Hammer Beam on top of Rastra Block (ICF)

[Jedon]

I'm in the planning stages and want a hammer beam cathedral ceiling for my great hall (25ft x 50ft). The walls will be 12" Rastra Block ( http://rastrausa.com ).  I have 97 acres of timber land and am hoping to be able to use the timber from that, plenty of Doug Fir, Incense Cedar, Madrone, Live and Tan Oaks. I start construction in spring of next year so if I cut in the next couple of months they would have a year and a half to dry. I have a Stihl MS361 saw that I thought I'd get an Alaskan type mill for. I want a rustic look (hewn would be best) so they don't need to be polished or anything.
So.. am I crazy? Is this doable? Thanks!
http://darklingcastle.com
-Jedon

[TexasTimbers]

Dude you are in for a heap of work. You can find out practically everything you need to know here on the forum though. Good luck & welcome Jedon.

[Jedon]

Thanks 
I don't want to do it all myself, if it's better to have someone come in and mill for me, then fine.
Things I don't know:
1. Can 12" Rastra support a Hammer Beam of that size?
2. Is it cheaper/better to just buy other peoples timbers than to have it cut off my property?
3. Is it cheaper/better still to have a Timber Frame company do the whole thing?

I'm not building the house, but I am designing it and will help build it, the subs will do all the actual tricky bits.

[TexasTimbers]

1. Can 12" Rastra support a Hammer Beam of that size?

You'll need to determine the total load that will be sitting on top of the blocks, and have an engineer at Rastra determine if it's copacetic.
On a project like you are talking about alot of engenieering needs to take place. Way beyond my limits.
Jim Rogers should be along at some point and he can point you in the right direction.

2. Is it cheaper/better to just buy other peoples timbers than to have it cut off my property?

Check with your local sawmills first, then check with your local sawyers and see what they would charge.

3. Is it cheaper/better still to have a Timber Frame company do the whole thing?

If you can afford to have a company do it and don't have the "need" to do it yourself, just to say you did, then by all means you should hire it out. To some (like me), the journey is more important than the destination. But if you really just want  to enjoy living in the TF, having it done is easier (much) and quicker (usually) and certainly less stressful.

[srjones]

Hi Jedon,

I'm going to write up a longer reply, but let me ask...where abouts are you?  State/region, etc.

-srj

[Jedon]

North San Juan, California. It's about 2 hours north east of Sacramento. It's off the grid at 4000ft on a north facing slope, the property ranges from 3400 to 4000 ft elevation, slowload is 120psf. Building site is at 3700ft.
http://gallery.darklingcastle.com/main.php?g2_view=core.ShowItem&g2_itemId=342

[srjones]

Oh, okay thanks.

Here's my take. 

1.  I think Rastra is a great choice for what you're doing--insulation, assembly, fire protection. 
2.  I'm almost positive that you'll need to enlist the services of a structural engineer that can 'stamp' in California, and that's just for the blocks.  The trusses will need engineering too, and the foundation. 
3.  It looks like you're fairly remote so falling/milling your own trees makes good sense.  However, check with your county building inspector to see what they expect for grade certification.  Timber grade is also a consideration the structural engineer will take into account.  What you might consider is this:  First figure out what you need (plans, engineering, etc).  Then, go cut down the trees you want to make them.  If you're going to saw them yourself (with a chain mill) then saw them where they fall, but if you're going to hire someone, you'll need to yard them to a central area.
4.  I think your saw might be underpowered for milling, especially if you're going to do a lot of it.

1. Can 12" Rastra support a Hammer Beam of that size?

This system gets filled with concrete and uses rebar, right?  Check with the engineer that you'll need to hired, but my guess is YES
5. 

. Is it cheaper/better to just buy other peoples timbers than to have it cut off my property?

Cheaper is a quantifier but better is a qualifier.  Do the cost comparison of each and include transportation, taxes, time, labor.  But, if you choose specific trees for specific beams/posts you might think that's better.  And if the house you build comes from the trees on the land, you might think that's better too.

6.   

Is it cheaper/better still to have a Timber Frame company do the whole thing?

Don't know about this one, but it would probably be faster.  Also, if you go that route, it's likely that they won't be your timbers.  However, it depends on who you go with.

7. 

So.. am I crazy? Is this doable?

Are you?  Oh yeah, but hey, aren't we all? :D  Is it doable?  Sure given enough time, money an perserverance. 

Good luck.

-Steve

[Don P]

Crazy? I'm not sure that asking the other patients in the ward is going to lead to an unbiased answer to that .
We have a fellow locally in his later 70's who has been building a mountaintop castle for the past 5 years or so, turrets, curtain walls, the whole thing. Another local contractor called the other night, a client wants him to fell, hand hew and construct a timberframe. If you're under 75 I wouldn't even call you eccentric.

That is one serious snow load, its 4 times our entire roof load, design accordingly!

Don't know if you've come across this page in your castle searches. I happened upon it while looking up an old pile of rocks and trying to visualize what it had been.
http://www.maybole.org/history/castles/index.htm

(I think the Mallow on your page is mullen?)

[woodbeard]

The only thing I can add here is that your MS361 is way too small a saw for the job. Check out other threads here on chainsaw milling. I have milled with an 046 Stihl and found it quite underpowered for the application, even on small logs. Otherwise, It sounds like an awesome project. Brings to mind pictures I've seen of English great barns and such, with stone walls and timbered roofs.

[Jedon]

This system gets filled with concrete and uses rebar, right?

Yes is does, it forms a reinforced concrete grid. Rastra said to send over my plans and they would have their structural engineer check it out.  I will still need a local engineer I can work with closely since as you point out, most of it needs to be engineered, especially with my high snowload.

your MS361 is way too small a saw for the job

I guess I should use my saw to get firewood and do some clearing and leave the milling up to the professionals. I'll enquire about people with portable mills in the area, I've seen them
driving around.

How long do the timbers need to dry for roof trusses? How about for floor beams? Is 6 months to a year enough? I read that you should timber frame with wood that isn't completely dry to make it easier to work with, is that true? Otherwise it would take years to dry a bunch of 12x12 beams  :(

[woodbeard]

I guess I should use my saw to get firewood and do some clearing and leave the milling up to the professionals. I'll enquire about people with portable mills in the area, I've seen them
driving around.

There ya go! Maybe one of them is one of us anyway! :D

BTW, just looked at your website, very cool indeed! Do I smell SCA? Are you going to dig a moat?

[Jedon]

BTW, just looked at your website, very cool indeed!p

Thanks!

Do I smell SCA?

Hehe you have a good nose

Are you going to dig a moat?

Not at first, I would like to have some kind of water feature later but I'm limiting initial plans to just the castle itself to make sure it actually gets done...

[Thehardway]

Jedon,

From what I have seen on the Rastra website they use what the ICF industry calls a "waffle grid"  or "post and beam" system (the forms create a wall which is composed of a grid of solid concrete posts tied together by concrete beams when the form is filled with concrete which is properly vibrated/consolidated).  Although this system creates a very strong wall in terms of strength/weight ratio for horizontal loads in my opinion it is not as well suited as a solid or "monlithic" type ICF system for non-distributed heavy bearing loads. Using heavy timber trusses places a very heavy load at specific points on your wall system (8'-16' OC as opposed to standard lightweight trusses spaced 16"- 24" OC).  Concentrating the weight in this manner means that the trusses must fall in line with the "post" in the wall system.  Locating trusses over "beam" portions could be catastrophic.  If you go ahead with the Rastra system I would pour a reinforcieng pilaster of solid concrete/steel under each truss.  If you really want to go for that medieval look you could buttress the trusses with a perpendicular exterior wall.   This would help a lot in preventing outward thrust from your hammer beams and would lend authenticity to the structure. 

http://en.wikipedia.org/wiki/Buttress


I am working on a similar project, planning to use Fold-Form ICF walls and king-post trusses.

Your greatest dificulty may be in setting the trusses atop the walls at completion.  Trusses have to be "set" requiring that the entire weight of the assembly be lifted at once whereas bents only need to be "raised" or stood up with the posts bearing much of the weight in the process and providing a leverage point.

You had better plan how to get a crane on site!