Tuesday, March 4, 2014

Tiny Home Building: Roof Specs

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A few roof specs for the curious ones out there! So the roof was the last really important structural aspect we had to build on the house. We wanted to maximize the amount of space in the house, so instead of a conventional gable or hip roof that peaks in the middle, we went for the slanted shed type roof. It's a really low slope but this maximizes the amount of space on the inside. Plus it made the building and applying of the rafters really easy. 
After we got all the walls up, all we had to do was cut out the little notches on either end of our rafter boards (we used 2x6's) and slid them into place. We put ours 16" on center. Then we secured them on on each end with hurricane ties (these are the ones we used). This was really important for us especially because it has to be able to sustain winds while traveling/transporting. 
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One thing I did struggle with a little bit was the ends of the roofs and how to finish them. This was really really confusing for me until I did a ton of research and finally got my head wrapped around it. If you look at the picture below, you can see that the roof extends beyond the walls on all sides. I wanted this extra protection from the rain that could cause damage to the sides of the house plus I liked the way it looks!
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Where the rafters extend beyond the wall, it was pretty easy but we had to build supports for on the sides of the house where the rafters run parallel to it, like right above the window in the picture up there ^^ You can see the extra pieces of wood we used to support the part extending out. 
And now, I want to talk a little about finishing the edges of your roof. So once you get your rafters on, there's some awkward spaces where the rafters meet the walls and what you can do to cover that up. We actually did the finishing of the roof edges a little backwards because we were learning as we went (woops!). 

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First, we used blocking which are essentially blocks that are placed between the rafters in the space between the top of the wall that it's resting on and the roof sheathing on top of the rafter. This helps to fill in the gap but also prevents the rafters from racking back and forth in case of a hurricane or something. You can read some articles about that here, here, and here. 
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To make that edge of the blocking even with the exterior wall sheathing (the plywood we put up on the outside of the wall), we added frieze boards. We realized this would have been a lot easier if we had done these prior to the hurricane ties and plywood roof sheathing! *note taken*
But it's alright, we were in a hurry to complete the roof to protect the insulation in the floors. You win some, you lose some, right? Since we did it a little bit backwards, there were some awkward gaps but we filled those in later with spray foam. 
Then I had to decided how to finish the eaves/corniceWe put up a fascia board to cover up the exposed ends of the rafters...
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But now I had two choices, I could leave the space open like this where you can still see the roof rafters: 
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Or I could use a soffit and close the space up like this: 
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After much research (with not very many results, surprisingly) and much deliberation, I ultimately decided to go with the open version because it's less expensive, requires less work, and looks pretty, like this: 
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You can also kind of see the open look on this tiny house too. I love the way this looks, it definitely adds more character. 
However, something to consider especially if you live in a wildfire prone is to use soffits as a means to slow down a house fire. Read more here
Here is a helpful image I used to figure out exactly where to put everything. Seriously, this picture was so helpful! 
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Also, here is excellent resource for building and construction, specifically page 267-273 for how the end of roofs are put together

After all of that fun stuff was figured out, we moved on to the roofing!
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First, we applied an overlapped layer of  #30 felt paper (about 3 rolls) with capped roofing nails. Then we attached drip edges around the entire roof. We also kind of messed up the order of this part too. Although we were able to kind of work around it, we should have applied the drip edge along the eave (bottom most edge) first because that should go underneath the felt. And then it goes on top of the felt at the gable (top most edge) and sides of the roof. You can read up why, here and here. We forgot this part when applying the felt but were able to tuck it under at the eave anyways. Oh also, when we attached the drip edges, we applied roofing cement on the inside of them to ensure a good seal. 
Next, we put on the roll roofing! We chose to use roll roofing because 1) it's cheap and 2) because we couldn't use shingles with such a low sloped roof. Our ideal roof would have been metal but we would've had to order special standing seam roofing for our low slope and that's not exactly in our budget right now. 
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Anyways, roll roofing is pretty easy. We used 3 rolls of a white colored one so that it doesn't attract heat. Basically all you do is roll it out and tack it down. Then layer on the next one and so on. And then we used roofing cement to cover up the nails so that water wouldn't leak through them. We also used roofing cement where we layered one strip of roll roofing over another one so that water wouldn't seep up under it. And also around the edges where the roll roofing ended, making sure to do the topmost edge of the roof really well. It's not the prettiest thing in the world but hey, no one's going up to look at our roof! And it'll do the trick until we can afford some nicer, more long-term roofing. 
Here's a funny little video on roll roofing. If anything, just watch the intro. It's pretty hilarious!
Here is a how to on installing shingles (for anyone that may need it). 

And something I looked into whilst researching roofs is the use of radiant barriers. I found out that I wouldn't be able to use one for two reasons, 1) I will have no attic, the radiant barrier needs an air gap to reflect the heat and 2) because I have roofing directly on my roof sheathing thereby leaving no air gap again. However, when we look into getting metal roofing, this is something I will definitely consider since it will actually be an option at that time. 
Something else I will look into in the future is installing an exhaust fan for above my kitchen. Here is a video series on how to install one- 1, 2, 3, 4, 5
The supplies we used to build our roof (prices coming later): 
Plywood sheathing (most was what we got for free) 
(13) 2x6x10 
26 hurricane ties 
nails for hurricane ties
3 rolls of rolled roofing 
3 rolls #30 felt paper 
about 3-5 tubes of roofing cement
hooked blade razor knife (to cut roll roofing and felt paper)
roofing nails with and without caps 
drip edges to cover all edges of roof 
Order of building for next time- exterior plywood sheathing all the way up to the top of the wall. Rafters. Blocking, frieze boards. Hurricane ties, plywood roof sheathing. Fascia board, bottom drip edge, felt, rest of drip edge. Roll roofing. Gutters? 

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