Just a small question here on trussed roofs, where the things are made in a factory and are installed by idiots in the field.
Normal pitch here is 22 or 30 degrees to the horizontal plane.
Ok that isn't usually a problem, what is, is the plans for the Electrical after the trusses and the cieling runners are up.
You could put money on the fact that most of your lights will be in the middle of a runner,especially where these are stated by the Architect "as plans dictate".
I had a stand-up argument with an Architect one day about his lighting plan, and he didn't like being told that unless he signed the Certificate Of Compliance (Electrical) he could go and get........

Don't know exactly what you are saying, sounds like either the carpenters never saw the lighting plan, there is no detail for runner/truss location from the architect or the lighting layout (or architect) is inflexible in accounting for the framing.

At any rate it all falls on the architect. He/she engineered this thing and it is up to them to make it work.

-Hal

Mike,

Would you have a picture showing the type of construction and situation you are talking about?

Are you talking about Recessed fixtures that have to go where a beam exists?

Bill

Mike-

I'll admit to being a little confused as well, but I think it's partly with your "Aussie-ese" :


Over here, we usually refer to the pitch in "rise-over-run" terms. If the roof rises 4" in a 12" horizontal run, then it's referred to as a "four-twelve"... pretty much an "ordinary roof".

The bottom chord of the truss is usually used as the ceiling runner - the surface to which the drywall (gypsum board) is nailed/screwed, if I understand your post.

As far as the light location per plan corresponding with structural members in reality, I'll attest to that - and it's not just in trussville. I've seen plenty of stick-built houses that call for a fixture where an I-beam, glulam, or other "non-cuttable" support is located.

Most of the architects I've actually seen out in the field get the "DUH!" once they are able to compare "spec" to "as-built", and they usually allow us to fudge the can over by the required 2-4"

There are also "pancake boxes" that will help in some circumstances.

Roger

Trussed roof systems are common on modern houses here as well, but as I rarely get involved with new construction, it's not generally a problem.

In the world of refurbishment to existing homes, if I find I can't put a fixture in the exact spot the customer requests I just explain why and suggest moving it over a couple of inches. Not usually a problem.

Sorry,
I forgot about this post.
Generally here, the roof trusses are erected before we even set foot on site.
the cieling runners are run at right angles to the trusses and are nailed to the bottom chord of the truss.
This is what the Gib (Gypsum) board is nailed to.
The problems start when an Architect specifies that all the light fittings (all recessed R-95 Downlights) have to be placed where stated in the Electrical Location diagram, even when told on site that it just won't work.
Under ECP53 here, light fittings of any type have to be distanced from timber by at least 100mm (4"), that I have no problem with.
As a FF, I agree with it.
But when Architects start telling you to cut bits of the building Structure out, I really lose my rag!.
It's un-necessary and should not be happening.
Sure, I have have tried to take the tack of Pauluk, but, oh no that is the way they planned the lighting.
Just a shame that these young idiots can't design a roof to save themselves.
If I did as they said and cut the runners to bits and the cieling collapses, who carries the can then?.
After all we are sub contractors on these jobs.
Sorry about the rant guys, but I take real pride in a well-done job, without compromise.

I don't see how cutting the runners (the boards running perpendicular to the truss) would really endanger the stability of the truss, as long as the trusses are anchored to the walls, the roof decking is securely fastened, and all the runners aren't cut in a line between all the trusses.

It seems that the runners are there basically as support for the drywall, and less as structural members.

That said, I agree with you Mike... I also chafe when told to "cut something out of the way" for the sake of decor when it negatively affects structural stability!

BTW - does the 4" rule apply to the frames of your recesed lights, or just the lamp housings? And does an "IC" rating effect it at all?

some lighting design calls for certain lights to be placed in a certain area,plus or minus an inch or so, if not right on the nose!, which if done right during the design/planning, and building would have the required sturture in place just like a door is placed during construction and etc.....cutting the lathing for dry wall is ok....cutting the truss is a no no and the "Architect, designer, GC, builder shouldnt ask you to cut any structure! also on the plans if they wanted the lights locked in a certain place with 1 inch plus or minus on the location or with no plus/minus, this should have been covered and noted during the plan review, and bids! calling someone an "idiot" is a bit harsh even when we feel its a just word to use! I know first hand how it feels to be called an idiot after i made an honest mistake and even a dumb one and was called an idiot. Sad feeling for sure.




[This message has been edited by cs409 (edited 06-20-2004).]