Victor, While the explanation of water backing up may be true, I think it is not.
More usually when water comes through light fixtures and other ceiling areas it is because of moisture which has migrated up through the ceiling or maybe even been pumped into the attic space with a disconnected bathroom fan duct some of which are never properly vented to the outside. During prolonged cold weather this moisture condenses on the under side of your roof decking and if that is cold enough it will freeze there. Moisture continues to condense on the ice which increases in thickness. When the attic space warms up this collected moisture stored in that reservoir of ice is released and falls onto the top of the ceiling. Often there will be some form of vapor barrier but this is also often breached where holes have been cut for lighting fixtures or other electrical penetrations. Water will readily fall through and often the same ceiling penetrations provide a chimney up through which moisture laden warm air rises condensing and perhaps freezing right above the hole ready to fall back through when it melts. This is a situation for better ventilation in that attic space. You want to withdraw and evaporate that moist air before it condenses and can rain out. Don't know how you can know for sure which is what, every situation will be unique, one hint would be that water coming through due to ice dam formation should be near the edges of the building, the outside walls of rooms and maybe even in those walls. Again, in the case of ice dam formation water on the roof runs down toward the edge but because the edge is not over the warm part of the building that strip of roof will be cooler and the water freezes on the top side of the roof. This forms an increasingly thicker layer of ice along the edge of the roof which dams more water coming down. The trouble finding leaks like that from the under side of the roof deck is that the water can creep quite a distance before falling but once on the under side of the deck it will creep down hill toward the edge of the roof before getting heavy enough to fall to the ceiling below.Water won't run up hill except in a limited way by capillary action. In either case though there has probably been the presence of water in the past, maybe not quite enough to come through but quite possibly enough to promote rot in the deck and maybe even in the rafters or trusses so do include inspection and repair of those members in the cost of the roof. What ever that costs it will be a lot cheaper than premature removal of the new roofing to replace those members in a couple of years should they fail. And if you increase ventilation don't bother with those wind driven turbines. Although they do move air they only do so when there is sufficient wind to drive them. When there is sufficient wind to drive them there is also sufficient wind to circulate air through passive if inefficient vents. You want to be sure that the soffit is clear of obstruction and has plenty of air holes in it both at the eves and up the rake so that fresh air can enter at the eaves and leave near the peak of the roof. Installing a ridge vent works even better as air can enter the eve, slide up along the under side of the roof deck between the trusses or rafters and exit at the ridge or peak of the roof. You can then also add insulation over the ceiling to help keep the attic space as cool as possible while keeping the heat of the house inside the house. If you have gable ends you can add venting there or even add a powered vent maybe on a humidistat but generally a good passive vent system should be sufficient. Good luck! Weather or not ice shield is required get it down anyway. The cost is negligible. Although you can usually lay new shingles over one already present layer which saves you the cost of removing and cleaning up the original shingles it won't permit inspection of the current decking and the additional heat trapped in the hot summer will accelerate the degradation of the new shingles which means they will fail sooner and cost you to replace sooner. this might also be a good time to look at eves trough replacement and maybe even the fascia and soffet depending on their present condition. The new aluminium stuff is pretty cheap and goes up well. You might be able to arrange some cooperation with the roofers and their scaffolding to have that seamless eves trough installed at the same time. I wish I had done that, for sure I will when it is time to replace this roof. Installing the eves trough alone was a bear of a job, it is the plastic stuff and it shifts in the summer and the junctions open up usually in the most inconvenient places and I hate it. It almost makes me anxious for the shingles to need replacement. Dale Leavens, Cochrane Ontario Canada [EMAIL PROTECTED] Skype DaleLeavens Come and meet Aurora, Nakita and Nanook at our polar bear habitat. ----- Original Message ----- From: Victor Gouveia To: blindhandyman@yahoogroups.com Sent: Wednesday, November 07, 2007 10:07 PM Subject: Re: [BlindHandyMan] Laying Down a Roof Hi Dale, RJ and everyone else who posted on my query, As I said, RJ, my initial fear was the bonding of the shingles to each other, creating a kink in the link, so to speak. Lord knows we get some mighty strong prevailing winds up here, and I'm afraid that if the shingles don't bond to each other, a gust of wind will start flapping them around, and snow or water will creep up under them. Apparently, As you may have read from Dale's message, not having them seal to each other is also a good thing, as it allows for them to adjust to their new homes. As to your comment about the ice shields Dale, that is specifically why we are replacing the roof. During our last ice storm back in January, we found that it started raining from our light fixtures when the ice melted off of the roof. This prompted me to call a roofer to find out why it did that, and how I could prevent it from happening again. He essentially told me that the roof was laid without any ice shields, so the water just backed up into the rafters, and onto my ceiling. My daughter thought it was really pretty...I did not. In any case, I can't really say whether the ice shield is a code requirement or not, but considering the ice and leaks we've been getting, I would say that we needed one anyway. Thanks everyone for your comments, and I'll let you know what he says when he starts on the roof and I address my concerns with him. Victor Gouveia [Non-text portions of this message have been removed]
