From the course: SketchUp for Architecture: Details

Roof layering - SketchUp Tutorial

From the course: SketchUp for Architecture: Details

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Roof layering

- [Instructor] Chapter 204, roof layering. We're going to consider the makeup of this roof and what I've put where. To start off with, again, like the wall, we need rainscreen. This is the protective barrier from the rain or to get rid of most of the moisture, but not all of it. So we need another layer underneath that. This is our breather membrane. This is there to act as our Gore-Tex jacket made by Dupont. The same people who make Gore-Tex. And this could then be fitted to our OSB and any moisture that gets through this, now this is an asphalt shingle roof, it's right on the edge of whether it should be used or not. This is a 10 degree pitch. So asphalt roofing, anything sort of shallower than 9 1/2 degrees is probably not recommended. And you can image wind blowing along here maybe lifting up these things driving rain in. So, special precautions needed to be taken when fitting this thing. Otherwise you for a tile or a different type of roof, maybe a metal roof, or something that's going to be suitable for this shallow pitch. So once we've got down to this layer. This is our OSB. So this is allowing us to fix our shingles. So manufacturers instructions on the fixing of the shingles sort of eight probably nails thereabouts per run of shingle. That goes through this membrane and then we've got our insulation below. This is a rigid insulation, so we can put our board on. It's not going to sag or anything. This is more like a phenolic type of insulation which is a very good insulator. Another board, then, underneath that. This is fixed to the top of our joists. The joists are designed, they're 11 by two, and I took these from some span tables that recommend a span of this width for the house. So again, I'm not a structural engineer, I would guess at this, but then a structural engineer would look at it and say, well maybe they're a bit heavy or they're a bit under-strength or maybe we go for some sort of, engineered joists. Whether it's an OSB style one, or whether it's one with one of those metal, sort of, spaces in the middle. So again we've got different options for the rafters on our roof. Then we come down to sort of the insulation bits. We've got one above and we have another one here. So we need a warm roof for this cold climate. So this is about six inches of mineral wool. I've placed it at the top edge, but I could've easily have placed it under the bottom edge. Friction fitted, so it's just pushed in to the space. And I've got a nice little, sort of roll of insulation there as well just to seal this gap. So we've got a nice warm, cozy interior. Now I've also put a vapor barrier. Because of the fact that it's highly unlikely that this space is going to get cold, because of the amount of insulation. But any moisture that did get through, let's say it was a ridiculously cold weather and there was some sort of cold spot in there then that vapor might condense. So by putting a vapor barrier in I'm providing that all the holes that you have for light fittings and other types of fittings in the roof and the switches, etc., if they're all treated really well. So you've minimized the amount of vapor that you get through. Then, that might be a suitable solution. Okay, it's unvented. Because of the fact that there's not going to be any sort of moisture in that cold space that needs to be vented out, I decided to go for an unvented one. But we have this void here which should be quite warm. It's probably going to be very similar to the temperature of the room. And then we've got the interior. So we've got our batten to hold our interior planks on. And that makes up the inside. Now this could be drywall, this could be anything that we wanted on this surface, and I've just taken that through to the outside. We've got a fascia at this point, so again you need to consider that sort of thing. And, I've got a trim, then, that finishes off the join between that. So all the gaps, hopefully, are well-sealed. Hopefully it's well-insulated and we've got no problem with future condensation issues. Okay, so these are the sorts of things that you need to consider. Rainscreen on the outside and then insulation through the middle, whether it's vented or unvented and then some sort of finish on the inside. So, many, many different ways of doing this. If I was to put tiles on here then I'd need to know the weight of the tile because I might have to increase the size of these joists. I'd also need to consider the spacing of the battens because not all tiles are suitable for all pitches. And I'd really struggle to find a tile that would be suitable for this shallow pitch. So those are a few things to consider, not all the things to consider. I'm no expert on fitting roofs, but the point to get across here is that you need to talk to the people who are experts and also appreciate that it's not just one thing that makes up a roof, it's a lot of things.

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