Finishing attic space

[chris kennedy]

I have a couple questions for the resi people.

1) Can NM cable be run in the truss system prior to the application of spray foam insulation?

2) Can a 3/8 hole be drilled in a 2 by 6 truss that the roof deck is attached to for the NM to run through?

Thank you.

[ItsHot]

#1. yes..# 2 yes.. keep your 1 and 1/4" rule from edge going.

[cadpoint]

I have a couple questions for the resi people.

1) Can NM cable be run in the truss system prior to the application of spray foam insulation?

2) Can a 3/8 hole be drilled in a 2 by 6 truss that the roof deck is attached to for the NM to run through?

Thank you.
Found using, "sprayed nm" here (http://forums.mikeholt.com/showthread.php?t=87425&page=3&highlight=sprayed) (this forum). ((forgot I was on page three, its all Good))
I seem to remember a Canadian UL (something)link to, I didn't find that.

[chris kennedy]

Found using, "sprayed nm" here (http://forums.mikeholt.com/showthread.php?t=87425&page=3&highlight=sprayed) (this forum). ((forgot I was on page three, its all Good))
I seem to remember a Canadian UL (something)link to, I didn't find that.

Thanks for looking. Mabey the Canadian link was on another Forum. I can't find it either.

[cadpoint]

Here it was California not Canada.
You brother Dennis scooped this:
http://forums.mikeholt.com/showthread.php?t=90704&highlight=sprayed
Doh It is via Canada

[ultramegabob]

altering trusses without an engineers sign off is a bad idea, I would try to find a route around it if possible.

[Dennis Alwon]

If this is truly a truss then you cannot drill it.

Also are they spraying the foam on the rafters or in the ceiling? If it is the ceiling then you definitely want your wiring down first.-- I hate that stuff

[chris kennedy]

Thanks all.

They are trusses. This could be furred down 3/4 inch. I've never drilled one but it seems like 3/8 inch in a 2 by 6 wouldn't hurt anything.

[Dennis Alwon]

I've never drilled one but it seems like 3/8 inch in a 2 by 6 wouldn't hurt anything.
Tell that to the building inspector. :)

[growler]

If this is truly a truss then you cannot drill it.



I was thinking the same things and then it occured to me that if this really is a truss system there is not room because of the way the supports are ran to finish off living space anyway. That's the only problem I have with a truss system is the fact that it limits attic useage. If you can't finish the space then why drill any holes.

[ceb58]

Thanks all.

They are trusses. This could be furred down 3/4 inch. I've never drilled one but it seems like 3/8 inch in a 2 by 6 wouldn't hurt anything.

Chris,
You can go back to the mfg. of the trusses to ask this question, if there eng. allows drilling he can provide you with specks, ie size hole, were to drill, and how many. If they provide the specks, DO NOT throw them away you will need them if the inspector gigs you on drilling.

[chris kennedy]

Chris,
You can go back to the mfg. of the trusses to ask this question, if there eng. allows drilling he can provide you with specks, ie size hole, were to drill, and how many. If they provide the specks, DO NOT throw them away you will need them if the inspector gigs you on drilling.

The builder lives 3 houses up the road and is friendly with the HO. This could be easy info to get.

I was thinking the same things and then it occured to me that if this really is a truss system there is not room because of the way the supports are ran to finish off living space anyway. That's the only problem I have with a truss system is the fact that it limits attic useage. If you can't finish the space then why drill any holes.

I have pics but I'm out of town and forgot my flash drive. This is not your average attic. I'ts usable space and was designed for build-out.

[LarryFine]

I was thinking the same things and then it occured to me that if this really is a truss system there is not room because of the way the supports are ran to finish off living space anyway. That's the only problem I have with a truss system is the fact that it limits attic useage. If you can't finish the space then why drill any holes.You are mistaken, Grasshopper. Here are examples of attic trusses:

http://www.islandtruss.com/assets/images/products/fullsize/attic_truss_38.jpg http://www.conestogabuilders.com/woodridge/images/attic_trusses.jpg

[mdshunk]

I have pics but I'm out of town and forgot my flash drive. This is not your average attic. I'ts usable space and was designed for build-out.Yeah, they do that here a lot to get a "bonus room" when the roof pitch accomodates. You can ID these trusses pretty quickly by their unusually tall bottom chord. Where you'd normally find a 2x4, it'll be something like a 2x10

[chris kennedy]

Yeah, they do that here a lot to get a "bonus room" when the roof pitch accomodates. You can ID these trusses pretty quickly by their unusually tall bottom chord. Where you'd normally find a 2x4, it'll be something like a 2x10

What I'm looking at is the same system in Larry's picture.(Nice job Larry)

The panel schedule says:

Lights Bonus Room.

[mdshunk]

I wire these rooms by laying the wiring behind the knee wall area, in the "V". Naturally, you can't drill anything. I'm not even sure why you think you need to drill a hole. You have to run a lot more wire, but you can wire these things up without drilling holes.

[LarryFine]

I wire these rooms by laying the wiring behind the knee wall area, in the "V". Naturally, you can't drill anything. I'm not even sure why you think you need to drill a hole. You have to run a lot more wire, but you can wire these things up without drilling holes.
Absolutely. Three years ago, we did an attic finish; not just the wiring, the entire thing. Naturally, it was a third-floor attic. I made a hoist for building materials.

We framed walls for closets and doors, plumbed the bathroom, ran the HVAC ducting, wired, insulated, drywalled, trimmed, everything but the floor and paint.

We used sloped-ceiling recessed cans and trims, we did the bath fixture installations, including the sink, shower, and toilet. We have pix if anyone is interested.

[chris kennedy]

Yup, it's the 'alot more wire' thing. I see up and down wiring is no problem, just wondering how you experts do it.

This is in Bryan County Ga. so my long past Fla. resi experiance doesn't help as this type of construction is new to me.

[growler]

I have pics but I'm out of town and forgot my flash drive. This is not your average attic. I'ts usable space and was designed for build-out.

I have seen a " super truss" system that's designed for build out but you don't need to drill holes as there is plenty of space overhead and behind the walls to run wiring without damage to the structure. Those have enough room even for AC duct to run.

If it is just a 2 X 6 joist or rafter on a 24" center it's not going to have much of a load rating. Those pictures that Larry posted would only be good enough for storage and not living space. If you notice even they have a collar tie at the top where you could run wire and to limit the span.

[Dennis Alwon]

If it is just a 2 X 6 joist or rafter on a 24" center it's not going to have much of a load rating.

I agree. From what I recall the 2x6 bottom truss may be good for dead loads such as storage but not for live loads. So just put dead people up there when you are done.

[peter d]

I wire these rooms by laying the wiring behind the knee wall area, in the "V". Naturally, you can't drill anything.

'Round these parts, the roof section of that would be strapped, so no need to go around the world and back again.

[LarryFine]

Those pictures that Larry posted would only be good enough for storage and not living space.Au contraire, mon ami! Those trusses are indeed suitable for living space.

[mdshunk]

I have seen a " super truss" system that's designed for build out ....Those pictures that Larry posted would only be good enough for storage and not living space.So, you're an engineer? You must know these things come with a packet of sealed details from an engineer, saying they are good for actual living space. I think the fact that you havn't seen them is what the main trouble is. They're common as dirt in my area. Matter of fact, when a builder takes his prints to the truss manufacturer, they'll often suggest places where they can make the trusses good for an extra bonus room.

[cadpoint]

The full head room is only two studs each side of the roof peak, my best guess. I've sleep under one of these for years all though more of a standard roof though... 4/12 verse a 1 to 1 or 1/2 as shown in Picture.:D

[growler]

Au contraire, mon ami! Those trusses are indeed suitable for living space.

The picture may be deceptive. I can't see it. The minimum size of a room for habitable space is 70 sq ft. at least 50% of required area must have head room of 7 ft. That room looks like it is about 2 ft wide at the required 7 ft. of head room and would need to be 18 ft long to meet said requirement of 50%.

The minimum live load rating for a sleeping area that does not exceed 30 psf and those trusses look to be about 12 ft long. The longest span for a 2 X 6 on 24" centers rated not to exceed 30 psf is 9'-11" and that's made from douglas fir-larch SS ( the best there is). For this room to meet the required load rating there would need to be a support walls under it before the 9'-11". Even though the room looks small it's the supporting walls below that count when calculating the span of floor joist.

If someone turned this into living space that's great but I would have my doubts after just seeing the pictures.