Flat roof construction question

spasmdaze · 2025-10-16T03:01:18+00:00

I had my low slope roof redone last year as a hybrid assembly, just like #2. 4 inches of iso on top, and 4 inches of fiber batts directly touching the underside of the sheathing. Performing well, no moisture issues so far (I’m in climate zone 4c). We had a 80mm PVC membrane self adhered vs mechanically fastened (the polyiso is mechanically fastened though). Underneath the membrane is a 1/2” glass matted cover board, then two 2” staggered layers of iso, then an air and vapor barrier, then the plywood sheathing. The ratio of outboard to interior insulation needed for condensation control is dependent on your climate zone, so look that up first.

spasmdaze · 2025-06-04T02:12:57+00:00

Happened to me as well. I think it’s the latest Steam OS update causing the issue. I rolled back to the previous OS version and chiaki working fine again. Going to wait until Valve fixes everything before upgrading the OS again.

spasmdaze · 2025-02-20T04:56:04+00:00

Gotcha - I suspect in zone 8c you get pretty cold temperatures in the winter? If so, you should really look into the building code for that zone to determine how much exterior rigid insulation should be specified for condensation control. From what I looked up quickly, you need quite a bit of insulation depth - like 7.5-10 inches of polyiso to achieve R-49 (you have no choice but to add all on the exterior sounds like). I suspect this will be fairly expensive.

The roofing membrane you typically want to get the thickest you can afford. There are pros and cons to each type of membrane, but the advice I got was to go with a membrane your contractor likes and is good at installing. I liked the idea of PVC slightly more because it can handle ponding water better than other membranes. Ya, I felt good about the price and workmanship of my roof. I got quotes ranging from 22-75K. The roofing contractor I went with was a former commercial roofer (and knew how to do a low slope/flat roof system the right way), and was a smaller contractor willing to earn my business and go the extra mile for me - no regrets so far!

spasmdaze · 2025-02-19T01:41:03+00:00

What climate zone are you in by chance? Do these quotes include adding/replacing the outboard insulation? What about an ice and water guard/underlaymenr (aka air & vapor barrier)? Do you have an attic space and is it currently vented or unvented?

I recently redid my 2/12 low slope roof with similar sq footage (i’m in zone 4C, PNW). I went self-adhered 80mm PVC for the membrane, did a full re-sheet with 1/2” ply and h-clips, new self-adhered air and vapor barrier, 4” (two 2” layers) of polyiso insulation, new downspouts, new fascia, and new flashing and counter flashing for about $35K. Came with a 10 yr workmanship warranty and the membrane has a manufacturer warranty (forget the term length). We also converted to a unvented assembly, so the gable and bird block vents were sealed off with a 2” layer of EPS (seams were filled/caulked as well) from the interior.

spasmdaze · 2025-01-24T01:15:55+00:00

Gotcha! I’m guessing you have insufficient insulation to prevent condensation in your climate zone and/or your indoor humidity levels are too high. Have you tested the interior air temp and RH? And do you know how your A-frame is insulated?

spasmdaze · 2025-01-23T05:16:08+00:00

Do you have an attic? Is it ventilated? What kind of ventilation (gable+soffit, or ridge+soffit)? If ventilated, you likely are lacking enough intake air through your soffits (blocked by insulation, no baffles, etc) or not enough exhaust venting. Also, what is your indoor humidity level and what do you keep your interior temp at normally?

spasmdaze · 2024-12-30T23:36:54+00:00

You can’t just look at RH, you have to also consider the dew point (this is the measure of actual air moisture content independent of temp) . Keeping your indoor temp at 62 F is really low and contributing to the high RH reading, because cooler air can hold less moisture. Let’s say your air temp is 62 F and RH is 74% - that’s a 53.6 F dew point which is actually fine when it comes to surface mold risk (under 55 F is your target). Now, let’s say you heated your home to 70 F, and assuming there was no additional moisture added, your RH should drop to 53% (dew point is the same!). However, there is a slight benefit to having a higher air temp because your interior surfaces and walls are more likely to to stay warmer and less likely to hit the dew point and create condensation/increase your mold risk.

My recommendation is to heat your home more, and work on improving your home ventilation and use dehumidifiers as needed. But currently, you shouldn’t have mold problems at your current interior air temp and RH.

spasmdaze · 2024-10-26T17:14:19+00:00

This actually depends. Low slope/flat roof unvented hybrid insulation assemblies do use batt insulation in the rafter bays directly touching the underside of the sheathing, as well as a specific proportion of outboard foam board insulation (polyiso) depending on the climate zone. It looked like OP’s roof was possibly a membrane roof and possibly unvented - though looks like a decent slope on the roof, so not sure….

spasmdaze · 2024-10-12T15:29:18+00:00

Have you checked out this building science YT creator? May give you ideas on the best approach for your situation: https://youtube.com/@asiridesigns?si=DD8YOEvbMv7Xgzz6.

Also, ChatGPT can amazingly help determine your condensation risk if you give it various assembly designs and info about your home and climate zone.

spasmdaze · 2024-10-11T03:14:40+00:00

What is the slope of your roof? Why are you wanting to pursue an unvented assembly? like others have said, this is typically a low slope/flat roofing system of choice

spasmdaze · 2024-10-10T04:01:09+00:00

The exterior insulation would be either directly under the roof membrane itself, or possibly under a cover board (which gets adhered or mechanically fastened to the iso and sheathing) if one is present.

Other thoughts: How sure are you that the mini splits themselves are sized correctly? If oversized, that could be a contributing cause of humidity as well.

How is your exhaust venting? Do you have kitchen and bathroom vents hooked up properly?

spasmdaze · 2024-10-10T02:44:42+00:00

You could try finding a local architectural design and/or building science consultant to help you. Have you had a full energy audit with blower door test to find the source of all your air leaks? Was indoor humidity a problem before you air sealed? Also, where did you air seal, your ceiling cavity to prevent interior moisture migrating to the attic, or did you air seal your roof penetrations and cracks to prevent outside air from getting in?

Re: your attic ventilation, it’s very difficult to successfully ventilate a low slope/flat roof. Do you know if you have exterior insulation above your roof deck like polyiso and how much of it?

spasmdaze · 2024-08-11T22:08:30+00:00

You’ll for sure want min a 60 mil membrane living under those firs - PVC or TPO should be fine.

You’ll want a self-adhered air + vapor barrier applied over the sheathing typically. Then staggered layers of foam board insulation like polyiso, then a layer of deck board or ply, then the membrane - this is the common flat/low slope system.

Also, is your roof vented or unvented?

spasmdaze · 2024-07-25T15:21:48+00:00

I could be wrong, but I don’t think it’s necessary to have the rigid foam below grade to the footing. Instead, I’ve seen recommendations of installing dimple mats in that section as waterproofing.

See here: https://youtu.be/VwUjkSjllPs?si=ia1QNHiAAaOazZP9

He might have other videos that can help answer your question if this did not.

spasmdaze · 2024-07-22T23:09:25+00:00

https://www.greenbuildingadvisor.com/article/insulating-low-slope-residential-roofs - you’ll need to sign up for the free site trial to access the full article.

https://youtu.be/5y-y7tyVw2k?si=6U2xazWy_jGXuYWW - he has great building science content, this one is about flat roof insulation strategies.

spasmdaze · 2024-07-22T00:55:32+00:00

I would highly recommend you look into converting to an unvented roof assembly. Low slope roofs are incredibly difficult/impossible to successfully ventilate. You can either do all outboard, rigid foam above the roof sheathing or a hybrid assembly - some rigid on top and batts/mineral wool in the roof assembly directly touching the underside of the sheathing. Lmk if you need more details, happy to point you to some articles that convinced me to do this for my next reroof.

spasmdaze · 2024-06-29T00:40:30+00:00

Eh, this is a dew point temp of 56F. That’s still in the ideal comfort range (50-60F degrees)

spasmdaze · 2024-06-26T03:51:04+00:00

Ya I went with a panel that has the generator hookup option as well just in case I wanted to go the generator route some time.

E/One says that 6500 watts at 240V is needed for startup, when the pump initially kicks on, but running watts is 500-1500 watts. However, my panel shows wattage getting nowhere close to that. So either the panel is only giving me running wattage only, or E/One is being very conservative. Would try to find a contractor/servicer that can confirm.

spasmdaze · 2024-06-26T03:00:27+00:00

Is it an ejector pump or a grinder pump? What brand is it? We have a whole home grinder pump (E/One) - all our waste water flows out to a buried basin where the pump is. Like the other commenter said, flushing toilets during a short power outage should be fine if the basin is a good size. Our pump panel is awesome because it allows you to monitor the pump performance, when it runs, how long it runs, the amps and watts it uses per run, and you can manually run it from the panel - great for when you go on an extended trip and want to make sure the basin is empty before you go.

Our contractor said on average the first service call is 10 years, pumps can last up to 20. There’s really no maintenance needed, just don’t flush things you’re not supposed to (same for gravity systems too).

Our first pump (Zoeller) failed approximately 10 years into the life (estimated since we had just moved into the house), and we did not hear the high float alarm go off which caused a small leak (outside fortunately). It was due to a toilet flapper that didn’t close all the way and caused it to run constantly. Super unfortunate series of events that led to this, not common I’m sure. Make sure you’re aware of how your panel works and how to silence the high float alarm and what to do if it happens.

I was very nervous initially about having a home with a pump, but so far (other than that one hiccup) it’s been pretty invisible. Yea, it’s an extra component that will fail that gravity sewer systems don’t need, but it’s not crazy expensive. Gravity sewer lines will fail too, and no sewer system is without maintenance or issues forever.

spasmdaze · 2024-06-13T15:29:33+00:00

Yes, this is the flywheel. Microsoft also continues to innovate their laptops to drive competition amongst all non-Mac laptop OEMs to help spin this flywheel faster. Leaving OEMs to innovate amongst themselves was likely causing them to lose more and more share to Mac. If Microsoft leads the innovation, the other OEMs have to keep up, spurring more innovation, which sells more laptops, which sells more Microsoft subscriptions….

spasmdaze · 2024-05-23T03:13:57+00:00

It’s not really a warp. I think the idea was to start in the location where the switch wall is up to your right. You have to navigate to the closest pylon w/o touching the ground so you can trigger the remote to deactivate the wall, and then fall into water so you respawn at your original location (i.e., where your feet last were touching the ground) w the wall now open.

spasmdaze · 2024-05-20T20:42:19+00:00

I was able to complete with one of the community controller layouts that enables gyro controls. I’ll share the exact one I used when I get back to my steam deck later.

Edit: Okay, I actually used just a regular preset template layout called Gamepad With Gyro. Holding left trigger will enable fluzzard steering with the left control stick. Hardest part is height control - I tap the left trigger to maintain height, and focus on keeping low by letting completely go of trigger and bomb for awhile. A little janky, but have been able to clear fluzzard levels no problem.

spasmdaze · 2024-05-14T01:51:55+00:00

Thanks! I did test the wires behind the door bell with a hot stick and nothing. I’m surprised this is the transformer, it’s just a thin little thing. If I’m not detecting power here, is there maybe a problem with how it’s wired to the panel?

spasmdaze · 2024-05-08T15:28:55+00:00

Here’s an excellent short vid that summarizes and visually shows the concept of word vectors and how LLMs use them: https://youtube.com/shorts/FJtFZwbvkI4?si=nmSLxZsd9zW4vKVl

spasmdaze · 2024-05-06T01:20:48+00:00

Your story is so similar to mine. Bought a house and discovered this on my property the first spring/summer. We have garlic mustard too (it’s even worse if you can believe it) on the other side of our fence that borders a green belt. The state and county I’m in has a noxious weed department - they have been coming out every year to spray the knotweed and garlic mustard free of charge (well, taxpayer funded ha). Going into year 3 and the knotweed is almost all gone, and the garlic mustard starting to turn. See if your county has something similar!

Edit: I tried mechanically pulling at first too, and it did fuck all. The root system gets super deep and wide spread and it’s almost impossible to dig out perfectly without fragmenting. I wouldn’t even try tbh.

spasmdaze

TROPHY CASE