I have a slate roof on my house. Everyone who sees it raves how a slate roof is the best roof that you can have, which is immediately followed by a big, “but…”
It seems that after every storm, as last night, I walk outside in the morning to find a handful of broken slates littering my property. These slates are obviously from my house since my neighbors’ houses have shingle roofs. It also seems that I have to pay someone 500 dollars at least once a year to come out and replace these missing slates.
So, what is the Straight Dope on slate roofs?
Are they really the best roof a house can have?
If so, why don’t brand new houses have slate roofs?
Why do slates, some of them fully intact with unbroken nail holes, fall off my house?
When someone states that a slate roof is the best type of roof that a house can have, are they taking into account the maintenance costs?
And, lastly, what is the makeup of a slate roof? I mean, as I slowly lose a slate here and there, that doesn’t mean that the house underneath is exposed to the elements, does it? I’m assuming that a slate roof actually consists of a couple layers of slate, right?
I would imagine that the reason you are losing tiles is because either the lats under the tiles have rotted, or the tack holding the tiles onto the lats have corroded.
Tiles are laid in rows across your roof, the top edge of the tiles rests upon a wooden lat, and the tiles are tacked on to those lats.
The lats are usually fairly thin cheap bits of wood, the weight of other overlapping tiles does much to hold each tile down.
This arrangements does allows the loft space to ‘breathe’ and helps stop the roof timbers from rotting and deteriorating.
If you are psedning this sort of money regualarly on roof repairs it says to me that you maybe need to strat thinking and saving to get the lats and tacks replaced.
It’s possible that the tiles are not really appropriate for the slope of your roof, or perhaps the prevailing weather conditions in your area.
As for why new houses don’t have slate tiles, simple - cost, pot tiles are much cheaper than slate, and they can be made in a variety of colours, shapes etc.
A slate roof takes a much beefier structure to support them, but it will last for a hundred years easily. Yours is probably held on with galvanized nails which are rusting away. Copper or stainless steel is the ticket here. You can fashion a strap that is nailed under the shingle, the shingle is slid into place and the strap is bent over to hold it. If a slate falls I reccomend immediate replacement, because most likely a gap between the lower nest two slate is exposed allowing rain to enter your attic and start the decay process.
They are very good, since they do not deteriorate with age. Stone is very long lasting.
They are more expensive than most any other roof.
I would guess either the wrong kind of nails were used, and the nails themselves are deteriorating.
Yes, that’s the main reason they are favored. They should need almost no maintenance except to repair slates broken when something falls on them, or if a slate blows off in a VERY high wind. It should take gale-force winds to do this, as slates are heavy.
No, there is only one layer of slate, though the rows overlap sufficiently so that if all slates are in place any given spot is two layers thick.
Summary: if slates are falling off after regularly, you have a faulty installation.
They are very rare here…I’ve only seen ONE in this area. They should last for ever…how much do they cost? And, do they turn green immediately, or does this take time?
Cost is somewhere between slate and asphalt. For reference, I was quoted about $20K for a copper roof, and a new asphalt shingle roof (with high quality shingles) cost $10k. Should last as long as slate (100 years, give or take), and weight isn’t an issue (which is a big issue with slate, if the house wasn’t designed for it). Chemicals can be applied to speed up the color change, and to give a different color.
Large deposits of slate suitable for mining are infrequent.
Lack of mechanization. Much of the splitting and shaping must be done using early 20th-century technology, because of the irregularity and brittleness inherent in slate.
