Author Topic: Adding Rafter Tails?  (Read 7187 times)

birdman2003

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Adding Rafter Tails?
« on: February 27, 2014, 08:16:32 AM »
The gabled roof on my house has zero overhang, and it's causing problems with water getting inside my mustachian palace built in the 1940's.  In a thread I posted to the "Ask a Mustachian a Question" section, Greg recommended that I add rafter tails.

Has anyone done this to their roof?  Any recommendations on whether to install these on each side of each rafter, or only on 1 side of each rafter?

Also I attached a sketch I made with Microsoft paint.  I found a picture from this book on google http://books.google.com/books?id=vTVE7kRgQ38C&lpg=PA554&ots=QZAjsYSNLp&dq=no%20rafter%20tails&pg=PA555#v=onepage&q=no%20rafter%20tails&f=false
Is the orange piece what I should think about fabricating?  That's my rough plan at this time at least.

Greg

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Re: Adding Rafter Tails?
« Reply #1 on: February 27, 2014, 09:14:30 AM »
Now look what I did.  Usually you add the tail to only one side of an existing rafter.  It's a good idea to be consistent about which side so that the on-center spacing stays the same, at least for the extension part.  Typically you want 2x the new tail to nail to the side of the old rafter.  Meaning if you want to add 1' of new overhanging tail, the part you can't see needs to be 2' long.  You can use nails, but self-drilling screws might be easier.  I like to use torx drive screws and a cordless impact driver.

At the gable ends it will get harder, because you want the new rafter tails to be flush with the gable end wall.  So in these locations, the new rafter may consist of what looks like 2 rafters sandwiched together, though only one extends up into the existing rafter framing.

As a plus, doing this may give you opportunity to add eave venting for the attic.  Usually it's in the form of "bird blocking" or 2x material with screened holes.  There's another way to do it with 1" strip corrugated plastic vent if you don't want the bird blocking look.

Your rafter tails can be pointed "plumb cut" like your illustrations, square cut, or something else depending on the style of your house.  When they're plumb cut you can also install a fascia board that hides the tails and provides a vertical surface for gutter installation.

Exflyboy

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Re: Adding Rafter Tails?
« Reply #2 on: February 27, 2014, 01:10:34 PM »
What Greg said,

I was going to add that getting to this location can be a challenge but if your going to be replacing the roof anyway you and simply pull up a 2 foot strip of roof sheathing when you get the old roof off.

If you have 1*6 planks you can pull up a 4 courses of those, or if you 8*4 sheathing you can cut the lower strip off with a skill saw (set to depth), just remember to stagger the joints when you put it back and use extra clips if you have 7/16ths sheathing.

I think I would probably pull up (or cut) a 3 ft strip off and then replace with a full 4ft wide sheet to cover up the strip and the rafter tail all in one.

Frank

Greg

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Re: Adding Rafter Tails?
« Reply #3 on: February 27, 2014, 01:29:13 PM »
I think I would probably pull up (or cut) a 3 ft strip off and then replace with a full 4ft wide sheet to cover up the strip and the rafter tail all in one.

This is the best method.  In addition to providing access for adding the tails, it allows you to use a "full sheet" of sheathing instead of having to custom rip it.  The sheathing overlap will provide extra strength to the overhangs as well.

paddedhat

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Re: Adding Rafter Tails?
« Reply #4 on: February 28, 2014, 05:03:18 AM »
Solid advice so far. I would add that a cordless impact and deck screws will probably work great for this, unless your existing rafters are really rock hard. This can certainly be the case with some species that are dense and had the chance to dry for most of a century. In that case, you may end up actually breaking a lot of screws off. The other option would be an air powered mini palm nailer. I have a cheap one ($39) that works awesome in cases like this.

The other issue is one that any framer will tell you can be a challenge. The new tails, and facia will be as straight and crisp as the top of the existing wall is. In new construction, any competent framer takes great care in the "line and plumb" process of straightening the walls, prior to installing rafters. This involves using a string line, or laser line, and pushing, pulling, and bracing the walls to get the outer edge of the top plate deal straight. After that, well cut rafters will slam tight to it, and the facia will be dead nuts beautiful.

In your proposal, if you cut every false tail exactly the same, with the exact birds mouth, you will follow the existing building exactly. It the wall is wavy, your new work will really show that. I would do one of two options. I would cut and nail the tails at each end then stretch a string from one to the other, to measure each added tail. OR, I would reduce the dimensions of the new tail so that the board was narrow enough that it didn't need a birds mouth. Then you could just have a plumb cut on the end, and slide the tail up and down the rafter, till it met the string line. I have do this before, and it's quick and easy. Precut all the plumb cuts on a chop saw, hold the tail flush with the top of the existing rafter. Slide down until you just about touch the string line and shoot it fast.
Hopefully. I have explained this somewhat clearly? Good luck.

birdman2003

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Re: Adding Rafter Tails?
« Reply #5 on: March 03, 2014, 09:12:12 AM »
You guys are great.  Thanks for these excellent suggestions.  I can't wait for the snow to melt and summer to get here so I can get up there and work!