Thursday, April 26, 2007

slate roof update - tower 50% complete

Just a quick picture update of our slate roof progress. We've worked about 15 man-days on the tower slate so far... It is not really as complete as the picture might lead you to believe.We have a lot more slate to put on the back side of the tower, but I like how it looks so far, so I guess we'll keep going! The fish scale slates are for my wife - she thinks I'm a slacker for not doing the whole house with that style of slate.

I hope to find some kind of weather-vane, compass, finial, lightning rod, or combination thereof, to place on top of the tower. Has myth-busters done an episode on lightning rods yet? Does anyone know if they actually work?


Anonymous Jim K in PA said...


I saw your lightning post over on Joe Jenkins site, but I did not have time to respond when I read it.

Yes, if properly installed, lighting rods do work, and will reduce the risk of damage to the house when the get struck.

There are some good sources on the web, and plenty of options for hardware. I am going to install them on my house once my slate is done. Mine will be all copper with dual ground rods.

DO NOT INSTALL THEM INSIDE THE STRUCTURE! The mega-current will likely melt some of the cabling, and you don't want that to happen in nice dry, wooden spaces. Use standoffs where the cabling runs along a combustible material.

Feel free to email me if you have other questions.

Jim K

May 3, 2007 at 7:34 PM  
Anonymous Shawn said...

Nice work on the slate roof. They are a thing of beauty!

What good advice would you give a novice about installing 20 squares of 18 inch, random width slate in September? Advice such as what tools you found an absolute must, how long, on average, did it take you to install a square, etc.

I hope to emulate the "staggard or ragged-butt" look (reminds me of the marathon-running days :-)). If I understand correctly, all one need to do with uniform length slate is to chalk for a 4" headlap and install every other slate one inch below the chalk line.

Very nice work and a pleasure following your blog.


May 5, 2007 at 3:58 PM  
Anonymous Jim K in PA said...


I am sure Thomas will reply, but while we are waiting, get yourself over to Buy a copy of the Slate Roof Bible. Peruse Joe Jenkins' site and you will learn an enormous amount. Just be sure to allow yourself enough time to get the job done. I have installed about 15 out of 18 squares so far on my house (9x18 Virginia B'ham). I will be finishing the last of it this month. I started in late 2005. Mine was a restoration/re-roof, so there was a lot of prep time.

Best of luck.


May 8, 2007 at 7:42 PM  
Blogger oldmilwaukee said...


Thanks for the compliments. If you would like some advice, well I'm full of it. I have some advice too. :)

Jim is right-on. Even if you use salvaged slate and provide 100% of the labor, the value of your finished slate roof is going to be no less than $20,000. So, learn everything you can and start by buying the "slate roof bible" from Joe Jenkins. Read it from front to back. You'll probably want a slate roof more than ever after reading the book. If you're still convinced you want to do the work yourself, then buy "The Slate Book". It's not as good as J. Jenkins' book, but it fills in a lot of gaps and gives you another perspective.

Off the cuff, some advice that I haven't found in the slate books...

1. Order samples _now_ from the quarries you are considering. Samples are free. My four slate samples are nailed to the roof now. :)

2. When you pick a quarry, order the slate long before you need it and stay on top of the order so they don't forget you. They probably have bigger orders than yours with established clients, so it could take them a little longer to fill your order, regardless of what they say. If by some miracle, the slate arrives a month before you need it, it will not rot in your yard. It's 400 million years old, it can wait a few more weeks to go on your roof.

3. Get a safety harness, good rope, a lanyard, and rope grabs (a ratcheting mechanism that goes between your lanyard and the rope.) Get someone to show you how to use these. (Most union carpenters that do commercial work have gone through a class or orientation on the safety equipment.) A slate roof won't do you any good if you die while putting it on.

4. This one is in the slate roof bible, but it bears repeating (sorry I don't have the exact quote, but it goes something like this...) Almost everything you do on the roof would be really easy if you were standing on the ground and had the work in front of you. Figure out how to simulate those working conditions up on the roof.

5. get the roof watertight and only tear up the part of the roof that you think you can finish before the next rain. Felt/tar paper provides no means of water protection once it has slate nails going through it.

OK, to try and answer your questions...

If you had an unskilled helper handing/packing the slate to you, you could perhaps nail down one square per day. Maybe even two square on your best 12 hour day, once you get into a groove and your help can anticipate the size slate you will need next. That time estimate goes flying out the window when you have to slate valleys and hips. Those parts of the project are measured in "tenths of a square" per day. Also, it can be slow going at the eaves, ridge, and gable ends. Figure half a square if any part of the roof that day includes a substantial amount of any of those features. I haven't seen anyone willing to apply a slate roof for less than $500 per square (labor) and high end companies will ask more than twice of that, so let that be your guide. I doubt the pros that ask $1000 per square are averaging a full square per day per person, or they would be very rich, even after taking out workers comp, liability ins., etc.

If you look back in the archives, you can see an outhouse that I slated with a hexagonal pattern - it was about 0.64 square and it took 20 hours - but that included nailing down the oak skip sheeting, cutting the slates, applying the ridge cap, etc.

Regardless of whether you're doing patterns or just plain random slate, the absolute must-have tool is a slate cutter. Looks like a paper cutter. No noise, no electricity, no dust. Bone simple and it works. You might want to buy it and practice on the quarry samples. Cutting the samples will also help you tell if one slate is harder (possibly better?) than another. When I ordered my slate, I thought of it like a "slate kit," and I would just nail it on. I was wrong. Its more like a bunch of 2x4's and you cut them to suit more often than you would think.

Next important tool is a slate hammer. My brother-in-law has nailed on as much slate as I have and he's still using a regular Estwing carpenter hammer (and occasionally a 1/4-20 bolt or 60 penny nail as an improvised nail-set), but I like the real slate hammer myself. You can trim slate on the roof with a slate hammer, and its a lot easier to hook on to the roof when you want to lay it down without watching it slide to the ground. (be forewarned, it looks like some medival battle implement, and is probably just as deadly)

OK, that's all for now. I told you I was full of it. Main advice is to buy those books, and don't believe anything you read on the internet. :)


May 8, 2007 at 9:16 PM  
Blogger oldmilwaukee said...


I think I will put lightning protection on my roof. Still looking for definitive scientific proof that it works, but I guess annecdotal evidence and conventional wisdom will have to be my guide. Someone was nice enough to send me a document that is the "recognized code" for how to install lightning rods. I'll post something about it when I get 'round tuit. :)

Got some more pics of your buckingham roof?! It was looking awesome last time I checked.


May 8, 2007 at 9:23 PM  
Blogger oldmilwaukee said...

oops, forgot to respond to your staggered butt question. (yes, lots of good jokes in that terminolgy - I won't go there!)

I think using one size slate and adjusting the headlap is a reasonable approach. I looked at doing it that way, but for some reason (I can't remember what it was, but I'm sure I had a reason - I think I calculated it was cheaper to do it differently.), I decided to buy 50%:50% 18 inch and 20 inch slates and alternate them. I set the headlap at 3" and the exposure at 7.5", just as you would for 18" slates. Everything was laid out for applying 18" slates. Then I nailed the 20" slates such that the butts were 1.5" lower and the tops were .5" higher than the neighboring 18" slates. In this manner, the quarry-punched nail holes of the 20" slates lined up with the nail holes of the 18" slates. Which brings me to my next point...

When the quarry punches the holes for you, they do it for a specified headlap. For instance, the 18" slate that I bought could not be applied with 5" of headlap (4", maybe), even if I wanted to. At 3" of headlap, the nails of the overlying slates just barely miss the tops of the underlying slates. Something to think about... this is a very subtle point and the books don't even really address it, so ask for samples and be very specific about nail hole placement when ordering from the quarry, or just buy 20" and 18" slate like I did. In any case, tell the quarry what you want to do with the slate and make sure the nail holes will work for what you want.

May 8, 2007 at 9:39 PM  
Anonymous Anonymous said...


I'm not convinced that lightning rods work. I have been worrying about that question since I took an energy class in undergraduate school.

As I understand it, lightning is static electricity. Static electricity is the discharge/equalization of charges between two masses of same charged particles; each mass is either positively or negatively charged.

My understanding is that lightning can be either positively charged or negatively charged. The earth is negatively charged. Things not connected to the earth (I believe) are positively charged. What is your house? My guess is positively charged. What is your basement? My guess is negatively charged. So what kind of lightning rods are you going to put on your house? Negative ones to "draw" the lightning to the ground via the cable on your house? Or positive ones? Presumably you don't have to worry about negative lightning since your house is positively charged. What would "positive" lightning rods do? Ward off the lightning? How? The problem is that static discharge involves two masses of like-charged particles. Putting a bunch of negatively charged cables on your house won't (in my opinion) help at all with the lightning that would be seeking to discharge on your positively charged house. If you could change your whole house to a negative charge, then that's a different story, but you can't do that, I don't think--and if you did, you'd still attract the negatively charged lightning.

You pose an excellent question and I've never found a definite answer. I've posed the same questions to physics professors and they are stumped.

I put lightning rods in the same category as shark repellent: Good for warm fuzzies but that's about all.

Your cousin Beth's husband in Maysville

June 6, 2007 at 1:14 PM  
Anonymous Anonymous said...

I can understand your comments, but it is not really about "positive" and "negative". It is really about relative positive and negative. An example would be the number 5(positive) is greater than 4(negative), but 4 > 3. In the later comparison 4 would be considered positive and 3 negative.

In the case of lightning the ground is always the lowest "number" no matter what particles are in the air relative to each other. Therefore when put up a lightning rod you bring the lowest possible "negative" to your roof, so that your roof/house is not the closest relative "negative" to the charged particles in the air.

The rule is that the charged particles always will seek/flow to the nearest largest difference in charge to themselves. (Example: 5 will ALWAYS bypass a 4 for a 3.)

Mark W E.E.

July 23, 2007 at 10:32 AM  
Anonymous Anonymous said...


Thanks for your reply to my not-so-articulate thoughts. And I agree with you that the larger number will bypass the medium number for the smaller number. But the positive and negative 'angle' is necessary (I believe) when it comes to the lightning discussion. Let me start over.

Ligtning terminates/originates in the clouds and is a static discharge. Sometimes (actually most of the time) lightning goes cloud to cloud and bypasses the ground altogether--so the ground is not necessary when it comes to lightning.

Clouds contain masses of particles that are negatively charged and positively charged, therefore the lightning/static is either positively or negatively charged. Presumably we have to prevent both kinds from striking the house, right? As I understand the theory behind lightning rods, you drive a copper rod (or many of them) into the ground and attach it to metal rods on the roof via a metal wire. My understanding is that this 'draws' the lightning to the ground via the exterior wire rather than through the roof. But this only works for negative static discharge that, presumably, wouldn't be interested in a positively charged house, anyway.

The real challenge is to prevent a house (which by my reckoning is a huge mass of positively charged particles) from being struck by positive lightning. I don't think its possible to do that with lightning rods that are buried in the earth. Perhaps it would help some if there were two or three larger houses next door to the house that you seek to protect. Haven't really thought that one out, yet.

But I believe for sure that 'grounded' lightning rods do not help with positive lightning.

I'm taking from your initials that you are an electrical engineer and, therefore, that puts you higher in the pecking order in this discussion, but I do believe that the issue of positive vs negative is very important in this blog.

aww in may

August 1, 2007 at 8:11 PM  
Blogger oldmilwaukee said...

Great discussion... I still haven't added my lightning rod(s). I can't help but wonder... if they really worked, why wouldn't building codes or insurance policies require them?

August 12, 2007 at 7:58 PM  

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