Learn me slate roofs

So the house my wife fell in love with (that I'm supposed to go look at tomorrow) has a slate roof. it was listed as having a metal roof and this only came out in a conversation with the listing agent (:/).

Fortunately it's supposed to p*ss down tomorrow so if there are any obvious leaks I'll probably see them. According to the sellers they are not aware of any issues, but allegedly the property had been under contract before and the buyers backed out because "their home inspector told them how much redoing the roof with shingles would cost and that is too much". They never shared the result of the home inspection with the listing agent or home owner so we don't currently know if they made stuff up to get out of the contract or if there really is an issue. At least I'll have a GC (FoF) coming with me tomorrow who might be able to notice things really out of order.

Anyway, back to slate roofs. I'm assuming I might need a specialised roofer if it needs any fixes. The materials should still be available, right?

[As an aside, I'm also looking at a new-ish house on Saturday, but we really do want something old. And this place is five minutes from a real racetrack].

No comment on costs over here, but my parents house in the UK is approx. 130 years old and it was only in the last decade that the slate roof needed any attention at all.  YEs they cost a fortune, but they effectively out last the human occupants when done right.  No idea on the age or condition of the place you're looking at, but high cost of replacement is only a factor when it needs replacing, which as I should say, shouldn't be for a century.

Edit.  P.S. that isn't just true for my parents house, it's for all people I know with a slate roof.  

P.P.S.  make sure it really is a slate roof.  Slate lasts effectively for ever.  I've seen stone rooves called slate rooves and they don't last anywhere near as long in damp areas with freeze thaw cycles as most stone is somewhat permeable to water which gets in, freezes, spalls and fails.

Slate roofs are almost permanent with reasonable care and maintenance.  The problem is the reasonable care and maintenance.

You'll need to find a roofer who is good at slate roofs and have them look it over.  There still are some.  Assuming it's laid over skip sheathing (many / most are; it's like 1x6s about 4" to 6" apart) you can probably go up in the attic and inspect it from underneath.

If it has a few weak spots, there are ways to fix it without having to re-slate the entire roof.  And there are synthetic replacement slates available that are less expensive than natural stone, but last just as long and look good enough from the ground.

We put shingles on our house, came with a slate roof. The cost was not bad at all. Mind you we did it our selfs. 

Roofing slate can be very hard to come by depending on the area. 

House was built around 1890, and it looks like someone spent a pretty penny on it back then. Sounds like a good look at the underside of the roof is in order to see if there is any obvious damage. The house looks in decent shape so far - it might need updating, but from what I've seen so far it doesn't look like it needs work before we can move in. And a lot of the original features haven't been improved away.

Like Adrian and Duke said, I would expect this kind of roof to almost last longer than the structure underneath and unless it's absolutely necessary I'd rather not replace it or part of it, especially not with a standard shingle roof. 

If you do have to replace it, these are your ticket:

DaVinci synthetic slates

There are other products around, too.  We have specified Tamko in the past, but I'm starting to hear of a few durability issues with them.

Very expensive to repair and not easy to find the tradesmen to do the work.

My brother's FIL has a huge old Historical Society type house with a slate roof and  he "Saves up" to do a shingle when he can; you really never need a new roof, its more like a never ending series of localized repairs.

Pete

We did a DaVinci roof on our house in 2017.  We love it. 

My facility had several building with slate roofs.  You really can’t walk on it, far too brittle and will either snap underfoot or shear away.  Either way, the risk of walking on it is too high.

The slates themselves are essentially permanent but the valleys between them are usually flashed with copper or similar. This is where the leaks occur.  Acidity in the rain eats the copper and you get leaks.

A few years back the slate roofed buildings were starting to have problems at the edges like that and it was decided to go with “50 year” asphalt shingles instead of trying to work around the fragile old slate.

My house came with a beaten-up slate roof and all the houses in our neighborhood were built with them. 

If the roof is in good shape, it will last forever so long as you properly maintain it. That means probably over $1k/year in maintenance.

If the roof is in bad shape, it's difficult and expensive to fix. We ended up replacing ours after finding numerous leaks in our home inspection. The synthetic tiles cost a fortune so we just put architectural shingles on. Buyer beware!

Could you elaborate a bit on the maintenance side? I did find some information over on nps.gov but their recommendations don't seem to be that different from concrete tile roof maintenance (our current house has one of those)?

Basically, regularly clean the gutters, don't walk on the roof and get cracked tiles replaced sharpish.