Little House Plans Mod. to 16x28: Loft Floor Height?...

[ajbremer]

I noticed on the pics of the nash building (http://www.countryplans.com/nash.html) that the loft floor looks a foot or two lower than where the roof starts.

On the 16x28 Cabin Plans [Modified Little House Plans, pdf file available here], I noticed that the cross section view on pg.5 shows the roof height to be 6'8" to the underside of the ridge board - where the 45 degree angles meet. That doesn't seem like much head room to walk around in up there. I also notice that it looks like it's 8' from the floor to the ceiling (bottom of the loft joists).

I would like to have more head room to walk around up there and noticed that the nash building looks like he made the loft floor lower. How do I modify my plans to do this? Should I order another set of plans that show this step? Here's a good pic of one of nashes shots:

http://www.countryplans.com/images/nash/bigtolittleloft.jpg

[johnky]

I'm not positive but I think what he did was use 12' studs instead of 10'.  That's how he got the higher knee wall.  There is a thread somewhere on here where this is all hashed out. 

The reason he was able to use 12' was because his loft covers almost the entire floor plan - or at least you could say he has a loft at each end.  It could almost be considered a second story, not a 1.5 story because of this. 

If you have a loft on one end only, and then want to have a cathedral ceiling on the other end, then you can't use 12' wall studs.  The 4' spacing on rafter ties for the cathedral ceiling is not enough support for 12' studs.  The limit is 10' if you're going to have a cathedral ceiling.

If you are dead set on having that higher knee wall in the loft on one half of the cabin and still want a cathedral ceiling on the other half, I think you're only option is to go with a ridge beam and ridge poles so that you're 12' wall studs are not carrying the roof load and thus won't deflect.

hope that helps...

[HoustonDave]

I looked at the same situation and the responses that I got were:

10' walls are the highest you can go with cathedral ceilings using standard rafters.  The reason is you have basically a 10' lever hinged at the sole plate with the roof rafters pushing outward at the top.  Extend that length to 12' high walls and you are pushing design limits and asking for deflection at the top plate.

If you want more loft headroom, your options are:

A) Lower the loft floor where you have minimum headroom on first floor underneath (I believe that is 7' 6").
B) Give up cathedral ceilings in the non-loft area.  You would need rafter ties at every rafter.  You could raise the rafter ties to the upper portion of the bottom 1/3 of the rafters and make a cambered ceiling.
C) Use 12' walls and use engineered scissor trusses in the cathedral section instead of standard rafters.

The Nash cabin uses 10' walls I believe, and lowered the loft floor and looks like he used closely spaced and smaller joists in the loft floor to gain a little more room.  Add to that a 12/12 (45 degree) roof pitch and he gained quite a bit of head room in the loft area.

[MountainDon]

from that it does appear to be a ten foot sidewall. There's also a center beam and posts under the loft to reduce loft joist size.

If that would suit you we can advise what method to use. It begins with using 2x6 for wall studs.

[ajbremer]

Thanks MountainDon, this is the method that I want to use. Please advise me further of what I need to do. Do I need to purchase different plans?

[MountainDon]

You only need to modify the present plan. Use 2x6 wall studs and "let in" a ledger. There is an old thread on the subject but virtually all the photo link are dead.

This is a very rough hand drawn illustration. Your studs should be straighter than the one drawn.  . The let in 2x should be even with the stud face not inset as hurredly drawn.



The notches can be cut before constructing the wall. That way all the studs that need the notch cab be clamped together with a bar clamp. The position is measured and marked. The cut can be done with a skilsaw set to the right depth or a tad shallow. Cut several times across and clean out with a chisel. A router can also be used with nailed on guides.

The ledger has to be positioned to not interfere with windows and window headers. Just a matter of thinking it out on paper first.

[ajbremer]

Tuesday Night - January 4th, 2011 @ 6:49pm Oklahoma, USA

Thanks for that drawing and info on the Ledger "Let-in" Don.

Over on another post of mine (http://countryplans.com/smf/index.php?topic=10064.0) astidham gave me the link to dugs very long project over at: http://countryplans.com/smf/index.php?topic=8038.0

Wow, what a cool learning post that is and a great place that he built! I breezed through it pretty quick for the first time, without reading hardly any of it.

I found a pretty good pic of what you described to me there Don. Here's the pick from page 7 of dugs great post:



That really shows a nice shot of a Ledger!

All I can say is Wow! I am learning so much. Of course all you guys forgot more than I know about building. Almost all the things in my life have gone on hold while I'm trying to figure out exactly how I'm going to build my 1st house. I thank God for this place!

[rwanders]

Using a properly supported ridge beam instead of a ridge board with all their required rafter and collar ties will permit, I believe, 12' 2x6 stud walls.  It seems a much easier way to maximize usable loft areas and have true cathedral ceilings.  Am I missing some other issues here?

[HoustonDave]

rwanders, you are right, that should have been in there as well. 

Someone please correct me if I'm off base here, I'm mostly summarizing what I've read here and elsewhere, but I think the options are if you want increased loft headroom:

A) Keep your 10' walls and lower the loft floor where you have minimum headroom on first floor underneath (I believe that is 7' 6"). 
B) Use a post or other load bearing base under the loft to allow you to use smaller loft joists and gain a bit more headroom as well.
C) Give up cathedral ceilings in the non-loft area and use 12' walls.  You would need rafter ties at every rafter.  You could raise the rafter ties to the upper portion of the bottom 1/3 of the rafters and make a cambered ceiling in the non-loft part.
D) Use 12' walls and engineered scissor trusses in the cathedral section instead of standard rafters.
E) Use a ridge beam (supported by gable walls and posts) instead of a ridge board (supported by eave-walls) to allow 12' walls.  

Roof pitch has a big impact on headroom and usable floor space in the loft too of course.  What is the steepest roof pitch folks would consider for a 1.5 story?  I've heard 12/12 thrown around, and I know that is zero fun to sheath and shingle.  I'm guessing that anything steeper than that is diminishing benefit.

The only problem I've heard mentioned here with true ridge beams is that they can be a little pricey and they are HEAVY during install.  For a small cabin not too bad, but a 28' long beam that high up would not be fun to install.  I'm sure there are ways to make it easier though  (heavy equipment, home-made block and tackle setup, etc).

[rwanders]

If your site is accessible, most suppliers deliver large beams with a crane truck and if you are ready for them, they will often put it in place for you without extra charge-----my beam was 6x16x36 feet----thank god for crane trucks!

[John Raabe]

I think HoustonDave has done a good review of options for raising loft headroom.

If you are doing 12' high walls in a cathedral area (no loft floor joists to tie the walls together) you may need additional ties depending on the size of the open room (check w/ inspector).

You may be able to offload the roof framing to a truss company. See if they can design an engineered truss like I show (as a site-built version) in the 20' wide 1-1/2 story plans. They can probably be delivered to loft level and might also work over the cathedral section of the house.

For a 16' wide building you will likely want a 12:12 pitch to provide headroom in the loft. For wider buildings you can go shallower and still have some usable width. If you are not ready for working on a 12:12 roof, you can  farm out just the roofing work to framers who have the safety equipment and experience working on steep slopes.

A roof has to get down to about 8:12 before most people feel comfortable walking around untethered.

[UK4X4]

Your ridge beam for the open section does not need to be full length of the building either if the post supporting the loft floor goes higher, ie loft area balloon walls and the front open section with a ridge beam.