Attic Truss Swap

ckruzer

ckruzer

Infidel
Joined
Jul 2, 2015
Location
asheville nc
Here is how my attic trusses are. One load bearing wall down the middle of the house.

Is there a away to reconfigure some of these to allow for making a 10x10 livable loft space?

IMG_2374.png


IMG_2375.png
 
@shawn

Before we built our new house, we looked into doing something similar at our old house. We were told the 'ceiling joists' were not sufficient to be used as 'floor joists'. I think they were 2x8's. I design truck brackets, not houses, so don't take my word for it.
 
drkelly said:
@shawn

Before we built our new house, we looked into doing something similar at our old house. We were told the 'ceiling joists' were not sufficient to be used as 'floor joists'. I think they were 2x8's. I design truck brackets, not houses, so don't take my word for it.
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This is definitely where you'll have problems.
What size are the joists? I'm gonna wager 2x4s or 2x6s.
The truss system there is designed to hold the walls square and the roof square by keeping it in tension, but not to carry any serious load. Unless you have 2x8s you won't have the support unless there are walls underneath in the right places to support them being used as joists.

My house is an early 70s ranch. The PO was a family of home builders and they built in a stairwell so you can walk into the attic (going overt he basement stairs). Super cool and convenient... and sooo tempting to use it as a small loft or serious storage.... except the goons only put the trusses 24' on center and used 2x4x. So It can't actually used for much besides convenient access for wiring and such. Soh.
 
RatLabGuy said:
This is definitely where you'll have problems.
What size are the joists? I'm gonna wager 2x4s or 2x6s.
The truss system there is designed to hold the walls square and the roof square by keeping it in tension, but not to carry any serious load. Unless you have 2x8s you won't have the support unless there are walls underneath in the right places to support them being used as joists.

My house is an early 70s ranch. The PO was a family of home builders and they built in a stairwell so you can walk into the attic (going overt he basement stairs). Super cool and convenient... and sooo tempting to use it as a small loft or serious storage.... except the goons only put the trusses 24' on center and used 2x4x. So It can't actually used for much besides convenient access for wiring and such. Soh.
Click to expand...

Joists are 2x4 and 24oc
 
RatLabGuy said:
This is definitely where you'll have problems.
What size are the joists? I'm gonna wager 2x4s or 2x6s.
The truss system there is designed to hold the walls square and the roof square by keeping it in tension, but not to carry any serious load. Unless you have 2x8s you won't have the support unless there are walls underneath in the right places to support them being used as joists.

My house is an early 70s ranch. The PO was a family of home builders and they built in a stairwell so you can walk into the attic (going overt he basement stairs). Super cool and convenient... and sooo tempting to use it as a small loft or serious storage.... except the goons only put the trusses 24' on center and used 2x4x. So It can't actually used for much besides convenient access for wiring and such. Soh.
Click to expand...

Excellent points on the load

In theory couldn’t I run 2x8s the whole span - outside wall to outside wall crossing over the middle load bearing wall?

End goal would be a kids reading loft
 
*Generally* speaking, shop-built trusses (floor and roof) cannot be modified without an engineered design and/or approval from the truss manufacturer. It can be done with a proper engineered design that factors in existing loads and proposed altered loading. But the juice may or may not be worth the squeeze.

Im a civil engineer by degree, a PE, and a building/construction consultant by practice. I don’t do much in the way of structural design. But my brother is a structural engineer, and does the kind of analysis and design you would need to have done in this application. Feel free to pm me if you are interested in going down this path, and I can get you connected with him.
 
If I could swap a number of the kingpost trusses to this style…. (Using 2x8 joists?)

Edit: or convert them

1743437177649.jpeg
 
Kickdeez said:
*Generally* speaking, shop-built trusses (floor and roof) cannot be modified without an engineered design and/or approval from the truss manufacturer. It can be done with a proper engineered design that factors in existing loads and proposed altered loading. But the juice may or may not be worth the squeeze.

Im a civil engineer by degree, a PE, and a building/construction consultant by practice. I don’t do much in the way of structural design. But my brother is a structural engineer, and does the kind of analysis and design you would need to have done in this application. Feel free to pm me if you are interested in going down this path, and I can get you connected with him.
Click to expand...

Thanks. I’ll take you up on that.
I’ll draw everything out an send it over
 
ckruzer said:
Excellent points on the load

In theory couldn’t I run 2x8s the whole span - outside wall to outside wall crossing over the middle load bearing wall?

End goal would be a kids reading loft
Click to expand...
Theoretically - possibly.
At that point you're not using the existing trusses at all. The 2x8s would sit 4" higher than the horizontal runners and would be a seperate system.
Its a question then of the support strength, if that wall happens to be in the center of them that would help. This is where it becomes a math / engineering game of joist support strength. Theoretically someone w/ a table could tell you if they're willing.

A fun challenge is that you have those 2x4 running every 24". If you run the new sleeper 2x8s at 16" centers you'll have an overlap every 4th one.
Although if the first one is offset by 2" then I think it would work out.

Another fun challenge though will be getting those 2x8s up there and placed with the rafters in the way.
 
When we investigated modifying our old house, three different people told us it wasn't worth it and we would be better off selling and moving to a new house. We ended up buying a lot and having a new house built exactly like we wanted.
 
Would require taking the existing roof trusses off and reframing that part of the roof, reinstalling ceilings, rewiring, etc. Existing trusses can't be easily modified. Huge project.
 
shawn said:
Would require taking the existing roof trusses off and reframing that part of the roof, reinstalling ceilings, rewiring, etc. Existing trusses can't be easily modified. Huge project.
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Incorrectly stated "kingpost" above. Oops
So there isnt a way to barney fife converting the Queen Post style to the shown Attic style? Keeping it 2x4s. Then span 2x8s at 12oc

Willing to listen. Willing to drop it if unsafe. Wanting to explore all options


1743514912679.png


1743515512203.png
 
@Kickdeez will something like this work for your brother? Or should I get some more measurements of the trusses?

As mentioned about getting the wood in there - Id figure that would be solved by install a skylight or window.

If i did it on the garage end above the bedrooms, I could use the bedroom walls for additional support. The problem is - whether or not the trusses can be modified - which doesnt look favorable like @shawn said

My investigations have shown that some people accomplish it without any roof removal. They, for example, build in standard rafters attaching to the top chords and addin collar ties.

Permitted goal would be truss modification for floor adding to use as storage storage space of approx 13x13 sizing.



IMG_2381.jpg
 
ckruzer said:
@Kickdeez will something like this work for your brother? Or should I get some more measurements of the trusses?

As mentioned about getting the wood in there - Id figure that would be solved by install a skylight or window.

If i did it on the garage end above the bedrooms, I could use the bedroom walls for additional support. The problem is - whether or not the trusses can be modified - which doesnt look favorable like @shawn said

My investigations have shown that some people accomplish it without any roof removal. They, for example, build in standard rafters attaching to the top chords and addin collar ties.

Permitted goal would be truss modification for floor adding to use as storage storage space of approx 13x13 sizing.



View attachment 435935
Click to expand...
Sent you a PM with contact info.
 
ckruzer said:
As mentioned about getting the wood in there - Id figure that would be solved by install a skylight or window.
Click to expand...
The problem isn't getting them up there.
Its being able to swing them around to get into place. The rafters will be in the way.
 
You could certainly reframe a portion of it as stick built rafters and ceiling joists. Maybe you could marry up to the 2x roof frames and then cut out the web members once everything is framed up. It probably still means removing some of the soffit or roof to get access to the roof/wall interface, and would likely mean making some interior walls load bearing that aren't currently, and adding headers, posts, footings, etc, to carry that all to ground. Or clear span the floors with some deep LVLs.

Incidentally, this topic came up yesterday afternoon with a friend of mine. He was involved in a project where they did basically this. Sounded like they got a hundred fifty, maybe 200 SF for about $100k.

How much headroom do you have? It doesn't look like much.
 
shawn said:
You could certainly reframe a portion of it as stick built rafters and ceiling joists. Maybe you could marry up to the 2x roof frames and then cut out the web members once everything is framed up. It probably still means removing some of the soffit or roof to get access to the roof/wall interface, and would likely mean making some interior walls load bearing that aren't currently, and adding headers, posts, footings, etc, to carry that all to ground. Or clear span the floors with some deep LVLs.

Incidentally, this topic came up yesterday afternoon with a friend of mine. He was involved in a project where they did basically this. Sounded like they got a hundred fifty, maybe 200 SF for about $100k.

How much headroom do you have? It doesn't look like much.
Click to expand...
This. The 2 options as I see it are:

1. Pop the top, remove existing trusses, replace with new shop-built trusses to accommodate living space, and rebuild roof. Will likely require analysis of existing exterior bearing walls and foundation/footings, and possibly beefing up both to accommodate loads for essentially adding another story.

2. Abandon existing trusses in place, stick build joists, rafters, ridge beam, ridge beam posts. Will likely require some amount of roof demo and replacement. Will also likely require similar analysis/beefing up of exterior walls, foundations/footings, as well as the same for an intermediate bearing wall/beam below added living space.

This work would have to be permitted through the city/county, which would absolutely require engineering. Any engineer worth the ink on their seal and signature would need to analyze the load path from top to bottom to make sure new loads are properly supported.
 
Welp
The expertz have spoken
Sounds like an insane undertaking
I reckon i lived around too many Fife family members as a kid, who would hack'n'tack new boards in place, lay some sheet and call it good.
It must have skewed my beliefs
:laughing:
 


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