Definitely would be useful on this side; even our standard “box” has raised ceiling joist (birds mouth at ~2.3m from FFL and ceiling tie at ~2.6m)
With the ceiling tie in place, I think that our collar tie is minimal: when we insulate and finish with pb, there is no flat section at the apex.
Our business has grown from installing glazed roof conservatories and we still do the occasional one - just thinking that this plugin could be used to form the roof glazing bars. (Or at least form a skeleton template.)
[quote=“AndrewRubySketch, post:99, topic:16452”]
We call the horizontal member collar ties down under, it is a big call to do with a truss as the tail of the rafter can push the walls out if the timber deflects. I assume they would be using a laminated veneer lumber in this instance or F27 hardwood.[/quote]
Nope - 175x50 timbers I think. Actually it could be 200x50 due to the span - the truss manufacturer specifies this (since he certifies it)
[quote]I would usually draw this type of roof with the rafter tool and then add the collar ties in. I guess it depends on how much detail you like to go into. I do quantity take offs from my models so I can keep a track of the cost to the client. One of my biggest gripes is redesigning due to budget restraints. It does not look like the client had a tight budget on that job, nice work
[/quote]We price/quote off drawings too; my biggest gripe is when clients try and boil things down to a m² rate without looking at the specification or scope of work. As I said, this is our show-site where we have 10 buildings showing various different shapes, sizes, finishes… etc. (This is not the most expensive room we have - the Orangary has a higher specification and greater scope.)
I’m getting ready to add in Glulam beams for rafter roofs. However, as I’m sorting out the details I’m trying to determine what would be the best way of modeling them. I would like to show the different plies but at the same time if someone wants to cut the beam, bevel it etc… I need to have it easily modifiable.
Texture?
Or change the depth of an image texture so that it repeats for each layer.
Or just grid the end/side faces so that it is still a solid ‘box’ with additional lines on the sides/ends.
Or make a group of lines and stretch it over the end/side (so that it’s not a part of the rafter’s geometry - it is an overlay on the relevant faces)
At first I was going to make a component for a single ply and then copy multiple instances. The problem with that idea is a beveled cut would then be difficult.
If anyone can give me links to resources documenting standard sizes for Glulam Beams (metric or imperial) I can work at getting those added into plugin and available for use.
Currently I have the following glulam beam standards available:
With metric input the inch units of the NDS glulam selection is converted to mm. This is merely a stop gap until I can get some standardized tables entered for metric sizes.
an idea is to use a generic ply size 33mm, so for any given depth, int(depth/33) would give number of ply, then division of ply number will give the ply size for a given depth.
Which gives some standard sizes based on Grade. It states that these are the nominal beam widths and depths, I’m not sure if that is the actual size but I will assume so for now.
Some of these depths would suggest that the typical ply thickness is 30mm however there are also quite a few depths where this 30mm does not work. Either there is a different ply thickness for these other depths or they are planing down the larger beams to get to this size.
For example within GL18 the following depths exist: 270, 280, 300, 315, 330. 270, 300, and 330 fit nicely with a 30mm ply thickness, how is the 280 and 315 constructed?
I’ve added an extra input for the beam which allows ones to specify the overhang of the beam from the outside of the wall. With zero overhang the beam will be flush with the wall framing and not exposed. If the beam overhang is less than the gable overhang, the fly will be as shown below (up to the roof peak). If the beam overhang is greater than the gable overhang it will project past and the fly will adjust accordingly. The beam overhang is not restricted in any manner.
I remember a few years back when I was in college and working a side job as a construction laborer we framed up a roof similar to this. The rafters were large I-Joists (TJI 560 equiv.) and were hangered from the glulam beam. The beam was probably almost 2 feet deep. I just remember I was glad I was cutting the blocking on the miter saw and not the one at the peak of the roof setting the rafters into the hangers.
With that being said I am wondering how often I-Joists are used in this type of application versus common lumber. I can probably add in an option to use them instead of common lumber. One question I have though is what to do at the other end, where they bear at the wall. I would need to study this further.
I-joists are used more and more often like this, especially when loads are higher. Out here (Colorado, where we can have 100+ PSF snow load), rafters would not be used on a large roof like that, only trusses or I-joists.
All of the pertinent details for I-Joists can be found here:
All have to think about this one. The problem with I-joists is the bevel cuts are more difficult since it requires more operations to model. The outlookers at the gable ends would need to notch around the top flange of the I-joist. A double or single bearing plate is required at the ridge or hangers from the beam, notching at the high end of the roof joist is not allowed. Birdsmouth cut at the low end of the joist is allowed but requires web stiffeners on both sides of the joist.
If I can figure out a good method of making the beveled cuts of complicated profiles that would greatly facilitate things.
With I-joist roofs don’t think I would model in any of the web stiffeners, otherwise the model gets too heavy, same goes for small fasteners and hangers.
I haven’t even considered the option yet with the rafters resting on top of the beam (dropped ridge). The I-joist manufacturers do not allow notching at the top end and therefore a beveled bearing plate or strip is required with web stiffeners on both sides of the I-joist. Their detail shows a strap across the tops of the I-joists tying them together across the beam, I’m pretty familiar with this detail from some local jobs I’ve done recently. However, I’m also wondering about the beveled strip on top of the ridge beam, how is it made, thickness at the butt etc…
With common sawn rafters how would you typically handle a dropped beam? Would you use a beveled strip or would you apply a birdsmouth cut at the ridge? I think I’ve seen both details but what is the preferred method if there is one.
The problem is I’m not out in the field enough so I never get to see this stuff actually go together very often.
When the plugin is loaded in a metric template it will now utilize a web dialog with metric sizes for glulam beams. The menu and glulam beam sizes are currently listed at the following link:
I probably don’t list every combination possible or manufactured in each respective country or jurisdiction but hopefully I list the most common sizes. So far I have entered in data for the United Kingdom (Great Britain), South Africa, and Australia (and New Zealand).
I can enter in more countries if provided the data (width, depth, locale name and ply thickness). Now that I have the web dialogs and html files setup it is not a big deal to add more entries.
When the plugin is loaded in inches or feet then the US sizes or AWC NDS tables are loaded. So far I have only found one country that still uses the old units.
With regards to outlookers and I-joist roofs I also noticed in the TJ-4000 (Detail O) they only show the outlookers in a vertical orientation. Are we allowed to do a horizontal orientation (outlookers laid flat)? And if so how do we make that attachment?
