Part three.
Protecting It From The Rain: The Porch Roof
In part three of the porch renovation, we will look at possibly the most important part of the protection of the porch; the porch roof.
The Options:
When we looked at doing this work, we had the option of doing it ourselves or hiring a contractor to do the work. After looking at the logistics of stripping off the old roof, making what we assumed were extensive repairs, making the section waterproof, and then doing the roofing on a large curved section, we realized this was more than we could do by ourselves. The three most challenging parts of the reroofing were the flat section by the door, the two curved sections, and rebuilding the built-in gutter. We decided to hire a contractor to do the work.
The pitched roof section had a gable, and more problematic, curves on both ends of the porch. We had seen several ways of handling these round sections and we knew we did not want some of them. We showed pictures of what we did not want to the contractors as they came to bid on the project. We also requested references from the contractors of homes/businesses that had rounded roofs that had been worked on by them. We then followed up on their references by calling and going to see the samples of their work.
Our roofing material was a matter of taste. Originally, the roofs all had cedar shakes. We did not want that as it would drive up our homeowners fire insurance (primarily, because it is an old house with a wooden roof; we were told newer homes with cedar shingles are not as high an insurance cost as old homes). So we opted for a shingle by Certainteed called Grand Manor which is a slate look alike shingle with a lifetime warrantee. The warrantee is for shingle cost replacement of 100% for 10 years, then a gradual decrease in replacement value over the next 30 years until it gets to 20%, then it remains at 20% during the rest of the lifetime of the roof. Since we were planning on living in the house forever, and the cost of the shingles (about $10,000) was only 25% of the total cost of the roof repair, we went with the more expensive shingle. It should be noted that this price was for the whole house in addition to the porch roof. (Approximately 50 squares)
For the valley flashing, there are many choices. The most common material today is aluminum. It is easy to work with, and comes in many colors. For us, the problem was that aluminum had only a 25 year life, and we had shingles that had a 40+ year life. We did not want the valley flashing to fail before the shingles. The traditional flashing in long lasting roofs is 16 oz copper. That is the material we decided to use. (See side bar info at end of article about valley flashing material.)
With roof shingles, if you have only one layer of shingles and they are in reasonable shape, the new shingles can be placed over the old shingles without removing the old shingles. In our case, we could see from inside the attic that the original wood shingles were present on the roof, along with at least one layer of asphalt shingles. We also had several areas of the porch roof that we were concerned had some rot or damage, so we decided to strip the shingles down to the decking. When we did strip off the roof shingles, we found there was some extensive damage to the structure. We also found an interesting situation. The top layer of shingles had been roofed over by putting 2x4 sleepers on the old roof, and new decking over the short roof. The box gutters were just covered over by roofing right over the top; an interesting finding that had covered up a lot of damage to the main porch roof structure.
Most of our preparation for this phase of the project was deciding on materials for the roof. The type of shingles and how the gutters would be repaired were the main items to research. I have already discussed the shingle decisions, now let me discuss the options for the box gutters. Box gutters are gutters that are built into the roof detail. The rafter tails are extended and the gutter is formed in the end of that section. The main part of the box lining is constructed with a skeleton of exterior grade plywood. The board joints are not made water tight. The reason is so that if there is a leak in the waterproof liner, the water leaks through and drips through the soffit, so it is noticed right away. If the wooden part is sealed, the water stays put in that part of the gutter and starts the rotting process. The leak may then not be noticed until a significant section of the wood is rotted, thus creating a much larger problem. In our situation, there was more than enough of the old material to copy rafter tails and support for the gutter. This made it much easier to re-fabricate the rotted sections.
The materials available to line the box gutters are numerous, and new methods, techniques, and materials make this decision an interesting process. The traditional material is copper or tin, with soldered joints. The problem is that the technique used to make water proof solder joints, is a learned technique and takes time to perfect. Our contractor felt comfortable using the soldering, and that is what he used. The other factor entering in is the round sections of the roof which required numerous joints and had a high potential for leaking. Our contractor also used a product with an aluminum UV shield and butyl rubber liner that adheres to metal well as an additional liner on top of the copper. The product is MFM Peel & Seal. (MFM Building Product Corp., 525 Orange St, PO Box 340, Coshooton, OH 43812, 614-622-2645)
We then put 30 lb. tar paper on the top of the decking for a temporary water barrier while we finished the gutter. When repairing a box gutter, it is easiest, if possible, to wait to place the shingles until after the box gutter is lined. It is then easier to place the shingles over the gutter liner. Otherwise you would have to lift the shingles up to get the gutter lining under them. Ideally, the box gutter liner should run a minimum of 12 inches on the roof side of the gutter. Some of the length is dependent on the pitch of the roof. The more pitch there is, the less of the gutter lining is needed. Our pitch of the porch roof is 3/12, so we had an 18" pan liner for the gutter.
We also put the ice dam liner on the entire roof. The total extra cost for the ice dam protector was only $200 compared with the entire porch roof redo which was $3500 not counting the shingles.
The roofer we used had a specialty of using rubber roofing for the flat sections of roofs. The rubber roof was the last section of the roof that was put in place (as it was uphill from the shingles).
The maintenance of the porch roof is like any other roof. The important part is to make sure the gutters and down spouts are empty of leaves and twigs. As you have seen in the pictures, we have two large 50+ year old maple trees overhanging the porch roof, so keeping them cleaned out is an ongoing job. I don't have any magic screen (the ones I used clogged up for me) or magic hat for the gutter to wear. I just make sure leaves, twigs and maple seeds are cleaned out regularly (during fall, about once every two weeks or after every hard rain). Fortunately, it is made easier because we do not have to get a ladder out every time. Remember the door from the master bedroom that opens onto the flat roof balcony section? I use that, and a broom to keep the gutter clean of excessive leaves and small twigs that would clog the down spouts. On the occasion that I let the leaves accumulate to the point of clogging up the down spouts, I am reminded by the cascading water over the front of the gutter.
I hope this glimpse of our porch renovation gives you inspiration to tackle your own porch renovation. Feel free to ask questions by going to the question section, or by subscribing to the Old House-L listserv.
When we started our porch renovation, we knew our porch roof was in need of repair. The asphalt
shingles were almost all worn down and there were even soft spots that were evident when walking
on the porch. We also had a gutter that was in poor shape attached to the outside of the roof
(soffit and fascia). This was an add on, and we suspected that the original box gutters were
still there and might be able to be resurrected. We also noticed during numerous rainstorms prior
to repairing the roof that the current gutters did not hold the rain in the gutters but allowed
the water to cascade over the edge.
Flat roofs do have unique problems, and the section of our porch roof that is flat is no exception. Our section is also a balcony that is open from the master bedroom. So not only is it flat, but it doubles as a walked on space. Our contractor recommended a rubber membrane roof using the thickest material.
The other common options for box gutters are Butyl rubber liner and Acrymax elastomeric liner. If I had been doing the work myself, I would have done the Acrymax elastomeric liner. It is a little easier for the do it yourselfer. Acrymax is a paint on latex compound. You can also embed a fiberglass mesh into the product to give it more support. The other nice thing is that it patches very easily. (AcryMax, Preservation Products, 221 Booke St, Media, PA 19063, 800-553-0523, 610-566-7470, fax 610-891-0834)
After the rotted material was removed from the porch roof structure, it was replaced with new structural 2x4 material and OSB (Oriented Strand Board) as decking.
One side benefit of having to redo the porch decking material is that the attic was exposed. This allowed us to very easily run extra 12 gauge wire to extra places for future lights. We also took pictures of the inside of the porch roof. Why you ask? I am not sure, but while we had the chance we took them for future reference.
The shingles we used were the Certainteed Grand manor shingle that mimics the slate roof. These shingles are multilayered and do not cut or curve easily. The most difficult of the reroofing part was the round section of the roof. We had the roofers cut the shingles into 3 pieces and treat the shingles as individual slate sections overlapping each individual shingle. The result is a rounded section of roof that has a pleasing effect on the eye and sheds water wonderfully.
Valley Material
Type
Advantages
Disadvantages
Shingles
cheap and readily available
they wear out faster than other materials
Tar Paper
cheap
very thin relative to the rest of the roof
Aluminum
different colors, readily available, not overly expensive
does have limited life
Galvanized Steel
long lasting
needs periodic painting to prevent rust and to prolong life
Copper
very long life
most expensive option
Any metal valley must be fastened with nails or screws of the same metal. Steel nails on aluminum or copper flashing causes a galvanic reaction to occur that causes rust to progress much more quickly than if the same metal was used.