I was wondering if any of you may have experience with attaching a timber roof to an Insulated Concrete form wall. This is for a northern Canadian project, so the insulation beyond the plate is important...

thanks in advance,
brock

I've attached more conventional big timber to ICF's but not traditional timber frames. I don't see why it couldn't be done though. Are they trusses, rafters?

Geez - my first post was rather non-descript - I may have been drinking decaf.

The idea is to build a traditional timberframe building without the posts, braces or anything else below the plate. Instead of the frame relying on the posts to stay standing, I'd like the roof system to bear on the exterior concrete walls.

It would be nice to place an 8" timber directly on top of an 8'ICF (timber visible inside and out) but I would rather move the timbers inward to allow for insulation. I'm just curious how far 'in' you could move before you'd require a post to hold the thing up....

Here's a thought:

Use principal rafters (common purlins) implemented with a king-post truss. Hold the tie beam of the king-post-truss all the way to the bottom of the truss, so that the rafter feet sit on the tie beam. Tie beam (which sits on the ICFs) could be a few inches longer than the span of the rafter feet, leaving room for your insulation. Not sure if the point load would be too great for the ICFs in this design though. However, using a truss design (like this) that imparts no spreading forces to the tops of the ICF walls would be a very good thing.

I've contemplated ICF walls (later faced with stone) with timber trusses for my garage (when my house is finished!), and that's the design I keep coming back to. I would be leery of common rafters on (unbuttressed) ICF walls unless I used collar ties and held them very close to the bottom of the rafters.

Just a thought!

Good ideas. Honestly, i hadn't really given alot of consideration to the out thrust issue when using rafters... I was thinking that if you could design a roof to sit on timber posts without thrusting, you could place the same system on a concrete wall. Your comments have provoked alot of thought....

There must be a way of seamlessly incorporating the two - they seem so good together. Any engineers out there care to throw a bone?

Outward thrust is almost always an issue in a pitched roof, unless the ridge is fully supporting the rafters (load transferred vertically down to the foundation). If any of this is unfamiliar territory, I STRONGLY suggest you consult someone such as an engineer regarding the details before you get too far into it. So far, your posts have not provided an adequate picture of your roof design ideas. You should get the mechanics squared away first. The options for attaching to an ICF wall are many but the design of the roof system has to come first. Good luck.

Thanks Dan. Indeed, I wouldn't proceed on such a project without consultation. I'm but a young buck with large ideas.

I understand that full length posts from floor to rafter (or mid span plate) could alleviate some thrusting issues. Clear spans are not a neccessity for the project. By no means is there a plan on paper right now - just gaining opinions. Thanks everyone, by the way, for your 2 cents.

Brock

Very fun looking project Derek! It's tricky to see the detail of where the frame meets the ICF's at the roofline, but that's the part I'm interested in. Looks like a purlin roof - no connector or purlin at the foot of the rafter, or so I can see? Do tell...

We built a conventional Timber Framed roof and loft inside and on the exterior ICF wall.

It even had a 4 knee wall and second floor loft.

Only 2 posts inside were actually structural the rest were just for looks.

Very nice project when it was done.

Not a bad way to go if $ is tight and the customer wants high R Value.

And yes the Romans used concrete, don't know if they invented it though. Some of the largest Roman structures still standing had concrete in them.