[chuffer]

I can feel your eyes rolling and judging me from here, BUT my shop roof has condensation and leak problems.

It is a metal & wood polebarn. For non US people that is a wood frame with corrugated metal walls and roof. The building is 60' x 80' feet with 16' walls and a 22' peak. Under the roof panels is a layer of plastic backed insulation - the fiberglass type. Last year we swapped all of the screws on the roof panels out for longer larger-diameter screws. I have also found a few holes and broken screws and repaired those.

Unfortunately, the fucker still leaks. Granted it leaks less, but it still leaks... With the insulation it is about impossible to tell exactly where it leaks from. With the current leaks (about 6 significant spots), I have inspected the general area of the roof (in-line with where it leaks), but just can't find any loose or missing screws. The panels seem ok too.

Naturally, the roof has a pretty big condensation issue too. It is about 20 years old at this point. As a result the insulation is damaged in some spots. Logically, these spots are where I notice the condensation (it drips!). I am not sure sure if the damaged insulation just lets the condensation drip out or if the condensation is worse because the metal panel sees a more extreme temperature difference between the inside and outside...

So, what to do?

If budget were not a concern, I'd just rip the old roof off and re-do it with standing seam panels, which is what we have on our dwelling. However, even in this case I am not completely sure what the best construction technique is. From the outside toward the inside would the proper order be: Metal panels, ice shield underlayment, vapor barrier (??), plywood sheathing, insulation, vapor barrier and then a final inside ceiling? Does that seem correct?

What about these places offering to come and "repair" metal roofing? It sounds almost like they powerwash the roof and spray it with something akin to truck bedliner?

What would you do?

Paging the construction builder DIYer types: @Adventurous @gonefirefightin @johnbryanpeters @DaveW or anyone from the peanut gallery...

 

[SkaredShtles]

 

[chuffer]

Not gonna lie… The thought has crossed my mind

 

[gonefirefightin]

It's hard to say without any definitive pics, or removing some metal and or underlayment/insulation to see what the issues are. If it is corrugated tin roofing the screw placement was quite the debate back in the day (on a ridge or in a valley) and the degree of overlap would also be a characteristic of the current metal to determine. if you are in a fairly windy site the pitch would also be of concern that would indicate some seepage and be a factor for what style of roofing goes on to match the roof pitch.

Being the building is pretty big in size and your dimensions suggest a low-pitch roof I would assume you have some short overlaps are part of the culprit as well as underlayment degradation due to heat and moisture. Also due to the size replacing the roof doesnt sound too cheap at this point.

If it were me I would pull a panel or two of roofing, and the corresponding insulation/underlayment and inspect what the issue is before moving too far forward as being 20 years with moisture and leaks you may have more problems with the framing than you realize.

 

[chuffer]

Thanks!

A couple of clarifications- the interior is unfinished. Thus, I can see the framing (perlons?) & trusses in the roof. I can also see the 2x6 framing (horizontal stringers) in the walls. The top 2x6 on the west wall and the lowest perlon on the west face of the roof - the framing at the eaves - will need replaced. Everything else looks good and will hold a screw tight.

The roof is super simple - the plastic backed insulation is sandwiched between the exterior panels and the 2x6 perlons. Plastic side facing the interior. That’s it.

What else?

Screws are on the flats of the panels.

Over lap is 6-10” where I can see it.

Actual slope (i was misremembering before) is 8’ over 30’. Pretty common around here.

Therr is definitely a heavy west wind. We sit right in the mouth of the so-called Van Duzer corridor.

I’ll snap some pics tonight. It actually isn’t pissing out right now. I’m gonna go ride…

 

[gonefirefightin]

well it sounds like if you need to replace some lumber you might as well start shopping for a more modern metal roof system and some pals to help install it as the new stuff can actually be bought at full length sheets and will require some effort to install. Standing seam as you know is best for low pitch and windy conditions but isn't cheap but still cheaper than Corten. But still requires some special tools and has a learning curve that can be iffy when dealing with full-length sheets. I would also assume there is no sheathing, which would be your condensation issue. Even a little bit of substrate under the steel will prevent the moisture from wicking. You don't have to use a zip system but a heavy vapor barrier such as the single bubble foil-backed stuff is cheap and is easy to lay down.

I would assume the screws are without rubber washers and may be proud a bit that is also what may be part of the issue is, the constant heat and cold will work dimples and shift screws and create intrusion spots especially in the low valleys if thats where they are screwed.

 

[Westy]

 

[boostindoubles]

Lay a new roof on the old roof and/or pull down the old insulation and have someone qualified spray foam the underside with some waterproof insulation.

 

[Adventurous]

How much time and money do you wanna spend on this? Cause there are a myriad of band aid solutions, but as long as the roof is compromised they are all just half measures.

I'm sure you already know this, but the wetted out insulation is just feeding the ongoing cycle of degradation. R-value gets reduced, more condensation accumulates, more insulation wets out and so on and so on. It's a wonder you don't have wood rot, but it's only a matter of time. Not to mention the potential for mold growth.

Ideally, you'd have sheathing and a water resistive barrier under the metal. That plus a decent insulation scheme (and ventilation!) would do it. But that's not gonna come cheap.

@Jozz, you have a metal roof on your joint? I'm sure you've got input on this.

 

[chuffer]

@Westy i might as well own stock in flex seal.

@boostindoubles someone on here, GFF I think, made some pretty strong arguments against spray foam. I like your way of thinking though!

@Adventurous and @gonefirefightin you both make it sound like sheathing and a barrier layer will be a big part of the solution.

Would I be making an absolute idiot out of myself / wasting a bunch of money by trying to re-use the existing metal? In other words strip the roof, rip out the insulation, sheath the roof, put down a moisture barrier and then reuse the metal panels again? I am just not sure I can / want to buy 5000+ square feet of standing seam panels.

 

[Westy]

My hillbilly brain likes the roof on a roof idea.

My engineer brain says:

 

[Adventurous]

@Westy i might as well own stock in flex seal.

@boostindoubles someone on here, GFF I think, made some pretty strong arguments against spray foam. I like your way of thinking though!

@Adventurous and @gonefirefightin you both make it sound like sheathing and a barrier layer will be a big part of the solution.

Would I be making an absolute idiot out of myself / wasting a bunch of money by trying to re-use the existing metal? In other words strip the roof, rip out the insulation, sheath the roof, put down a moisture barrier and then reuse the metal panels again? I am just not sure I can / want to buy 5000+ square feet of standing seam panels.

Honestly, if it were me, I'd use them again. Would a brand new standing seam metal roof be the best solution? Yup, no doubt. But even DIY that's gonna cost tens of thousands, and that's a lot of roof to lay.

If you do re-use them, I'd be tempted to add firring strips to the decking to promote ventilation. You know water is going to get under there, might as well give it every opportunity to drain and dry.

Is this barn for personal or professional use?

 

[6thElement]

Is this barn for personal or professional use?

He uses it for his onlyfarms.com fan page.

 

[SkaredShtles]

He uses it for his onlyfarms.com fan page.

Bow-chikka-bow-bow...

 

[Westy]

Fixing the leak may help with the condensation, but condensation is typically a ventilation problem. Removing any sources of moisture is important as is air exchange. My father was fond of installing heat exchangers in cold climate airplane hangers to keep them both warm and dry.

 

[chuffer]

Is this barn for personal or professional use?

That depends on who is asking and why.

We are in a bit of gray area with the county. The structure was built and permitted as a residential shop and we are using a portion of it for commercial operations. The only upgrades that was required of us for permits was to put in a 2 hour firewall separating commercial and residential.

Normally for a new commercial construction this building would never meet code, but bc it was converted from residential there are a bunch of loopholes.

 

[gonefirefightin]

I am not sure I understand correctly, after reading some replies, are you wanting to reuse the materials? I would advise against it since the materials and methods currently being used are either incorrect materials for the application or incorrectly installed, maybe a bit of both.

At the very minimum of replacing anything would be modern screws but that still makes you go through the labor and time of replacing the roof but still doesn't fix the moisture issues.

 

[SkaredShtles]

 

[Westy]

View attachment 206797

Just tell the insurance guy you volcanoed your bong. Such accidents are common with sheds.

 

[chuffer]

I am not sure I understand correctly, after reading some replies, are you wanting to reuse the materials? I would advise against it since the materials and methods currently being used are either incorrect materials for the application or incorrectly installed, maybe a bit of both.

At the very minimum of replacing anything would be modern screws but that still makes you go through the labor and time of replacing the roof but still doesn't fix the moisture issues.

Haven't made any decisions yet. In the end I will very likely just have a "pro" do it, but I haven't been thrilled with some of the pros I have hired recently and I want to make sure I understand every single aspect of the project before I hire someone.

To start, I am curious which aspects you think might be incorrect materials or installation? The panels, end-caps, flashing and hardware (metal roofing screws with the gaskets on the washers) appear to be the correct application. The original install quality of these components seems OK, but not excellent. I can see some isolated mistakes, but no really horrible work.

The sheathing (none), vapor barrier and insulation I think while they are probably "to-code" were not well thought out and executed for this location. These components are where I really have my questions.

The only materials that I am considering re-using is the corrugated steel panels. Regardless of whether I re-use the old ones or buy new ones, I need to address what goes under them first.

Sheathing - I was thinking 1/2" plywood. With the slope of the roof being 3.2:12, 3/4" plywood might be better. You also mentioned the ZIP product that I hadn't heard of before, but looks like a possibility.

Barrier - (between sheathing and metal panels) I think what makes the most sense is "synthetic water and ice shield." Probably not self adhering. I think this adds about 0.3 lbs/sqft dead load.

Insulation - (on the underside of the sheathing) I assume I should go as high R-value as I can afford and will fit. I also assume I should go with backed insulated here. What is the difference between plastic and paper backed insulation?

The other thing that has me a little concerned is total "dead load." I do not know exactly what my building is engineered to, but sheathing, insulation, etc. add up quickly!

3/4" plywood is 1.9 psf (lbs/sq ft)
Steel panels are ~1 psf (my best guess without measuring the gage)
Barrier is about .25 psf
R30 Insulation is about .5 psf

The 3/4" ply and barrier would bump the roofing materials dead load from 1.5 psf currently (panels and insulation) to 3.65 psf. That is more than double. 1/2" ply would be a little lighter at 1.42 psf...

So many things. Appreciate any and all feedback. Including the "burn it to the ground," because it crosses my mind regularly...

 

[Adventurous]

Haven't made any decisions yet. In the end I will very likely just have a "pro" do it, but I haven't been thrilled with some of the pros I have hired recently and I want to make sure I understand every single aspect of the project before I hire someone.

To start, I am curious which aspects you think might be incorrect materials or installation? The panels, end-caps, flashing and hardware (metal roofing screws with the gaskets on the washers) appear to be the correct application. The original install quality of these components seems OK, but not excellent. I can see some isolated mistakes, but no really horrible work.

The sheathing (none), vapor barrier and insulation I think while they are probably "to-code" were not well thought out and executed for this location. These components are where I really have my questions.

The only materials that I am considering re-using is the corrugated steel panels. Regardless of whether I re-use the old ones or buy new ones, I need to address what goes under them first.

Sheathing - I was thinking 1/2" plywood. With the slope of the roof being 3.2:12, 3/4" plywood might be better. You also mentioned the ZIP product that I hadn't heard of before, but looks like a possibility.

Barrier - (between sheathing and metal panels) I think what makes the most sense is "synthetic water and ice shield." Probably not self adhering. I think this adds about 0.3 lbs/sqft dead load.

Insulation - (on the underside of the sheathing) I assume I should go as high R-value as I can afford and will fit. I also assume I should go with backed insulated here. What is the difference between plastic and paper backed insulation?

The other thing that has me a little concerned is total "dead load." I do not know exactly what my building is engineered to, but sheathing, insulation, etc. add up quickly!

3/4" plywood is 1.9 psf (lbs/sq ft)
Steel panels are ~1 psf (my best guess without measuring the gage)
Barrier is about .25 psf
R30 Insulation is about .5 psf

The 3/4" ply and barrier would bump the roofing materials dead load from 1.5 psf currently (panels and insulation) to 3.65 psf. That is more than double. 1/2" ply would be a little lighter at 1.42 psf...

So many things. Appreciate any and all feedback. Including the "burn it to the ground," because it crosses my mind regularly...

Zip roof sheathing (red vs 1/2" green colored wall sheathing) is 5/8", so you'd save a wee bit of weight there vs 3/4" ply. The integrated coating + taped seams also provide improved weather resistance over plywood, along with an air barrier. If you want to get fancy, they offer those same zip panels attached to rigid foam insulation.

 

[gonefirefightin]

Haven't made any decisions yet. In the end I will very likely just have a "pro" do it, but I haven't been thrilled with some of the pros I have hired recently and I want to make sure I understand every single aspect of the project before I hire someone.

To start, I am curious which aspects you think might be incorrect materials or installation? The panels, end-caps, flashing and hardware (metal roofing screws with the gaskets on the washers) appear to be the correct application. The original install quality of these components seems OK, but not excellent. I can see some isolated mistakes, but no really horrible work.

The sheathing (none), vapor barrier and insulation I think while they are probably "to-code" were not well thought out and executed for this location. These components are where I really have my questions.

The only materials that I am considering re-using is the corrugated steel panels. Regardless of whether I re-use the old ones or buy new ones, I need to address what goes under them first.

Sheathing - I was thinking 1/2" plywood. With the slope of the roof being 3.2:12, 3/4" plywood might be better. You also mentioned the ZIP product that I hadn't heard of before, but looks like a possibility.

Barrier - (between sheathing and metal panels) I think what makes the most sense is "synthetic water and ice shield." Probably not self adhering. I think this adds about 0.3 lbs/sqft dead load.

Insulation - (on the underside of the sheathing) I assume I should go as high R-value as I can afford and will fit. I also assume I should go with backed insulated here. What is the difference between plastic and paper backed insulation?

The other thing that has me a little concerned is total "dead load." I do not know exactly what my building is engineered to, but sheathing, insulation, etc. add up quickly!

3/4" plywood is 1.9 psf (lbs/sq ft)
Steel panels are ~1 psf (my best guess without measuring the gage)
Barrier is about .25 psf
R30 Insulation is about .5 psf

The 3/4" ply and barrier would bump the roofing materials dead load from 1.5 psf currently (panels and insulation) to 3.65 psf. That is more than double. 1/2" ply would be a little lighter at 1.42 psf...

So many things. Appreciate any and all feedback. Including the "burn it to the ground," because it crosses my mind regularly...

Your dead load isn't that much of a concern as much as your zip code or region for snow/ice load ratings and that will be the number that you will want to adhere to. Being you have such a low pitch I doubt you have much of a snow load rating there. If it is a post and beam style structure I would be willing to bet you have at least two 2x6 or greater for your spans on each post which is plenty for snow load, its the spacing of them on centers that makes the load ratings.

I agree with you on contractors, I've been doing every job myself for the last 5 years because the subs are crap around here. one option if you have the time is to hire a general to walk you through the process while you do the work and supply the labor. I help a ton of folks doing it this way.

If you are reusing the 20 yr old steel I would suspect you will be slowed down quite a by making sure old holes have some sealant and or plugs, the new hex head metal roof screws can be ordered with wider flanges and gaskets but the come at a pretty penny. It will just be tedious using old holes and making sure everything gets sealed. Your overlaps would require a bead of silicone down the full sheet as well in an overlap to accommodate for wind/water seepage.

Zip or foam board or both is the standard these days since the heat metal absorbs is the main cause of fastener creep and moisture issues. I like the foam back plywood systems as they are essentially all in one and when taped and sealed correctly they will actually serve as a temp waterproof lid for up to 2 years in theory and I have seen some projects last that long in phases.

The bottom line is the more substrate under your metal the less issues you will have down the road. If you have a true water tight roof system it then doesnt matter what style of backed insulation you use. foam panels are by far the easiest and most reliable method for buildings like your since they are less susceptible to moisture issues, bat insulation is not of easy as an instal since it cant be glue/taped but it provides more R value in the long run.

I suspect your fastener schedule is a bit light on spacing since you are getting them to work up and leak. Typically these days with any metal roof system the schedule calls for 12-14" spacing and at least 1" into the substrate (not including barriers/insulation) so I would guess you have half the fasteners that are required. These days we use collated deck guns for driving in these fasteners every 12" inches. it takes a while even with the guns and a crew of 3 but it works well.

 

[chuffer]

Great info in here. Thanks.

Also @Westy we have some high volume exhaust fans that we run during fermentation to make sure we don’t get CO2 build up. I never thought of using them to reduce condensation and humidity in the building, but I let them run all day today. Can’t say quantitatively, but it seems that the humidity has dropped a touch…

 

[boostindoubles]

@chuffer do you know for sure it's a leak? If warm and wet air gets behind the insulation it'll condense like crazy on the underside of that metal roof.

 

[DaveW]

Yep without a decent vented cavity, condensation is a given.
If you get stuck with that, I'm sure @Westy can offer some good well studied thoughts on cavity ventilation?

 

[Westy]

Yep without a decent vented cavity, condensation is a given.
If you get stuck with that, I'm sure @Westy can offer some good well studied thougths on cavity ventilation?

 

[DaveW]

......

 

[Westy]

......

Hey, I am an automation engineer. If you want cavity ventilation I am going to give it to you economically, at high volumes and quality. Call a Catholic priest if you want to be held in the process.

 

[chuffer]

schittscreekmeme.jpg

I leave this thread alone for a minutes to go sling some booze and mop up some floors and @Westy has lead us into industrialized sodomy territory. I'm horrified and proud at the same time. Well done...I think.

What were we talking about in here, anyway?

 

[chuffer]

@chuffer do you know for sure it's a leak? If warm and wet air gets behind the insulation it'll condense like crazy on the underside of that metal roof.

Good question. I am pretty sure it is a little of both. Like I said, I turned on the big exhaust fans yesterday. We'll see if they help and how much. The rafters are open so the fans do a pretty good job of circulating all of the air. The fact that the wife, the dogs and I are all still alive attests to this - ferementers make A LOT of CO2.

 

[Westy]

schittscreekmeme.jpg

I leave this thread alone for a minutes to go sling some booze and mop up some floors and @Westy has lead us into industrialized sodomy territory. I'm horrified and proud at the same time. Well done...I think.

What were we talking about in here, anyway?

I was looking for the old school panty debuncher image, which is a hog cutter, and I fell into a new rabbithole of horror as it would seem the meat packing industry is becoming automated. That robot is an automated bung cutter, which means it has a vision system and some engineer somewhere has tens of thousands of images of pig assholes.

Not necessarily not work friendly, definitely not vegan friendly.

AiRA RBD Bung Dropper - Fully automatic bunging of pigs

The AiRA bung dropper ensures high-speed and accurate bunging, while maintaining the highest hygienic levels ✓ Automatic Precision Bunging ✓ Yield

www.frontmatec.com

 

[chuffer]

Years ago I was tasked with a metrology project for rotating blades that were used somehow in the processing of hogs and cows. It was a truncated cone made of ~1 mm thick tool steel with a blade on one edge and a ring gear on the opposite edge. All I could think of is how happy I was that I'd never have to operate that tool...

 

[Westy]

Good question. I am pretty sure it is a little of both. Like I said, I turned on the big exhaust fans yesterday. We'll see if they help and how much. The rafters are open so the fans do a pretty good job of circulating all of the air. The fact that the wife, the dogs and I are all still alive attests to this - ferementers make A LOT of CO2.

Blow the fans the other way, if you have positive pressure you can see the leaks bubble.

 

[chuffer]

Yeah, so this guy, right here. After yesterday's rain and warm humid air the wife and I literally had the "should we just tear the fucking building down and start over" discussion.

It seems to be leaking, condensing and somehow the concrete slab is "sweating" or something.

 

[Westy]

Yeah, so this guy, right here. After yesterday's rain and warm humid air the wife and I literally had the "should we just tear the fucking building down and start over" discussion.

It seems to be leaking, condensing and somehow the concrete slab is "sweating" or something.

Pretty sure I could drill a hole in my basement floor and install a gage and see a few PSI of water pressure after rain like yesterday.

 

[boostindoubles]

Yeah, so this guy, right here. After yesterday's rain and warm humid air the wife and I literally had the "should we just tear the fucking building down and start over" discussion.

It seems to be leaking, condensing and somehow the concrete slab is "sweating" or something.

I've been kicking the can with Pacific Building Systems out of Woodburn. I need me a building to work out of.

They seem like a legit business. You definitely need a new metal building.

 

[chuffer]

You definitely need a new metal building.

The wife and I came to a slightly different conclusion this morning. There are lot better places we could spend $250k. We'll continue to band-aid this thing for another decade...

The rain yesterday was "something else." We sit on the top of an 800' elevation bump in the middle of a valley through the Coastal Mtns that connects the Willamette Valley to the coast. We just get hammered on days like yesterday...

 

[gonefirefightin]

The wife and I came to a slightly different conclusion this morning. There are lot better places we could spend $250k. We'll continue to band-aid this thing for another decade...

The rain yesterday was "something else." We sit on the top of an 800' elevation bump in the middle of a valley through the Coastal Mtns that connects the Willamette Valley to the coast. We just get hammered on days like yesterday...

Shit, I didnt know you were in the valley, Im through there all the time, hit me up if you need a set of eyes and suggestions.

 

[Westy]

There is always the Florida special

 

[gonefirefightin]

There is always the Florida specialView attachment 206904

Dont lie, that's Olympia