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John
Posted on Tuesday, November 25, 2003 - 12:52 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I currently am planning on reroofing my house with slate (North Country Black) and am greatly intrigued with the Boston hip. (My house has alot of dormers with hips and valleys.) Although my reading has shed some light on the topic, I would like to have some input from all the professionals out there.

Here are some of my questions:

What would be the normal width of the hip slate given a 20x10 or a 16x10 field slate size? Are these hips slates usually provided as a special size or are they a field slate cut down to size?

Is the joint between the hip slates (along the hip line) usually lapped or mitered? Would this joint be saw cut to provide a "crisp" edge or cut with a slate cutter?

Elastic cement is usually called for under the hip slate as well as for pointing the joint. What type of cement or brand of product would be recommended?

What is the usual ridge treatment for a roof with Boston Hips?

How labor intensive or costly is this hip treatment as compared to utilizing a hip or ridge metal covering? Which treatment performs better?

Does anybody have any good pictures of a Boston hip roof? What do you think of the Boston hip?

Thanks in advance for your input.

Regards,

John
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admin
Posted on Tuesday, November 25, 2003 - 11:48 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Traditionally, slate hips are made from the same size slate as the field slates. Today, however, narrower slates are often specified for hips and ridges. I suppose it's an architectural preference.

The joints are usually mitered (edges butted). There is no need to cut the edges square. You can install flashing under the mitered joints if you want (traditionally this was uncommon, but not unheard of and it's probably a good idea in the long run, although not necessary).

Cement should not be used under hips. It creates huge headaches if the roof needs repaired later. Yes, I know that the old book, Slate Roofs, recommends roof cement under hips, and therefore the NRCA manual shows this specification, but it's a mistake. There is nothing more annoying to a slate roof restoration professional than slates that have been glued to the roof. If a hip slate breaks (falling tree branch, for example) and you want to replace it, you will have a heck of a time getting the roof to come apart if it is cemented together. Nails are sufficient and 99.9% of traditionally installed slate roofs have no elastic cement under the ridges or hips (thankfully, most old-time slaters never read those books, or, if they did, they also knew they were bogus).

Slate hips and ridges take more time and cost more money than copper ridge roll, but they also last longer and have a different look that may be preferable.

Joe Jenkins
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slateworks
Posted on Tuesday, November 25, 2003 - 09:39 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Installing slate caps on hips-We usually nail a piece of lath or 1" X 3" or 4"board(depends on thickness of slate and width of cap slate) up both sides of the hip,close to the hip center,cut your field slate to the edge of this nailer,this nailer also keeps you from nailing thru the field slate,Also in determining width of nailer your hip slate should lap onto your feild slate by 2" or 3",Install a piece of 30# felt-2" shorter than your Hip slates an 16" x 8" slate would work well on your roof..-felt 14" wide(the felt is not necessary but we use this to waterproof the roof while under installation and we also chalk a line up the hips for a refernce guide to keep caps straight-When you but the two caps together they should find center themselves,but have found this line does help keep them straight-we punch 3 or 4 holes so they line up with width of nailer,helps to keep caps from sliding downhill(have repaired many loose hip slates with just 2 nails in them)butt together your 2 caps,install your back nails first(at top of slate)then sort of over tighten your butt joint at bottom edge of slate and nail your lowest set of nails( just above your headlap)this really help to keep hip joints tight.You can install a metal flashing with each row-leave it dry -or use roof cement or caulking just on the area where the 2 caps meet and are going to be covered by the next 2 caps-this way no sealant is exposed and it is such a small amount that if future repairs are needed it's not a big deal.We have found at times when you install your first set of caps you may need to install a shorter starter course first to kick up front of first set,they seem to lay a little nicer.Just some input from our Boston hip experiences.It is a great look.It is more labor intensive-Metal is much faster-Good luck.
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John
Posted on Tuesday, November 25, 2003 - 10:07 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Thanks for your input. This is great advise.

How about the cuts on the hip slates? It seems to me that you need hip slates that are a five sided polygon (see page 207 in the Slate Roof Bible) with the hip edge not parallel to the line established on the field slates. I also don't understand how one would "miter" the joint between the hip slates on adjacent roof slopes. Is this angle saw cut or can a slate cutter and chipper hammer do the job?
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Walter Musson
Posted on Wednesday, November 26, 2003 - 05:15 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

John,
It sounds like you are using two approaches here.
If you truly want to miter two slates to meet very tightly at the apex of a hip or ridge,then yes a wet saw with diamond blade is the proper tool to use.If you wanted a mitered hip with no caps then a sawn miter looks superb.You say you want to use a saddle hip procedure,or Boston hip.
Where I work in Maine we always do a saddle hip much like Ron points out with great care in nailing them on ,to assure that gravity doesn't tend to make them slowly fall out of the alignment that they were installed as.His nailer set up is just how I do it.
I think the sawn hip slate looks better,but if you are using a hand slate cutter then cut the hips where they join from the front side so that a cleaner line is left as a reveal.
A true Boston hip or ridge has one cap overlap it's abutter on one course and then is overlapped on the next,a system meant more for cedar shingles than slates.
I always step flash under each pair of hip caps with 16 oz. copper or other metal as required,during the installation process.
Because wind ,gravity,and other forces wreck havoc on these smaller more exposed slates I also put a small spot of cement the size of a quarter under the exposed portion of each hip cap .It helps hold them,but will not impede future repair work if needed.
The saw I bought from Braxton-Bragg in Tenn. cost me $2800 8 years ago,so if it's just one job I suggest you order one of Joe's cutters from this site.
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Walter Musson
Posted on Wednesday, November 26, 2003 - 05:22 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

John,I just went back to read your first posting.If using 10" wide field slates then cut each hip slate 5" minus the saw kerf or cutter width.You might ask the quarry to cut them for you since it sounds like new slate.
If you cut them yoursef take care in punching your holes,since the slates need extra holes in narrower slates.I use an old drill press with a masnry drill bit so there is less frustration from breakage.
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John
Posted on Wednesday, November 26, 2003 - 09:53 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Thank you Walter for your insight.

Just a point of clarification. Isn't there a difference between a Boston Hip and a Saddle Hip? From page 207 of the Slate Roof Bible, the hip slate for the Boston Hip appears to be trimmed at its top edge to be in the same plane of the field slates of the row above the hip slate while a saddle hip sits on top of all the field slates and is sort of "stacked" up as one works up the hip line. Please correct me if I am wrong.

Regarding the wet saw, I have a tile contractor buddy who has a large wet saw for cutting tile who would let me use it for this project. Would this be suitable for mitering the joints between the hips? Would you still recommend the alternate lapping procedure at the hip joint (even with a straight saw cut)?

If you drill the nail holes for the hip slates, how do you drill or grind the bevel to allow the nail to be countersunk?

Questions, questions, questions!!!

I appreciate all of your input. Thanks in advance.

Regards,

John
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Walter Musson
Posted on Wednesday, November 26, 2003 - 11:38 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

John,
I like them to join smoothly with a mitered joint.I confused the issue with the colloquial term we use for Boston hips.The nails in the hip slates aren't as crucial to be contersunk as those in field slates even though you should try.They dont have the same weight of slate,snow and ice etc. weighing down on them to wear thru the upper slate.These nails want to be nailed tighter than field slate nails to help hold them in place. They are alone on the hip with no neighboring slate to keep them properly aligned.
Yes a good tile wet saw will make an excellent cut,but will it cut the proper bevel cut?
Yes these types of hip and ridge treatments are a lot more labor intensive but look really good when completed.
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slateworks
Posted on Wednesday, November 26, 2003 - 05:54 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Yes There is a difference,I was describing what we do for saddle hips where the slate rides sort of stacked above the field slate,We also will put a dab of sealant under the exposed portion of hip cap. Yes you are right The boston hip is cut at the same plane to align with row above hip slate.I agree with Walter that these nails do not need countersunk for the reasons he stated,What we did once we installed a few caps we would use a right and left pattern with pre-drilled or punched holes and make a jig to hold 3-4 slate,lay the pattern slate on top and drill these 3 or 4 caps all at on time,Also while installing we have a good cordless drill with a 3/16" masonary bit in case you need a few extra holes.Use copper nails the heads are thinner than other types.The last saddle ridge we installed the owner wanted it straight but rough looking so we installed the slate with out cutting a mitered edge,It really looked good with the exposed rough edges.Good luck.
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slateworks
Posted on Wednesday, November 26, 2003 - 11:12 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

When installing your feild slate you can chalk a line up your hip where the inside of your nailer will be(if a nailer is used),Do not install nailer,Run your field slate first using the chalk line as a guide to cut your field slate,you can use slate cutter or run your slate long over the guide line, nail in place and take a 4" grinder with a diamond wheel and cut the slate to the guide line(you can run several rows at one time, then take a straight edge mark the slate and cut all at once),saves alot of time,then install nailer after all slate are in place.Enjoy the Holiday.
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John
Posted on Thursday, November 27, 2003 - 10:11 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Thank you Slateworks, Walter and Joe,

This is a really great idea about the nailer strip and the diamond grinder to cut the straight line up the hip for the nailer.

What about the field slate that butts up against the hip slate (see Figure 22 in the National Slate Association's, Standard Details Slate Hips)? It seems that the width of the "b" slate shown in the figure also is a custom cut to meet the intersection of the edge of the hip slates and bottom edge of field slates.

Any ideas here?

Regards,

John
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Walter Musson
Posted on Thursday, November 27, 2003 - 11:53 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

John,
Just be careful not to cut the underlayment along the nailer line when using the grinder.This area is exposed to wind driven rain and the hip slate only overlaps the nailer by about an inch usually.I prefer to cut,fit and nail each slate individually,after the nailer is in place.I know I've got a nice tight fit this way with no chance of penetration by wind driven rain.Since slating isn't a fast production endeavor,I prefer the tried and true ,fitting and nailing each piece as I go.Maybe I'm just old fashioned.
Ron's idea of keeping the cordless drill handy is one I also use.Punching a narrow slate can result in frustration.
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slateworks
Posted on Saturday, November 29, 2003 - 06:14 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Yes you have to watch you do not cut the underlayment,1 pc. at a time is better,the roof we would cut more than 1 at a time were 1/2" + thick slate(new slate),you actually cut one slate at a time,we did not cut all the way thru the top couple of inches where the slate(this area would break off easily) was touching the roof the rest of the slate is either not touching the underlayment or is laying on top of the slate below and once you cut a few hundred you get a pretty good feel to not cut the underlayment.Although it seemed faster to cut 4 or 5 at once,I do not think we saved all that much time by the end of job we were marking and cutting 1 row at a time.Most salvaged slate we use a slate cutter,some of the new slate is so hard to cut that a grinder really helps on hidden cuts. Ron

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