How To Build a New Deck

How To Build a New 10'x20' Deck

1 Determine if the Deck Size Blends Your Home
Refer to our deck planning article to size your deck correctly. Use a deck plan approved in your area or have a building designer or architect to design your deck.

2 Who will Build the Deck?
Do you have the skills needed for the deck construction or will you contact a contractor for this project? If you choose a contractor working with a quality deck builder is recommended. Ask for a list of references. Your deck builder may take care of the below requirements and your job is over after you select a builder. If you are building the deck continue to read.

3 Contact Your Local Building Inspector
Most areas require building permits for deck construction so be sure to review requirements with your local building inspector. You may need your plot/site plan with the new deck design drawn onto the plan.
Apply for the required building permits. You may also be required to submit a deck building material list to the inspector.

4 Deck Building Materials
To ensure an accurate material list for your area and also obtain the best possible pricing consider contacting three local building material suppliers or lumberyards for your deck pricing. Note the height above ground for your new deck as this will change the stairway materials and your post length. We live in Michigan and build our decks with 12" - 16" footings 42" below grade. With the 20' wide deck three posts may be sufficient although four posts will keep the spacing under 8' which may be required for two story decks. You may need to update your post and stairway materials.

Note: Use good quality treated or equivalent materials.

4 8' 4x6 Support Posts
6 12" Concrete Foundation Cookies (Two for Bottom of Stairway)
4 Bags of Concrete Gravel Mix
24' J Channel matching the home siding color
24' Deck Z Flashing
24' Deck Waterproofing/ Termite Shield
21 10' 2x10 or equivalent Deck and Rim Joists
60' 2x12 Double support beam and stairway stringers
440' 5/4 Decking Materials
40' Decking Materials for Stairway
Decking Fasteners
12 5/8" x 8" Carriage Bolts for Beam
30 Lag Screw Fasteners to fasten rim joist to the home
2 Corner Support Brackets
16 Exterior Grade 2x10/ Equivalent Joist Hangers
5 4x4x8 Posts - Handrail Supports
36' Hand-railing
8' Stairway handrail (May flex pending on your height above grade)
Grass seed or landscaping plantings to repair around your support posts.

5 Deck Footing & Foundation
There are various deck footing options. The most common method in the northern country here in Michigan is the post and beam method. We keep our beam 16" from the front of the deck and our side posts 16" in from the left and right deck edges. With the 10' deep deck the measurement to the center of the deck footing is 100". Dig and place the two outside footings 42" below grade with concrete mix placed under the footings. Set and brace the two support posts and then run a string line to set the additional intermediate posts. An good alternative option is to install temporary supports and place your footing and support posts after your deck frame is constructed.

6 Attach Your 2x10 Rim Joists To the Home
Cut away the siding where your deck will be attached. Place ice guard or termite shield behind the area where the rim joist will be attached. Cutting the siding 1 1/2" above the rim joist will leave a 1/2" recommended gap with 1" decking material. Install your J channel at this point.

7 Build the Deck Frame
With a single rim joist on each end your joists will be cut to a 117" length. Level and attach the two outside joists with an L metal hanger. Be sure to square the outside corners. Then install and support the intermediate joists with joist hangers.

8 Install the Decking Boards
Install the decking leaving around a 1/8" gap between the deck boards. If the material is treated and is very wet the boards may be installed tight as they will dry leaving a sufficient gap. Be sure the frame is installed square prior to installing the decking.

9 Construct your Staircase

10 Install the Railing Support Posts and Railing

Remember: Check with your building inspector about required inspections. They may require a footing inspection prior to back-fill of soil.

Tip: To help settle the soil around the posts consider using a garden hose after compaction. When the soil is completely settled add grass seed or decorative landscaping to complete a finishing touch to your new deck.