sorry I need advice on leanto build!

[BryanM]

JB4310 that is exactly what I had pictured in my mind. I would like to go with a steel rough though. I think everyone is going with rubberized roof do to weight. I just wanted to use perlins and steel rough panels.

Just wondering if you got much snow, I know with steel roofing the slighest sunlight heats the roof up in a hurry.

 

[JB4310]

JB4310 that is exactly what I had pictured in my mind. I would like to go with a steel rough though. I think everyone is going with rubberized roof do to weight. I just wanted to use perlins and steel rough panels.

Just wondering if you got much snow, I know with steel roofing the slighest sunlight heats the roof up in a hurry.

Not sure how much is much but we do get snow, and I am concerned about it, it's only been up for a few years, last year it had over 2 ft built up, I did shovel a few paths to let the water drain in case it rained on it or melted fast, but it never did, just melted slowly.

I didn't get an engineers stamp of approval that's why I said don't follow my specs, I simply looked at other similar sized structures and made mine heavier or the same as the others I'd seen. The heaviest framed one I saw with the same overall dimension was on a town owned maintenance facility, pretty much copied it. Figured if it's good enough for Govt it should be good enough for me.

Actually saw a 20 ft wide carport on a house framed with 2x6 rafters, I know that's under built but it's been up for 20 years, I'd really be afraid with snow on that.

The light weight of the rubber is a benafit but it's more about how water/weatherproof it is, especialy on low pitch roofs where shingles could not be used.

 

[Maknwine]

JD 4310, your place and leanto build look great. I hope you have better luck with the rubber roof than I have had with mine. Our house came with a covered lean to porch area in the back. Leaked a little after a heavy rain when we first bought the house and continually got worse over seven years. Now it leaks like a sieve. Have tried patches with no luck. Will wait till spring and probably just do away with it alltogether.

 

[JB4310]

JD 4310, your place and leanto build look great. I hope you have better luck with the rubber roof than I have had with mine. Our house came with a covered lean to porch area in the back. Leaked a little after a heavy rain when we first bought the house and continually got worse over seven years. Now it leaks like a sieve. Have tried patches with no luck. Will wait till spring and probably just do away with it alltogether.

Any roof with proper pitch, but especially single ply, then extra especially EPDM wont leak from the "field" of the roof. Leaks occur at the seams, flashings, valleys or other transitions and breaches in and thru the open (field) areas.
With the proper pitch even thatch roofs last for years.

One problem with EPDM rubber is that the base materials are more further advanced than the adhesives. it's not like a "welded" seam like you think of with PVC materials, where you can not pull them apart without destroying the surrounding materials. EPDM seams can be pulled apart, they rely on larger surface area and more of a contact hold, On low pitch roofs where there can be standing water these seams actually have to be caulked to get full warranty.

So it's not the rubber roof material that's the problem, it's probably the most impervious roof material out there. May not of been installed properly.

 

[2manyrocks]

I would estimate the durability of a rubber roof to be 10-15 years, and the durability of a metal roof to be 30+. Our barn roof is 70 years plus and still on the same metal.

A rubber roof that is properly installed should not be leaking anywhere. It's good for low pitched roofs, but the general idea is to first use a higher pitch to shed water and snow where possible, and then when not possible, then use the lower pitch and build accordingly.

 

[Maknwine]

If a rubber roof is only good for 10-15 years than ours is probably just leaking due to age.

 

[JB4310]

If a rubber roof is only good for 10-15 years than ours is probably just leaking due to age.

I don't know where that number comes from But I've read trade papers where they laid this stuff out in in the desert proving grounds over 40 years ago and it still shows little signs of degradation,

Maintenance of EPDM Roofs

See answer to question 12, POTENTIAL life span of 50+ years.

That's the base material but like I said the seams and flashings are not gonna last as long as the base material. Only seen 1 epdm roof replaced and that was due to poor installation, which was a common problem 15-20 years ago when architects and engineers first started specifying it in earnest.

 

[bugstruck]

I tired a longer post that failed so heres the brief version. 18' span at say 3.5/12 pitch for conventional shinges is a 63" drop. Isn't your max. roof height 144"? If yes, the math jumps right out at you. Then deduct rafter depths and header depths.

If I have the correct picture you need conventional gable or flat roof.

 

[BryanM]

What do you think about engineered lumber? would that solve my problem? Or another thought was coming out from the barn at a 2;12 pitch for about 8 ft the jump to a 3/12 pitch? what do you think?

 

[deepNdirt]

If you have these type of truss built to this configuration your talking about you may well be running up into some expence,..... I'm not sure if I remember reading that you need this to be all open area, or if perhaps there would be some place you could put a center support post? with you going 18 ft out then what ever extra you want for hangover and what ever roof pitch you dicide there will be additional charge for extra length rafters, although they are available,speacial order so much $$ a ft. usually the standard lenths are 16 ft..... what i am getting at is being your addition will be 32' wide could you not add a post at halfway point (16') and then inward at the (9ft) and use a double header beam and use 12ft' length rafters this would allow you enough overlap on the beam and also some hangover and consideration of your roof pitch without paying for special order materials,
actually if you didn't want to use the center support post you could get a 32' LvL beam, although this might also run your cost up again,
but still I think less then truss or special order 2x8's
I'm also wondering about if the barn is at all built on an elevation? somewhat of a hill? and wondering if there is any ground slope? if you could perhaps dig down to level uf the lowest grade and perhaps build a retaining wall against the barn and add wings wall on each side of the 32'? this would of course allow you to have the hight you need as well as give you more roof pitch,
Just a few things to mention... and here is a scetch i drew up of what I'm talking about on the ground slope.. but if you have no slope just discard the drawing