Thread: House design question?

what is the type of wall shown in the picture called - is that a pony wall? and does anyone have a reference on how to design one , can't find in building codes i've looked at. what to do a 1 1/2 storey with a 12/12 roof but would loke to start roof 2' off the floor tio have some head room.

It appears that wall above was framed with longer studs, then joisted a couple feet below the top plate to create a pony wall, Doug. You could gable the sides to make more headroom, but it might increase the snow load in doing so. But that would be so.........chalet. Or if the load isn't that great, dormers are easier.

edit: a pony wall is often a wall built atop a foundation to save money over running an all mud wall, but would likely apply in this case as well.

Splat, you seem to know framing. Are those rafters going to hold snowload without collar beams, or will ceiling joists be enough to hold it together?

I call that a knee wall. It's nice to see people still cut rafters, using a truss system seems like such a waste of potential useable space.

CMHC has a book called Canadian Wood-Frame House Construction which goes into great detail on how things are built in Canada. I bought mine at the local trade school but CMHC might sell them too.

In the picture the knee/pony wall would be non-load bearing. Otherwise the rafters would spread at the bottom like my barn.

book title edit: can't even read a title any more

Looks like they're load-bearing by that pic...which brings to mind if those are six inch studs???

gordyman - they'll be tied together with ceiling joists, I would assume. But if I had that roof in big snow country, I'd think about a 45 support into the rafters off the side of the house up into the soffets for a little extra diaganol strength. Actually, it wouldn't provide all that much, but it'd look nice. I like exposed truss/kingpin/queenpin setups (handbuilt, with character) in big load roofs. Especally when done in log framing.

edit: yeah, nice to see the cuts in those rafters...

OH baby, don't do it like that.

A cathedral ceiling is supposed to be framed with a big ridge beam, unlike that one.

The ridge beam carries half of the roof loads properly over to the gable ends -- which is the triangular framed wall at each end of the structure. Buuuut, in this case, you have no framed wall at the gable ends, for the pretty views and such.

That's cool, but therefore you'll have to expect the rafters to pick up all the vertical loads, and they aren't sized/spaced to do that (unless your engineer begs to differ, but it reeeally duzzint look it).

So IMHO you're gonna have to collar-tie it ASAP, my friend.

Unless you wanna rip out the 2x ridge beam, drop in a engineer-spec'd LVL (recutting the plumb cut @ each rafter to make it fit and re-connecting all of 'em w/ steel hangers), and framing in a proper gable at each end to support it. You could still have windows but not all the way across...

Go man go.

-Shawn

^^Agreed. Who in the heck designed and built this thing for you. You need to get on this ASAP.^^

Originally Posted by splat

Looks like they're load-bearing by that pic...which brings to mind if those are six inch studs???

2x6 exterior walls are common up here for people building their own houses. It makes a big difference for winter heating.

No sorry the pic is just a clear pic of the pony wall. Just a pic off the net but feel free to pic out the negative points.

It certainly is load bearing. That is my concern in that the outward thrust of the roof does not go immediately into the ceiling joists. Seems that there would be a moment on the wall.

I thought a knee was structural where a knee wall was just to box in the space , the triangle , between the rafters and ceiling joists.

that does not look like a knee wall to me. it looks like a balloon frame...which is a smart move if so. therefore, you do not have to drop the collar ties as far down as you typically would with a typical knee wall in place.

collar ties are or end up being your ceiling joists. look at how your floor joists are attached. my guess is you have some sort of ledger and that is lagged in place. this is old school, but may be applicable in that application.

bearing is on the rafters down to the studs on the wall. your gable end is non-bearing. collar ties tie the roof in from flattening like a pancake.

if you were going w/ a cathedral it wouldn't work. as said previously...

Originally Posted by strawjack

if you were going w/ a cathedral it wouldn't work. as said previously...

Why is that the case?? , assuming there was a ridge beam and collar ties ,though high enough so you would hit your head on them.

Here's a pic of what I want to do but have reservations about.



why do I want to do this ? to increase the effective floor space in a loft.

Trying to find out if its worth the effort.

A ridge beam and pearlings with a steeper slope to the outside walls (kind of like a gambrel) will give you more headroom, Doug.
It would also put the bulk of the load to the beams and allow you you to use that setup on the wall.

I agree with strawjack that it looks like balloon framing in the pic. to me. Very old school. It works, but I'd use a ridge beam for new framing. Engineered wood products are everybodies friend.

The picture above could work, but the connections (and especially the connections not shown in the picture) are critical.

Rob

Originally Posted by DougW

Here's a pic of what I want to do but have reservations about.

Normally the ceiling joist must be attached to the rafter. Otherwise the only thing holding the rafter in place is a couple of nails.

Originally Posted by Snow Dog

Normally the ceiling joist must be attached to the rafter. Otherwise the only thing holding the rafter in place is a couple of nails.

ya, kind of. there sometimes is a difference between a collar tie and a ceiling joist. most times they are one in the same.

to go w/ a cathedral you need to have a bearing ridge beam (as said before). The ridge pictured (most are this way) is not bearing. also, your 'gable end' would bear the ridge beam making your gable bearing (generally they are not). this doesn't mean you can't have a window in your gable...you just need to 'head' it off just like every other window.

from the picture i would check w/ whomever stamped your prints to see exactly how high you can put your collar ties. otherwise you will have to go with a bearing ridge beam. you might have to go w/ both to get the height you want anyway...a blend if you will

Originally Posted by Snow Dog

Normally the ceiling joist must be attached to the rafter. Otherwise the only thing holding the rafter in place is a couple of nails.

The exception being hurricane ties....

Originally Posted by strawjack

ya, kind of. there sometimes is a difference between a collar tie and a ceiling joist. most times they are one in the same.

to go w/ a cathedral you need to have a bearing ridge beam (as said before).

I just realized that my construction book doesn't describe cathedral style roofs. I guess they have to be engineered up here.

Originally Posted by strawjack

from the picture i would check w/ whomever stamped your prints to see exactly how high you can put your collar ties. otherwise you will have to go with a bearing ridge beam. you might have to go w/ both to get the height you want anyway...a blend if you will

no this pic is just a pic off the net. It was used to ilustrate the problem of using the pony wall with out effective collar ties - you get this

http://www.unified-eng.com/ch/thrust.html


and look at the ridge

exactly. the collar ties are not at the correct height based on span and pitch. there is a rule of thumb for the location of collar ties, but i can't recall it.

that ridge is non-bearing, generally they are just used as a nailer for the rafters. the ridge in that picture is irrelevant if other structural procedures were in place.

in your case and maybe the house in the picture...depending on snow loads, wind loads etc. you should use (ive said this already, sorry) a bearing ridge beam and collar ties. a bearing ridge will carry some of the load from the rafters and take some pressure from the walls. this will definitely allow you to raise the height of the ceiling.

i would consult with the engineer that stamped your prints to see exactly what your options are.

btw...i haven't built anything in over 12yrs, except a tree fort!

also, i highly recommend this book.. http://www.acontractorslicense.com/b...f-chapter.html

book bought, thanks

I'm in a differnet situation here in that don't need to have any thing stamped or even looked at by building inspector. No building code out where the cabin will be. A couple of restrictions in the purchase agreement but really only cover outside materials. Want to make it simple and strong.

pearlings......

Originally Posted by splat

pearlings......

errr purlins??