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Here’s hoping the folks out there can help with a family “discussion” currently ongoing regarding our Mother’s house’s slate roof.
We estimate the age of the house, located in the northeast corner of Wisconsin, to be somewhere in the 40-60 years old range. A more contemporary addition was put on its rear (an enclosed sun porch) decades ago. One fireplace and chimney operate. The other was for old kitchen and chimney stands while original fireplace in kitchen is blocked off.
As to the roof: the only leaks in past 30 years were at the flashing by the chimney for the abandoned kitchen fireplace…or at the roof (shingled) for the sun porch. The house roof is slate, with the exception of the sunporch addition.
One sibling believes that the slate wears out and our mother should be budgeting for its removal and replacement (with shingles). Another feels, after inspecting roof from ground with binoculars in June, that the slate roof looks fine and should last “the lifetime” of the house. There are no obvious missing slate tiles, no leaks.
What is the readers of breaktime’s input re: slate roof longevity?
Replies
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Clara,
First off, I know NOTHING about a slate roof. That being said I do know about the common tile roof we have a lot of in Floirda and the tile itself never really goes "bad", its just the substrutcure underneath it. I would assume that slate is much the same way. The actual stone piece lasts a long time but if water can work its way up and under it, after a while the wood supporting it would be affected.
With no apparent leaks, I would assume it (the slate) is still doing its job.
Peace of mind could always be obtained through an inspection done by a skilled roofer in your area with slate experience.
Mike
*Slate lasts forever. Its rock. There are buildings in Europe with slate roofs that are hundreds of years old. Of course, they must've been installed correctly to last so long.I love the look too.
*Yes, the slate shingles themselves last forever. The wooden slats underneath do age as they get so hot and dried out seasonally. From relatives in Europe, my understanding is that they are taken off every 50 years or so to replace the wooden slats underneath and then the same slates are reused. I worked on some slate roofs in the US but families don't stay in one place long enough to give a multi-century history of the roof.Several other thoughts: As with any roof, flashing is very important. But if the slates last forever and the installation goes for at least 50 years, the flashing should be good for that long too. Like lead or thick copper. Galvinized or aluminum have suseptiblity to acid rain and salt air, respectively.Individual slates can be replaced while leaving everything else in place. It involves a special tool to shear off or pull out the nails (hopefully copper) for that shingle and then hang the new one off of hooked metal straps. Use those binoculars on some other slates roofs and you can make out the lip of the strap hook at the bottom edge of the new (slightly different color/weathering) slates.Final answer: Inspect from underneath to assess the wooden supports and then possibly budget for a reroof (using existing slates) X decades in the future. Do not budget for the slates wearing out. They don't. -David
*I was born and brought up in the UK. My brother still farms the family farm which has been around I'd guess in essentially its present form for about 300 years, and my old home, the farmhouse, was also built centuries ago. In terms of age, it and its slate roof has been around the block once or twice. My father had a trick of salvaging slates from any house within 30 miles that was being demolished, and re-using them to roof new buildings or for repairing existing storm damaged roofs, or even to sell to roofers for jobs ranging from restorations to new houses. The nails and the rafters, etc., generally seem to give up the ghost decades before the slates perish, and about the only times I can think of that a roof slate becomes unusable is if it falls off in a storm and breaks, or if it has been frosted, rained on, and sun beaten for a couple of hundred years or more. Slainte, RJ
*Clara - I see that your post has stimulated the further dissemination of myths about slate. How about some truths?The longevity of a slate roof depends on the type of slate, its thickness, size, installation and maintenance.For example, a properly-installed Vermont unfading gray-green slate roof well-maintained can last 150 years. A top-quality Welsh black slate roof is almost in the same category. A poorly-installed, poorly-maintained Bangor black Pennsylvania slate roof can only be expected to last 25 to 35 years. Obviously, slate is a natural material and varies much in strength depending on where it was quarried and how thick it is relative to the size of the slate. Larger thinner slates will break sooner than smaller thicker slates of the same material.Slate does not last forever. The poorer grades become embrittled with age, delaminate and break due to weathering, tree limbs falling or when stepped on. Slate should be installed somewhat 'loosely' (hanging on the nails) and if nailed too tightly will crack at the corners and break.Slate should be underlain with heavy felt. Asphalt saturated felt was in relatively short supply during the war years so we see some roofs with decent slate that nevertheless must be redone because they were slated without underlayment. The slates are fine but the roofs leak due to lack of felt or felt deterioration. Slate should be installed with copper nails but other fasteners were sometimes used. Slate roofs can fail due to fastener corrosion or extrusion (the fastener extrudes itself causing the slate to break). In the above cases it is rarely economically feasible to strip and re-use the slate unless there is a lot of life left or the slate is a rare color like unfading red.Copper flashing, unless unusually thick or you are unusally lucky, is an 80-year product. Lead flashing (more commonly used in Europe) or lead-coated copper can last a lot longer. As noted, the flashing can fail before the slate itself. It is a very fussy job to replace flashing and valleys while retaining the slate.You should consult a local roofer with slate experience for more information, but they will tell you much of the same. If they know their stuff, their input on maintenance and the timing for replacement should help you plan effectively. Copper 'baby' repairs to replace individual slates are a standard maintenance approach.Keep other trades (gutter cleaners, painters, chimney sweeps, etc.) off the roof unless they know what they are doing, have padded chicken run ladders and are careful.For more information, see if you can get hold of a very good book called 'The Slate Roofer's Bible.'Jeff
*ditto what jeff said..it depends...but keep anyone off the roof who doesn't know about slate..and don't let anyone who is not an experienced slate installer do repairs..most of the slate roofs here in Rhode Island are all past the century mark... but most of them are Vermont slatecheck out the book that Jeff recommended..if you have a good slate roof ... i wouldn't dream of replacing it with anything else...
*Jeff and Mark are right on the mark. I've never done slate work myself, but have hired out slate repairs dozens of times because we have a boatload of slate roofs on campus. If you have a university of any age near you, call the Facilities group there. Chances are they have some guys around that do nothing but slate repair for them full time. They may be interested in side work (repairs or just to survey the condition), or at least know who in the area they'd trust to do it.Keep the roof if you can. Few people have the bucks to put slate back on.
*Here's a deal for you, take off that old fashioned slate, and get some nice modern fiberglass shingles. Heck I'll even come over there and haul off your slate just 'cause I'm such a nice guy......
*Jeff,If your book says that a Welsh slate roof can 'almost' last 150 years I suggest the author visit Wales and open his bloody eyes!To remove damaged slates a tool called a 'Slate Rip' is used. Basically all it is is a strip of steel about 15" long, by 2" wide, by 3/16" thick with a notch on each side about 1/2" from the end.To use it, the slate rip is slid up under the slate, feeling with the edge of it for the fixing nail. The idea is that the notch is located around the fixing nail and the end of the rip is struck with a hammer, 'ripping' the nail out.Clara,I don't know the slate in question, but as long as there are no signs of delamination (and the best sign of that happening would be finding lots of small pieces of slate in the guttering) there is no need to replace it.
*I love the freedom of being able to walk on my asphalt shingle roof without worrying about anything fragile.That is one thing I've always wondered about slate, copper, cedar shingled roofs. What would happen on a slate roof ?
*jeff is right on the money about slate quality. I grew up in a neighborhood that was built in the 40's and 50's, and the pennsylvania slate roofs are delaminating like crazy. the community association has agreed to allow covenent changes that permit shingle roof materials to replace slates. too expensive to get good slates for most homeowners taste.
*Slate is not a suitable material for a low-pitch so it would be difficult to walk on them anyway.The usual method is a crawl-board supported on sacks filled with straw.I don't know about asphalt shingles -- I guess we'd consider anything with that short a life as 'temporary roofing'
*Alan - Slate, copper and cedar are all generally more treacherous, and slate and cedar are generally more fragile. One thing to keep in mind, however, is that the most fragile thing on your roof is probably YOU. Example: There was an older mason in town last week about two blocks from our house finishing some chimney repointing. He hosed down his brickwork and unfortunately must have forgotten that it was a slate roof. One step onto the wet slate and he fell 40 feet to a bluestone patio. He died shortly after arriving at the ER.I've been present for a similar accident on a cedar shake roof where a carpenter stepped out a window onto a 7:12 in the rain to adjust something. Wet cedar is incredibly slick and he went off the edge falling about 18 feet. Since he landed on his side in the mud he was fine.If you slip and slide down a copper roof you hope that the architect didn't specify soldered-on snowguards or you will be singing soprano.The moral is: If you have a special roof treat it with special care and don't climb on it unless you know what you are doing.Jeff
*I just replaced some slates broken by tree limbs and baseballs (an old school) The building is over ninety years old and the assumption is that the roofing is original. I don't see why it won't go another 90.There is absolutely nothing slicker than wet slate. Most materials give you time to say "ooops" or something just asa you realize you are going. With slate, you are feeling the THUMP before you know you're going down. This is from one who's had 5-6 falls. Believe me, it's slicker than Wee Willie Clinton.
*Thanks for the replies to my mid-post.Yup, I do have a low pitched hiproof and never considered slate or other exotic roofing material.And I assumed they would be very very slick and dangerous when wet.Was more curious about how easily they would break/crack if it was impractical for someone to rig up a chicken ladder (?).We have many houses, churches, academic buildings in our town topped with slate. Most of them seem to not have any trees nearby or anything that would cause frequent climbing on the roof.I have also observed several different slate installations - they seem to be installed with no plans for anyone ever having to climb the roof anytime soon.The material doesn't seem to "age" or support any living organisms.
*Alan,It would be about equivalent to walking on ceramic tiles. They break very easily.
*A 40-60 year old slate roof is practically new.....I don't care what kind......as long as it was properly installed. And if there haven't been any leaks in the past 40-60, I'd guess the install was OK. My folks house......and alot of others I see.....is about 90 yrs young....and must have the good Penna stuff......'cause most of them....the folks included......are still in great shape. Take a close up look....if it's brittle and crumbly.....it's close to shot......if it's solid......it's a solid roof. Jeff
*b WBA At Your ServiceIan, The roof stones lasting 300 years in Europe are 3/4 " thick. The slate that gets on our homes here in the USA is 3/8 ". Thicker is nice, yes, until you ask the roofer his opinion about lifting twice the weight and lastly the person paying the bill. Which will be more than double. What Jeff said, above, plus a little help with a link, I hope.http://www.oldworlddistributors.com/books.html
*Roofing slate for general housing use here is 3/16" to 1/4" thick, not 3/8" and most of London up to 1950s or 60s was roofed with slate. My father, in 1958, bought Kenley Grange on 3 acres in South London. He built 10 houses on the land and converted the Grange into 2 dwellings. I was sent down to the local council offices and got a photocopy of the original plans, deposited 1828 (completion cert. issued 1830). That was roofed with slate in perfect condition and was by no means the earliest building in the area.'Almost 40 years' for the life of good quality slate (and Welsh is good quality) is an absurd statement -- even a wheat-straw thatch will last 60 years.Believe me, it would never have been used as a roofing material if its life expectancy was that short.If you ever get to London, spend a little time looking up.
*Ian: I have an old shack up in Kansas that had 3-tab asphalt shingles that lasted nearly 40 years without leaking. And I do hope to go to England soon...comedian on TV last night called it the "Honkey Motherland".
*Ian - We rate the Welsh slate that we import to the US as S1, S2 and S3 with S1 being the longest-lasting. By 'nearly in the same category' I meant that the best grade (S1) should last over 100 years if well-maintained. JeffPS - I grew up in London - spent i mostof my time looking up!
*Jeff,with the advent of the concrete roofing tile here in the 1950s slate was used less and less and is now restricted to repairs, extensions and luxury homes because of its cost -- also slating is a dying trade,so most houses with slate roofs are old.Admittedly it doesn't last nearly as long as clay tile but then nothing does.It's not a good idea to spend most of your time in London looking up, not with all the pigeons about.
*I wanted to thank ALL of you for your comments, opinions, experience sharing, book recommendations, etc! Sounds like I'll be climbing the extension ladder and measuring the slate tile's thickness next visit to Mom's house...after reading "The Slate Roofer's Bible" of course! FYI: There's no gutters and no evidence on the ground at drip edge of any bits or pieces of broken slate; to the gent who mentioned that.Message to Jeff Clarke: "Si Hoc Legere Scis Nimium Eruditionis Habes" Clara
*Your welcome - the book title is:The Slate Roof Bible ISBN 0-9644258-0-7 by Joseph Jenkins. Carried by Barnes & Noble - about $35.00.Jeff
*Jeff, got it - thanks again. Ciao!
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Here's hoping the folks out there can help with a family "discussion" currently ongoing regarding our Mother's house's slate roof.
We estimate the age of the house, located in the northeast corner of Wisconsin, to be somewhere in the 40-60 years old range. A more contemporary addition was put on its rear (an enclosed sun porch) decades ago. One fireplace and chimney operate. The other was for old kitchen and chimney stands while original fireplace in kitchen is blocked off.
As to the roof: the only leaks in past 30 years were at the flashing by the chimney for the abandoned kitchen fireplace...or at the roof (shingled) for the sun porch. The house roof is slate, with the exception of the sunporch addition.
One sibling believes that the slate wears out and our mother should be budgeting for its removal and replacement (with shingles). Another feels, after inspecting roof from ground with binoculars in June, that the slate roof looks fine and should last "the lifetime" of the house. There are no obvious missing slate tiles, no leaks.
What is the readers of breaktime's input re: slate roof longevity?