length of loft joist

Started by chrisbrowning, May 23, 2005, 11:34:57 AM

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chrisbrowning

ON the 12x18 house with a steep gable roof.
If the width of my house is 12ft would the length of the loft joist be 12ft. Or would it be 12ft-1 1/2 inch. I am looking at the plans and trying to picture how the rafters and the joists tie in. There is suppose to be 2x4 blocking. Does this 2x4 blocking run the entire length of the house?

Is the loft joist next to the rafter. I have looked at other building books (which is probably why I am confused) and they have got the rafters setting on top of the joists with tie plates.

Also on the ridge vent peak what is this made of? Is it something that you buy that sits on top of the ridge board?
Help me John and Glenn!

glenn kangiser

Hi Chris,

I don't have the plan information so can't help on this one, however John is due back soon - today I think - also he checked in from NYC, so with you posting here in plan support you should get a reply from him quickly.
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.


John Raabe

Chris:

The 12x18 Little House has a 12' dimension to the outside of the studs. The loft joists or collar tie (detail on sht. 5 for clipped or extended eaves) is full width - 12'. Blocking fits between rafters. The joist or collar tie overlap the rafter and get nailed to it. See Wagner "House Framing" p. 130 for more info.

The ridge vent is something you ask at the lumber yard for. There are different products in different areas. I like to use cor-a-vent which is corrugated plastic. Other times builders use a preformed aluminum vent nailed on either side of the roof sheathing.

Here is one of the cor-a-vent products I have used:
http://www.cor-a-vent.com/v600.htm
None of us are as smart as all of us.

chrisbrowning

Thank you John for responding.

So according to the drawing it looks like that there are TWO 2x4 blockings.
1)between the rafters that are notched by a cut 1 and 1/2 inchs into the 2x4. How wide should the notch be?
2)On the outside of the sheathing that is centered at each rafter with a 6 inch space between each block so one can attach a insect screen.
Is this all correct?

That would mean that the end  of the  rafter would also have to be flush with the outside of the 12 foot wall (on a clipped roof- right?

John Raabe

#4
Thats right, the rafters are cut at such an angle (45ยบ for the 12:12 roof) that the rafter has full bearing on the top plate. They are then plumb cut vertically at the wall line.

You will do this via a full scale layout template on the platform floor that has been snapped with a chaulkline. You make two template rafters first and test the fit before cutting the rest of the rafters. (Read your Wagner.)

Now, install the loft joists and collar ties. These hold the rafters from wanting to hop off the wall - nail them well :D. Cut blocking to 21" where these joists or collar ties lap over the rafters. Cut blocking at 22 1/2" long where there are no collar ties. This should keep your rafters on your 24" layout marks.

Now sheath the walls with the OSB or plywood. Nail this into the blocking and rafter ends as this sheathing membrane ties everything together as a unit.

When you are ready to sheath the roof, put up the vent blocking on the outside of the sheathing and install the facia to that (for the clipped eave roof).
None of us are as smart as all of us.