layer of both boards so the rings point the same way down. Place the 2nd layer so the rings face up. Place the 3rd layer so the rings face down. When the boards dry out and try to warp, this alternating of the rings will help keep your beam straight and not warp or bow. OK here's where you need some extra muscle. You must at this point do a little math again. With the support post standing, you need to figure how long the posts need to be, plus the beam, plus the floor joists and then the decking. So again: (* actual size)

floor joists 7 5/8"*

beam 9 5/8"*

total 17 1/4"* OR 1'-5 1/4"* ALL TOGETHER.

Remember you have to add the thickness' of the pieces you are using. Above is an example only.

Now is the time to install the framing anchors. Install one framing anchor for each interior floor joist. The end joist or band joists get nailed to the end of the ledger and do not require a framing anchor. Nail one of the framing joist hanger on line either to the left or right side of the floor joist. Many people like it one way or the other. Whatever works best for you. Do NOT nail both sides to the ledger. Ok beam setting time. Having figured out the height of the beam and joist assembly, transfer the elevation of the TOP of the ledger on the house out to your posts. The mark on the posts, will be level with the top of the ledger. The tripod and level you rented, make this short work. It is possible to use a string line and bubble level but that is not as accurate and is really tough to do. Do not try it with a 4' carpenters level. If the level is off by only 1 /16" per foot, in a 12' wide deck that's 3/8" out of level not counting pencil marks. Most carpenter levels are off more than that. Trust me.

OK with the posts marked, deduct the height of your joist/beam assembly as in the example 1'-5 ?". Make this line BELOW the upper mark. This is where you cut your posts. REMEMBER-MEASURE TWICE, CUT ONCE. Cut off the posts with your saw and be careful. Standing on a ladder is awkward. Make sure you have someone holding the ladder and you have a firm footing. Watch where the top of the post is going to fall. Don't hit your partner, your going to need him shortly. Ok now, with the posts securely braced, get all the help you can find to lift the beam into place on top of the posts. This was a good day to have a picnic or some other way to trick your friends or relatives into coming over. (Don't tell it is to do work!). All together, lift the beam into place squarely on top of the posts. Hopefully you have two or more ladders so the beam can be nailed into the posts as quickly as possible. You don't want to balance it any longer than you have too. Now you can also see why I keep repeating the requirement for bracing the posts so well. Your braces are holding both the post and the beam at this point but not for long.

Now with all your help, start installing the floor joists. Drop one into each joist hanger on the ledger and place the other end on top of the beam. While one person nails the ledger end on the layout mark and against the nailed side of the of the hanger, the other person nails it into place on top of the beam. Jump around a little putting joists in every 3rd of 4th one and you will find that each one will help stabilize your beam and post assembly. Once a few are done, the assembly becomes much more stable and easier to work on. Toenail each joist securely to the ledger and top of the beam. Now you can complete your metal ledger joist hangers and beam to post connectors. Bend the ledger joist hangers around the joist until they are tight against each side and the bottom of the joist. These hanger have 2 indented metal fingers on each side that you can drive in with your hammer to hold them securely in place. Each hanger comes with short nails that are required to be driven into each hole in the hanger. Some hangers have 4 holes some 5 but whatever it is, install a nail in each hole both into the ledger and into the joist on both sides. The building inspector will look for these nails.

Bridging- In the case of a deck where the span between the ledger and the edge of the beam is 8' or greater, bridging is required to prevent the joists from warping and spreading apart thereby loosening the nails in the decking or possibly pulling out the nails from the ledger or the beam causing the deck structure to fail. Bridging can be either cut from left over pieces of wood joists, or metal bridging which is available at all lumberyards. Wood bridging or blocking is cut to fit in between two joists. Nail each one on center line of the deck offsetting the ends left and right so as to be bale to end nail them through the joist itself. Do not toenail them. When your done you will have one row approximately center of deck all the way across. Metal bridging simply nails form the top of one joist to the bottom of the other. Make sure you tell the salesperson what your joist centers are. 16"OC are longer than 12" OC. Metal strap bridging comes laid flat. Nail one end to top of joist, bend down and under the next and nail to the bottom of the 2nd joist in a criss cross manner. They are available in several different brands.

Now it is the time to take a break. Look over your work so far. There is bound to be nail missing or not driven completely into the wood. Finish all this first and then you can remove the braces for you posts.

REMOVE ALL NAILS FROM YOUR BRACES! Stepping on a nail sticking out a board is very painful and will cause a severe foot injury. Always strip all nails from wood when it is removed. Don't put it off untill later.

Cleanup- Cleanup all the debris from your framing work. Make sure the ground is leveled around your footing piers and rocks and other debris is removed. Even a small rock can cause you to twist an ankle.

Decking-After installing a flashing over the ledger board, start you decking against the house and work outward. I always leave a ?" space between the house and the first decking board. This will allow rain to fall through the opening and not wick down your siding or house plywood. It once was thought correct to leave a nail width between decking boards but this is not a good idea. Wood shrinks. Butt the boards together without forcing them. Either nail or screw them to the joists below. Use at least two screws for each deck board to each joist. Three is better. Use the longest length deck boards you can get. The less end joints the better. If you must butt two boards together, make sure you center the butt over the center of the joist and toenail or screw each one to the joist. Many carpenter like to let the boards "run wild" over one end of the deck, and then strike a chalk line at the end of the installation and cut them all at once. This will give you a better finished look instead of cutting each board and trying to line them up in a perfect straight line.

Handrails-Every state is different in its requirements. My state requires handrails 36" high with a mid point rail as well as a minimum if the deck is more than 30" above the ground. Railings must withstand a 250 pound side load push. Designs can vary by what the homeowner wants to see as a finished product. Handrails could be cedar, PT lumber, plastic, vinyl or even pipe. The types and styles are endless. A few points though to remember. The handrail posts must be securely fastened to the exterior band joist by either through bolting them or lagging them. Through bolting is far the better manner. Cutting away ? of the post to provide a rectangular notch the height of the band joist and the decking and then bolting makes a strong, secure handrail post. Two bolts minimum in each post to the exterior band joint is required. The handrails and top cap can then be nailed or screwed to the posts and provide a safe barrier against an accidental fall. Just about anything you can imagine, you can build for a handrail system

Final-Buy a couple of sheets of 100 or 120 grit sandpaper, Wrap the sandpaper around a piece of 2x4 and rub it along the edges of the handrails and posts. This will remove and potential splinters for soft hands.

Place the picnic table and barbecue on the deck, sit back and enjoy your hard work!

Pete

Your Friendly Building Inspector

http://www.Wagsys.com

BICES-Building Inspection & Code Enforcement System Software




Pete Ackerson is a 30+ year building inspector with experience in both public and private construction industries. From schools to treatment plants, from private homes and condo projects, to large residential landscaping projects, he has worked both in the building design areas and field construction in the Eastern US. In 2006 he formed along with two other building inspectors, Wagsys LLC which produced software for municipal agencies in the fields of building departments, planning boards and Zoning Boards of Appeals.





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