I have the pleasure of re-building a 1951 house, 720 sq ft, for my son to live in. I’m sure I’ll have more questions as I go along but this one has me puzzled. I am a DIY’er with 2 re-models under my belt.
The house is all 2×4 framing. The Building Inspector (and me) want 2×6 roof framing. So my plan is to sister 2×6’s next to the 2×4’s and move to the next project. Problem is that the bird’s mouth on the 2×6 will have to be severe and I’m afraid that the rafters will split eventually where they meet the wall. (sketch attached) Is there a trick to doing this without raising the roof? I have been scratching my head over this one. The only thing I can think of is to attach a metal plate to the side of the rafter to keep it from splitting.
Thanks,
Jim
Replies
Put blocking between the 2x4s and use joist hangers for the 2x6s with a seat cut the same length as the pocket of the hanger.
Done.
Rik
Something like this?
Yup but if yer doing the moony wall I would drop the top block and use it as a ledger as a previous poster noted. It depends if you can get full bearing on the bottom of the 2x6. You may still want to use hangers as shown in yer pic to keep the rafters above your ceiling . Either looks structurally adequate.Rik
A ledger, the obvious answer. That's why I missed it.
Time to finish digging the new piers so I can get to the fun stuff.
Jim
Art has basically the same idea that I do.
Only I would leave out the blocking, Sister the 2x6's with a notch cut instead of cutting the 2x6's off flat on the bottom.
Then cut ordinary hangers on one side, and install as per usual.
View Image
Just because they want to make it personal,
doesn't mean you have to take it personal.
Why not raise the roof?
Are you planning to insulate? If so 5 1/2" isn't much and you also lose some with the double studs.
Seems like a no brainer to tear the whole top off and start fresh, particularly if you're doing it for family.
Joe H
My first thought was to rip the roof off, order some trusses, and git-er-done. Next, it was work with the existing shell to avoid and issues with the minimum standard for the neighborhood. Now I'm looking at the work involved in fixing the roof structure. There is some rot in the 1x12 decking, sag, bowing in the walls. A smart person may do like you said, rip it off, do it over. I'll check truss prices vs lots of 2x6's. Trusses would eliminate the two beams I was going to install to open the kitchen and ligving areas.
My son and I should be able to install 24 ft trusses without a crane, yes????
Still wonder if there is a trick way to solve my problem. Blocking, joist hangers, cover the mess with crown moulding.
Jim
24' trusses you can set alone, two of you no problem.
You can straighten your bowed walls at the same time & have room for a decent amount of insulation.
Probably faster too.
Joe H
Edited 12/15/2008 6:25 pm by JoeH
Why do you want 2x6? If it's because the 2x4 rafters are overspanned then you may just be able to add 2x4 sistered next to each one, rather than needing 2x4 + 2x6. If it's for insulation depth, then the question is, what is the required R value?
I am planning to do Mooney walls and 10" of blown in for the attic. I'm getting in touch with the HVAC contractor this week do discuss options and sizing. I may also foam the roof deck if I feel rich and in the mood. As small as the house is the heating and AC bills will be small so the pay-back will be a long time for foam.
Jim,If you are doing a Mooney wall just let the top piece of strapping act as a ledger for the 2x6 rafter that has a plumb cut nailed to pressure blocking.KK
Yup
Me too, yep. Or here in Texas, you bet.
Also the Mooney wall sounds like the best option short of foaming the whole house. Our issue here is summer AC that's why foaming the roof may make sense.
This house originally was 24x20. It had 12 ft added on the back in the early 60's. The old part was fraimed 2 ft OC with a single top plate (done wrong). The newer part is 2x4 16in OC with a double top plate. Studs are 92in in the newer part.
I could raise the roof one rafter at a time (remember this is a "hobby"). Jack 3 rafters up, cut the nails, install the new rafter in the center, move over one rafter, repete. It's only 12 rafters per wall.
Jim
boss will jump in on this... but i'm pretty sure you could make your 2x4's into trusses with plywood gussets... maybe a 2x6 joist/bottom cord...
alot more work ... but maybe less money than rip'n it all off and set'n trusses but i've done dumber things...
p
Basically the BI said the roof framing needed to be 2x6. I'll ask if doubled 2x4's with purlins properly braced is OK. He will be out inspecting the foundation forms soon and I'll ask (the foundation is crumbling away). No snow load here and it has had 2x4's on 2 ft centers since 1951. Here is a picture. A real beauty!
If I understand your situation correctly it's the same roof framing as this 1952 house I'm currently living in. Very little space for ceiling insulation, near the outside walls.
That alone makes a big difference in long term value received from demo-ing the old roof and installing trusses with plenty of height above the exterior bearing walls.
I needed to sister up the ceiling joists around a new stairway I was cutting in. The ceiling was 2x12s pocketed into a brick wall at one end.
My engineer told me that butting the sisters up to the brick was fine. They would add the necessary strength and stiffness, and the existing joist would have plenty of shear strength.
This is probably the case for you, too -- square-cut ends, top and bottom, should be fine.
But that doesn’t mean that your BI will sign off on it without an engineering stamp.
Full service lumberyards often have in-house engineers who can help with straightforward stuff like this.
And if not, it's still probably worth your while to hire an engineer -- unless it’s a complete tear-off, sheathing and all, you can’t get new, full-length rafters in. You’ll have to cheat somewhat on the length anyway.
AitchKay