How to repair my roof truss - cut bottom chord

darlingm · 01-02-2012, 02:36 AM

[I have two similar posts - but they aren't duplicates. This post is about the web pieces, the other is about a bottom chord. They seem like separate topics to me.]

We're about to blow in cellulose before winter turns nasty, completing a several month long attic project (air sealing, replacing electrical).

It's a 1000sqft ranch, with a Fink truss gable roof.

Some idiot(s) in the past cut a piece out of the bottom chord, where it is above a kitchen soffet. It's just waiting to collapse into my kitchen! The cut on the right side of this picture is attached to a wall top plate. I believe this wall is load bearing, because the wall is for a hallway that goes through the middle of the house beneath the roof peak. The cut on the left side of this picture is attached to a kitchen soffet top plate. No structural integrity there.

The angle of this picture makes it look like the oven vent goes through where the bottom chord would have been. But that's an illusion from the angle it's taken from. There's about 6-8" between where the bottom chord would be to the side of the vent, plenty of room to make repairs. I guess a previous kitchen layout must have needed a vent where the bottom chord was, and some idiot(s) didn't know he couldn't do this.

I'm thinking that I could cut out a piece of wood to fill the gap, and act against the two sides being compressed toward each other.

I'm thinking then that I could put 2x4's on each side of the bottom chord, and screw them in. I'd have this extend almost all the way from the front of the house to the back. I know it would need to be a lot longer than just the missing gap.

Would this be a good way to go? If so, should I use regular 2x4's, or plywood?

You will see on the right, the bottom chord has an extra piece of wood on each side of it. All the bottom chords have this around where the roof peak is. Not sure if these provide extra support, or if it's so it's easier to walk along the center.

In case it helps, here are some overall pictures of my truss system:

Windows on Wash · 01-02-2012, 08:44 AM

Sister up some lumber and cross brace them.

Based on that picture, the ceiling is not going to collapse (supported wall on both sides of the cabinets if the soffit is tied into the side walls) but the more likely force is trying to spread that chord apart.

This is purely my observance from here. I am not a carpenter or framer by trade so I will defer to some of the guys on here.

packer_rich · 01-02-2012, 09:07 AM

You should be OK sistering 2x4's along the bottom cord. Make these as long as you can, and are still able to fasten them. I would also use some construction adhesive on the 2x4's. Really shouldn't be a problem, but it's the right time to repair it.

rossfingal · 01-02-2012, 10:46 AM

I'm not disagreeing with anything that has been posted.
However, anytime you're dealing with an "Engineered", structural,
component (Trusses) - there can be ramifications.
It's considered unacceptable to cut/alter/modify anything on a "Truss".
However, that being said - you might want to seek out advice from
someone in your area who has experience, dealing with this.
They can look at your exact, situation and possibly, give you some
guidance.
Trusses, can be repaired/altered -
However, some type of guidance, always helps!
It's, sometimes, not what might happen now (structural failure) -
But, what might happen later - over time.
(Eventual, structural - problems)
Just some considerations.

"You will see on the right, the bottom chord has an extra piece of wood on each side of it. All the bottom chords have this around where the roof peak is. Not sure if these provide extra support, or if it's so it's easier to walk along the center."

If you mean the 1 X 6 (4?), layed, flat on the top of the bottom chords?
That's just to line up the trusses and and minimize deflection of the bottom chord -
not really "structural", support.

rossfingal

**BigJim** · 01-02-2012, 11:32 AM

Another thing to take into consideration is wood that close to an exhaust pipe. Under normal use that pipe will not get hot enough to do any damage but if a heavy grease fire it could, that is the reason there are codes against wood being close to a heated or exhaust pipe and probably the reason the cord is missing there.

darlingm · 01-02-2012, 07:58 PM

Thanks guys!

rossfingal - I agree getting professional advise on trusses is a good idea, but it's not in the budget, and we have little time left to get the cellulose in. It seems like a project we'll be able to do, by making all the boards as long as we can.

I was pointing out in the first image, how on the left of the vent, the bottom chord is just a 1x... 4 maybe 6. But, on the right of the vent, there's two additional 1x4 or 1x6's attached, to sort of make it like a 3x4 or 3x6. Those extra pieces are just under the roof peak. For whatever reason they are there, it makes it a lot easier to walk on/crawl on in those parts!

jiju1943 - Thanks for pointing that out. I looked into building code requirements today, and it looks like 6" is needed between the exhaust pipe and the wood. I'll make sure that whatever I do keeps this distance.

**Gary in WA** · 01-03-2012, 12:06 AM

You'll want to insulate the range exhaust to prevent inside condensation when using it. (Cold pipe-- warm moist air from boiling water, etc).
Your site-built trusses are different. They are "one of a kind", so to speak: Page #179: http://books.google.com/books?id=bwt...page&q&f=false

http://docs.google.com/viewer?a=v&q=...6fTirapfPwoKzA

Air seal the attic, especially those drop ceilings: http://www.google.com/url?sa=t&sourc...O842EQ&cad=rja

Gary

darlingm · 01-03-2012, 12:50 AM

GBR in WA - WOW, thank you so much for those links! That guide to air sealing you linked to is fantastic! I've done a ton of research about air sealing, and that guide's the best I've seen actually.

**Gary in WA** · 01-04-2012, 06:06 PM

Glad we could help! Here are some others you probably found already; http://www.jlconline.com/cgi-local/v...170a32100a05c7

stack effect; http://www.wag-aic.org/1999/WAG_99_baker.pdf

dirty f.g.; http://www.finehomebuilding.com/PDF/Free/021105092.pdf

cert. installer check list; http://www.bpi.org/Web%20Download/In...V1.3_DRAFT.pdf

DIY air-sealing; http://www.google.com/url?sa=t&sourc...bfK_vw&cad=rja

B.A. best practices; http://www.google.com/url?sa=t&sourc...wWATQw&cad=rja

How to: http://www.familyhandyman.com/DIY-Pr...s/Step-By-Step

That's most of them...... enjoy!

Gary

mae-ling · 01-04-2012, 10:40 PM

Homemade trusses were at one time common in some areas, and still allowed in some areas. Usually require a engineers stamp.

How long has it been cut for?

Use a fire resistant insulation around that oven vent.

Windows on Wash · 01-05-2012, 08:48 AM

Quote:

Originally Posted by mae-ling

Homemade trusses were at one time common in some areas, and still allowed in some areas. Usually require a engineers stamp.

How long has it been cut for?

Use a fire resistant insulation around that oven vent.

Should use metal around the vent for 6" clearance and then insulate in a perfect world.

Seal with an intumescent sealant for proper air seal.