Adding Eaves to Existing Metal Pole Barn

[Jayhawk_Aviator]

My build has the roof that pretty much ends at the wall. I'd like to dress it up with 1 or 2 foot overhangs all the way around. I'm planning to replace the roof shet metal, so it will be exposed and a good time to do it.

Anyone done it before? I'm not totally visualizing how I will go about doing it, as it seems my existing truss stops at he wall and to sister an extensionsion it would gave to go through the header board.

Thanks,
Scott

 

[mcbane]

If you have snow loads you can probably extend the sheet metal a few inches without issue. No snow loads and you can probably go a foot before wind becomes an issue.

Metal buildings designed for significant eave overhang have framing that extends beyond the wall and purlins spanning between frames to handle wi d and snow loads.


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[matt_i]

You are going to have to make a "T" joint in wood which is a thing fraught with peril.

There are a couple of ways. Use dowels, use structural screws, use a plywood rectangle to strengthen it. You'd need a mitersaw to get the proper angles on the short pieces. You'd be a factory making a large number of the same part. Then you'd screw these parts to the top plates to align with the existing trusses and help extend the roof plane. I would consider some pieces of flat metal ******** the top surface going over to the truss to help build tension. I would do these every 2 feet at minimum. Every 16" or 12" would be better yet. Some consideration needed for how to align all of the ends. In your "factory" from above you could easily make a jig and make them all the same length, but typical truss tails are cut in the field to a snapped line. So maybe an assessment of the straightness of the wall with a string line is a good initial check.

The more troublesome side would be trimming the new fascia. Ideally the bottom side should have intake venting if you have a vented roof, I'm not sure if a punched metal sheet or strip exists. I've not worked a lot with steel trim but I don't think it can be bent like the aluminum trim coil. But I can visualize a drip edge, a vertical piece and then a "L" shaped transition to the under-fascia.

Your truss tails could be even stronger if triangulated back to the wall but I think that would require trimming the sidewall sheet at the top to expose more framing and probably blow the project out of reasonable as far as a time commitment.

 

[simonjsmith]

I have done this to my house and I think a good rule of thumb to follow would be to sister 2x the length of the overhang back up the top chord of your truss.Screwed and maybe some construction adhesive. This is the common formula used to cantilever floor joist. On the gable ends a simple ladder type structure reinforced with some metal ties and blocking back in to the first truss should do. This would need to be installed with existing roof sheeting off. Has worked well on my house and was done almost 30 years ago.

 

[fourbyford]

This can be a pretty straightforward project with no need to cut into your existing structure. You mentioned 1' or 2' overhangs... for simplicity, we'll go with 1'. You'll start with lumber approximately 12" wide... either a good grade of construction lumber (2 x 12) or 2 strips of 3/4" plywood glued together... make sure the end of the board is trimmed "square". Now, on one side of the lumber, (we'll say the right side) measure up the distance you want your sub-fascia board to be... I used 2 x 6, bevel cut to match roof pitch, so I measured up 5 1/2". Now, from that point, using a speed square, draw an angled line across to the other (left) side... angle is equal to the pitch of your roof. From the point the angle terminates, measure up another 5 1/2" and square a line across the lumber. You've just drawn two blocks that will be your "rafter tails". I would space these blocks 24" on center along the side walls of your building. Glue and screw them to strips of 3/4" plywood... width will be equal to the "long side" of the blocks you just created. The last block on a strip should overhang the end by 1/2 the material thickness so that the end of the next strip to be installed (no block installed on the first end) will "tuck under" and maintain your 24" o/c spacing. Step and repeat. This will require that you remove the siding (but, you were thinking of doing that anyways?) and will probably need to add a girt to support the bottom of the plywood strip... and extend far enough below the strip to reattach your (shortened) siding. As others have mentioned, the gable ends are easy. Build "ladders" from 2 x 6... glued and screwed for strength and add to the end walls. The plumb cut at the end of each ladder should match the plumb cut on the "rafter tails" created previously. Insure you get the proper angles cut at the peak of the roof... pull tightly together, glue and screw. On the eaves, run your sub-fascia all the way out to the end of the "ladder" assembly and screw in place. Using this method, you will have overhangs that are well supported and ridgid without cutting into your existing frame. On the big barn I built, I used 2 x 6 material for the ladders and sub-fascia, then used 2 x 8's for the fascia and rake boards. I figured anything less wouldn't fit the scale of the building. The soffit can be attached to the underside of the framework you've just created... "J" channel below the soffit, then you're ready for siding. Also, I had the metals supplier bend up some "J's" sized to cover my fascia... no painting! It's easier to install these before the roofing is installed... drip edge will cover the top of the metal fascia. I know all this sounds complicated... it's really not... just building a few ladders, and cutting some blocks. Of course, sizes can be adjusted to your preference. HTH...
Be sure to post progress... and pics!
...D

 

[Jayhawk_Aviator]

thank you. It seems it would be easy on the gable end, but I'm have a little toruble visualizing on the other sides.

 

[firebirdparts]

On the gutter sides you'll have to sister every rafter with a little extension.

 

[fourbyford]

...no worries...
Envision a rectangle 12" wide by 9 1/2" high... (this will assume your roof is a 4/12 pitch... and that you want to use a bevel cut 2 x 6 as a sub-fascia)... on one side of the rectangle, measure up from the bottom 5 1/2" (the height of the sub-fascia that will be fastened here later)... from this mark, use a straight edge and draw a line to the opposite upper corner. You have just created a block that is 12" wide and has a "short side" of 5 1/2" and a "long side" of 9 1/2"... a 4/12 pitch... the same as our hypothetical roof. These blocks will be "ribs" glued and screwed to strips of 3/4" plywood... 24" on center... which will be attached at the top of your wall... sloped portion of each rib will be the same slope as the pitch of your roof... when positioned flush with the surface of the roof deck, they will function the same as rafter tails... but will be infinitely stronger because of the shape of the lower portion of the block that can (by first attaching it to a strip of plywood) be securely attached to your wall... (unlike trying to attach a short section of a 2 x 4 as a rafter extension... or, as others have mentioned, "sistering" a full length 2 x 4 along the top chord of your truss which would require cutting into the upper grit to allow the rafter to pass through). Once all the "ribs" are in place on one side of your building (24" on center), you can attach the sub-fascia to the outer ends (the "short" 5 1/2" side) of the blocks (ribs) and the soffits to the underside...
Sorry I dont have a way to post pics at the moment...
PM if you want... I could email a pic to you, no prob
...D