Garage roof upgrade

[Jackthestopper]

My garage roof has two problems - it's leaking and it's hot as hell during summer, so I plan to tear it off and redo it completely. This means I have two questions

- what is the best heat insulator?
- how to make it as water tight as possible so it doesn't leak

 

[JRobert Oppenheimer]

My garage roof has two problems - it's leaking and it's hot as hell during summer, so I plan to tear it off and redo it completely. This means I have two questions

- what is the best heat insulator?
- how to make it as water tight as possible so it doesn't leak

For the insulation, it would be nice to use polyiso or spray foam since they're wonderful in hotter climates. I agree summer's coming up and it sure will be hot as hell. But nothing's hotter than when I went for a quick Asia tour lol. Waterproofing? Easy. You just need ice and water shield underlayment + metal roofing. Don't forget the ventilation!

 

[Hoeegarden]

Rigid foam boards like polyiso should be one of your options it provides decent thermal resistance. To prevent leaks, use a high quality waterproof membrane or roofing underlayment combined with proper flashing and a durable roofing material like metal or asphalt shingles installed properly

 

[BubbleWrapBandit]

Great advice! Pairing quality insulation with effective waterproofing and flashing is essential for ensuring a durable, leak-free setup. It's a smart building strategy

 

[JRobert Oppenheimer]

If you're ripping it all out anyway, maybe you can go big with a closed-cell spray foam for insulation. For waterproofing, layer up with an ice and water shield, then go metal roof or torch-down membrane.

 

[BOOM!]

@JRobert Oppenheimer I like the closed-cell spray foam idea, especially if you want both insulation and extra sealing. But it's better to make sure the waterproofing details around edges and penetrations are done right or you'll be chasing leaks again. Who wouldn't want that?

 

[syllabus900]

For the insulation, it would be nice to use polyiso or spray foam since they're wonderful in hotter climates. I agree summer's coming up and it sure will be hot as hell. But nothing's hotter than when I went for a quick Asia tour lol. Waterproofing? Easy. You just need ice and water shield underlayment + metal roofing. Don't forget the ventilation!

I'm prepping a garage conversion in East LA and looking into insulation options now, polyiso sounds promising for our heat. I read it can lose some R-value in colder temps, but that shouldn't be a big deal here, right? Also curious: between open-cell and closed-cell spray foam, which holds up better under a metal roof with high sun exposure?

 

[hotriot]

You can use EPDM rubber or liquid rubber for a seamless waterproof layer. Are you going to rebuild your roof? You can combine proper insulation with a continuous waterproofing, which will give you both temperature control and long term protection from water.

 

[Alan]

Roof redos can get complicated when you're solving multiple issues at once, sheesh. Very helpful replies here by the way