Historic standing seam metal roof


#1

I recently purchased a historic home (200yo) with a historic standing seam metal roof (probably about 100yo?) and am searching for individuals who have experience (maintenance/repair/replacement) with this kind of roof, for forum questions. Thanks.


#2

What do you have, zinc or copper? At 100 years old, I’m thinking maybe you have zinc, unless you are saying the 100 year old roof needs to be replaced.


#3

I believe that I have zinc, painted green. The roof is still functional, and so I don’t believe that I need to replace it, yet (will likely be an eventual topic!). I did notice recently however, that I have condensate on the inner surface of the roof, which collects and drips onto the floor (not enough for ceiling damage). The apex beam (all original hewn structures) contains mold, so I believe a ventilation problem? will a simple louver help?, or directing heat to the attic? (probably not helpful). No tar paper present- just metal directly on wood structure. Wood is generally intact.


#4

You need some ventilation in the attic and find where the condensation is coming from. Leaky dryer vent, leaky radiator, bathroom vent, of cooking steam are the usual ‘first’ look culprits.

Tin directly over wood is ‘standard’, though the underside should have been painted if the pitch is not steep.


#5

Called the roofer who refurbished a section last summer- turns out that the roof is galvanized steel. He is also not sure why condensation is happening- roof exists over a log cabin (1807), and a foursquare 1840 add-on…neither of which have plumbing to upstairs/no dryer/kitchen. I haven’t installed any new systems…propane furnace 1845, and wood burning stove cabin. Perhaps louver plus fan plus visquene covering floor would help…not sure if I need a certain size louver (attic feels breezy as it is!).


#6

My understanding is that propane creates LOTS of moisture. We need a dehumidifier when using the heat in our camper. You might end up with one of them.


#7

Thanks. You might be right about the propane being a culprit- the steam is directed via a vent pipe outdoors, but it does make alot (plus it makes a lot of water that is drained via piping), though rest of house isn’t moldy/damp. and maybe fireplace chimney heat in cabin attic meeting cold air makes steam? haven’t quite figured out where inside moisture would be coming from, especially in cabin, to freeze on inside metal (only heat in cabin is woodburning stove). Husband thinks that soffit vents plus louver should help anyway…probably not til spring/summer though. Don’t know if fan/dehumidifier in attic would do any good in the meantime. just checking others’ opinions/experience, and for any other ideas!
Different question…for really old metal roofs like this, that are swayback (timbers intact, just swayed), I’ve been told that I can’t put new metal on without rebuilding/replacing timbers. ever hear of anyone placing a new metal roof on top of/structuring a new roof external to old? probably a rediculous idea, and too heavy for old timbers.


#8

I would consider the following…

  1. remove all exisiting roof system and recycle
  2. cover entire roof area with roofing membrane
  3. take steps necessary to straighten roof framing/
    sheathing surface out/ flat enough to receive
    new metal roof, either sister up rafters while jacking sag out of roof or shimming sleepers.
  4. option/ additional sheathing over sleepers if roof can hold weight
  5. install new roof/ metal roof on sleepers/ purlins
    is a widely accepted method of installing metal roofing by most readers in this forum, I beleive.

hope this helps

David


#9

[quote=“thebaycompany”]I would consider the following…

  1. remove all exisiting roof system and recycle
  2. cover entire roof area with roofing membrane
  3. take steps necessary to straighten roof framing/
    sheathing surface out/ flat enough to receive
    new metal roof, either sister up rafters while jacking sag out of roof or shimming sleepers.
  4. option/ additional sheathing over sleepers if roof can hold weight
  5. install new roof/ metal roof on sleepers/ purlins
    is a widely accepted method of installing metal roofing by most readers in this forum, I beleive.

hope this helps

David[/quote]

Why would you suggest she replace her roof, when she stated that it is doing fine except for the condensation?


#10

Different question…for really old metal roofs like this, that are swayback (timbers intact, just swayed), I’ve been told that I can’t put new metal on without rebuilding/replacing timbers. ever hear of anyone placing a new metal roof on top of/structuring a new roof external to old? probably a rediculous idea, and too heavy for old timbers.

You’re being sold a bill of BS.

I just tore one off about 90 years old. It was doing OK, but owner did mods to the house I couldn’t tie into the old tin.
http://www.albertsroofing.com/Tin%20Roofing%20photo_gallery.htm
As per standard practice, you’ll notice I didn’t re-deck it. I did replace the lowest plank so it would overhang the fascia by 3/4".


#11

Original posters question

Different question…for really old metal roofs like this, that are swayback (timbers intact, just swayed), I’ve been told that I can’t put new metal on without rebuilding/replacing timbers. ever hear of anyone placing a new metal roof on top of/structuring a new roof external to old? probably a rediculous idea, and too heavy for old timbers.

I wasn’t suggesting that the existing roof be replaced, especially if the problem is condensation related,
I was responding to the additional question as quoted above…that be, if the roof did need replacement…
Sorry for the confusion…I would never suggest replacement without at least seeing pictures, or visiting the site…

David


#12

Sounds like a little ventilation plus sealing the attic floor from indoor air leakage would suffice.

If you do find you need to replace the roof, I would install the same as the original. Like tinner said, strip the metal, replace any bad planks with matching, and install metal directly to wood.


#13

Thanks for good discussion! When the time comes, structural integrity of underlying planks/beams (ie tree trunks!) and joists will need to be assessed- mostly intact as far as I/we can tell, but if they are structurally sound, looks like there are folks out there who will replace metal on top of existing wood (company in town said I couldn’t do it). and, sounds like metal goes back onto wood (another question answered- wondered if tar paper needs to go under, if/when metal panels replaced). also sounds like metal should be painted both sides, depending on pitch (as currently is not). I’m trying to upload a pic of the cabin roof (externa anyway, until I can get camera battery functioning for internal view), but server won’t yet let me load. It will be under SJ: historic standing seam, if I can get it to work.
Don’t think I need replacement yet…I gather I will eventually, when pinholes develop. is rusty as is, in parts, but had 1845 section buffed and repainted, new flashing around chimney, and so far, so good. will do same to cabin next summer.


#14

Underlay will void warranty. It makes the metal sweat at times, and the water can’t evaporate if that happens. The metal will then rust through.


#15

I fixed the link up above, It’s hard to tell maybe, but my metal is painted with a light-grey primer on the bottoms of those panels. The paint should be visible near the lower edges.


#16

Thanks Tinner and will take a look at your pics. I can’t get my pic to upload- maybe a safari problem. Will try from PC and if not working, contact webmaster. sunny day here- bet I have spring showers taking place in the attics!


#17

I just checked with 3 manufacturers regarding
underlay voiding warranties, Englert, Follansbee and Petersen. All three require 30# felt and rubber membrane eave detail. Follansbee also recommends pink rosin paper on top of 30# felt as a slip sheet.
I think that wood purlin spacers over vapor barrier system allows proper ventilation to under panel, but
to directly attach pre-fabricated metal roofing panels to wood sheathing without some sort of seperator
would be an issue with warranty concerns.


#18

Pretty interesting since Follansbee literature and labels both point out underlay voids their warranty.
And it hasn’t been an issue in 150 years.


#19

I forgot to add, my info is current as of this week.


#20

I am praying that your information is
somewhat left for interpretation by the engineer
because we are involved in a small 18 sq ocean side standing seam roof with the following specs from Follansbee: The builder covered the entire roof with Ice & Water and is now installing 1x4 sleepers for ventilation over a 30#felt slip sheet. Most decisions made as to how to proceed here were based on this Follansbee documentation. Frank…could you send me a link to that warranty restriction…please.

TCS II
Specifications

Download the TCS II Specification

1.4 PRODUCT

A. ZT ALLOY® Coated Stainless Steel (TCS II):
ASTM.240, type 304 stainless steel coated both sides with a minimum alloy (50 Tin/50 Zinc) to a thickness of 20 microns and a mill applied gray pre-weathering.

B. Standing Seam Roof Panels: Standing seam system shall be designed for concealed mechanical attachment of roofing panels to substrate.

C. Cleats: Use Follansbee preformed cleats or fabricate from TCS II flat stock sheet product to Follansbee’s Specifications.

D. Slip Sheet: Use rosin sized paper as final underlayments under TCS II

E. Felt Underlayment: Minimum one layer 15 lb./100 sq. ft. asphalt saturated felt paper.

F. Fasteners: Minimum 7/8" Series 300 stainless steel ring shank nail or equal screw type fastener.

G. Solder: Remove pre-weather wash coat around edges to be soldered with lacquer thinner. To facilitate soldering, it is recommended that the edges of sheets to be joined be pre-tinned. Use pure tin solder with rosin of Follansbee speed flux. Flux residues must be neutralized with soda water and removed. Use soldering irons only. Do not use abrasives in preparing the surface for solder.