building a deck, need advice?

I've not done much in the line of construction before but I have watched others and now that I'm a home-owner it's time to do some work on my own. So I'm building a deck on the back of my mobile home. I've got treated 4X4s to go in the ground and enough wood to make roughly a 10X10' deck. Basically I'm going to have 8 of the 4X4s planted in the ground going around the outside of my [square] deck and one cut off to go in the middle/underneath to help with support. (I've got enough wood to go around the perimeter to add strength as well and obviously I will need to have some for what I would call joists (correct me if that's the wrong term for the boards that would run underneath and give support to the deck) The only part I'm really curious is whether or not I would need to put something such as rock or quickrete...or both in the post holes for my 4X4s (the holes I've dug are 3' deep). The deck is going on the rear of the trailer and that side gets and seems to hold a lot of water so I'm thinking I probably do need something in the post holes to keep my deck from sinking over time. Can anyone share any advice for the first time builder?

Additionally, After I've gotten the first couple of 4X4s in the ground and leveled, how would I go about making sure that the deck itself is square (like around the perimeter?) ...if I were to put 3 posts up next to the mobile home, how would I make sure that the other posts are in the right position? hope that makes sense!

9 Answers

  • 1 decade ago
    Favorite Answer

    Hi there. Setting the 4x4s in concrete will make the deck more durable and stable. If the posts are placed directly into the ground without the support of concrete, they will rot sooner and might even attract termites even though the lumber is treated. Measuring from the trailer to the posts and then from the inner posts to the outer posts will help you to assure that the deck is even. I suggest using graph paper to draw your plan for the deck with each square representing a foot. That will help you to determine how much lumber you need and where to place the posts and supports.

  • Anonymous
    5 years ago

    Some advice. 1. Measure twice before cutting the wood. 2. Use wood that has been previously used if not to badly damaged cheaper and saves some trees also some times you can find good finds that make you deck have character. 3. treat the metal for rust prevention ( painting or some other way) bolts that secure your deck to the wall or its supports can rust so treat them so rusting will not happen also remember metal washers for the nuts. 4. Check building inspector to make sure all permits and other documents are signed before building and afterward to make sure it is to code. 5. Do not tackle it yourself for a few bucks ($50 - $200) friends teenage children ( 18 or older) with experience or at least handy can help you out it may cost you more you think, but time is money and in fact you save by getting it done faster and you don't need them for everything just to help out in certain areas. 6. Make sure you have proper foundation and a way to secure the decks supports. 7. Place proper warning signs. You might not think it is important, but if some idiot stumbles into your yard and injuries himself well problems may happen. Also Inform your neighbors as it is respectful and allows them to keep their kids and animals from wandering into your yard and also informs them that you will building something and to expect noise and other things when you build. 8. Secure all tools and building material as they tend to walk off at night or when nobody is around. 9. It is better to error on the side of more than less. In cutting wood it is better to make cuts longer since you can always shorten it latter, also plan for more wood than needed since some will be ruined and more paint or varnish or nails than you think you will need. 10. remember wood expands and contracts slightly in cold and warm weather so leave some gap to account for this and prevent splitting of the wood.

  • Anonymous
    1 decade ago

    How to make a SQUARE..porch..don't place the 4 x 4's into the dirt--instead..create your cement footing by useing a deep trench..square or what-ever..and place the 4 x 4's onto the cement..built blocks..(wood will rot)..if buried in dirt..if you pick four corners..for a cement...footing(Block-form) can make your more exact adjustment by useing a CHALK-Line..finding center..

    Use some sort of a marker--like a stick..tie a string..creating your square--pound the stick into the ground by eye..and then use a tape measure to better adjust the sticks..

    10-feet out from the Mobile Home..pound in a stick..

    Go to the other side of the porch--and place another stick--10-feet out from the Mobile Home..that leaves a dimension to place 10-feet across..that's square..

    Next is LEVEL..and will need a create the level portion of all the concrete footings--

    You don't need the 4 x 4's...placed directly center of the concrete footings--

    This can hide some portion of the concrete--under the porch..(just off center)..inside..


    Just build your concrete...parimeter..4-blocks..and find the center for another block..

    Use string..use a Line-Level..


    You may find a Cinder Block..useful..


    Place the 4 x 4 wood on top of cement..don't bury your wood.

  • Anonymous
    6 years ago

    If you have to find nice ideas for woodworking i can suggest you to check here

    It's perfect if you are just starting out or if you're a seasoned carpenter. you will like it for sure !

    It has almost 20.000 woodworking plans and you have a CAD/DWG software to view and edit the plans. You have step-by-step instructions with photos and high quality blueprints and schematics. If you are a beginner this is the easiest way to start your woodworking projects, and if you already have experience you can anyway find a lot of interesting ideas!

    Hope you will enjoy it :)

  • How do you think about the answers? You can sign in to vote the answer.
  • Anonymous
    1 decade ago

    Instead of putting the 4x4s into the ground, pour concrete into the holes to above ground level (make forms or set boxes or something on the ground) , be sure they are level with each other and put metal brackets into the wet concrete. The brackets are to anchor the posts without getting wood into dirt and should be firmly buried in the concrete. Ask about them at the hardware or builder supply store.

  • 4 years ago


    Source(s): Woodworking Techniques
  • Anonymous
    5 years ago

    Mcgrath is a very dedicated and experienced woodworker who knows what he is talking about when it comes to woodworking and DIY projects s he has been a woodworker for many many years. Read here

    There is also a lifetime member acess included in the package and you get these extras for no cost to you as they are free with no additional charges at all!

  • rick
    Lv 5
    1 decade ago

    follow these instructions. You only need 4x4's at all four corners only. If you want to attach it to the trailer, then just do 2 4x4's at the corners away from the trailer and use 3/8"x 4 1/2" galvinized lag screws to fasten it to the trailer. I suggest the post at all 4 corner scenario. To ensure your holes are in the right location, mount a treated 2x8 to the trailer with some nails. If your deck is exactly 10' cut the 2x8 at 9'9" (leaving it 1 1/2" short on each end. Next nail a 10' 2x8 (as the end joists) to each end and use a 2x4 as a temp brace to hold the outside level. Next nail another 9' 9" 2x8 on the outside making the fourth side side of your frame. nail thru the 2 side pieces to hold it (no add'l bracing is necessary). Next you need to square the frame. You do this by measuing diagonally, corner to corner. You will need to shift it until you get the same measurement when you measure side to side. For example: if one side measurement is 11' 1" and the other direction is 11' 5", you need to shift it 1/2 of what the difference is (or 2" in this case). you need to brace it once you've got it squared. The easiest way to do this is nail a 2x4 at an angle on top of the 2x8's. One on each side will suffice. Dig your 4-holes 12" diameter 30"deep and pour 2- bags of concrete in each hole. 8" thickness minimum. the 2 posts against the trailer should be placed so they sit under the 2x8 against the trailer and the 2x8 joist (the posts for the railingins will mount latter). Before you cut the outside posts, check for level and adjust as necessary. then measure and install the posts. Next Layout for the rest of the joists. Hook ur tape on one end and mark 15 1/4", 31 1/4', 47 1/4", 63 1/4", 79 1/4", 95 1/4", 107 1/4". The joists will sit on the side of each mark that is away from the side you hooked ur tape on to start measuring from. The center of each joist should be 16" to the center from the side you layed out from. Cut 7-2x8's at 9' 9" and nail them in place. Next install joist hangers on each end of those 7 joists. you are now structurally safe. Next install your decking (typically 2x6's). start against the trailer and work outward. next cut 4x4's for rail posts at 42" mount them flush with bottom of the joists (they shoud be 34 1/2" above the decking), Place them 1 1/2" from each corner and one between the corner ones, so you have roughly 4' 5 1/4" between each post. Nail them with a couple nails to hold until you can lag screw them in place with 3/8x5" lag screws. one per post. Next install the 2x6 top rail, and split the overhang of the 2x6 evenly on the posts. When you decide how you want you rail design, remember the spacing between the pickets cannot exceed 4".

  • 1 decade ago

    I have to leave for work now, so don't have time to give a detailed answer, but if you will e-mail me through my avatar, I'll walk you through it.

Still have questions? Get your answers by asking now.