Here we are in May and the rains are just around the corner. It’s time to get out the ladder and go up on your roof and give it a visual check. Over the winter we have had an earthquake. Even though it was a small one it did do some shaking and without doubt it opened up a crack or two on some roofs.
It doesn’t take much movement to cause a roof to leak. Most roof problems begin on the ground. If there is any movement under the foundation then that movement will be amplified by the distance to the roof. For instance, if the foundation moves a fraction of an inch by settling that fraction of an inch will become a leak as it moves up the wall and onto the roof. If a column moves outward due to settling by the smallest amount, it will open a drip on the roof.
Generally the reason the column moves is that during construction the dalas were not tied into the columns sufficiently well to prevent it from doing so. In older houses this problem is more common than in newer houses due to deterioration of concrete and construction practices of times past.
If you discover that your roof is leaking you need to be aware of these facts. I have seen many people try to fix a roof leak by filling up the crack with some type of gunk. There are any number of brand name roof gunks available. They range from silicon to tar to stylized petroleum products. They are all wonderful. The problem is that filling the crack on a post and beam constructed roof with gunk is like taking aspirin for a brain tumor. It may make the pain go away for the time being but it is not addressing the problem.
Let’s say that a given house has settled due to being built on fill. Over the years the fill settles as does the foundation and the zapatas under the columns as does the column itself. This settling puts strain on the steel inside the columns and dalas. As the stress to the steel increases let’s say that at one corner the steel begins to pull out of the concrete that surrounds it. This movement will affect the roof that is setting on top of that steel structure and water begins to find its way into the inside of the house.
If the fill continues to settle so will the foundation, the zapata, and the column and the steel will continue to pull out of the concrete. The homeowner will try to put one of the many roof gunks on the roof to staunch the flow of water into his house. This is all quite logical but the problem really isn’t on the roof. The leak is only the symptom. It would be better to shore up the sinking zapata/foundation before even attempting to fix the leak. The reason is that the crack on the roof will continue to grow and require more gunk. Each time there is more movement, the new gunk will have less ability to seal the growing crack.
If you can determine that the settling has come to an end, then you can treat the roof with a product that gives a wall-to-wall seal. I have suggested Fester brand products in this space before. I still think that this brand is the best on the market. There are three levels of density in this product. One is black, one is red, and one is white. The white is the densest and therefore the most expensive. All should be used with a cloth felt between two applications of product. The felt gives the product a certain flexibility. Even so, if the reason for the crack isn’t addressed then even a good product like Fester is no more than a band aid. It will not hold the steel securely into the concrete.
The only way I know of to address the problem of the steel separating from the concrete is to chip out the concrete around the steel and weld the steel together. This process has some inherent problems because the concrete can never be as sound as it was to begin with but welding the steel together will stop the separation.
