Pole barn lean to

[Slong1958]

I built a 24x40 pole barn awhile back now I want to add a lean to, but the pole barn is only 10ft tall and has a 12 over hang. The lean to I was thinking about you added another ledger board and went from there. I starting looking around on the web and saw this but Im not sure just what has to be done. The 1st is what I came across on the internet the other 2 are what I have. The problem with adding the lean to too my building as in my drawing is the height of the ceiling. The pic with the circle drawn around it looks like the rafter most be either sitting on the top ledger board or attached to it and that would rise everything up and would be ok. I think I know what has to be done but not sure. The 2nd pic is just something I put up to see how tall the roof would be.

 

[EddieWalker]

Cut off your rafter tails and install your 2x6's on top of the existing wall. Also attach them to the sides of your rafters.

How wide is your lean to going to be? Do you need to worry about snow sitting on top of it?

I said 2x6's in my first sentence, but that would be a minimum. Depending on your location and your span, bigger might be needed.

 

[CADplans]

The problem with adding the lean to too my building as in my drawing is the height of the ceiling.

Can you lower the area of dirt that would be under the lean-to?
lower the floor, rather than raise the ceiling!! :thumbsup:

 

[Slong1958]

Is this what your talking about as far as cutting the tresses and adding the rafters for the lean to. The lean to will be 12ft deep with a 24 in over hang the whole length of barn which will be 52 ft long when finished. The tin on the back will be moved to that wall leaving it open to the barn. Im also wanting to add another 12ft bay then enclose that 22x 36 and make it as dry as possible to house my vintage vehicles. Im going to remove the post that is circled yellow then add a 16 or 18 ft roll up door. This being a load bearing wall how big of a bean would I need?

 

[ovrszd]

As Eddie said, fasten to the side of your rafters rather than under.

Not sure about snow load in Tn.

Also not sure how far your lean to will extend?

 

[ovrszd]

Sorry, I was typing as you were.

I'll yield to Eddie for answers to your questions. Trust his word.

 

[s219]

I went through this same decision process, in fact there is a thread here with some conversation:

https://www.tractorbynet.com/forums...-door-headroom-challenge-lean.html?highlight=

Here is what I ended up doing, work still in progress:

This was the best solution to get the headroom I wanted, however I estimate there was a 40-50% additional time penalty to knit the new roof into the old roof versus just going under the eave for the new roof (with a ledger board). Every step of the process was more complicated and took more time and introduced more "to-do" items that had to get done before the next step.

And of course before I could make forward progress I had to go backwards to tear off the old fascia/soffit, remove soffit blocking under the rafter tails, notch the wood siding to allow the new rafters to reach the header, cut back the gable soffit and fascia to the proper joint angle for the new trim, etc.... I have an asphalt roof, and weaving the new shingles into the old shingles at the transition also took a fair bit of work and preparation, and I put ice/water shield under that area since it is more prone to leaks right there.

So yes, I think it is the "right" approach to tie into the old roof, but be prepared for a lot more BS along the way. I feel like there is no shame in just going under the eave with the new roof attached to a ledger if you are looking for a more productive approach. I would have been done by now if I did that!

You can estimate how much more vertical space you'd gain/lose with each approach and make an informed decision. I gained about 7" of headroom by tying into the roof versus going under the eave, which made a critical difference in door height (slightly more than 7' versus well under 7').

 

[BoylermanCT]

I went the under the eaves route and put in a ledger board to attach the rafters to. I would also consider lowering the floor if you need more headroom.

 

[Woody65]

Slapped this lean to together over the summer. Debated the same thing you are now and decided to take the easy way out and went under the existing soffit. Lack of extra help and disassembling everything along with cutting the steel roofing back to make a proper transition all played a part in the decision.

 

[hslogger]

I think you would be better served with 2 by 8 for your span instead of 2 by 6. in the long run I would expect you see some sag.

 

[Slong1958]

Thanks everyone for the info, keep it coming.

 

[KennyG]

I think you would be better served with 2 by 8 for your span instead of 2 by 6. in the long run I would expect you see some sag.

Assuming you have lightweight roofing and minimal snow load, and the actual span between the ledger board and post is about 12 feet, the span tables indicate that a 2 x 6 No. 2 rafter is OK at 16" spacing. However, if you go to 2 x 8 at 24" spacing you will have a bit more margin.

 

[EddieWalker]

Is this what your talking about as far as cutting the tresses and adding the rafters for the lean to. The lean to will be 12ft deep with a 24 in over hang the whole length of barn which will be 52 ft long when finished. The tin on the back will be moved to that wall leaving it open to the barn. Im also wanting to add another 12ft bay then enclose that 22x 36 and make it as dry as possible to house my vintage vehicles. Im going to remove the post that is circled yellow then add a 16 or 18 ft roll up door. This being a load bearing wall how big of a bean would I need?

Yes, the drawing shows what I would do to get more height. As others have posted, it's faster, easier and cheaper to attach a ledger board to the wall and build the leanto under your existing eaves, but you sacrifice height by doing it that way. I would use 2x8s for that span and space them the same as your existing trusses.

For your garage door, millions of garage door headers where built with two 2x12x16's and half inch plywood between them all over the country for decades. I've never seen this fail, but I it's not done anymore that I'm aware of. Now we use engineered beams, or gluelam beams. They are more expensive, but stronger. I don't see why you need to spend the extra money for a gluelam to do this project, but it's up to you and your budget and local weather conditions. Just be sure to frame it correctly with the beam resting on Jack Studs.

 

[drivesitfar]

I'm here to watch and learn and maybe help if I can. I like both the methods of extending the rafters and going under them and guess it would depend on the height you need under your lien too when finished.

good luck!!

 

[MapleLeafFarmer]

I built a 24x40 pole barn awhile back now I want to add a lean to, but the pole barn is only 10ft tall and has a 12 over hang. The lean to I was thinking about you added another ledger board and went from there. I starting looking around on the web and saw this but Im not sure just what has to be done. The 1st is what I came across on the internet the other 2 are what I have. The problem with adding the lean to too my building as in my drawing is the height of the ceiling. The pic with the circle drawn around it looks like the rafter most be either sitting on the top ledger board or attached to it and that would rise everything up and would be ok. I think I know what has to be done but not sure. The 2nd pic is just something I put up to see how tall the roof would be.

If your property line allows.... can you consider expanding out the gable end versus the side?

I was in same position and after some consideration side seemed easy and logical at first but gable end extension was much more useful in the long run for me.

 

[Slong1958]

Eddie you said space my lean to 2x8 the same as my trusses there 48 apart do you think spacing the lean to 2x8x14 will be ok or do I need to go 24?
Guys how much pitch do you think I could get by with on the lean to. I know going with putting another ledger board onto the wall under the roof would only give me around 6 of fall and about 80 of head height on the low low end.
I live near Memphis so we done have much snow.


This video is real helpful
How to frame a lean to roof with rafters and a notched birdsmouth - Pole Barn Shop Build Part 10 - YouTube

 

[EddieWalker]

Assuming that you are going to attach your metal roofing to purlins, I don't see any problem with 2x8's every 48 inches. I would use 2x4's on the flat for purlins and get them 16 feet long. I would also stagger the joints. Do something like cut the first 16 footer in half and put it on, then a full 16 foot long for the next one, then cut another 16 footer in half and so on. Depending on your metal, and from what I see in your picture, I'd probably put my purlins on every 2 feet.

General rule of thumb for metal roofing is that 2:12 is the lowest you should go without having issues. If you seal each panel where they overlap, 1:12 can work, but it's not ideal and more likely to give you issues in the future.

 

[drivesitfar]

Slong: your minimum pitch would have a lot to do with how much snow you get cause rainwater doesn't need much. more snow equals more roof pitch and support. good luck