Add a Room to Your Home
Buying a new home to get the additional space you're looking for is costly, especially in this market. You may find a good deal, but what about the current resale value of your house? Even before the mortgage debacle, it made good financial sense to add a room to your home.
It is not realistic for this article to explain in detail all of the steps required to complete a room. Use this as a guideline. Seek out other articles that detail separate steps within this article, such as "Frame Exterior Walls". Does this Spark an idea?
Instructions
1. Planning & Design
It is vastly easier and less expensive to add a room to the first floor of the house. Tinker with the floor plan and create a first floor room addition that will match your spatial requirements. Make a scale drawing and hand it to a structural engineer so that you have a stamped, engineered plan to submit for permit. If you are satified with your floor plan solution, you do not need an architect.
2. Choosing a Foundation System
You will either have a slab foundation or a perimeter stem wall foundation. A perimeter stem wall foundation requires a lot more formwork, so you had better be a good carpenter. It also requires more excavation because you need to provide a 18" crawl space beneath the floor joists. A concrete slab might be the best method for you, so discuss with your engineer.
3. Laying Out the Foundation
Remove 16" of siding and sheathing from the bottom of the exterior wall. This will expose the rim joist and existing floor plate, which the floor of the new room needs to match.
Layout your footings with a string line and stakes. This process will enable you to create straight lines and square corners. Hammer three stakes into the ground about 3'-0" past the corner markers of the foundation. Each stake should be about 3'-0" away from the other creating a square corner. Screw a 1x4 piece of wood across the stakes, this is your batter board. Importantly, the batter boards don't need to be totally square themselves. The string line is the only component that is required to be square.
4. Square Up for Excavation
Square up the lines using one of two proven formulas. First is the Hypotenuse Rule or 3-4-5 check, which states the hypotenuse should be 10'-0" when one leg is 6'-0" and one leg is 8'-0". Just measure back from one corner 6'-0" and mark the string, then measure the opposite string back 8'-0" and mark it. Finally, measure the diagonal between those two marks to the hypotenuse. You can also use the Diagonal Method in which you measure both diagonals as pictured and adjust your strings until both diagonals are exactly equal. Once your lines are good, mark the ground with white spray paint and excavate the footings.
5. Final Prep Before Concrete Pour
If you are doing a concrete slab foundation, make sure the proper amount of gravel and sand are in place as outlined in the engineered drawings. Lay down the vapor barrier. Install all of the anchor bolts into the perimeter formwork. Prop the rebar up on concrete dobies.
6. Pouring and Finishing Concrete
If you are lucky and the chute of the concrete truck can reach out into your form work, then use the chute to dump the concrete directly where you need it. If not, fill a wheelbarrow or two at a time with concrete and begin to dump it into your form work. Start in a corner and work your way out.
You can use a concrete pump truck, however, if you are a novice, the pump is going to dispense the concrete far faster than you will be able to manage it. Stick with the wheel barrow, it has worked for centuries.
Use the shovel and metal rake to initially level out the concrete dumped from the wheel barrow. Even though this process is rough, try to get as close as possible to the finish concrete level. This will make the finishing concrete much easier and more efficient.
7. Framing
Once the foundation has cured for 48 hours, it's ready for you to start framing. Install the perimeter mudsill fist. Use pressure treated wood since it will be resting against concrete. Fasten the mudsill down to the foundation anchor bolts.
Frame your walls on the ground. Typically, you will only need a 2x4 wall for a single story addition and this makes the framing easy. Make sure you have all the proper rough opening dimensions for the window and door manufacturers. Stand the walls up with help and use 2x4 supports nailed to the wall and then back to the floor at 45 degree angles.
Frame the roof last. Prefabricated roof trusses are a Godsend for do-it-yourself builders. You will need help hoisting them into place, but all of the angle cuts are done for you. You just fasten them into place.
8. Water Proofing & Windows
Install flashing around all the window openings. Use a peel and stick bituthene flashing. Apply the bottom first, then the sides (allow them to overlap the bottom piece) and finally the top. I use 9" wide pieces on the top and bottom and 6" wide on the sides.
Install the windows and either apply another layer of peel and stick flashing over the nail fin or smother the nail fin with polyurethane caulking, such as Sikaflex.
Hire a roofing company install gutters and the shingle roof, or match whatever system is on your existing roof. It doesn't make any sense to do the roof yourself consider the possible consequences of your mistakes. Roofing is not an expensive scope to sub out. Your work will never look as good as a roofing sub either.
9. Wrap the Structure
Use DuPont Tyvek building wrap or similar to cover the entire exterior wall surface. Use Tyvek tape at all the seams to ensure a tight seal.
10. Siding and Trim
Match your existing house trim. Start on the top and work your way down. Make sure your nailing pattern is consistent and the nails are in nice vertical lines from top to bottom.
Tags: anchor bolts, both diagonals, concrete slab, exterior wall, first floor, floor plan
