Preserving a Natural Slate Roof
Slate Roofs: A Primer on their Repair and Restoration — Slate has been used as a roofing product for centuries in Europe and also has been the preferred choice for houses and also structures in the United States since the 19th century. Slate roofings are still seen frequently in upstate New York city and also throughout New England.
Just what does not exist, nonetheless, is a ready-supply of proficient, capable specialists to repair and bring back slate roofs. With a standard understanding of this highly-specialized roofing system, home owners can usually assess the current condition of their slate roofing, its life span as well as, if needed, the potential for reconstruction. The info that follows will help in evaluating and identifying your roofing system’s requirements as you, equipped with this info, thoroughly screen potential roofing contractors to effect these repair services. Olde Mohawk Historic Conservation is the favored professional for such work in Boston and throughout New England.
What fails with slate roofs?
In a lot of instances, the issue is among the following:
– Variations in duration and quality
– Flashings and other metalwork requirement replacement
– Earlier repairs by careless professional roofer
Variants in period and quality of slate – Slate is pulled from the earth in massive slabs and dressed down into individual shingles mostly by hand. Slate is stone, and stone is long lasting. Nonetheless, stone is a natural material and may have minute or even invisible fissures that will ultimately cause slates to damage and slide off the roofing. Roofing slates are ranked by ANSI according to solidity. Softer slates (ranked S2 or S3) may end up being crunchy as well as will delaminate, in some cases, as early as 55 years, as well as definitely by 80-100 years. These softer slate roofing systems (commonly from Pennsylvania) can not be saved or restored, for the most part, however repairs could buy time.
Better, hard slate, like most New York, Vermont, Peach Bottom, Buckingham, or Monson, will last for centuries on a properly looked after roof covering. It is important that individuals who have, inspect or work on slate roofing systems are able to recognize the slate on the roof in question. This single-most crucial information will certainly supply details as to its type, origin, durability, attributes, and also qualities. Contact Olde Mohawk for a free appointment specific to your slate roof. Roofing slate is still being quarried and sold in New york city and Vermont (as well as Pennsylvania as well as Virginia.) Slate was likewise once quarried in Georgia and Maine (home of the world-famous Monson slate.).
Blinking replacement as well as integrated gutter systems.
While the slate might last “permanently,” the steel flashings will not. Flashings are essentially the metalwork used to stop the seepage of water wherever there is a sudden angle or position in the roofing (ie, smokeshafts, valleys, dormers.) Frequently, flashings were made from terne-coated steel, which is a steel coated with a lead/tin mix. This is in some cases, improperly, called “tin.” Terne-coated steel has to be repainted on a regular basis or rust will occur.
Copper flashings (either ordinary copper or lead-coated) were most frequently set up on government structures, churches, and also similar institutions as well as high end homes. Copper will certainly oxidize as vert de gris shows up. Copper will certainly begin to neglect after about 60 to 70 years in areas of high wear, such as valleys. The copper sector suggests a life of 80 years. Older copper flashings can be repainted in order to extend their lives. Too often, the flashings fail and also underhanded roof repair specialists persuade homeowners to change their good, slate roof with asphalt. Only the flashings should be changed, not the entire roof.
These kinds of projects are routine for slate roof mitigation insulation contractors. The adjacent slates are eliminated to enable replacement of the flashings. The eliminated slate are then installed in their initial locations, laving the roof, in look, as it was before, except for the flashing. The requirement upon which a repair is judged is that it must not appear to the layperson that any type of repair, at all, happened, besides new, visible flashings.
Box gutter linings, or “built-in” gutter systems, are an additional common problem on aged slate roofings considering that the metal degrades and also leaks. Similar to valleys and various other flashings, they can be replaced without eliminating as well as changing the whole roofing system. If left unchecked, the entire gutter boxes will rot and have to be rebuilt and changed.
Be careful of irresponsible roofing specialists.
The cause of numerous leaking slate roofs is not natural wear, metal failures, and even broke slates. It is, fairly simply, bad work. Many unqualified individuals claim to have the ability to repair slate roofs. Fully half of the work done annually by a typical slate roofing contractor involves the removal and replacement of faulty repair work. Residence owners with slate roof coverings commonly pay exorbitant sums to have their roofings trashed by these fly-by-nighters, then they have to pay a lot more of their hard-earned cash to have them dealt with and also repaired properly. The types misuses committed versus slate roofing systems include the ones that are face-nailed, tarred, fixed with non-matching slates, coated, or reflashed incorrectly (see photos). One should NEVER tar or coat the surfaces of slate roofs. Such activities are aesthetically displeasing, often permanent, and ineffective. Roofing contractors are notorious for recommending homeowners to change a perfectly excellent roof covering. House owners will certainly usually pay attention to such suggestions when a lack of experienced slaters makes it the only guidance available. These concerns, combined, have been the downfall of many slate roofs, lost permanently to lack of knowledge, forget, and misery. Get in touch with Olde Mohawk for a cost-free analysis and also conversation of your roofing’s demands. As you look for price quotes and suggestions from various other roofing professionals, use the information in this paper to test their understanding and also evaluate their approaches. Watch their eyes widen as they recognize YOU understand a lot more about slate roofing compared to they do!
Replacing busted and absent slate.
It is not unusual for a century-old slate roof covering to have 50 or even more slates simply neglect from a range of sources. Slate has natural faults or hairline fractures as well as might eventually damage. A 20 square roofing system (2,000 square feet), with a typical 10″x 20″ slate, will certainly have about 3,400 slates. If 50 of them fail after a hundred years, after that the failing price of the roof covering is 1.5 percent over ONE HUNDRED years– or a 98.5 percent success rate over a century. That’s an A+. Nonetheless, simply one missing slate is all a leakage has to begin. For an expert slater, the solution is not rocket science. Replacement slates must never ever be attached in position with visible straps or subjected nails (called “face-nails”). I duplicate, if a contractor explains face-nailing to you as his recommended method, inform him to leave your home QUICKLY. NEVER allowed him on your roofing system and also ask him to neglect your address. Ask that he not even take a look at the slate if he ever happens to drive past your property in the future!
There are 2 appropriate techniques for attaching replacement slates: the “nail and bib” technique or the “slate hook”. The nail and also bib method is one of the most commonly made use of. The damaged slate is removed with a slate ripper and also the replacement slate is secured with a nail in the slot between the two, overlying slates. A little square of blinking is glided under both, overlying slates on the following course, above, and also over the new nail head. The bib is angled a little so rubbing keeps it in position. Bibs can be light weight aluminum, copper, or other non-corrodible steel, yet glossy and reflective steels that are visible from the ground should never ever be utilized.
Copper or brown-painted aluminum (coilstock) mixes perfectly into the roof. A slate hook is a hard wire hook constructed from galvanized steel, copper or stainless-steel, approximately three inches long. A small exposed loop hooks the substitute slate in position. This is one instance when an exposed repair work tool serves because the little hook is practically unnoticeable from the ground. Stainless-steel hooks are more powerful compared to copper hooks. Slate hooks are more suitable to the nail as well as bib on brand-new slate roofs, especially for repair services in the field of the roof. Using straphangers to repair the roof needs to be avoided; they’re unattractive and they deface the roofing system.
The device required for removing slates from a roof covering is the slate ripper– a swordlike things that moves up under the slate and also pulls out both nails that hold it in position. You never ever want to cut the nail due to the fact that the item of nail left under the slate will interfere with moving the replacement slate into area. A slate hammer, one more essential slate roof covering tool, has an opening punch at one end used to punch nail holes in slates. New slates could be hard and weak and also require some method for very easy punching with a slate hammer. Conventional thickness slates (3/16″ to 1/4″) are readily cut with an easy hand-held gadget, a slate cutter.
While the slate roof covering could last “forever,” the metal flashings will not. Not all slate is the same in quality and toughness. Dishonest contractors will certainly butcher your roof or even replace it with asphalt shingles, if you let them. Armed with the above information, you are ready to wonder about potential slaters as well as evaluate your roof covering’s needs.