In this Instructable I will show you the steps I am going through to build a comfortable modern backyard shed that you can use as an office, a studio, a workshop, etc. It is definitely a huge step up from your standard shed meant to store a lawn mower or other tools.

The main challenge I faced is that my backyard is sloped towards the back and it gets flooded in winter / spring. I had to find a solution that would keep the shed dry while keeping it far enough away from the house to still enjoy the lawn.

Note: I am located in Washington state where it rains quite a bit so I put an emphasis on building it as waterproof as I could. Also, where I live I can add an external structure up to 200 square feet without the requirement of a building permit. I still went to the city hall to double check that everything I wanted to do was compliant with the city. It's free, quick (10 minutes) and may save you from future possible troubles. I highly recommend it.

Credit: I mainly followed the instruction from this website iCreatables for all the basic on shed building.

Final Note: This is still an ongoing project and I will add to it as I move forward.

Step 1: Design Phase

I spend a lot of time researching designs on Google Image, Houzz and especially Pinterest:

Example 1, Example 2, Example 3, Example 4

I was always going back to modern designs with full window walls, flat roofs, a mix of wood and cement board for the final look. Unfortunately I didn't have quite the budget to go that crazy so I fell back on a design closer to what Studio-Shed offers.

I went through a pretty good number of iteration for my design (done with Sketchup).
At first I was looking for an 8' x 10' structure but I quickly felt that if I would put so much effort in building this, I should try to make a bit more roomy. Who knows, maybe my wife will turn it into a yoga studio or my kid in a teenage den!

In the end I went for a 10' x 16' building with a small tool shed on the outside. Nice, 2 in 1!

I was also looking at reusing older windows bought from a second hand store to save a lot of money ... but that changed later.

Step 2: Electrifying

I started this project at the end of summer 2017 thinking "if I take 3 weeks off I can weep most of this".

What a mistake!

I rented this trencher and stared to run into trouble right from the get go. You see, my backyard gets flooded in winter and for this reason there is a sum pump in the very back. This means that there is a power line going from the house to the pump as well as an evacuation pipe going from the pump back to the house.

I was expecting (since I didn't have any drawing of where all that stuff was) that both the electric line and the pipe would leave straight from the house then do a 90 degree angle near the pump. No, no and no. Don't assume things. For some reason the electric line left the house straight then half way to the pump made a 30 degree angle to the pump. The evacuation pipe left the house at a 30 degree angle then half way went straight. Needless to say, I ended up cutting though everything. Which meant spending unexpected time fixing the mess.

Then I laid out two electrical conduits: one for electricity (with 2 power lines) and one for internet and cable.
They are 2 to 3 feet underground, covered with plastic to warn of their presence when digging.

Unfortunately I don't have many pictures from that time.

Step 3: Foundation

As I said earlier, I started during summer 2017 then the rain and cold came so I waited for spring 2018 to start on the foundation.

To alleviate the flooding issue I decided to use pier blocks on top of which I put 4" x 6" pressure treated beams, on top of which I added 2" x 6" pressure treated studs for the floor.

Since I had the whole winter 2017-18 to check the flood level, I was able to verify how high I had to raise the foundation.

Note: the worst flooding happens when I turn off the sump pump and I end up 4" or 5" of water on a 1/4 of my backyard. I'm not talking heavy floods, I actually don't live in a flooding zone. This is more an issue of really slow drainage.

Then I positioned my beams 16' x 6" x 4" that I carried with a dolly in different location to finally settle in the far back corner.

I used 9 pier blocks and 3 beams for the foundation. The blocks rest on top of foot of gravel to stabilize them.

The sump pump evacuation pipe was right below where I needed my pier block to be so I had to move the pipe around to make sure it wouldn't get crushed under the weight of the shed.

Step 4: Floor

The next step consisted in building the floor itself by adding 10' x 6" x 2" studs spaced 24" apart.

I chose 6" deep walls and floor to maximize the insulation and be up to code.

The floor insulation is made of 2 layers of rigid foam (each R-10 for a total of R-20). The rigid foam is water resistant and acts as a moisture barrier. I couldn't install an actual moisture barrier on the ground because of the flooding issue. It would have made things worse by preventing the water from draining away.

With such a high floor (1' on the high side, 6" on the low side) I needed to prevent rodents and pest from nesting under so I dug all around and added a 1/2" wire mesh to block all access.

Finally I installed a 3/4" OSB sub-floor on top of it. You don't want to go lower for the floor, especially with 24" spacing otherwise it will bend and feel unstable.

Step 5: Framing the Walls

Time for the walls! First you lay down all the studs, mark the spacing on the top and bottom plates then nail everything and lift the walls.

After framing the first wall, I had second thoughts about my design. I went back to the drawing board and ended up getting rid of the tool shed and utilize the whole space for the office space! Much nicer and cleaner design in my opinion.

Instead of going with 2 windows and 2 doors (see original designs), I went with a double slider and a casement windows. I couldn't find anything used that would fit my need so I ordered new windows. If I had stuck with basics, it would have ended up even price wise. But I went for black windows to keep the modern style I was looking for. It is probably the only splurge I have done on this project.

I kept raising walls and attaching them to each other's until all four were done.

Step 6: Adding Roof Framing and OSB to the Walls

I finished the framing by adding the roof studs, spread 24" on center again with a little overhang on the side and in the front. The idea is to add some down lights to highlight the design of the shed and provide a little bit of lighting during the dark months of the year.

Like all the rest of my material, the OSB sheets where stored in my garage and I used the dolly to carry them out by myself. I screwed the OSB sheets length wise to provide strength to the structure and avoid having to create bracing. This is important, most shed structures designs I looked at nailed the siding on one side and the drywall on the other side. It is probably not good from a strength point of view. You either need a diagonal brace or OSB sheeting to reinforce your structure.

It also provides a protective layer between the outside and the insulation. Remember, this is not just a tool shed. I wanted something comfortable to work in even in the colder month of winter.

The OSB sheeting has a strength orientation to help you figure out how to install it. I discovered it also has an inside and an outside. The shiny side has to face out since it is the most moisture resistant.

I roughly cut the panels to the right size, exceeding by an inch or two and used a router to trim it flush. First time using this tool ... it's messy but efficient! Just remember all the tools safety rules, protect your ears and eyes (and mouth, it flies everywhere) and you will be good.

Step 7: OSB Roof

I built the roof similarly to the walls.

I opted for a pretty flat roof because I loved the look but living in the Pacific Northwest, I had to find a proper roof cover. It has a 4" rise over a 10' run (which is a 1/30 pitch - 1.9° angle - 3% slope). I used this calculator to get a sense of what that meant when looking at building codes.

I couldn't use shingles for this because the pitch of my roof was to low and water would have infiltrated so I opted for an EPDM membrane roofing. I got great insights on this from this YouTube video of a British guy building a similar structure. It is pretty much a 60 mil plastic membrane that gets glued to the OSB shitting of the roof and has an expected life span of 50 yeas. The EPDM membrane I chose is made of a single piece which means that once it is glued on the roof there is no risk of leak or water infiltration.

Step 8: House Wrap

This is a fairly straight forward process. I just got two rolls of Everbrite house wrap and special nails with red caps to hold the wrap without tearing it apart. I put a nail about every 24". The house wrap is 3' wide by 100' long so I was able to just wrap the shed all around with 3 long pieces. Each 3' wide piece is placed from the bottom up with 6" overlap. Once everything was nailed properly in place, I taped the overlap seams with Tyvek tape to prevent moisture and wind flow to get through.

I haven't yet chosen the siding I want to install so this house wrap will be a good protection during the coming rainy days.

(pictures to come ... I forgot to upload them)

Step 9: EPDM Roofing

I got the tip on the EPDM roofing material from this YouTube video :

It is from a British guy building a bigger shed than mine but he has a lot of detailed videos.

EPDM roofing is great for a low pitch roof like mine (4" rise over a 10' run - which is a 1/30 pitch - 1.9° angle - 3% slope) because it is made of a single 60 mil membrane. So long as you are careful not puncturing it, it will be leak proof for the next 50 years.

I ordered mine (20'x 15' and a 5 gallon bucket of water based glue) from Lottes Roofing available either on Amazon or eBay.

It got delivered through UPS and I enlisted the help of my brother to carry the 70 lbs package up on the roof. Then we laid it flat in place for a week on the roof in order to flatten it and remove the creases.

I then proceeded to fold half of the EPDM membrane on one side of the roof and used the broom to clean both the roof and the EPDM membrane from debris. I also used a blower to help with this process.

I then proceeded to cover a 1/4 of the roof with the slime looking glue. It is suggested to put 1/8" thick of glue with a trowel although I used a cheap paint roller and it worked perfectly. Don't cover the whole roof with glue at once since you need to move around and be able to pull the EPDM membrane. And you don't want the glue to dry to soon either.

Pull the EPDM membrane over the glue, making sure the glued side is clean then use the broom from the center to push all air bubbles out. Finish with a roller to make sure it stick properly then keep going until the whole roof is done.

Depending on the finish you are looking for, the next step may vary. I chose to glue the EPDM on the front, left and right sides of the roof line to protect the wood.Those three sides will be ultimately covered with a galvanized black fascia profile.

The back side is glued on a galvanized drop edge (that is nailed on the roof) then covered by a black T style edge flashing (screwed all the way in). It sandwiches the EPDM membrane between two pieces of flashing: the galvanized one prevents the water from reaching the roof's plywood; the T style one prevents the wind and time from pealing the EPDM membrane from the edge of the roof.

If water ever gets under the T style flashing, it will run against the EPDM membrane until it reaches the galvanized flashing which itself drips into a gutter.

Step 10: Steps to Come...

After inspecting the windows I received, it turns out they are all scratched, pushed in and pieces are missing (handles, keys, screws, etc.)

I'm getting a bit the run around between HomeDepot, Jeld-Wen and the delivery company. Seems like I am going to have to settle for a replacement screen, handles and touch up paint. I feel the customer service is lacking on that point, when you are spending that kind of money.

Stay tuned for the next steps: