Extending loft

[builderboy]

In the 14' wide little house, I'm looking at extending length to 26' and the loft to 12'. I'm wondering if the bathroom is needed support under the loft or are the 4"x8" loft beams ok spanning about 13' unsupported? (for the extra 4' of extended loft where there is no bathroom underneath).

[jraabe]

4x8 at 4' o/c would be a little too springy I think. If you could space them 36" that would work but then it doesn't hit the spacing for the rafter ties. I would suggest a 6x8 or 4x10 @ 48" o/c where the beam is fully loaded and full span.

Now, that said I see that the end beam you are proposing is only loaded from one side (2' of the 4" span landing on it). In that case the 4x8 would be fine.

[builderboy]

Also considering lowering the loft to 7' on 8' walls using the detail for optional 8' loft on 12' walls as per pgs E-4&6 of little house plans. Would that change you previous answer? Any other considerations on this?

[glenn-k]

That wouldn't give you enough headroom below if you are talking about the elevation of the finished floor.

[builderboy]

I was thinking 7' clearance to the bottom of the loft joists, not the loft deck. John's plans show the loft joists sitting on top of 8' walls -wouldn't that be 8' headroom underneath them? So if I dropped a foot I'd have 7' ? My 1.5 story home has about 7' ceilings on the upper level. It's fine.

[jraabe]

If it matters, 7'-6" is the usual code minimum for headroom. You can count to the bottom of the decking if the beams are 3' o/c or more.

[builderboy]

Thanks John. Methinks it matters.

[builderboy]

Talked to the permit guy. He's ok with 7 ft from floor to bottom of loft joists when the under loft is open to the loft decking. (actually he said mininum 6'8"). If enclosing the under loft then he wanted 7'6" floor to ceiling. So, any problems with using the 8ft loft on 12 ft wall option to lower my loft to 7' on 8'walls?

[glenn kangiser]

I'd use the let in 2x if you are using 2x6 walls -     semi-balloon framing.  PEG mentioned that some inspectors will want you to plane the ribbon 2x that is let in down a bit so it is not over the depth of cut they allow.  You could ask the inspector before you do it so there are not problems later.  Some don't care.  I don't remember if it is a 2x4 or 2x6 - search "let in" for more info.

Use the text line search at the end of the words Design/Build  Forum above.

[builderboy]

Thanks Glenn. I followed the thread on the let-in loft ledger/notch depth discussion. It seems my guy is in the don't care group but I'll make sure so no problems later. It sounded like he was ok with a 1x ledger but I'm not. My approach - if in doubt, beef it up. Wood's not cheap, but engineers are worse!

[builderboy]

I'm wondering if I should be using ties to tie my rafters to top plate since the lowered loft joists aren't there to tie to? John's raised roof option on the 14' wide shows simpson 2.5 hurricane ties for rafter to top plate. If in doubt , beef it up.

[glenn kangiser]

Sounds like a good plan - follow PEG's advice.

John is going to be a little scarce here for a bit yet.

[PEG688]

I'm wondering if I should be using ties to tie my rafters to top plate since the lowered loft joists aren't there to tie to? John's raised roof option on the 14' wide shows simpson 2.5 hurricane ties for rafter to top plate. If in doubt , beef it up.

Use H1's where ever you can , H2.5 where only one side of the rafter is excessable.  , In case you have floor joist H2.5 are the way to go.

H1:

[John Raabe]

Thanks guys... good advice all.

You may never put the clips to work unless you have that 100 year wind storm. Still, it's inexpensive insurance. And, it can give the inspector confidence in your building that might be helpful somewhere else.