I keep hearing that argument about synthetics trapping heat, but honestly, I’ve never seen it play out in real life either. Maybe if you had zero ventilation it’d matter, but most of the time, attic airflow and shingle color do way more for temps up there. What I do notice is how much easier synthetics are to work with, especially on steeper pitches or when you’ve got a couple days between dry-in and shingles. No more chasing felt that’s torn loose after a windy night.
That said, in super humid stretches, I’ve had felt hold up surprisingly well—just gets a bit wavy sometimes if it sits too long. Synthetics don’t always “breathe” as much, but they’re tough as nails. I guess it comes down to what kind of abuse your roof is likely to see during install and before final cover. Around here, with all the pop-up storms, I’ll take the tear resistance every time... but I get why some folks still stick with felt for tradition or cost.
- Had both on my last two roofs (asphalt, midwest weather).
- Synthetics are way less drama—felt turned into a soggy mess after one bad storm, but the synthetic stuff just shrugged it off.
- Only downside: synthetic is slippery as heck if you’re up there in sneakers... ask me how I know.
- Haven’t noticed any heat issues either, but my attic’s got decent vents.
- If you’re in a spot with wild weather swings, I’d lean synthetic. If you’re pinching pennies or just like the old-school way, felt still gets the job done.
- Seen a lot of both on inspections, especially around here where the weather can turn nasty fast.
- Synthetic underlayment holds up better to water and wind exposure if the shingles get delayed. Felt just doesn’t bounce back after it gets soaked—starts to wrinkle, sometimes even tears if you walk on it after a storm.
- Agree about the slipperiness. I’ve watched more than one homeowner nearly eat it trying to check their own roof with synthetic down. Boots with some grip are a must.
- Haven’t seen much difference in attic temps between the two, as long as ventilation’s decent. If your vents are blocked or undersized, you’ll have bigger problems than underlayment choice anyway.
- Price is still a factor. Synthetics cost more up front, but if you’re paying for labor, sometimes it goes down faster since it’s lighter and comes in bigger rolls. That can offset the material cost a bit.
- Only real downside I’ve noticed: some cheap synthetics can tear at the nail holes if installers aren’t careful or use too few fasteners. Not common, but worth watching for if you’re hiring out.
- For most folks in the Midwest or anywhere with big weather swings, synthetic is usually the safer bet long-term. If you’re flipping a house or just need something to last a few years, felt will do in a pinch.
- One thing—if you’re doing it yourself, don’t try to install either in high wind. Both can turn into sails pretty quick... seen more than one roll of felt end up in a neighbor’s yard.
Bottom line: synthetic usually lasts longer and handles bad weather better, but felt still has its place if budget’s tight or you’re going for tradition. Just depends what matters most for your situation.
I get the love for synthetics, but I’ve seen felt hold up better than folks expect, especially on older houses with a ton of weird angles and valleys. Sometimes that heavier felt just hugs the deck tighter, especially if you’re dealing with a lot of flashing or patchwork repairs. Sure, it wrinkles if it gets soaked, but if you’re quick with shingles and not leaving it exposed for days, it’s pretty forgiving. Plus, felt doesn’t turn into a slip-n-slide every time there’s morning dew... ask me how I know.
I’ve noticed the same thing with felt, especially on my 1950s ranch. The heavier stuff really does seem to conform better around all the weird dormers and valleys. I get why synthetics are popular, but I’ve slipped more than once on those in the morning... not fun. For me, the cost difference is hard to ignore too—felt’s just easier on the wallet if you’re careful about exposure time.
