I am assuming you don’t plan to replace the roof of your home as a DIY project. Although replacing a roof could be described as a straightforward project, if you do make a mistake, it might go unnoticed until several months have passed, and a small leak has done considerable damage. Unless you are specifically experienced in replacing a roof, you should really opt for getting the roof replaced by a licensed, bonded, insured and experienced roofer.
What happens when a roof is “replaced” on your house?
Taking the old roofing materials away
Replacing a roof – most roofs, anyway – is in two main stages. The first stage is removing all the old surface materials (shakes, sheeting, or whatever is the part you can “see” and is exposed to daylight) the old waterproofing layers underneath that, and any rotten wood that needs to be removed. In most cases, especially if the home owner has been diligent in the upkeep of their home, none of the infrastructure needs to be removed. Where homeowners wait until there is a crisis, like water flooding through the roof into their kitchen, there is often a lot more damage to be taken care of. If rafters have been exposed to moisture over a long period of time, they may have to be replaced before the next stage is to occur.
Most roofing companies will want to know exactly what they are up against before they even submit a bid for possible work. If there is damage to anything more than the “consumable” part of the roof (shakes, tiles, sheeting, etc.), they will want to hire out a general contractor to do that part of the project. That repair work must be done right after the first stage, but must be done quickly, as the innards of the home are now exposed.
Let’s look at a situation where there is real damage to the supporting infrastructure of a roof. Perhaps a small leak occurred during a storm, where a shake was bent up and ripped a slight tear in the hitherto waterproof layer underneath it. The tear wasn’t enough either to be visible from the ground, nor big enough to cause a substantial amount of water – enough to be obvious from inside the home during the next rain storm. A year or two go by, and a small amount of water finds its way from outside the house to the plywood layer under the waterproofing, and later, to the rafters holding the roof up. Now, the plywood is repeatedly soaked, then dried out, then soaked, then dried out. This eventually destroys the affected plywood, and now lets water travel further, reaching the supporting rafters. Still, there is no sign of it from any room in the house, so life goes on while the house is slowly damaged by this moisture. It’s small enough not to be noticed, but substantial enough to do damage over time. The roofer comes in to do an inspection, and the damage is easily recognized by the smell of mold and the inspection of the rafters. From there, it’s important to know the complete extent of the damage, so that repairs are understood in advance of any work being done.
A general contractor crew can be scheduled to do the repair work at the right time, as long as you know exactly what’s to be done. That’s why a thorough roof inspection is essential before any work is done.
After all of the old material is removed from the top of your house, it is usually dispatched to some disposal station in a container of some sort. In any case, it’s good to have all of the old out of the way, so that installation of the new is unhindered by anything in the driveway or area around the house.
Installing the new roof
If any structural repair work was needed, that of course will have to be done before the new roofing materials are fastened into place. Having said that, if structural damage is, say, confined to one remote corner of the house, that could, in theory be repaired as the roof on the other end of the house is being nailed into place. It takes a bit of project management, but it can be done.
Most roof replacements do not involve the replacement of the plywood under the waterproof layers. If they were damaged, then for sure they need to be replaced, but most projects do not need plywood replacement. On top of that, the waterproofing layers are carefully secured, so that their overlapping provides a 1005 waterproofing layer before the outermost layer is added.
There are nails and there are roof nails. It takes a specially designed nail to go through a waterproof layer of PVC and maintain a perfect seal. Use the wrong nail, and you risk producing a thousand opportunities for the water to enter your home later.
Once the final layer is secured in place, the only thing left is to apply a treatment, assuming the roofing materials are of a certain kind. If you are using natural wood shakes, then you definitely want to apply a sealant – usually in the form of an oil of some kind, but there are many products on the market that will work well – but most of the new synthetic materials do not need any treatment of any kind. They are often made from oil – the stuff they pump out of the ground – so they are very water resistant indeed.
More next week!